Appendix 2-C Software User Manuals Chanter Two

Searching for a specific information.

To search fro a specific information, first you will have to choose the location of the search from the
Search Menu:
This Chapter searches for the information in a chapter or a portin of the chapter.
Entire Book searches for the information in the whole book.
When you sre searching for the information in a chaptey, a Find dialog box will appear. (See Figure 4.} Here
are the steps to search for a specific phrase or term in a chapter.

1. Enter the terms or phrase to search in the Find box, choose the search direction, and then press OK.
Boolean conditions can be assigned to the search string. For example, the search string "(cats and dogs)
or “wild horses"" will execute a search for the documents that contain the terms “cats” and "dogs" or
the phrase “wild horses”.

2. The Hypermedia Viewer will display and highlight the first occurance of the search term.

3. Use either the Find Next icon or the Find Next menu item to find the next instances.

4. Use cither the Find Previous icon or the Find Prev menu item to find the previous instances.

5.) Here are the steps to search for a specific phrase or term in a book.

1, Enter the terms or phrase to search in the Enter Search: box. Boolean conditions can be assigned to
the search suing. For example, the search string "(cats and dogs) or “wild horses"” will execute a
search for documents that contain the terms “cats” and “dogs” or the phrase “wild horses".

Check the Same Paragraph button when you want to locate the paragraphs that contains all the
search terms or phrases.

Press the Enter kcy or the Do Search bution.

The Topic Found box will display all topics where search conditions were satisfied.

Press the topic twice to view the document.

tv

bal albed

Copying information to the PTRS form.

You can copy any information from the Viewer jnio the comment box in Section IV of the PTRS form. Here
are the steps to copy the information:

Open the desired document.

Select the portion you wish to copy by dragging your pen (or mouse) across the document.

Select Copy from the Edit menu.

Switch to the PENS PTRS form.

Press the TRANSCRISE button.

Press Shift-Insert keys simultaneously.

PAB we

Exiting the On-line Documentation.
Choose Exit from the File menu.

50

ADA294756


Chapter Seven

Correlates of Individual Differences in NDI Performance

CHAPTER SEVEN
CORRELATES OF INDIVIDUAL DIFFERENCES IN
NONDESTRUCTIVE INSPECTION PERFORMANCE

Richard 1. Thackray, Ph.D.
Galaxy Scientific Corporation

7.0 INTRODUCTION

Aviation maintenance requires a high level of
quality assurance, with reliable nondestructive in-
spection (NDY) a critical component in this (FAA/
AAM & GSC, 1993). The Air Force and the nu-
clear power industry conducted a recent review of
studies and programs in the area of NDI reliabil-
ity. The review revealed a repeated finding: large
individual differences existed among inspectors in
their NDI proficiency (FAA/AAM & GSC,
1993). The few studics the review cited that at-
tempted to determine possible reasons for differ-
ences in NDI proficiency were generally
unsuccessful.

The Sandia Corporation has recently cum-
pleted an FAA-funded field study, somewhat
comparable to the Air Force’s "Have Cracks. Will
Travel” study, to provide information on the mag-
nitude of differences among NDI inspectors in
commercial aviation (Spencer et al., 1992). Al-
though the results of this study have not been
published, preliminary data suggest that sizable
individual differences in the commercial
field as well (Schurman, 1994).

As noted in the above review report, labora-
tory and field studies of individual differences in
the areas of inspection and vigilance. opinions of
experts in the NDI field, and interviews NDI
inspectors and training supervisors have sug-
gested a number of variables, measures of which
would appear to be potentially relevant to NDI
selection and/or proficienc . A number of these
variables (e.g., concentraticn/attention, patience.
temperament. motivation, mechanical aptitude}
also corresponded to those suggested by South-
west Research Instinne in their recommendations
to the Air Force of sclection measures to improve
technician proficiency (Schroeder, Dunavant, and
Godwin, 1988). The variables suggested dy these

the

vari can atad int
be CPALalS MS GE

VaTiOUs SGUICES Can Of TOU.
following categories:

* Boredom Susceptibility

© = Concentration/Anentiveness/Distracti-

bility

Exroversion/Impulsivity
Motivation/Perseverance
ision Making/Judgement
Mechanical/Electronics Apittude
Need for Autonomy.

eee we

AA principal intent of the stady reported here
was to determine the relationship between se-
lected tests and measures derived from the above
categories and performance on an NDI task. A
second intent wus to investigate whether sus-
tained performance during a simulated one-day
shift resulted in any significant decline in pes-
formance and to examine possible interaction ef-
fects between performance changes and the
above-mentioned individual differences variables.

This study empluyed a computer-simulated
NDI eddy-current task developed by Drury and
colleagues at the State University of New
York (SUNY) at Buffalo. The task is described in
studies by Drury, Prabhu. Gramopadhye, and
Latorella, (1991) and Latorella, Gramopadhye.
Prabhu, Drury. Smith, and Shanahan. (1992). In
essence, the task utilized a SUN SPARC work-
station and incorporated a standard keyboard and
optical three-button mouse as input devices. As
Latorelt. et al. (1962) emphasized, the aim in de-
veloping this task was neither to develop a simu-
tator for training on actual NDI tasks nor to
develop a task to measure absolute values of the
probahility of detecting particular types and sizes
of faults. Their aim was to devise a task closely
approximating the characteristics and require-
ments of eddy-current inspection tasks to enable

ADA294756


Agpendix 2-A Evaluation Forms Chapter Two

Evaluation Form Instructions

Please use the Computer A, Computer B, Compater C, and Computer D forms to evaluate the
individual computers at the end of each week. (One form per week. i

At the end of the evaluation period. use the form labelled Evaiuation of Pen Computer Products to
evaluate all four computers at once. At that time, please use the PENS Software Evaluation form to tell us

what you think of the project.

Chuck Layton will rem between mid-January and early February to debrief you and answer individual
questions.

Evaluation Form Instructions i/i

ADA294756


Chapter Nine

Reliability in Airctaft Inspection: UK and USA

Perspectives

Hangar-Fioor Operations: Detailed obser-
vations of the practice of inspection, and its or-
ganisational constraints, were made by following
an inspector for all or part of a shift. As the in-
specior progressed through a job, questions were
asked conceming the inspection itseif and ancil-
lary operations, such as spares availability from
stores, or time availability for training. Thus a
reasonably complete task description and analysis
could be written on the inspection task itself,
while obtaining information on the wider context
of the inspector’s job. This technique also al-
lowed the collection of anecdotal recollections of
previous jobs, and other events from the past.
While these had an obviously lower evidence
value than direct observation of task performance,
they did provide a valuable adjunct to the data
collection process.

Sites visited included major air carriers. re-
gional or second-level airlines, repair stations and
NDT companies. In addition visits were made to
FAA and CAA personnel and to a Royal Air
Force base where maintenance and inspection
procedures are written.

9.4 RESULTS AND DISCUSSION

In this section points of difference berween
the two systems will be described for a number of
areas judged by the authors to represent poten-
tially transferable ideas. No attempt is made to
compare the legal framework in the two coun-
tries, as this information is rather well known to
the two regulatory bodies, and to most airline
managements, often from direct international ex-
perience. Rather, the experiences and evaluations
of the participants will be stressed to determine
how the systems worked in practice.

When an area is presented, the points of
similarity are discussed first, including any obser-
vations on the relative variability between and
within countries. Next, the different features of
each country’s practice are presented. These sec-
tions establish the factual basis for evaluation and
discussion of the importance of differences, needs
for improvement in both countries, and any trans-
ferable features which could improve airworthi-

149

ness. Conclusions from all of the areas are
brought together in the final section.

9.4.1 Maintenance/Inspection
Responsibilities

Both countries: Maintenance and inspection
tasks are separated in a similar manner in both US
and UK, both within the maintenance schedule
and on the task cards at hangar floor level. Task
cards are individually assigned to either mainte-
nance technicians or licensed inspectors. Defects
arising from the inspection, also termed non-
routine repair (NRR), squawks or snags, are the
subject of further cards which are raised by the
inspector and, after rectification, signed off, or
stamped off, by an inspector.

UK variations: The management structure of
maintenance and inspection is usually closely in-
termeshed. In the past it was sometimes the case
that the engineering manager and the quality con-
trol chief were the same person and, although this
is not the case in large transport aircraft it can still
be the case in smaller commuter airlines. Work
arising from an inspection can be allocated to
maintenance technicians by the inspector who is
often also a supervisor, or by a senior person who
has responsibility for both inspection and mainte-
nance. The inspector is frequently consulted dur-
ing the defect rectification, in some cases is the
actual supervisor of that work, and will usually be
the person to accept the repair.

US variations: The management siructure of
maintenance and inspection is separated up to a
Jevel well beyond the hangar floor. A wide varia-
tion of management authority was found whereby
either of maintenance and inspection, or even
planning, could dominate (Taylor, 1990).

In a few companies visited there was provi-
sion for some coordination between the two, by
an engineer whose job was to ensure some cross
talk. This person could also serve the function of
shift change co-ordinator.

Work arising from an inspection is often allc-
cated by a maintenance supervisor so that the in-
spector who raised the defect has no

ADA294756


Results of the ECS Tutor Experiment at Clayton Staie Coilege

were important in determining the average per-
formance of the groups. An experiment with a
larger sample size may find a significant differ-
ence in performance between the two groups.

Also, it may be that the troubleshooting task
was not difficult enough for the intelligent help
component to play a part in determining perform-
ance. The traces of tutor usage indicated that only
four of the 150 problems (fifteen subjects with ten
problems each) were not completed correctly. Of
these four problems, there were 1wo uncompleted
problems in each group. No subject fad more
than one incomplete problem. These results may
have been due to the large amount of help avail-
able to the subjects during troubleshooting. For an
ITS to be effective, the problems have ta be suf-
ficiently hard for the users to make mistakes.

8.5.2 Ensuring Adequate Background
Knowledge

The previous point highlights the importance
of adequate background knowledge for trouble-
shooting performance. The students were given a
thorough introduction to ECS configuration,
function, and behavior and did not have to “hunt”
for this information while using the tutor. If the
students had not been given such an in-depth in-
troduction, it is likely that error-driven help would
have been activated more often and weuld have
improved the performance of the subjects in the
“with THA" group.

Although most subjects did not use the intel-
ligent help component, the three subjects who
made enough mistakes to activate the IHA im-
proved their performance as they gained experi-
ence in solving problems. There was a wide range
in problem-solving times for the first few prob-
Jems. but a much smaller range for the last few
problems. Some of this variability is probably due
to differences in computer experience. but other
data indicate that at least some performance im-
provement was due to troubleshooting skills. For
example. the number of unnecessary component
replacements (the most expensive action in terms
of time and money} was fairty constant as the
students solved problems. even though the last
few problems were more difficult than the first

few. Subjects did not make increasingly more
mistakes as the problems became harder; this re-
sult would indicate that they were improving their
troubleshooting performance.

8.5.3 Usability of the ECS Tutor

Results of the post-experiment poll indicate
that subjects had few problems using the ECS
Tutor. No problems previously pointed out were
raised during this experiment because feedback
from previous usability studies led to improve-
ments in the tutor’s interface. For example. in the
first Clayton Siate usability study, several subjects
were confused by the "radio button" control on
one of the screens used to select between the mu-
tor’s two modes of operation. Radio buttons are
commonly used in software with graphical user
interface. However, subjects who have not used
such computers frequently do not understand
what the radio buttons do until they have been
explained. Rather than have the instructor explain
radio buttons, it was easier to replace them with
graphical toggle switches that the target audience
easily recognizes and understands.

A user of a CBT program should be concen-
trating on the task, not on the actions required to
operate the interface. It is important that the inter-
face be as “transparent” as possible. When a user
has to struggle to lear how to use a CBT pro-
gram, it is unlikely that he or she will be able to
solve the target problem or, more importantly, te
remember what he or she did during the training
session. Because we integrated the results of us-
ability studies and user feedback, we minimized
the problems subjects had in using the ECS Tutor.

8.5.4 Graphical Resol

tn designing the ECS Tutor, there was a
tradeoff between providing high-quality graphics
and producing a program that could function on a
large number of computers. Because the number
of computers in the aviation industry that support
high-resolution graphics is small. it would make
little sense to require that the tutor work only on
high-end computers. The ECS Tutor was de-
signed to work in the standard VGA mode com-
mon on most business computers. Standard VGA
mode only supports 16 colors and is fine for dis-

ANADQATRL


NOTICE

This document is disseminated under

the U.S. Department of Transportation in the interes: of

formation exchange. The United States Government
assumes no liability for the contents or use thereof.

ADA294756


Hypermedia information System Chapter Six
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plays it appropriately; it offers seamless incorpo-
ration.

6.L2.3_ The Multimedia Viewer

More innovative types of media are now
available for computer presentation (e.g., sound,
video, animation, etc.). The Multimedia Viewer is
provided for such media. The Multimedia Viewer
is also seamless, determining the type of media
when the reader selects a Hot Link to a media
source and playing it appropriately. The HIS cvr-
rently supports ali MCI-supported media, includ-
ing animation. video, cd-audio, and audio-video
interleave,

6.2 HYPERMEDIA DOCUMENT
CREATION

Because a hypermedia document is more than
just a digital version of a paper document, it is
hecessary to transform a document from its origi-
nal form into a form containing information for
the HIS. This information runs the garnut from
basic text format such as which font to use to

112

links to other documents, graphics, animation, or
other software programs. The HIS currently pro-
vides support for the following document types:
WordPerfect. Standard Generalized Markup Lan-
guage (SGML) that conforms to the Air Trans-
part Association (ATA) Specification 100. and
ANSI. The transformation process for each type
is described briefly below.

For document types such as WordPerfect, the
transformation process is partially automated. It is
possible to include WordPerfect formatting such
as boldface, italics. fonts, headers. etc.. with an
in-house filter that converts inherent WordPerfect
commands into commands that the HIS under-
stands. A similar filter could be created for other
word processor formats such as Microsoft Word
and would behave similarly. The hypermedia
author then adds hypermedia-specific information
such as Topics and Hot Links.

The transformation process for SGML docu-
ments that conform to ATA Spec 100, such as the
Boeing 757 Aircraft Maintenance Manual, is

ADA294756



Chapter Three

3.2.3.1 Features of the System

The computer-based workcard meets these
design guidelines with the following features.
The first workcard screen is the input manager
the inspector/mechanic uses te enter data nor-
maliy found at the .op of every page; the inspec-
tor/mechanic, the supervisor, and aircraft's
identification number. This information is then
repreduced on all other documentation such a5
the Accountability List and the Non-Routine
Repair forms, relieving the inspector of repeti-
tive form filling. The global view displays ail in-
spection tasks and highlights completed tasks,
serving as an external display to augment
working memory. While performing the tasks.
the inspector/mechanic has direct access to both
input and output information such as the general
maintenance manual, the airplane's manufac-
turer maintenance manual, engineering change
repair aurhorization(s), airworthiness directives,
end attachments. This eliminates the need for the
inspector/mechanic to carry bulky attachments
or to leave the inspection site to refer toa
manual. For each task, the inspector/mechanic
has options of signing off, reporting a non-
routine repair, making a note on the writeup note
feature, going to the home screen to show the
signoffs remaining for the task, going to the
global screen, viewing an overview feature dis-
playing the number of completed signoffs. or
using a help feature. All these features reduce
memory and information processing requite-
ments on the inspector/mechanic. A continu-
ously updated Accountability List may also be
viewed any time. This feature records the in-
spector/mechanic’s activity using the workcard
such as signoffs done, notes made, and tasks
previewed.

The system's outputs are the Accountability
List and the Non-Routine repairs the inspec-
tor/mechanic wrote up.

An inspector/mechanic accesses these fea-
tures by selecting icons or radio buttons with
pictures or labeis designed for rapid learning.
Links between these features are explicit and
always have a backtrack option. Information for
performing the tasks was categorized and lay-

Design of Portable Computer-based Workcards for Aviation Inspection

ered to assist both experienced and inexperi-
enced inspectors. General information was
separated from specific task-directive informa-
tion. All spatial information was conveyed
through graphics. Thus, these features meet de-
sign requirements and address the issues for de-
veloping workcards for aircraft inspection and
ihe guidelines for human-computer interfaces.

3.2.4. Usability Evaluation of the
Computer-Based Werkcard

3.2.4.1 Methodology

The computer-based workcard was com-
pared against the current paper-based workcard
and against the proposed paper-based workcard
designed in Phase II of this project. The com-
parison was made using questions derived from
the issues identified by the taxonomies in Ta-
bles 3.1 and 3.2. The evaluation and the specific
questions were designed to be similar to the
evaluation of the C-check workcard performed
in Phase HI. Eight mechanics used all three de-
signs of the A-check workcards to perform a
nose landing gear inspection with fifteen
signoffs. They were given an overall briefing as
to the purpose of the study and general instruc-
tions, and they answered a questionnaire on per-
sonal data. Before using the computer-based
workcard, mechanics were given a training ses-
sion. A quiz on using the computer-based work-
card ensured that they understood how to use the
workcard. After mechanics completed the in-
speccion using each form of the workeard. they
were asked to complete a questionnaire evaluat-
ing that werkeard. The subjects rated their
evaluatio:, of the issues addressed vy each ques-
tion on a 9-point rating scale.

3.2.4.2 Results

Demographic data on the eight mechanics
participating in the experiment are shown in
Table 3.4. All values were reasonabie for the
mechanic population, including a large variabil-
ity in number of A-checks they perform each
monih.

ANADOATERSL


Chapter Nine

Reliability in Aircraft Inspection: UK and USA Perspectives

CHAPTER NINE
RELIABILITY IN AIRCRAFT INSPECTION: UK AND USA
PERSPECTIVES

Dr. Colin G. Drury
State University of New York, Buffalo, USA
Department of Industrial Engineering

Dr, M. W. 8. Lock
Cranfield Instinte, UK

9.6 ABSTRACT

In response to recent concerns about the reli-
ability of aixcraft inspection and maintenance
procedures, the CAA and the FAA have been in-
vestigating human factors issues. Two investiga-
tors who had separately studied human factors in
civil aircraft inspection undertook to study each
others’ jurisdictions to compare techniques and
problems in the USA and UK. Aiucraft inspection
sites were visited jointly and separately in both
countries, with an analysis made of the overall in-
spection/maintenance system and of larger floor
operations.

The overall conclusion was that similarities
were more common than differences due to the
technical specification of the tasks, the regulatory
similarities and the skili and motivation of inspec-
tors. Differences between companies outweighed
jurisdictional differences in many areas, suggest-
ing that a common policy can be followed to im-
prove such areas as visual inspection lighting,
Physical access to inspected areas. and the infor-
mationai environment.

Larger differences were observed in the areas
of work organisation and nondestructive testing
(NDT), with sharing of experiences in both areas
being possible for improved inspection reliability.

In the UK, the inspectors and maintenance
technicians were closely integrated in the formal
organisation. with inspectors often acting as su-
pervisors for a maintenance team which per-
formed the repaic. In the USA, a more formal
division existed between inspection and mainte-
nance. with coordination usually through the su-

pervisory levels. While both approaches are
viable, both need better support for integration
and communications. Training is needed in su-
pervisory skills, as well as management structures
and documentation which aiiow all concerned to
obiain the information necessary to successful
task completion.

In NDT operations there was a difference in
emphasis between: the two countries, with the
USA more concerned with rule-based perform-
ance and the UK with knowledge-based. In addi-
tion, inspectors in the USA were less likely to be
NDT specialists, performing both NDT and visual
inspection, although changes are now occurring
in this. Although both jurisdictions require both
operating modes at different times, this fact is not
well recognised. Hence, the training and docu-
mentary support for both levels is lacking, as is a
clear indication of switching rules between the
two.

With the increasing internationalisation of the
aircraft maintenance industry, accelerated by
well-publicised events with ageing aircraft, dif-
ferences may be expected to disappear over time.
However. this should be 2 controlled process
leading to utilisation of the best features of differ-
ent jurisdictions if the full potential of inspectors
within the system is to continue to be realised.

ANA?94754


Chapter Four

Ergonomic Audit for Visuai inspection of Aircraft

« has standards built into the analysis
program, rather than into the checklist
questionnaire, to reduce any tendency to
“pend” data in borderline cases

¢ relies on measurements and easily ob-
servable conditions to reduce judgment
errors

¢ is usable in different aviation envi-
ronments, ¢.z. large fixed wing aircraft,
general aviation aircraft, or rotary wing
aircraft.

With these features in mind we designed the
audit system described in the following section.

4.2.3 The Audit System Development
4231 Audit Checklist

Achecklist was produced from the taxon-
omy of factors and the three phases of the audit.
The audit can be either a paper-based system or
entered in the field on a portable computer,
whichever is more convenient. There are two
versions of the paper-based system available: a
large version has detailed instructions and pic-
torial examples; a much shorter version is used
when the auditor is sufficiently experienced to
be able to work without these aids. Figure 4.1
show's the checklist’s structure. The four factors
from the ergonomic taxonomy and the three
phases are overlaid on the detailed issues to be
evaluated.

i

PRE- INSPECTION PHASE

INSPECT:ON PHASE

POST-INSPECTION PHASE

readability, information content
information organ:zation 4

| [ INFORMATION
Yt teedback |
DOCUMENTATION

[snitt changes, incomplete work:

isupervisor, coworker

| COMMUNICATION J

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i | quaitative measures 1 task tighting VISUAL

| (Goartiaive wwasures 7 operate percenton | THERMAL]
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[AVAILABILITY, DISPLAYS

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STANDARDS

PHYSICAL ACTIVITY

7h

ADA294756


PENS Project Field Evaluation

Chapter Two

2.3 IMPROVED FORMS

As is typical with regulatory agencies, there
are several forms that must be completed while
performing an ASI task. Currently. these forms
are on paper and require that redundant informa-
tion be recorded on each form. After completing
the forms, the AS] either types the data into a Jo-
cal computer database or he/she submits the
forms to a data entry clerk. There are several
drawbacks to such an approach. First. redundant
recording of data on multiple forms takes time
that could be devoted io more productive activi-
ties. Second, the two-step process of recording
data on paper and then entering the data into a
computer is inefficient. Third, one is either paying
an inspector to do a task for which he/she is over-
qualified, or one is paying for a staff of data entry
clerks. Fourth, a data-entry clerk may make tran-
scription errors (due to misreading the inspector's
handwriting) or errors due to incomplete knowl-
edge and understanding of the inspector's activi-
ties. Such errors mean that the database is an
unreliable source of information. Finally, the cur-
rent process takes considerable time, which
means there is a delay in getting safety data into
the national database where it can be accessed by
other members of the FAA.

Pen computer technology can be easily ap-
plied to such tasks to minimize the number of
steps required to collect data and assimilate it into
the database. Forms will be linked together so that
an entry in one form prapagates to the other
forms, thus climinating redundant data entries.
Furthermore, the data will be collected so that
they are ready for direct downloading into the
database, This method of collecting data reduces
the need for data entry clerks and it reduces data
transcription errors. At the end of the work day,
the inspector will return to the office, connect the
pen computer to the network, aid initiate a
downloading procedure that will be carried out
overnight.

2.4 ON-LINE DOCUMENTATION

The secand major conuibution of PENS is an
on-line documentution system. Whereas ASIs
currently must carry two briefcases full of books

(including Federal Aviation Regulations (FAR),
ASI Handbooks. and other regulatory docu-
ments}, the necessary data will be stored on the
hard disk of the pen computer or on a CD-ROM
{compact disc, read-only memory). Not only is
the computer media more lightweight and com-
pact, it also facilitates guick retrieval of specific
information. For instance. an AS] will be able to
search the regulations for the word “corrosion” to
answer a question on reporting defects. PENS
would then indicate all of the instances of the
word corrosion. The ASI could then ask PENS to
retrieve the relevant documents and display the
pages that discuss the term.

Besides the bulk and inefficiency of the
books, inspectors must dea! with problems of in-
fonnation currency. One complaint made by in-
spectors is that they will tel] an operator that it is
not in compliance with the regulations, only to be
shown a more recent edition of those regulations.
That is, sometimes the operators get the most re-
cent editions of the regulations before the inspec-
tors do. This problem could be dealt with by
distributing updated documents to the pen com-
puters when they are connected to the database
computer network. Thus, a new edition of a
document could literally be published one day
and in the inspector's hands the next.

2.5 ADDITIONAL BENEFITS

A side benefit of using a computer to support
inspection activities is that it opens the door to
other types of activities and methads for docu-
menting an inspection. For example, an inspector
could follow an on-line checklist for an inspec-
tion. The checklist would then become the focus
of interaction with the computer: by completing
the checklist, ali of the necessary forms would be
automatically completed. We could even develop
a scheduling component that would remind the
inspector to follow up on an inspection. When
documenting an inspection. ASIs currently must
record their findings verbally. However. because
the bulk of a ramp inspection is conducted by
visually inspecting an aircraft, sketching is a more
natural method for recording the results of such
an inspection. Thus, if an inspector found a leax-

ADA294756



Correlates of individual Differences in NDI Performance

Chapter Seven

minute detail. Subjects point to the picture they
believe to be correct in each set and continue uniil
identifying the correct one. Both the time to first
response. and the number of errors are scored.
According to the test’s authors, the MFFT meas-
ures a cognitive style known as reflection-
impulsivity. Those who make quick, inaccurate
decisions on the test are said to have an impulsive
cognitive style; those who make slow, accurate
decisions are said to have a reflective cognitive
style.

This test has been used to measure the ten-
dency of subjects performing inspections tasks to
opt for speed or accuracy in their speed/accuracy
tradeoff (Drury, Gramopadhye, Latorella. Patel,
Prabhu, and Reynolds, 1992}. Presumably, im-
pulsive subjects tend to opt for speed at the ex-
pense of accuracy; conversely, reflective subjects
would opt for accuracy at the expense of speed. A
recent study found scores on the MFFT to be
significantly related to several measures of in-
spection performance (Latorella et al.. 1992).
Since the task used in this latter study was the
NDI simulation developed by them and used in
the present study, it seemed desirable to investi-
gate further the relationship of MFFT scores to
performance on this task.

7.1.3.8 Intemal-Extemal Locus of Controi Scale

Rotter’s (1966) Internal-External (1-E) Locus
of Control Scale was developed to measure dif-
ferences among individuals in the extent to which
they believe that rewards and reinforcements in
life experiences are contingent on or independent
of their own behavior. The internal person be-
lieves that rewards are contingent on his or her
own effort, attributes, or capacities; the external
person believes that life’s rewards result largely
from luck, chance, fate, or forces outside of his or
her control.

In a study of vigilance performance, Sanders.
Halcomb, Fray. and Owen (1976) hypothesized
that "internals," constantly striving for mastery of
a situation and exhibiting a belief in their own
ability to determine the outcome of their efforts.
would perform better on a vigilance task than
would “externals.” The results supported this hy-

pothesis in that internals, relative to externals,
missed significantly fewer signals. Also, internals
continued to progress in the monitoring task with
a very small decline in performance: extemnals
showed a consistent performance decrement.

Because the Rotter scale has apparently not
been used previously in inspection research, it
seemed important to determine whether relation-
ships similar to those found in vigilance would
apply 1o inspection performance.

7.1.3.9 Jackson Personality Research Form (PRF)

The Jackson Personality Research Form
(Jackson, 1974) is a widely used test designed to
yield a set of scores for personality traits broadly
relevant to the functioning of individuals in a
wide variety of situations. Jt is a personality test
that focuses primarily upon normal functioning,
rather than psychopathology.

The Form E used in this study consists of
sixteen scales, of which seven were employed in
this study. The included scales were (a)
Achievement, (b) Endurance, (cj Understanding,
(d) Cognitive Suructure, (e) Autonomy. (f)
Change, and (g) Impulsivity. A brief description
of each scale and the reason(s) for its inclusion
follows.

¢ Achievement. A measure of the willingness to
put forth considerable effort to accomplish
difficult tasks. This was included as a possi-
ble measure of intrinsic motivation or perse-
verance in task performance, mentioned
earlier in the review report as a desirable
quality for NDI technicians.

« = Endurance. A measure of the willingness to
work long hours and to be patient and unre-
lenting in work habits. This trait appears
somewhat related to the above measure, and,
in fact, loads on the same factor in a facior
analysis of the test. It was included for the
same reasons as the Achievement trait.

° Understanding. A measure of intellectual cu-
tiosity and the desire to understand many ar-
eas of knowledge. This was included because
it was felt that it might correlate negatively

ANMAVTOATCL


Correlates of Individual Differences in NDI Performance

Chapter Seven

Factor 1 - Impudsive/Impatient: This is one of
the easier factors to identify. The tests loading
positively on this factor (EPI Extroversion
and PRF Impulsivity) suggest an impulsive
personality style, while tests loading nega-
tively (PRF Endurance and PRF Cognitive
Szucture) suggest impatience, unwillingness
to work long hours, and a lack of meticulous-
ness.

Factor 2 - Reflective/Analytical: Kagan and
associates (Kagan et al., 1964) report that low
scores on the MFFT error measure relate toa
reflective personality style; high scores on the
PRF Understanding scale alse uggest a re-
flective, analytical style. Positive loadings on
the WAIS Arithmetic scale are related to
concentration/attentiveness (Goodenough and
Karp, 1961; Karp, 1963), and high scores on
the PRF Autonomy scale suggest self-
reliance. While not forming an entirely con-
sistent pattern, this factor seems best to typify
a reflective/analytical dimension.

factor 3 - Rapid/Adaprable: Positive loadings
on the WAIS Digit Symbol and negative
loadings on the MFFT Time measure suggest
an ability to perform new tasks rapidly. High
Joadings on the PRF Change scale suggest a
dislike of routine and an ability to adapt read-
ily to new and different experiences. While
aspects of this factor may seem to resembie
Factor I. the loadings are quite different. It
appears that Factor 3 represents more of a
tisk-taking. adventurous dimension than the
impulsive, impatient dimension of Factor 1.
Taken together, Factor 3 appears to reflect a
rapid/adaptable personality dimension.

Factor 4 - Mechanical Aptitude: This factor
appears to stand alone as an ability factor; the
other factors represent personality dimen-
sions. Only two tests load substantially on
this factor: the Bennett Mechanical Compre-
hension Test and the WAITS Digit Span scale.
The former seems to define the factor, while
the later suggests an important attentional
component.

Pearson product moment correlations be-
tween each factor score and t>> various perform-
ance criterion measures, how.-ver, showed only
two of the factors to be significantly related to
performance. Factor 4 was negatively correlated
with missed faults (r=-.38, p<.05) and with false
alarms (r=-.51, p<.01). Factor 1 was negatively
correlated with mean time/rivet (r=-.48, p<.05). A
summary interpretation of these relationships is
that good task performance (low numbers of
missed faults and false alarms) is related to both
mechanical aptitude and concentration/atten-
tiveness. Speed of inspection is related to both
impulsivity/impatience and an unwillingness to
devote long periods of time to work.

7.2.4 Gender, Liking for Inspection, and
Educational Level

At the end of the last performance session.
each subject was debriefed and asked whether or
not he or she might like inspection work or could
visualize himself or herself as an inspector. The
answers were coded "!" if inspection appealed to
them and "2" if it did not. The number of males
and females in each category are shown in Table
75.

Table 7.5

Males i

Females

Although there is a suggestion of a gender
difference in the data, with more males express-
ing a liking for inspection, a chi-square test re-
vealed this apparent gender difference to be
nonsignificant (p=.14). Liking for inspection.
however, was found to be related to educational
levci. As noted earlier, education levels of sub-
jects in this sample ranged from high school t
graduate school. This range was dichotomized.
High school graduates and those currently atiend-
ing a community college or technical schoo) were
placed in one category. and those currently en-
rolled in a university with junior status or higher
were placed in a second category. The lower edu-

ADA294756


Chapter Three

Design of Portable Computer-based Workcards for Aviation Inspection

workcard usability. Most of the improvements
from the computer-based system were also
found for the improved paper-based system. It is
important to make human factors improvements
to existing workcard systems even before they
are computerized. The mechanics found the
computer-based workcards interesting and
would like to see them implemented at the
workplace. The time necessary to become famil-
iar with the system was brief.

The next step ir implementing the com-
puter-based workcards is to update the system
with future hardware. Pen-based systems would
assist in meeting the goals of hypertext better
than lap-top portable computers. The advantages
of the computer-based workcards over their pa-
per counterparts make the implementation of the
system into the workplace on future hardware
well worth the effort, but the usefulness of the
improved paper-based system suggests that this
aspect should be implemented as a step towards
a computer-based workcard.

3.4 REFERENCES

Berk, E. and Devlin, J. (1991), What is Hyper-
text? In Berk, E. and Devlin, J. (ed), Jn Hyper-
text and Hypermedia Handbook, 285-297, NY:
McGraw-Hill.

Brown, C.M. (1988). Human-Computer Inter-
face Design Guidelines. Ablex Publishing Cor-
poration: Norwood, NJ.

Byte, (October, 1993}. PDAs arrive but aren’t
quite here yet. Vol. 18, No. 11, 66-86.

Conklin, I. (1987). Hypertext: An Introduction
and Survey. (Report STP-356-86}. Austin TX:
Microelectronics and Computer Technology
Corp.

Galaxy Scientific Corporation (1993). Human
Factors In Aviation Maintenance--Phase Three,
Volume I Progress Report, DOT/FAA/AM-
93/15, Springfield, VA: National Technical In-
formation Service, 113-131.

Giushko, R.J. (1989). CD-ROM and Hyperme-
dia for Maintenance Information. Proceedings
of the Second Federal Aviation Administration
Meeting on Human Factors Issues in Aircraft
Maintenance and Inspection "Information Ex-
change and Communications,” 121-140.

Higgins, R.G. (1989). Better Utilization of Air-
craft Maintenance Manuals. Proceedings of the
Second Federal Aviation Administration Meet-
ing on Human Factors Issues in Aircraft Main-
tenance and Inspection "Information Exchange
and Communications", 85-97.

Johnson, R.C. (1989). An Integrated Mainte-
nance Information System (IMIS): An Update.
Proceedings of the Second Federal Aviation
Administration Meeting on Human Factors Is-
sues in Aircraft Maintenance and Inspection
“Information Exchange and Communications,"
141-150,

Linderholm, O., Apiki, S., and Nadeau, M.
(1992). The PC Gets More Personal. Byte, July,
128-133.

Meyrowitz, N. (1991). Hypertext and Pen Com-
puting. Hypertext '9] Proceedings, 379.

Smith, S., and Mosier. J. (1986). Guidelines for
Designing User Interface Software. Bedford,
MA: MITRE.



Appendix 2-A Evaluation Forms

Chapier Two

What are the three largest drawbacks to all of these products? f._

2.

3.

The following is a description of two products. Which one would you prefer?

Product A.
Weight: 1-3 Ibs.
Runs only PTRS form
Doesn't run Windows
No keyboard

Product B.

Weight: 3-5 Ibs.
Runs complete PENS system
Runs Window's and Windows applications
Built-in or separate keyboard

Evaluation of Pen Computer Products 2/2



Ergonomic Factors Related to Posture and Fatigue in the Inspection Environment

Chapter Five

By Task
100% 5
80% -
mAC4
wAC3
60% 4 AC2
mAC1
DOACO
40% + AC = Action Category
26% 4
oy 4 E45 : I 0 : 03 : 4
Aft Cargo Stabilizers Tali interior Wheel Well

Table 5.5 7 Iworking aos
% of Work- Action
Task ingTime | Categories

STABILIZERS

1. Legs Straight. Trunk Straight, 2 Anns Below Shoulders 9.3% ACI

2. Kneeling or Crouched, Truck Bent and Twisted, and/or Arms Above Shoulders | 14.1% AC4

3. Leg(s) Straight, Trunk Straight, Arm(s)} Above Shoulder 12.0% ACI

4. Sitting or Laying, Trunk Bent and/or Twisted, Arms Below Shoulders 11.4% AC2-AC4

TAIL INTERIOR

1. Sitting, Trunk Straight, Arms Below Shoulder 21.1% AC2

2. Sitting, Trunk Bent, Arms Below Shoulder 16.5% AC3

3. Legs Straignt, Trunk Gent or Twisted, Arm{s) Above Shoulder i 21.9% ACt-AC2

WHEELWELUMAIN LANDING GEAR H

1. Leg{s) Straight, Trunk Bent and/or Twisted. and/or Arm(s} Above Shoulder 19.0% AC1-AC3

2. Kneeling‘Crouched, Trunk Bent and/or Twisted. and/or Armisi Above Shout- 24.7% AC3-AC4
der '

3. Leg(s). Trunk, Arms Neutral 21.49% AC1

4. One Leg Straight, Trunk Bent arid/or Twisted, andor Arms(s) Above Shoulder | 4.5% ACT-AC2

CARGO 1

1. Kneeling, Trunk Bent and/or Twisted, Arms Below Shoulder 33.2% AC3-AC4

2. Laying, Trunk Bent andor Twisted, and/or Arm(s) Above Shoulder 1 14.3% AC3-AC4

3. Sitting. Trunk Bent anc/or Twisted, and/or Asmis) Above Shoulder | 13.4% AC1-AC2

96

ADA294756


Chapter Two Appendix 2-B Training Slides

Appendix 2-B Training Slides

: 7 The Performance
PENS | ENhancemert System
H for Aviation Safety
| _

ADA294756


Chapter Nine

Reliability in Aircrajt Inspection: UK and USA Perspectives

as air or electricity supplies which cannot. These
trailing services are especially hazardous when
they originate away from the aircraft bay e.g. the
hangar walls and so hinder the movement of
wheeled equipment, e.g. staircases. In some han-
gars, the services come from a central line below
the aircraft belly and this is to be recommended as
it alleviates much of the more hazardous clutter;
service lines tending to remain within the foot-
print of the aircraft.

9.5 CONCLUSIONS

In this study, as in the previous studies of
Appendix I, it was apparent that all concemed
with civil aircraft inspection took their jobs most
seriously, and had very high standards. Neverthe-
less, there are still areas for system improvement
which can fully capitalise upon this highly moti-
vated workforce.

Most of the system differences were found
between individual companies rather than be-
tween the two countries. In any case, technical
differences were few. as these are dictated by
written regulations in each jurisdiction and cir-
cumscribed by the manufacturers’ requirements
for inspection tasks.

The main points raised in each of the results
sections follow, arranged in the order of occur-
sence and not that of importance,

95.1 Maintenance/Inspection
Responsibilities

‘The organisational position of inspectors
could vary between the separation of inspectors
from mainta‘aers in the USA to the inspector
serving as a maintenance supervisor in some UK
companies. There are arguments in favour of each
system with close integration of maintenance and
inspection, especially through long tasks with
multiple buy-back stages, weighted against per-
ceived impartiality of a separate inspectorate.

9.5.2 The Supervisor/inspection
Dichotomy

Whether inspectors have supervisory respon-
sibility or not, they require better support in the
areas of communications (written, verbal), the or-
ganisaticn to support these communications, and,
where appropriate, some interpersonal skills de-
velopment. Training and systems modifications
are needed to fully support these activities.

9.5.3 Non-Destructive Testing

in the NDT area, there was a difference in the
depth of training and degree of specialisation
between the USA and the UK, with the UK in-
spectors required to have deeper knowledge and
more specialisation. Both countries require in-
spectors to use rule-based and knowledge-based
behaviour, although to different extents. This
should be realised and support in training, hard-
ware, and documentation provided in both coun-
ties to enable inspectors to move easily and
recognisably between the two modes.

‘With the advent of increased NDT use and
much more complex systems, the current moves
towards NDT specialists with at ASNT level Il or
PCN level 2 should be encouraged.

Equipment should be made more portable
with greater use of repeater units in the same vis-
ual envelope as the probe elements in ultrasonic
and eddy current techniques.

9.5.4 Bonding

In the UK, it is generally accepted that
‘bonding’ personne) to pay back al] or part of
their training costs on leaving a company is un-
tenable in law. The practice is endemic in the
USA and is universally disliked by the inspectos-
ate force. The cost in terms of dissatisfaction
probably exceeds the monetary considerations.

A replacement system, involving mutual co-
operation and compensation by participating air-
craft engineering companies could solve the
major problems of poaching and uneven distribu-
tion of training costs. JATA or ATA or a similar



Chapter Three

Design of

>

P.

2. INFORMATION CONTENT

A. Appropriate Content

oeecenvoe

some level of inaccuracy in the information
incomplete information for certain tasks and lack of in-
formation on spatiai location

language difficult to use and comprehend

syntax not standardized

directive information ambiguous

generalization across aircraft types causes confusion
use of difficult acronyms

logical errors and contradictory statements
redundancy and repetition

does not foster generalizations across tasks, aS every
task is described differently

B. Graphic information

no figure numbering, even though the workcard refers to
specific figure numbers. fosters guessing and specula-
tion for interpretation

no consistent layout of figures, use of mixed layout with
no demarcation

no consistency in view directional information, €.g.. usé
of both UP-AFT & UP-FWD

non-contextual figure views, or views as the inspector
sees it, just perspective part drawings

no information to aid in spatial location of parts

no back references to the workcard page/task which
refers to the figure

improper usage of technical drawing terms, e.g.,
“section” and “view” are used interchangeably

no typographic differentiation between: figure titles, part
names, crack locations, notes, etc.

no use of standard drawing conventions, e.g., location
of sectional views

same graphics for both feft and right wing tasks, men-
tally inverting the figures causes high cognitive workload
some figures use high fidelity graphics, causing confu-
sion and clutter

no consistency of scaling graphics, close-up views not
differentiated from distant views

3. INFORMATION ORGANIZATION

A. Information Classification

no categorization or classification of tasks

notes, cautions, methods, directions, etc., not prioritized
no demarcation among directive information, refer-
ences, notes, methods, etc.

directive information is not broken up into command
verb, objects, and action qualifiers

directive information includes more than twe or three
related actions per step

genera and specific information chunked together
generai and specific tasks not properly demarcated

ADA294756



Results of the ECS Tutor Experiment at Clayion Sine College

tom ihe

Good training tool! { like it.

2. With more experience on the computer, the problems would have been easy to compiete.
3. [lI could not tell what the pictures of ECS parts were supposed to be] malfunctioned

(damaged) HX was confused with dirty HX.

4. [lt could not tell what the pictures of ECS parts were supposed to be] in the case of the heat

exchanger problem.

though subjects knew that there were ten trouble-
shooting problems, the tutor gave no indication of
how much time each problem should take. Some
subjects rushed through the problems without
spending much time to think about their actions.
This comment and the writen comments high-
light several important issues that the researchers
discovered during the evaluation.

84.3.1 Probh ith Linited C. Experi

Although there was only one written com-
ment conceming confusion over how to use the
ECS Tutor (number 2), the researchers observed
that several subjects took more time than others to
“become comfortable” with using the tutor. The
subject who made the comment indicated that he
had never used any type of computer before. It is
understandable that it takes some time to acquire
the hand/eye coordination necessary to use a
mouse. The researchers did net have these prob-
Jems in an earlier evaluation using computers
with touchscreens.

8.4.32 Problems with Graphics Resolution

Subjects did not have probiems understand-
ing what was being displayed in the majority of
the tutor graphics. However, as neted in com-
ments 3 and 4, a graphic of one of the heat ex-
changers (HXs) caused some confusion for some
subjects. The problem required the subject to de-
termine if the HX was dirty and clogged. Since
the tutor was designed to work on standard PC-
compatible hardware. graphics were limited to 16
colors. This was not an issue for most of the
equipment in the ECS Tutor, since the features
that indicated the state of the components were
well-defined. However, a clogged HX requires
close inspection for din and other foreign objects
and could not be adequately represented with the
resolution used during the experiment.

84.3.3 Estimating Time Allocation

The ECS Tutor gives a user feedback on his
or her performance on completed problems and
also tells him or her how many problems are left
in the current Jesson. However, it does not esti-
mate the time required to solve the remaining
problems. Several students rushed through prob-
lems because they were concerned that they
might run out of time. This problem of allocating
time between problems is more pronounced in
taining than on the job. This arises in a simulated
training environment, but not in actual job per-
formance, because of “compressed time” a simu-
lated environment presents to a user solving
problems.

8.5 IMPLICATIONS AND
RECOMMENDATIONS

This section covers the issues discovered
during the ECS Tutor evaluation at Clayton State
College and makes recommendations for future
ITSs for AMT training.

8.5.1 Use of Intelligent Help

Before this experiment, the researchers ex-
pected that the ITS" intelligent help component
would improve subjects’ troubleshooting per-
formance. This expectation was based on the as-
sumption that giving a subject more information
and feedback would heip him or her perform a
troubleshooting task. However, a statistical
analysis of the data did not confirm this expecta-
tion, and the researchers found no statistically
significant difference in the two groups’ perform-
ance.

There are several possible explanations for
this finding. Because of the small sample size in-
volved in the experiment, individual differences

ADA294756


Chapter Two Appendix 2-A Evaluation Forms
Miscellaneous

Numeric Mise

Loca! Use

National Use

Activity Time

Travel Time, Travel Cost

Section i. Personne]
Personnel Name
Position

Base

Remarks

New Entry, Save Entry, Clear Entry

Section II, Equipment
Manufacturer

Model

Serial #

Remarks

PENS Software Evaluation 3/6



Design of Portable Computer-based Workcards for Aircraft Inspection Chapter Three

3. Graphic informaticn « Use graphics to reduce display density
¢ _ Show ail spatial, numeric, ter:poral information graphically

4. Iconic information * Use icons for all direct manipulation

¢ Use icons to save display space and reduce clutter
« Use icons for ail extemal links

.

Use icons to permit cross-cultural usage

3. INFORMATION ORGANIZATION, MANIPULATION, AND ACCESS

1. Linking « Provide contextual interna! finks

* Use interna! links for all reference information

« Use external links sparingly and only for non-contextual informa-
tion

«  Provida a link backirack option

¢ Provide an UNDO option for navigation

« Make linking explicit; do not leave anything to exploration or

browsing

Use linking sparingly to avoid user confusion and disorientation

Label links where possible

Organize for progressive disclosure and graceful evolution

Keep iayered information optional

Do not use scrolling fields

Organize tasks in a fixed linear as well as optional nested struc-

tures

oe

2. General organizational
philosophy

4. OTHER PRAGMATIC ISSUES
1. Physical handling and infieid « Develop and implement standards for reverse video, contrast for
usability varied lighting conditions

¢ Follow a pencentric display design philosophy

° Design for a single-handed operation

« Minimize the use of key entries, use direct manipulation

2. Hardcopy + Provide feasible options for obtaining hardcopies in a fixed for-
mat

3. System response time @ Keep the system response times for all actions within standards

4. User acceptability ¢ Honor user preferences

Provide only those functions that a user will use

AMNADXOATOS


Chapter Five Ergonomic Factors Related to Posture and Fatigue in the Inspection Environment

1. Trunk Smaight 2 Arms Below 2. Trunk Bent and Twisted and/or
Shoulder, Legs Straight Amm(s) Above Shouiders, Kneeling
or Crouched

3. Trunk Swaight, Arm({s) Above 4. Siuing or Laying, Trunk Beat
Shoulder, Leg(s) Straight and/or Twisted, Arms Below
Shoulders

ADA294756


Chapter Ten

Guidelines for Designing and Implementing CBT for Aviation Maintenance

CHAPTER TEN
GUIDELINES FOR DESIGNING AND IMPLEMENTING
COMPUTER-BASED TRAINING FOR AVIATION MAINTENANCE

Michael Pearce and Kiki Widjaja
Galaxy Scientific Corporation
10.0 ABSTRACT must be considered when creating CBT pro-
This report is an bibliographic overview of grams.
selected issues in designing computer-based Bibliography:

training (CBT) systems. It covers instructional
design, information presentation formats, screen
design and layout, and hardware issues, This re-
port in the form of a bibliography for each of the
relevant CBT design issues.

10.1 INTRODUCTION

Broadly defined, a computer-based training
(CBT) system is a combination of computers and
special software for training and education.
Within this broad definition, there are many dif-
ferent approaches, systems, and technologies.
Their commen goal is to transfer skills and
knowledge from an expert to the student viaa
computer system in such a way that the know]-
edge will develop and/or improve performance on
a set of tasks. What differentiates a CBT system
from traditional teaching methods is that CBT can
be interactive, dynamic, and individualized. CBT
does not require one-on-one interaction with an
instructor. The computer program can be de-
signed to simulate a piece of equipment, to react
to user actions, and to provide appropriate feed-
back,

10.2 CBT SYSTEM DESIGN ISSUES

There are many decisions to make in design-
ing and implementing a CBT system. The selec-
tion of approaches and technologies should be
based on the organization's instructional needs
and budget. This section describes factors that

Air Transport Association. (1991, October).
Specification 104 - Guidelines for aircraft main-
tenance training. Washington, DC: Air Transport
Association.

Aviation Industry Computer Based Training
Committee. (1992, draft). CBT course-
ware/hardware matrix.

Eberts, R. E. & Brock, J. F. (1987). Computer-
assisted and computer-managed instruction. In G.
Salvendy (Ed.), Handbook of Human Factors
(pp. 963-975). New York: John Wiley & Sons.

Electric Power Research Institute. (1987, June).
Guidelines for the application of computer-based
instruction (Research Project 2294-2 Interim Re-
port).

Johnson, W.B. (1988). Pragmatic considerations
in development and implementation of intelligent
tutoring systems. In J.R. Richardson and M.C.
Polson (Eds.), Foundations of intelligent tutoring
systems (pp. 189-205). Hillsdale, NJ: Lawrence
Erlbaum Associates, Inc.

Depending on the type of information and
knowledge being taught to the student, there are
usually several appropriate instructional ap-
proaches. For example, to teach the rules of the
Toad, a standard present-and-test approach is ap-
propriate. Actual driving (or a simulation) is ap-

’ This project was supported by the FAA Office of Aviation Medicine.

ADA294756


Correlates of Individual Differences in NDI Performance

Chapter Seven

(These were simulated by 2 mm jagged
lines at random locations adjacent to a
rivet. Not all rivets contained such
“noise.” and no rivet contained more than
one such noise spot.)

7.12.4 Lower Right Window

The subject could use this area of the display
to exercise a number of options (e.g., to "zoom"
for a closer look at a rivet being inspected, to stop
the task for a break, or to display elapsed time).
The cnly feature used in this study caused a num-
ber to appear on each rivet. The experimenter
only used this feature during training feedback
sessions io enable subjects to locate and re-check
rivets incorrectly classified.

7.1.3 Predictors and/or Task Correlates

As previously noted, the earlier review report
(FAA/JAAM & GSC, 1993) identified a number
of variables, measures of which appear poten-
tially relevant to NDI selection and/or profi-
ciency. These variables could be roughly
separated into the following categories:

* Boredom Suscepubility

*  Concentration/Attentiveness/Distractibi-
lity
Extroversion/Impulsivity
Motivation/Perseverance
Decision Making/Iudgement
Mechanical Aptitude
Need for Autonomy.

eoceee

The following sections describe the tests and
scales, derived from the above categories, exam-
ined for their relationship to performance on the
NDI task.

7.13.1 Subjective Rating Scale (SRS)

The Subjective Rating Scale (SRS) is a sim-
ple self-rating scale the author has used in several
previous studies (Thackray, Bailey, and Touch-
stone, 1977; Thackray and Touchstone, 1993) to
assess current feeling levels. Measures generally
are taken before and after periods of task per-
formance. The basic instrument consists of five 9-
point scales measuring the dimensions of atten-
tiveness, tiredness, strain. interest. and annoy-

ance. Two additional scales measuring perceived
effort and perceived difficulty were used in the
more recent study by Thackray and Touchstone
(1991) and included here as well. The SRS was
extensively examined in the early Thackray, Bai-
ley, arid Touchstone (1977) study. In that study.
subjects falling at the extremes of rated interest
following performance of a simulated radar
monitoring task were compared on several per-
formance and subjective variables. In general,
those who rated the task as quite boring showed
the greatest decline in rated attentiveness and the
largest performance decrement.

7.1.3.2 Beanett Mechanical Comprehension Test

One recommendation of the Southwest Re-
search Institute study of ways to improve NDI
technician proficiency was to select individuals
who score high on mechanical/electronics apti-
tude (Schroeder, Dunavant, and Godwin, 1988).
This recommendation is echoed by NDI instruc-
tors who express their belief that individuals with
above average mechanical aptitude make better
inspectors (FAA/AAM & GSC, 1993). For these
reasons, the Bennett Mechanical Comprehension
Test was included in the test battery. This test
measures ability to perceive and understand rela-
tionships of physical forces and mechanical ele-
ments in practical situations. This ability may be
regarded as a measure of one aspect of intelli-
gence, if intelligence is broadly defined (Bennett,
1969}. This test has been validated on various
groups of aircraft employees such as shop train-
ees and aircraft factory employees in mechanical
jobs (Bennett, 1969). The performance criteria for
the validation studies were generally job ratings,
with validity coefficients (r’s) ranging from .52 to
62.

7.13.3 Typical Experiences Inventory

The ability to resist distraction. if it can be
measured. would appear to have at least face va-
lidity in selecting inspectors (Wiener, 1975). The
Typical Experiences Inventory was developed for
use in several previous studies (Pearson and
Thackray, 1970; Thackray, Jones, and Touch-
stone, 1973). This scale consists of a series of
statements designed to measure ability to work
under conditions of (a) time stress. (6) threat of

ADA294756


Chapter Two Appendix 2-B Training Slides

Tips
v Turn off the computer before plugging or unplugging any devices:
~keyboard
~floppy disk drive
~network connection

-CDROM
Wa Plug the computer into AC power when possibie and convenient

| VA Plug the computer into the cigarette lighter when possible
and convenient

VA Turn off the computer if it witli be idie for afi:

ADA294756


Chapter Four

Ergonomic Audit for Visual inspection of Aircraft

Reynolds, J, and Drury, C. G. (1993), An
evaluation of the visual environment in aircraft
inspection. Proceedings of the 37th Annuci Hu-
man Factors and Ergonomics Society Meeting,
Seattle, WA, 34-38.

Reynolds, J. L., Gramopadhys, A., and Drury, C.
G. (1992). Design of the aircraft inspec-
ton/maintenance visual environment. In Meeting
Proceedings of the Seventh Federal Aviation

79

in Aircraft Maintenance and Inspection, Atlanta,
GA, 'S1-162.

Rohmert, W. and Landau, K. (1989). Introduc-
tion to job analysis. A New Technique for Job
Analysis, Part i, London: Taylor & Francis Ltd.,
7-22.

Willingham, J. J. and Carmichael, P. R. (1979).

Sampling for audit evidence, Auditing Concepts
and Methods, 6, New York, McGraw-Hill, 166-
195,



Lis: of Abbreviations

LIST OF ABBREVIATIONS

Office of Aviation Medicine
Action Category
Aircraft Maintenance Manual
iation Maintenance Technician
Analysis of Variance
.-Airframe & Powerplant
Aviation Safety Inspector
Air Transport Association

Avi

- Built-in Test Equipment
desesee Bitmap
..Body Part Discomfort Chart

Civil Aviation Authority
‘omputer-based Training
‘ompact Disc, Read-only Memory

Environmental Control System
Eysenck Personality Inventory
.....- Encapsulated Postscript

Federal Aviation Administration
Federal Aviation Regulations

seve Fault Isolation Manual
Flight Standards Automation Subsystem
Flight Standards District Office
Flight Standards Service
...Feeling Tone Checklist

Graphics Interchange File
Galaxy Scientific Corporation

~ Hypermedia In Information System
... Heat Exchanger

.... Internal-External
ractive Electronic Technical Manual
THA. ecccsscsescesceescsecsssseconcasestesvereeanesnessceneeatsnersersecanceussassuasarseesueeaseensasssecncancaausneeneneneene Intelligent Help Agent
ntegrated Maintenance Information System
.... Hustrated Parts Catalog
intelligent Tutoring System

FP EG ose ecseetess cee ees tees tecaessatcaneeee seeneseneeecttesmanesmesseeneeemenseeneccneerees JOint Photographic Experts Group

Minimum: Equipment List
Matching Familiar Figures Test
... Main Landing Gear

xii

ANARAAIeS



Table of Contents

TABLE OF CONTENTS

Chapter One - Phase IV Overview

1.0 INTRODUCTION
1.1 PENS FIELD EVALUATION (CHAPTER TWO). 1
1,2 DESIGN OF PORTABLE COMPUTER-BASED WORKCARDS FOR AIRCRAFT INSPECTION
(CHAPTER THREE) 2
13 ERGONOMIC AUDIT FOR VISUAL INSPECTION CF AIRCRAFT (CHAPTER FOUR) 2
1.4 INVESTIGATION OF ERGONOMIC FACTORS RELATED TO POSTURE AND FATIGUE IN
THE INSPECTION ENVIRONMENT (CHAPTER FIVE) ....-.0.ssssessseeee
1.5 HYPERMEDIA INFORMATION SYSTEM (CHAPTER SIX).............
1.6 CORRELATES OF INDIVIDUAL DIFFERENCES IN NONDESTRUC-TIVE INSPECTION
PERFORMANCE (CHAPTER SEVEN) ........-sccsssscsssssssssnesecsesecssnessesseseescessauaesssusteseseersuneqnunssnneseestiea 3
1.7 RESULTS OF THE ENVIRONMENTAL CONTROL SYSTEM TUTOR EXPERIMENT AT
CLAYTON STATE COLLEGE (CHAPTER EIGHT)... svaeeeerene
1.8 RELIABILITY IN AIRCRAFT INSPECTION: UK AND USA PERSPECTIVES | (CHAPTER ..
NINE)... as
19 GUIDELINES FOR DESIGNING AND IMPLEMENTING COMPUTER-BASED TRAINING
FOR AVIATION MAINTENANCE (CHAPTER TEN).
1.10 FUTURE PLANS...
1.11 REFERENCES...

Chapter Two - PENS Project Field Evaluation

2.1 PENS: A PERFORMANCE ENHANCEMENT SYSTEM......0..-scssseseccssssesecsees
2.2. A BRIEF INTRODUCTION TO PEN COMPUTERS .
2.3. IMPROVED FORMS ............
2.4 ON-LINE DOCUMENTATION
2.5 ADDITIONAL BENEFITS...
2.6 EVALUATION AND IMPLEMENTATIO?
2.6.1 Design of the Evaluation............
2.6.2 Expected Outcomes of the Evaluation...
2.7 SUMMARY AND CONCLUSIONS :
2.8 REFERENCES... ee
APPENDIX 2-A EV. ALUATION FORMS
APPENDIX 2-B TRAINING SLIDES...
APPENDIX 2-C SOFTWARE USER MANU

SeIIADAUY

Chapter Three - Design of Portable Computer-based Workcards for Aircraft
Inspection

3.0 ABSTRACT
3.1 INTRODUCTION.

ADA294756


Chapter Eight

Results of the ECS Tutor Experiment at Ciavion State College

playing drawings and line art, but not good for
displaying recognizable photographs.

For the most part, subjects had little problem
recognizing or understanding the systems and
components presented in ECS tutor pictures. Be-
cause the nitor concentrated on high-level cogni-
tive skills (troubieshooting) instead of low-level
psychomotor skills (recognition, coordination),
few of the tasks required high-resolution graph-
ics. However, in the case of the heat exchanger
(HX), subjects had recognize that the HX in the
picture was damaged. The user must be able to
see fine irregularities in the component's struc-
ture, and it is difficult to show such damage wiih
a small number of display colors.

There are several ways to address the prob-
lem of limited computer display resolution. Since
recognition is not a major training goal of ECS
Tutor, it is possible to add a text Jabel saying that
there is damage to the component being shown.
This solution applies wherever damage recogni-
tion is not a problem with real components, as in
the case of physical damage to a part. However,
for cases where recognition is an important part
of the task being taught, it is necessary to use
higher-resolution graphics of the components
with high-resolution computer monitors or, when
fine detail is required, through a computer-
controlled videodisk.

8.5.5 Providing Adequate Feedback

Because the purpose of a training system is to
improve performance in terms of time, accuracy,
cost savings, etc., for a particular task, it should
be able to tell a user how well he or she is per-
forming, and how well he or she is expected to
perform. This feedback is needed so that the stu-
dent can

© regulate performance

make decisions about the need for further

practice.

The ECS Tutor’s IHA exists in part to sup-
port the second purpose; it tells a user when he or
she makes diagnostic reasoning errors. The wt.1r
provides feedback for performance regulation by
telling users how many problems remain in each

lesson and also approximately how much time
their actions would take were they actually repair-
ing an ECS. However, ECS Tutor does not esti-
mate how much time a user should spend on each
problem. Some subjects commented that they
tushed through the problems and made mistakes
they would not have made had they stopped to
think about their actions.

Subjects’ post-experiment comments point to
the importance of providing users with adequate
feedback. A training system should give ade-
quate feedback to users and should also provide
an estimate of how much time to spend on re-
maining problems. The consequences of not pro-
viding adequate feedback include users who do
not Icarn that they do not understand something
about a system and users who operate the training
system improperly and do not learn what was in-
tended. On the other hand, it is important that us-
ers not be given too much information while they
are using an ITS because of problems of learning
transfer from simple training tasks to complex
real world tasks.

Improved feedback in the ECS Tutor would
be helpful to future users. This could be done by
providing an conservative estimate of how much
time each problem should take (based on th>
user's computer experience) and providing a
clock counting the actual time. The feedback
screen should be designed so that the user does
net confuse the real time with the simulated time.
Since the user is leaming how to troubleshoot,
feedback should stress accuracy over speed until
the user has learned enough to diagnose faults
quickly. Several users also suggested that an
“estimated cost" evaluation be added to the per-
formance measures so that the student can lear
about the costs of poor troubleshooting, e.g. re-
placing working parts.

8.6 CONCLUSION

One goal of this experirnent was to measure
the effectiveness of the ECS Tutor’s Intelligent
Help Agent (HA). Our evaluation of the data did
not find any statistically significant difference in
performance between users with or without the



Appendix 2-B Training Slides

Chapter Two

{

i
;

You can harm the computer by:

dropping it

spilling liquids on it NY

throwing it against the wall

But if you do, you will make several
people very unhappy with you.

Tramng. Side 8

Training. Slide 7

ANADOATESL



Reliability in Aircraft Inspection: UK and USA

Chapter Nine

personnel who would only need training in the
company system.

9.4.7 Visual inspection and eye tests

Both Countries: Conditions for visual inspec-
tion varied greatly from operator to operator with
a similar variation of the good, the bad and the
ugly in cach country.

The provision of lighting varied widely with
respect to both hangar fixtures and portable
sources.

Provision for ensuring that an inspector could
actually see differed widely.

UK Variations: No mandatory eyesight test is
required for visual inspectors except as part of the
medical examination when entering the company.
The situation varied from greatly from regular
cwo-yearly tests to none at all. There seems a
great reluctance for operators to finance this pro-
gramme. NDT specialist inspectors are better
served with mandatory examination being part of
the annual requirement.

US Variations: All inspectors have regular
eye tests (?2as part of the FAA requirement??).
Particular vision standards are defined, e.g. 20/25
Snellen (near) and 20/30 (distance). Colour vision.
is handied as part of the physical requirements.

Operators generally finance these tests either
in their own medical centres or out-of-house.

Evatuation: Lighting within the hangar to-
gether with supplementary sources on docking
and independent stands is usually sufficient to
allow inspection of the outer surfaces of the air-
craft. However these lights are frequently bright
point sources which also reflect off the bare r
painted metal surfaces of the aircraft. If an inspec-
tor glances at these, a mild form of arc eye may
result from the direct or reflected giare. This de-
grades the acuity of vision and can take several
minutes to revert to normal. Inspection quality
during this time is greatly reduced. A greater
number of less bright sources such as daylight
fluorescents is recomm

It must be a universal requirement for an in-
spector to be able to see. Without regular testing,
the inspector may easily drift into inadequate vi-
sion. Gradual receding of the in-focus plane is all
part of the ageing process. An elementary test in
the UK, (Lock & Stmit. 1985) showed there to be
little or no correlation between the distance at
which typescript could be read and wither an in-
spector had had a recent eye test or whether he
wore glasses.

There is a reluctance on the part of the opera-
tor to declare an inspector unfit to continue in-
spection duties on the grounds of failing eyesight
whereas they would not hesitate if the inspector
was otherwise medically unfit.

9.4.8 Reporting imminent indications

Both Countries: (This is not an area where
there are transatlantic differences but, if taken up
it might have implications in both the UK and the
USA.) During much inspection work there are
occasions when some indication of a possible de-
fect is seen. For visual inspection this is not easy
to exemplify, but may take the form of incipient
corrosion or slight rubbing. In NDT such an indi-
cation is much easier to define. Most techniques
have a calibration step which sets a standard for
defect reporting. In ultrasonics. for instance, this
may be the height of the oscilloscope signa} or
simply a measured skin thickness. There is usu-
ally a substantial difference in these reportable
indications and the perfect component or material
appearance, in the visual case, or the background
electronic noise for ultrasonics or eddy currents
ete.

Evaluation: Tt would not take a great deal of
effort for the inspector to make an official note of
such a sub-reportable indication so that it could be
appended to the task card on the next inspection
check.

With the solid establishment of computer-
enhanced task card preparation, this should pres-
ent few problems. Corrosion initiation points
might be detected early and the system would
also provide a useful source of fracture mechanics

ADA294756


Design of Portable Computer-based Workcards for Aircraft Inspection

compariser

workeards:

Significance of Current Paper- | Significance of New
9 paint Rating Scale End based Workeard Versus Paper vs. Computer
issue Addressed Points we
0 4 New Paper Computer
Workcard Workcard
Readability of text Terrible Excellent 0.031 0.025 ns.
Task of reading Very difficutt Very easy ns. 0.025 ns.
Ease of understanding Vary difficult Very easy 0.025 0.01 ns.
Amount of information Too tittle Too much as. ns. ns.
Information covered every- Disagree Agree fully 0.025 0.005. As.
thing for task fully
Tasks were well organized Disagree Agree fully 0.031 0.005. fis.
fatly
Effort required in tocating Very difficult Very easy 0.005 0.665 ns.
information
Consistency of organization Terbie Exceltent 0.025 0.025 ns.
Separating information by Terrible Excellent 0.025 0.025, ns.
frequency of use
Chance of missing in‘orma- Always Never 0.625 0.005 ns.
tion
Flexibility of use Terrible Excellent 0.034 ns. ns.
Ease of physical use Very difficult Very easy 0.025 0.01 ns.
Ease of referring to attach- Very difficult Very easy 0.005 0.005 ns.
ments or manual
Ease of writing up an Very difficult Very easy 0.01 9.025 as.
Accountability List
Ease of writing up a Non- Very difficult Very easy 0.025 ns. ns.
Routine
Degree of interest Very boring | Very interesting 0.01 0.005 0.025
Degree to which rater would | Definitely not Definitely yes 0.01 0.01 0.025
like to use W/C again
Degree to which WIC like Definitely not Definitely yes 0.01 0.025 ns.
these should be used
Overall ease of usability of Tertibie Excelient 0.025 0.005 as.
Wie

3.3 CONCLUSIONS

A similar set of design guidelines to those
used to improve paper-based workcards was de-
veloped and used to design a portable computer-
based workcard system for A-checks and C-
checks. An evaluation of this system against
both the origina] and improved paper-based
workcards for one task of an A-check showed

that the computer-based system is better than
either paper-based system.

Direct access to documentation reduced re-
liance on memory and waiting time to retrieve
information. Compared to the original paper-
based workcard, the computer-based system was
easier to understand, reduced the effort to Jocate
information, increased organization and consis-
tency of information, and increased overall



Ergonomic Audit for Visual Inspection of Aircraft

Chapter Four

4.3.13 Step 3: Weighting the Factors

Itis possible to use the ranking values ob-
tained above to determine weightings for the
seven factors, using the Rank Order method
(Guilford, 1954). In Table 4.2, the average
ranks are shown in the first column. Fhe second
column gives the normalized ranks, assuming an
underlying normal distribution of ranking re-
sponses by inspectors. Weights are then derived
in the third column by dividing all the normai-
ized ranks by the largest one (6.5). Thus, accord-
ing to the inspectors’ judgements, the least
important factor (posture) should only receive
just over half of the weight (0.5!) of the most
important factor (safety).

FACTORS | MEAN | NORMALIZED

WEIGHTING
RANK RANK
Safety 6.5 65 1.60
Mental 63 64 0.98
Visual 41 5.4 0.78
Access 40 49 0.75
Physicat 28 46 0.71
Temporat 2.0 3.8 0.58
Posture 2.0 37 0.51

4.3.14 Step 4: Listing the Inspector Tasks

A comprehensive list of ali the inspection
tasks in a C-check were obtained from the airline
partners operating fixed-wing and rotary-wing
aireract. For the fixed-wing aircraft, the airframe
was segregated into six zcnes, depending upon
the area under inspection:

* Fuselage

@ Empennage

« Wings

© Wheel wel] and landing gear/cargo com-
partment
Power plant
Door and windows

A similar exercise was conducted for the rotary-
wing aircraft's inspection tasks, where the natural
classification was into phase inspections (Phase I
through Phase V).

43.15 Step §. Rating Tasks

For a particular zone selected, e.g., power
plant, experienced inspectors were asked to rate a
list of five tasks with respect to the seven factors
indicated. For each task. the inspectors were
asked to rate ine factors on a scale from | to 5 as
follows:

| _very easy

very demanding

From these ratings and from the weights assigned
earlier. sampling plans coukl be developed to
concentrate auditing effort onto the most critical
tasks.

43.2 Results of Sampling Pian

Three inspectors with ten or more years of
experience with C-checks were chosen to rate the
seven factors for each task listed under Power
Plant Inspection and “ving Inspection. For each
task, each factor ratmg is multiplied by its respec-
tive weight, and the values were summed over the
seven factors to give one final score. The scores
were then compared tc each other to estimate the
degree of criticality of each task. The final rank-
ing of the tasks is presented in Table 4.3.

For the rotary-wing airline partner. three in-
spectors with six or more years experience with
Phase inspections were chosen for a similar rat-
ing. The final ranking of the tasks is presented in
Table 4.4.

From the data presented in Tables 4.3 and
4.4, it is apparent that differences among tasks are
not large. Thus, while some tasks were found to
have more critical ergonomic needs than others,
none could be safely neglected,

ADA294756


DOT/FAA/AM-95/14

of Aviation Medicine
ington, DC 20591

Human Factors in Aviation
Maintenance — Phase Four
Progress Report

Willicam T. Shepherd

Office of Aviation Medicine
Federal Aviation Administration
Washington, DC 20591

Galaxy Scientific Corporation
Auanta, GA 30345

is)

May 1995

Final Report | 7@RONARU MON STRTESERT BT j

Approved for public rekoxey
Prardixiian Cidlinit

This document is available to the public
through the National Technical Information

Service, Springfield, Virginia 22161

@ DIG QUALATY INSPECTED 3

U.S. Deparment
of Transportation

Federal Aviation
Administration

ADA294756


Chapter Five

Ergonomic Factors Related to Posture and Fatigue in the Inspection Environment

The BPD and FTC difference values (end of
task - beginning of task) were averaged across in-
spectors and are presented in Figures 5.8 and 5.9.
Inspectors experienced significant increases in
body part discomfort in the tail interior (t = 2.35,
p< 0.05). Likewise, inspectors indicated the most
fatigue after inspecting the tail interior (t = 3.17, p
<0.0.005}. Body part discomfort and fatigue
were also judged as high in the aft cargo. The av-
erage fatigue value was skewed by one inspector
who rated his fatigue to be less (Figure 5.9). The

TLX data averaged across inspectors; results are
presented in Figure 5,10. There was a significant
difference among the overall workload levels (F =
2.89, p = 0.074), with workload being signifi-
cantly greater in the tail interior. In addition,
across all tasks, physical demand and perform-
ance were significantly greater than the other
components in contributing to the overall work-
load level (Tukey critical value = 2.70, & =
0.05).

iG)

}
By Task
5+
4; cc
3 - 4
3.3

2+ 2.5
1- 1.8
0 t T 1

Aft Cargo Siabilizers Tail interior Wheei Weil

ANADOATEYS


Chapter Seven Correlates of Individual Differences in NDI Performance
able Mean times per rivet across the four sessions
were 23.6, 21.9, 21.6, and 19.6 seconds. respec-
Period tively. Analysis of variance revealed this dectine
Session 1 2 Session to be significant (F(3/78)=8.96, p<.01). There
Means were no significant differences between males
7 154 23.8 19.6 and females, and the interaction of gender and
2 25.0 1 24.4 24.7 sessions was nonsignificant (p>.05). Comparisons
3 24.0 263 246 of changes within sessions (periods) were not
4 196 286 244 considered to add any additional useful informa-
Period Means | 21.0 | 25.5 | 232 tion. and none were made.

Session ; 1 2 Session
Mean
7 | o8 | 05 0.6
2 1.3 3.1 2.2
3 1.9 2.8 23
4 34 4.2 37
Period Means | 1.8 27 22

Both tables reveal generally poorer perform-
ance in the second period of each session, but
only false alarms showed a systematic increase
across sessions. Repeated measures of analyses of
variance (ANOVAs) conducted on the two error
measures revealed the differences between peri-
ods to be significant fer both missed faults and
false alarms (F(1/26)=9.88, p<.01 and
F(1/26)=7.29, p<.01), respectively. Differences
between sessions were significant for false alarms
(FG/78)=5.14, p<.0]), but not significant at the
.05 level for missed faulis. The interaction of ses-
sion by period was significant for both missed
faults (F(3/78)=4.43, p<.01) and false alarms
(F(3/78)=3.02, p<.05), although in neither case
did the patterns of cell mean differences lead to
meaningful conciusions. Because the pilot study
had suggested the possibility of sex (gender) dif-
ferences in performance, the analyses included
gender as a between-subject variable. Neither
analysis revealed any significant main effects or
interactions attributable to gender. Consequently,
the tables show only combined data of both sexes.

Some comments regarding the increase in
false alarms both within and between sessions is
in order. A possible increase in fatigue within a
session seems a plausible explanation for the in-
crease in missed faults. Subjects presumably be-
came less attentive and more careless. However,
it is somewhat puzzling to see how increasing
tiredness could also result in increases in false
alarms. False alaxms should logically occur only
when a meter indication resulting from “noise" is
wrongly attributed to a crack. In this task, how-
ever, most erroneous meter indications seemed to
resuit from a subject passing too close to 2 rivet’s
edge. The time spent examining each rivet stead-
ily decreased across sessions, and this couid indi-
cate less-careful examination of individual rivets.
Less-careful examination would likely increase
the number of times a rivet was touched, with the
resulting meter deflections misinterpreted as
faults.

7.2.2 Rating Scale Variables
7.2.2.1 Pre-io Post-Task Changes

Measures of attentiveness, tiredness, strain,
interest, and annoyance were obtained for each
subject at the beginning and end of the moming
and afternoon sessions of the second day. In ad-
dition, items relating to perceived task difficulty
and effort required to maintain alertness were also
administered at the end of the morning and after-
Noon sessions of this second day. Mean pre- and
post-task values for each rating variable are
shown in Table 7.3.



Reliability in Aircraft Inspectior:: UK and USA

Chapter Nine

Several managers with hangar responsibility
have responded to this suggestion positively and
said that they certainly consider paying compen-
sation to get the right employee.

Job advertisements in the aeronautical press
frequently mention bonding as one of the condi-
tion of employment. In view of the legal situation
this should be discontinued.

The most appropriate source of actions on the
above suggestions would be the representative
groups such as IATA and ATA, rather than the
regulatory bodies.

9.4.5 Working Times

Both Countries: Because of airline flight
schedules being confined largely to daytime op-
erations, it follows that much regular inspection
and maintenance activity involves night work. In-
spection in particular must precede maintenance
in heavy checks, so that there is considerable
pressure on the inspection department to complete
the incoming inspection in a timely manner. This
is usually achieved by a mixture of shift work and
overtime.

UK Variations: in many maintenance organi-
sations, shift work is allocated generally across
the organisaiion, with rotating shifts and moderate
use of overtime and weekend work, although in-
spectors still voice complaints about shift lengths
and allocations.

US Variations: In many airline maintenance
operations, shift work is allocated on the basis of
seniority. Thus the bulk of the socially-unpopular
night work is given to junior inspectors. Rela-
tively high amounts of overtime are worked
whenever an aircraft arrives for maintenance. At
some Sites an additional problem was caused by
the maintenance site being located in an area
whose housing costs are too high for maintenance
and inspection employees, leading to long com-
mutes, usually by private automobile cue to the
lack of public transport at shift change times.

Evaluation: Inspection ~vork can involve
constant afertess in the face of little stimulation.

with some use ef complex decision making. Both
of these activities show degraded performance
under conditions of sleep loss or disrupted
schedules. To mitigate these effects despite a
continuing requirement for night operations re-
quires the detailed application of human factors
knowledge relating to shift work (e.g.
Schwarzenau et al, 1986). Shift workers rarely
invert their body rhythms. so that a fre-
quently-rotating system is to be preferred to Gne
with long blocks of time on each shift. Because
organisation of working time is so heavily influ-
enced by social needs, the system used should be
a simple as possible for predictability. Obviously,
spreading night work over a larger population,
rather than having some groups bid out of it, will
minimise the overall effects of shift work, and
prevent the concentration of experience onte the
day shift. As with considerations of overtime,
there are historical reasons for the current sys-
tems. so that any change will not be easy in or-
ganisational terms.

The situation is exacerbated by the lack of
unanimity amongst workers: some preferring 12
hour shifts; others, night work etc. A solution in-
volving rotating shifts or, at least, volunteering for
the generally less popular shifts and some form of
flexi-time might be attempted although the prob-
lems at shift-change could be too complex.

Overtime for inspectors is. in general, nota
good idea from a strictly technical, haman factors
viewpoint. Data from laboratory studies shows
decreased detection abilities with prolonged
work, although degradation of decision perform-
ance in job operations is more difficult to docu-
ment. When combined with long commutes
involving active driving, there are also implica-
tions for worker safety at the end of an overtime
peried as well as for job performance.

9.4.6 Demand and Supply of
Mechanics/Inspectors

Both Countries: The typical progression to
inspector is from mechanic, so that the supply of
inspectors is largely dependent upon the survivor-
ship function of mechanics. With the increased
demands for inspection, caused in part by ageing

ADA294756


ACKNOWLEDGMENTS

The research team would like to thank Ms. Jean Watson, Office of Aviation Medicine, for
her assistance end support during this program.

The authors also wish to thank the many government and industry personnel who continue
to cooperate with the research team. As the work continues, the number of contributors (FAA
entities, air carriers, and consortiums of industry groups) has grown beyond a reasonable size
to individually list all those who have provided guidance and cooperation.

it

ADA294756


Ergonomic Factors Related to Posture and Fatigue in the Inspection Environment Chapter Five
By Task
5 >
44
4
| 34
25 i
i
2 2)
j 14 1.6 | i
| H
i) =
Aft Cargo Stabilizers Tall Interior Wheel We!!
FTC = Difference Values (End of Task - Beginning of Task) i

Fatigue Over

<
of
)
Vi
Law

100 -.
‘Weighted Workload

ry
i
4.

: Mental :
Demand

& Physical
Demand

& Tempora!
Demand

@ Performance

i Frustation

” Effort

162


Appendix 2-A Evaluation Forms Chanter Two

Wouitd you use this computer in the field as part of your job? Yes No

If not, why not?

Evaluation of Computer D 2/2



Chapter Four Appendix - Example Output from Ergonomic Audit

10. Excessive number of tasks per action statement. More than 3 actions/step
increases the probability of action slips.

NUMAN FACTORS MISMATCRES/RECOMMENUATIONS In PRE-INSPECTION/COmMUNICATION

WOMAK FACTORS MISMATCHES/PECOMMEMMATTONS TH PRE-INSPICTTOW/UTONAL, CHARACTERTSTICS
1. Mercury Vapor lamps: ‘Poor* color rendition properties. Color rendition is the
ability to distinguish true colors correctly. This is especially useful in detecting
corrosion faults. For best results consider incandescent bulbs.
2. No "shades/shields" on illumination sources. This may cause ‘direct’ or

“disability* glare.

HUMAN FACTORS MISMATCHES/RECOMMENDATIONS IN PRE-INSPECTION/ACCESS

ACCESS - STEP LADDERS

1. The neight of the step ladder is 36.09 inches. The maximem height should be
27 inches.

ACCESS - TALL STEP LADDERS

HUMAN FACTORS WISMATCHES/RECOMMENDATIONS IN INSPECTION/DOCUMENTATION-PHYSICAL HANDLING &
ENVIRONMENT FACILITY

2. The inspector does not sign off
of omission.

2. Writing tools do net faci
workeard holder.

3. The inspector does not discrepancy shee
as fault is detected. ‘This may lead to errers of

HOMAN FACTORS MISMATCHES/RECOMMENDATIONS IN INSPECTION/COMMUNICATION

1, The inspector felt that verbal instructions from the supervisor were not explicit.

ng the task. Consider

2. No performance feedbac S given to the inspectc: .
@n inspector was not

intermittent supervision by the superv.
performing up te standards.

3. The inspector was not encoura:
Desi:

4. The inspector was +
Procedures”

HUMAN FACTORS MISHATCHES/RECOMMENDATIONS IN INSPECTION/TASK LIGHTING

= mation is 72.59 foor canéle ‘fcr
The recommended task ilt tion should be 2
high.

i"

2. Hand lamps ¢
inadequate contr’

lamps

81



Ergonomic Audit for Visual Inspection of Aircraft

Chapter Four

Thus, results were different between the two
auditors. Since the significant test did not indi-
cate which questions had different responses be-
tween the auditors, these had to be determined by
post-hoc investigations. As these differences vere
found. the audit program was redesigned to pro-
vide a checklist giving identical results for each
auditor.

There are two ways to compare differences
between the auditors: by module and by question
type. First, the mismatches between the two
auditors were determined for each of the 18
modules; these results are shown in Figure 4.2.
The modules on Posture and Task Lighting
showed the greatest number mismatches, but ex-
amination of these moduies did not reveal a trend
in the type or the number of mismatches.

In order to better understand these disparities,
checklist questions were divided into three cafe-
gories, dependent upon the type of question and,
hence, upon possible errors in answering the
question. Thus, any question on the checklist ¢i-

ther result in either a Reading-Off Error, an Op-
erator Perception Error, or an Auditor Judgment
Error. Overall, 54% of the questions were read-
ing-off type questions; 24% operator perception
type; and 21% auditor judgement type. Figure
4.3 shows the percentage of each error type in-
spectors made on each of the three tests.

As seen in Figure 4.3, most errors were due
to auditor judgement, followed by operator
perception. Reading-off errors contributed a
very small percentage to the total errors.

Thus, in order to reduce the mismatch be-
tween auditors, auditor judgement errors have to
be reduced to the minimum. This can be achieved
by the following strategy:

* Have more explicit instructions assigned

to auditor judgement type questions

e Reduce the number of “auditor judge-

ment” type questions and increase the
number of “read-off" type questions.

* Provide better taining for auditors.

| {

{ft |

7 u

audit 1 S58T phase Ill insp
EEE audi! 2 wing insp
5 GREE audit 3 tavatory insp

frequency of mismatches

6 7 8

4 23 4 5 9 10 11 12 13 14 15 16 17) 48] |
“at —e| << oad meal
pre-insp mspecuon (INED 4 post} |
Iase}f

ADA294756


Chapter One

Phase IV Overview

ness Handbook. This edition of the HIS was re-
leased on a CD-ROM (Figure 1.3) in May 1994.

1.6 CORRELATES OF INDIVIDUAL
DIFFERENCES IN NONDESTRUC-
TIVE INSPECTION PERFORMANCE
(CHAPTER SEVEN)

A previous report reviewed literanire related
to differences in inspectors’ NDI proficiency
(FAA/AAM & GSC, 1993b: FAA/AAM & GSC.
in press). Several variables were identified which
would appear potentially relevant to NDI inspee-

tor selection and/or proficiency:

Boredom Susceptibility
Concentration’ Attentiveness/ Distrac-
tbility

Extroversion/Impulsivity
Motivation/Perseverance

Decision Making/Judgement
Mechanical/Electronics Aptitude
Need for Autonomy

eeeene

The goal of Phase IV research was to deter-
mine the relationship between selected tests and
measures derived from the above category and
performance on an NDI task. Research also in-
vestigated possible performance changes from
sustained performance during a simulated one-
day shift and interactive effects between pertorm-
ance changes and the variables identified above.

Chapter Seven reports on the findings of this re-
search.

1.7 RESULTS OF THE
ENVIRONMENTAL CONTROL
SYSTEM TUTOR EXPERIMENT AT
CLAYTON STATE COLLEGE
(CHAPTER EIGHT)

Chapter Eight describes an investigation to
determine the effect of an Intelligent Help Agent
(THA) on the effectiveness of computer-based
training. The training system used was. the Envi-
ronmental Control System (ECS) Tutor, a simu-
lation-based trainer developed in previous phases
of this research (Figure 1.4). Subjects used the
ECS Tutor either with or without an error-driven
IHA. Xo significant difference in performance
was found between the two groups. Other find-
ings are also discussed in the chapter.

1.8 RELIABILITY IN AIRCRAFT
INSPECTION: UK AND USA
PERSPECTIVES (CHAPTER NINE}

The CAA and the FAA co-sponsared an in-
vestigation of reliability in aircraft inspection in
the United Kingdom (UK} and the United States
of America (USA). Aircraft inspection sites a
both countries were visited with an analysis made
of the overall inspection‘maintenan:
of larger floor operations. Similarities were more
common than differences due to the technical
specification of the tasks, regulatory similurities.
and skill and motivation of inspectors. Larger

ADA294756



Chapter Two Appendix 2-C_ Software User Manuals

i)

NEW: Creates a new PTPS form, with a new Record ID Number. This Record ID Number is
temporary and can be used to help you track your own forms. A permanent Record ID Number
will be assigned when you transfer your data to FSAS. Temporary Record [D Numbers can be
recognized by the word TEMP in the middle.

OPEN: Opens a previously saved PTRS form for subsequent editing. This opened form will
either use a temporary Record ID Number or a Record ID Number. Along with the Record ID
number, PENS provides the Activity number, Designator, Aircraft, Status, Results, and
Verification status to help you identify the desired file. You can also specify an activity code
and 2 designator, PENS will list only these Record IDs. (See Section 2.1 for more detailed
information.)

SAVE VERIFY: Checks the PTRS data to ensure that Il required fields have been completed
and that there are no conflicts between data. You will be notified of either case, When a form
does not pass the verification, you will be returned to the PTRS form. Thick black borders will
be placed around fields that need correction. Modify the form and re-verify the data. Only
verified forms can be transmitted to FSAS.

SAVE: Saves the current file without any verification.

PTRS: Accesses the PTRS screen.

Job Aid (Not currently functional): Accesses the Job Aid screen for your PTRS activity if
there is one available. Any data you record on the job aid will be automatically shared with the
PTRS form and vice veisa.

REFS: Accesses the on-line versions of the Federal Aviation Regulations and the Inspector's
Handbooks. Which handbook is selected depends wpon the inspection type. (Currently, only
the Airworthiness Handbook is available.) These on-line documents aliow you to quickly find
specific information without having to thumb through the bulky paper buoks. Specific heip for
these on-line references is available when you are using them.

AIRCFT (Not currently functional): Hlustrates an improved capability to document visual
inspection. PENS provides line drawings for some Bocing and Airbus aircrafts. You can then
mark the area of defects and add your comment to the drawings. If the FSAS database were
modified properly, these drawings could then be saved with the PTRS data.

45

ADA294756


Chapter Ten Guidelines for Designi

ing and implementing CBT for Aviation Maintenance

10.2.3 Screen Design and Layout

This section describes the issues involved in
designing and laying out information on the com-
puter display.

Bibliography:

Engel, S.E. and Granda, R.E (1975). Guidelines
for man/display interfaces (Technical Report TR
00.2720). Poughkeepsie, NY: IBM

Helander. M. G. (1987}. Design of visual dis-
plays. In G. Salvendy (Ed.) Handbook of Human
Factors. New York: John Wiley & Sons, pp.
507-548,

Sewell, D.R., Rouse, W.B., and Johnson, W.B.
(1989). Initial evaluation of principles for graphi-
cal displays in maintenance problem solving
(Tech REpt. No. ST-TR-8817-061). Auanta, GA:
Search Technology.

Smith, S.L. and Mosier, J.N. (1986). Guidelines
for designing user interface software (Technical
Report ESD-TR-86-278). Hanscom Airforce

Base, MA: USAF Electronic Systems Division.

Tullis, T.S. (1988). Screen design. In Handbook
of Human Computer Interaction. Notth Holland:
Elsevier Science Publisher B.V., New York, NY,
377-407.

10.2.2. Screen Organization

Screen organization is important to the for the
users to be able to quickly understand any com-
puter screen. There is no one “optimal” design for
any particular tasks, although there are many
features that can decrease the quality of a sczeen.
Designers should strive for consistency within
each program and between other programs.

Bibliography:

Galitz, W. O. (1985). Handbook of screen formar
design. Q. E. D. Information Sciences, Wellesley.
MA.

Helander, M. G. (1987). Design of visual dis-
plays. in G. Salvendy (Fd.} Handbook of Human
Factors. New York: John Wiley & Sons, pp.
507-548.

167

Tullis, T.S., and Helander, M. (1988). Screen de-
sign. Handbook of Human-Computer Interaction.
North-Holland, New York, NY, pp. 377-411.

10.232 Color

Color is extremely useful for dividing a dis-
play into separate regions. Also, color differences
will be useful in a visual search task for particular
items, provided the user knows about the differ-
ences in advance. A minimum number of colors
should be used, because a large number of colors
for coding will increase the search time. Motiva-
tional effects of coloring display are complex, no
firm recommendations can be made. However, it
is noticed that viewers do express a preference for
color even when it does not objectively improve
their performance.

Bibliography:

Christ, R. E. (1975). Review and Analysis of
color coding research for visual displays. Hienan
Factors, 17(6), 542-570.

Davidoff, J. (1987). The role of color in visual
displays. In DJ. Osbome (Ed.), International
Reviews of Ergonomics, 1, 21-42.

Murch, M. M. (1984). Physiological principles
for the effective use of color. IEEE CG & A, No-
vember, 49-54,

Thorrel, L.G. and Smith, W.J., (1990). Using
Computer Color Effectively. New Jersey: Pren-
tice Hall.

410.2.3.3 Typography

Typographic design has the goal of making
text readable and understandable. When display-
ing text on a computer, there is a tradeoff between
limited screen space and legibility of the fonts.
Designers should consider the target users, com-
puters, and environment when designing a text
display.

Bibliography:

Marcus, A., “Typographic Design for Interfaces
of Information Systems, Proceedings of Human
Factors in Computer Systems, 1982, pp. 26-30.



Chapter Five

Ergonomic Factors Related «

Posture and Fatioue in the Inspection Environment

deterioration in the efficiency of human perform-
ance duzing prolonged work. Tiius, an adequate
visual environment is crucial to ensure acceptable
performance in aircrait inspection. In addition,
poor lighting demands that ‘uspectois adopt a
certain posuure for task performance by forcing a
specific visual angle. Thus, restricted areas fre-
quently force inspectors to adopt awkward head,
neck, and back angles induce stress and fatigue.
In addition. inadequate lighting requires inspec-
tors always co hold their flashlight in one band:
Ukewise, awkward portable lighting forces them
continually to struggle with and reposition the
lighting (Reynolds and Drury, 1993).

S.2.L5 __Social Factors

Social aspects of the environment may also
increase fatigue. As the number of people within
a given area increases, the amount of space for
any single person decreases. Uncomfortably close
spacing among individuals may limit their irdi-
vidual environmental tolerance. When mary in-
dividuals in the same area perform the same
tasks, the available resources may become lim-
ited, and people may become frustrated, e.g.
when specialized/portable lighting is not avail-
abk). Also, when more people share the same
space, there is an increased likelihocd of physical
interference among tasks.

5.1.1.6 _. Surface Condition

The surface condition of many work areas io
an aircraft hangar nas been noted to be poor:
dirty, uneven, cr rough. These surfaces cause in-
spectors either to limit the postures they are will-
ing co adopt or force them to adopt inefficient
postures. For example, operators may not sit ina
certain area to avoid oil-soaked clothing; instead,
they may stoop or crouch to perform the task.
These surfaces also present a safety concern, at
times causing inspectors to slip or trip. Further-
more, continued kneeling or laying on rough or
uneven surfaces can cause recurring aches and
pains.

In summary, the effects of restricted space
and its associated posture effects have been hy-
Pothesized to be the largest contributor prodhice a
fatigue response. possibly also affecting inspec-
tors’ workload and performance. The present

evaluation focuses on this factor while simultane-
ously considering other factors within the aviation
environment.

5.2.2. Physical and Perceived Spaces

Note: Sections 5.2.2 to 5.2.7 are included
from the Phase II Volume I progress report as
they form the basis for the studies undertaken.

The above factors can directly affect working
conditions. The workspace has physical charac-
teristics which can be easily defined and investi-
gated. but the operator also perceives the physical
space. Thus, the effective workspace is partially
created by physical elements within a fixed space
and partially by perceived elements. It is not nec-
essarily constant, but depends upon an individ-
v.""3 constantly changing perceptions. The effects
of this effective space must be inferred, as direct
observation is not logically possible.

3.2.3 Stress

It is logical to model inspector’s working
conditions within a traditional stress framework,
where extreme conditions act as a stressor. Con-
text-dependent examination of the factors allows
the specific stress-inducing situation to be de-
fined. Determining subjects’ perceptions assists in
interpreting their behavior (Meister, 1981). Thus,
field investigation is important for understanding
the specific response to aircraft maintenance/
inspection activities. In an effort to define stress
operationally, the we employ the following defi-
nitions (Alluisi, 1982; Pratt and Barling, 1988):

Stressor - The environmental, operator, and
task characteristics comprising the werk area and
impinging on the individual. In this context, both
physical and perceived spaces are the stressors.

Stress - A state within the individual caused
by the stressor’s perceived magnitude. The exis-
tence and interaction of various environmental,
operator, and task characteristics dictate the in-
tensity of stress.

Aircraft inspection performance normally
both physical and cognitive demands. Differen-
dating the stress these demands induce helps

ADA294756


Guidelines for Designing and Implementing CBT for A

vigton Maintenance

i Chapter Ten

Meyer, G.W., Rushmeier, H.E., Cohen, M.F.,
Greenberg, DP., Torrance, K.E. (1986). An ex-
perimental evaluation of computer graphics im-
agery. Association of Computing Machinery
Transactions on Graphics, 5(1), pp. 30-50

Verplank,W.L. (1988). Graphics, challenges in
designing object-oriented user interface. In
Handbook of Human Computer Interaction.
Nosth Holland: Elsevier Science Publisher B.V..
New York, NY.

oo.

An animation can be used to explain a proc-
ess or to demonstrate the steps of a procedure.
Examples include animations of flows in electri-
cal and hydraulic systems and animations of the
installation procedure for an avionics component.
Designers should:

® Makes the program more engaging

« Donot make longer than necessary

Bibliography:

Palmiter. S., Elkerton, J. and Bagget, P. (1991).
Animated demonstrations vs. written instructions
for learning procedural tasks: A preliminary in-
vestigation. international Journal of Man-
Machine Studies, 34, 687-701.

Park, O. and Gitielman, $.S. (1992). Selective use
of animation and feedback in computer-based in-

struction. Educational Technology Reseavch and
Development, 40(4), 20-38.

Rieber, L.P. (1990) Animation in Computer-
based instructior_ Educational Technology Re-
search and Design, 38(1}, 77-86.

1022.4 Audio

Audio, including narration, equipment
sounds, and musical accompaniment. is used to
add realism, increase entertainment factor, or
coramunicate long text passages. Designers
should:

e Not overuse; have a reason for using it

e Allow user to contro! volume, tum off

Bibliography:

Bly, S. (1982). Presenting Information in sound.
In Proceedings of Human Factors in Computer
Systems, 371-375.

Sorkin, R.D. (1987). Design of Auditory and
tactile displays. In G. Saivendy (Ed.) Handbook
of Human Factors. New York: John Wiley &
Sons, 549-576.

102.25, Video

Like animation, video can be used to describe
@ process or to show a procedure. Video differs
from animation in that it is a more accurate repre-
sentation of the "real world” and usually has an
accompanying soundtrack. Since video is more
realistic than animation, it is usually better for de-
seribing procedures such as test or installation
steps that a technician will perform on the job.
Computer system designers should:

* Give user contro} over playback

e Match purpose with video quality

Bibliography:
Fritz, M. (1993, January). Is interactive videodisc
dead yet? CBT Directions, pp. 24-32.

Pearce, M. (in press). How much is enough?
Choosing a computer-based video technology. In
Proceedings of the Second Annual Conference on
Multimedia in Education and Industry.

Silber, J. (1992, May/June} FlightSafety and the
DVI medium. {nstructional Delivery Systems, pp.
9-13.

Singh, R. (1986). Interactive video in education
and training. In K. S. Gill, (ed.} Artificial Intelli-
gence for Society. Chichester etc.: Wiley, pp.
229-234.

Swartz, M., Wallace, D.. and Tkacz, S. (1992).
The Influence of frame rate and resolution on
human performance. In Proceedings of the Hu-
man Factors Society 36th Annuai Meeting, pp.
1440-1444.


Chapter Four

Ergonomic Audit for Visual inspection of Aircraft

CHAPTER FOUR
ERGONOMIC AUDIT FOR VISUAL INSPECTION OF AIRCRAFT

Sanjay Koli and Colin Drury
State University of New York at Buffalo
Department of Industrial Engineering

John Cuneo
National Helicopter

Jay Lofgren
Continental Airlines

4.0 ABSTRACT

As more demonstrations of applying human
factors interventions in aircraft inspection have
been completed, the need has arisen to give air-
lines a too} te determine which interventions are
most urgent in their own operations. An ergo-
nomics audit was developed to provide a rapid
evaluation of potential human/machine mis-
matches in any inspection task. The audit con-
sists of a method of choosing tasks to be
audited, an audit checklist, and a computer pro-
gram evaluating checklist responses against na-
tional and international standards to produce an
audit report. An evaluation of all three parts of
the system showed that inspectors made consis-
tent judgements for choice of tasks, that the
audit checklist gave consistent reliability among
auditors, and that the computer program pro-
duced valuable results for the airline parmers
cost-effectively.

4.1 INTRODUCTION

An aircraft’s structure is designed to be used
indefinitely, provided that any defects arising
over time are identified and repaired correctly.
Most structural components do not have a de-
sign life but rely on periodic inspection and re-
pair fer their integrity. The primary defects are
cracks and corrosion, resulting from the inter-
mittent flexing of structures when in the air,
from pressure loads, and as a result of weather-
ing or chemicals.

inspection, Jike maintenance, is scheduicd
regularly for each aircraft. Each schedule is

67

tanslated into a se’. of workcards. Equipment
impeding access to the inspected area is re-
moved. The aircraft is then cleaned, and the ac-
cess hatches are opened. This is followed by the
inspection process. Inspection can be described
as a complex socio-technical system exerting
both mental and physical stress on the inspectors
and on other organizational players (Drury,
1985). Ata more detailed level, the inspection
task can be broken into a set of subtasks which
follow a logical order (Table 4.1).

With these seven task steps, the complex
problem of error control, design of equipment
used, and environmental issues become more
manageable as specific human factors knowl-
edge is brought to bear on each issue in tum.

Arising from human factors analyses of in-
spection tasks, a number of studies have been
completed under the auspices of the Federal
Aviation Administration, Office of Aviation

line industry have considered improved lighting
(Reynolds, Gramopadhye, and Drury, 1992},
better documentation design (Patel, Prabhu, and
Drury 1992), revised training for visual inspec-
tion (Gramopadhye, Drury, and Sharit, 1993)
and the impact of posture and restricted space
(Eberhardt, Reynolds, and Drury, 1993). The
aim of these studies has been to atlow airlines to
benefit from ergonomics without their necessar-
ily having wained ergonomists. There is now a
need to provide integrative tools enabling a
maintenance organization to develop an overall



Appendix 2-A_ Evaluation Forms

Chapter Two

New Entry, Save Entry, Clear Entry

Section IV, Comments
Primary

Key Heading

Key Word

Opinion

Clear Comment

Erase Last Ink

Erase All Ink

Undo Last Erase

Transcribe

Transcription Screen
Scratchpad Entries

Transcribed Text

Done For Now, Keep Ink

Done, Erase Ink

PENS Software Evaluation 4/6

26


Chapter Two Appendix 2-C Software User Manuals

3. If you know the Activity Number, you may write or type the number in the Activity # field instead of
performing step 2. PENS will automatically fill the Inspection Type. Section, Heading and Subheading (if
available) information.

Once you have entered an activity number, the FAR field will contain a list of relevant FARs for that
Y number. Select the appropniate FAR for the activity.

5. Hit one of the following buttons to continue:

CLEAR: Erases all input on the Login screen.

NEW: Creates new PTRS form with the information from the Login screen. If a backup PTRS exists.
PENS will give you a choice to restore or delete the backup.

OPEN: Opens a specific PTRS form. (See section 2.1)

CANCEL: Cancels the operation and exits from the PENS software.

2.1 Opening an existing PTRS form

The OPEN button accesses the Open Screen (Figure 1). The screen displays the Record ID Number for ail
PTRS forms found in the database. When the FSAS button is checked, PENS will display only the PTRS
forms in the FSAS database. Likewise. PENS will only display PTRS forms in the temporary directory
when the TEMPORARY bunon is checked. When a form is selected. PENS also provides the Activity
number, Designator, Aircraft, Stars. and Verification status to help you identify the desired PTRS forni.

‘Open Existing Form .
2 Activity FAR MEG Desig Make/Model Calltp statis Results

: ACHEDR-100 Cc a
WA-BTS c A

c c

we A

e A

e c

Lo, ¢

2es, c

AERMER-F BL: e €

1-22 c c

T-a3 c c

WA-B25 é c

Figure: 1.” The’Open Screen

34

ADA294756


Hypermedia Information System

Chapter Six

6.1.14 Searching

One of the most powerful features of a hy-
permedia system is its ability to quickly locate
specific information in large amounts of text
without forcing the reader to scan each line. A
reader searches by typing a query, as shown in
Figure 6.4. The HIS then rapidly searches all
documents in the library. The HES then dispiays a
list of Topics satisfying the query, also shown in
Figure 6.4. The reader can select one of the
Topics to view. When the selected Topic's text is
loaded, the search hits are highlighted, as shown
in Figure 6.5. To see other search hits, the reader
can either scroll through the text or use the mag-
nifying glass icons in the icon bar (Figure 6.5} to
go to the previous or next occurrence.

The HIS supports four types of searching:
term, wildcard, phrase, and Boolean. A term
search is a search for a specific word such as
aviation that is not a stopword. A stopword is a
word occurring so frequently in the document that
itis not important, such as the or and. Every
Topic containing the search term is listed ir the

A wiidcard search allows the reader to look
for variations of a term such as administrate, ad-
ministration, administer. The reader can append a
term or partial term with either an asterisk (*)
wildcard or a question mark (?) wildcard. The
asterisk represents zero or more characters, and
the question mark represents zero or one charac-
ter.

A phrase searching enables the reader to
specify the order and adjacency of multiple
search terms. For example, phrase searching for
“federal aviation administration" only displays
places where that exact phrase appears. The
reader specifies a phrase search by placing quotes
around the target phrase.

A Boolean search combines any/all of the
above types with Boolean operators (AND, OR.
NOT), as in “federal aviation administration" or
faa not airplane. \n this example. the search
would retum a list of all Topics containing either
federal aviation administration or faa. but not
containing airplane.

Search Query Dialogue Box.
= Galaxy Hypermedia igs]
File Edit Bookmarks Search Qutline Windows Help

ive for 2 period of not more than 90 43]

[o Swme Paragraph: |

, or revoked

Topics Found:

issued uncer this part that 1s su:
strator’s request, rerum it to

Section 141.5
Section 141.25
Section 141.43
Section 141.53
Section 141.63
Section 141.65
§ {Section 141.67

Section 141.73
Section 141.83
Section 141.87

2900, w apended by Amat 163-2, 22 FR 13574,

ment of lost er destroyed certificas
ge of name on 4 certificate issued
bed by the applicant's current certifi

urt order, or other document verifjia,

retumed tc the applica after inspect

110


Appendix 2-C_ Software User Manuais Chapier Tee

Remarks: For an examiner's certification activity, enter the certificate numbers of the applicant or
recommending instructors. Otherwise, enter any relevant data about the individual.

3.2 Section Il - Equipment
Current Manofacturer: Lists all manufacturers of the equipment or tools that are the subjects of the
inspector's evaluation or inspection. Selecting an entry from the list will display the data on that equipment

and enable you to modify the data. The default list is empty.

To record an entry into the database. enter the information to the corresponding fields and hin SAVE
ENTRY or NEW ENTRY tanon.

To erase an entry, select the desired entry from the Current Manufacturer list and hit CLEAR ENTRY.
Manufacturer: Enter the name of the manufacturer of the equipment. compouent. or tool.
Model: Enter the made] of the equipment, component, oF tool.

Serial #: Enter the serial number of the equipment, component, ar tool

Remarks: Enter any relevant remarks about

3.4 Section 1V-- Comment

Section 1V gives you the ability to classify observations or evaluations into specific areas of interest. The
fields: Primary, Key Heading, and Key Word, provide the means of this classification. It also contains a
special area where you can jot down short notes without the notes being wanslated to printed characters.
When you have the time, you can click the TRANSCRIBE button, which will bring up a new screen that
shows your notes. You may transcribe those notes, including adding information, vnti) you have completed
that comment. When you have completed the comment, press the DONE, ERASE !NK button or DONE,
KEEP iNK button. You must erase the ink before the PTRS form can be verified.

Primary: Select the general comment classification.

Key Heading: Select one of the headings.

Key Word: Select one of the key words for that heading.

Transcribe: Accesses a screen where vou can transcribe the short notes you have entered in the fie!d.

4. PENS Function Buttons

PENS Functions buttons are located on the right side of the screen. The available functions are:


Correlates of Individual Differences in NDI Performance

Chapter Seven

Drury, C. G.. Gramopadhye, A., Latorella, K.,
Patel, S., Prabhu, P.. & Reynolds, K. (1992).
Human reliability in aircraft inspection. Phase 1
Peport on FAA Contract to Galaxy Scientific
Corporation. Atlanta, Georgia.

Drury. C. G.. Prabhu, P.. Gramopadhye, A., &
Latorella, K. (1991). Nondestructive testing in
aircraft inspection. Report of a pilot study pre-
pared under subcontract 89-1014-SC-3 to Galaxy
Scientific Corporation. Mays Landing, New Jer-
sey.

Eysenck, H. J. (1967). The biological basis of
personality. Springfield. Minos: Thomas.

Farmer. R. & Sundberg. N. D. (1986). Boredom
proneness - The development and correlates of a
new scale. Journal ef Personality Assessment,
£0.4-17.

Federal Aviauon Administration Office of Avia-
tion Administration and Galaxy Scientific Corpo-
ration (FAA/AAM & GSC). (1993). Human
factors m aviation maintenance - phase three.
volume J progress repo. DOT/FAA/AM-93/15,
Office of Aviation Medicine. Washington. D. C.

Federal Aviation Administration Office of Avia~
tion Administration and Galaxy Scientific Corpo-
radeon (FAA/AAM & GSC). (in press). Hranan
factors maviason maintenance - phase three,
volure H pragress report. Office of Aviation
Medicine. Washington. D.C.

Gallwey. T. J. (1982). Selection of tests for vis-
ual inspection on a multiple fault type task. Er-
gonomics, 25. 1077-1092.

Galhwey T. J. d& Drury. C. G. 19861. Task
complexity tn visual inspection. Human Factors,
28. 385-606.

Goodenough. D. R..& Karp. S.A. f196@1). Field
depend: \d inteHecmal functioning. Journal

of Abnormal and Sacial Psvchalogy, 63, 241-246.

Jackson. D Mo1197-18. Personaliry Research
Form Manual. New York: Goshen.

Kagan, J., Rosman, B., Day, D., Albert, J., &
Phillips. W. (1964). Information processing in
the child: Significance of analytic and reflective
attitudes. Psychological Monographs, 78, (1,
Whole No. 578).

Karp. S. A. (1963). Field dependence and over-
coming embeddedness.
Journal of Consulting Psychology, 27, 294-382.

Koelega. H. S. (1992). Extraversion and vigi-
lance performance: 30 years of inconsistencies.
Psychotogical Bulletin, 172, 239-258.

Latorella. K. A., Gramopadhye, A. K., Prabhu. P.
V., Drury, C. C., Smith, M. A.. & Shanahan, D.
E. (1992, October). Computer-stinulated aircraft
tasks for off-line experimentation. Paper pre-
sented at the Annual Meeting of the Human Fac-
tors Society, Atlanta, Georgia.

Lewis. W. H., Pless, W, M. & Sproat. W. H.
(1978). Reliability of nondestructive inspections -
Final report. Report No. SA-ALC/MME 76-6-
38-1, Lockheed-Georgia Company, Marietta,
Georgia.

Munsinger. H. & Kessen, W. (1964). Uncer-
tainty. structure and preference. Psychological
Monographs: General and Applied, 78, Whoie
No. 9.

Pearson, D. W. & Thackray. R. J. (1970). Cansis-
tency of performance change and autonomic re-
sponse as a function of expressed attitude toward
aspecific stress situation. Psychophysiology, 6,
361-568.

Poulton. E. C. (1973). The effect of fatigue upon
inspection work. Applied Ereonomics, 4.2, 73-
83.

Router, J. B. (1966). Generalized expectancies for
intemal versus externa! control o, reinforcement.
Psychological Monographs: General and Ap-
Plied, 80,1. Whole No. 699).

Rzepa. T. 19841, Typologicul determinants of
opera INctioning in monvutonous work condi-
tions. Pofise Psychological Bulletin, 13, 135-14}

ADA294756


x#
S

Appendix 2-C Software User Manuals Chapter 7

You can also search for a specific PTRS form. To do this. follow these steps:

Check the FSAS or the TEMPORARY button to identify the database to search on.

Enter a specific activity number in the Activity: field.

Enter a specific Designator Code in the DESIGNATOR field.

Hit the SEARCH button. All records in the database that match the search information will be
displayed in the FORM ID# box.

Tap the desired form to select it. (Corresponding information about the file will
6. Press OK.

feNm

”

3. PERS

The screen is divided into four sections (see below). Depending on the Activity number, thick black borders
will be placed on several fields. This border indicates that the informatin is required for the activity (detailed
instructions for completing the form are provided in each section).

Section I: Used for describint the PTRS activity, the overall results, the subject and other basic
information

Section I: Used for recording informatin acquired on personnel (other thaa those recorded in Section
i) during the accomplishment of the task. It is also used to record a certificate applicant's information
along with the recommending instructor's information fer a ainer’s certification
activity.

Section 1: Used for identifying a particular item that was inspected by manufacturer, model and
serial number (other than that identified in Section 1).

Section IV: Used for classifying observations or evaluations into specific areas of interest in a coded
format.

34 Section i -- Gererai

The following paragraphs i!lustrare how to fill out Section { of the PTRS Screen:

Inspector Name Code, Inspection Type, Activity Number and FAR: These fields are not editable. To
modify this information. hit the SELECT button next to the Activity Number or FAR field. This action
takes you to the PENS Login Screen where you can change the information.

NPG: Check the box if the activity is an NPG required surveiliance.

Status: Select Closed, Open or Planned from the status Hst.

Cailup Date, Start Date and Compietion Date: Modify these fields using the corresponding arrow
buttons. (Some of these dates are automatically filled based on the activity status.)

Results: Select one of the following result codes:
Completed: Indicates that the activity was compicted. It is used to close out all work activities except

Surveillance.

40

ADA294756



Ergonomic Audit for Visual Inspection of Aircraft

Chapter Four

© one which the supervisor and the em-
ployees can understand and are willing
to accept

© easy to execute

© able to produce a high degree of accu-
racy (Lanham, 1955).

A points system fulfills these requirements.
The system uses judgements of inspectors
and/or management to determine which factors
are important to error reduction.

The point system provides the rater with a
scale or a "yardstick" to use in measuring the
differences among jobs. In designing a point
scale, the following steps must be completed:

¢ Select and define factors common tc all
the jobs to be evaluated

® Allocate the number of degrees to each
factor (length of the rating scale)

® Weigh the factors, depending upon their
relative importance

© Assign point values to each degree of
each factor.

The task to be rated is measured, factor by
factor, against the scale. The degree on the scale
most nearly describing that factor’s situation in
that task is selected. The number of points which
have been assigned to that degree on the scale is
assigned io the job. When the proper degree has
been selected for each job factor. the point val-
ues for the listed degrees are totaled. This sum
represents the final point value of the job in
question.

In addition to the final point vatue, each task
can also be judged, based upon the value of the
individual factors. For example, if one crucial
factor of a generally low-rated task has been
rated exceptionally high, that task. too. will be
audited,

4.2.2 The Ergonomics Audit System

After deciding which tasks to audit, the form
and content of the audit system itself need to be
determined. Our audit was conceived as a two-
past system. The first part is a checklist, present-

ing the auditor with a set of ergonomic ques-
tions. Having answered the questions, the
auditor uses the second part, a computer pro-
gram, to compare the answers against ergo-
nomic standards and to prepare an audit report
detailing the inspector/system mismatches.

The audit’s aim is to determine which as-
pects (task, operator, machine, environment)
may impact inspector-system mismatches. The
content of the audit checklist could use any con-
venient taxonomy of factors affecting human
performance. Following Prabhu and Drury
{1992) and Latorella and Drury (1992), the fol-
lowing taxonomy:

© Information Requirements - docu-
ments, communication

o Egquipment/Job Aids - design issues,
availability, standards
Environment - visua!, auditory, thermal
Physical Activity/Workspace - access,
posture, safety.

Although this taxonomy defines factors af-
fecting human/system mismatches, it is not in
the most convenient form for the auditor. To ex-
pedite auditing. it is preferable to turn to the ge-
neric task description found in Table 4.1 and to
restructure the audit to follow the sequence of
inspection tasks. These can be grouped into a
pre-inspection phase (Initiate), an inspection
phase (access, search, decision, respond), and a
post-inspection phase (repair, buy-back).

With this structure, it was possible to define
more clearly the features necessary in the
overall audit system. An audit system must have
the following features:

¢ is modular, so as to include maximum
coverage without unnecessary length.
Inserting new modules to modify the
checklist and program for a particular
industry is easy

¢ is self-explanatory, so as to minimize
training time for auditors

¢ is based on standards from ergonom-
icsfhuman factors

ADA294756


Appendix - Example Output from Ergonomic Audit Chapter Four

CHAPTER FOUR APPENDIX - Example Output from Ergonomic Audit

TO ?Ms Supervisor
FROM tA.N. Auditor

tt Inspection.

Task Description
1993

Date
tine

Stetion

Bay
Aircraft No.
M/E Bo.

Q/A No.

HUMAN FACTORS MISMATCHES/RECOMMENDATIONS IN PRE-INSPECTION/DOCUMENTATION

A. Information readability

i. Typographic layout of the current workcard is
cards. Maintain interdecument c:
a: Spatial organization b: Font

¢: Typographic cues (e.g., boidfaci

2. Make use of typographic cues. For spat y
a: Vertical spacing b: Lateral positioning c: Paragrapni

a: Heading positioning

thin the spatial layout use secondary type cues li
a: Bold-fa od B: Italics ¢: Capital cue.

3. Det matrix printers with a 5X7 matrix of dot characters is ménin
acceptable for reading purposes. If used, check for character speci
Minimum Character Height = 3.imm to 4.2Zmm
Maximum Character Height = 4.5mm
Width/Height re 25:4 - 4:5
IMPORTANT: De not use lower case letters, since features can get easily confused.

rw

ications:

sible.

ay B:

ration

4. Graphics/attachrents i
a: Photocopy deteriora
¢: Blueprint copy dete:

‘ and "QUALITY" standards to ensure

5. Standards are not prescribed.

consistent print quali

=. Informaticn Content

Text

6. Feedfcrward information not provided to the inspector. Present
a: previous faults detected locations of pricr faui
areas for the spec. task

Graphics

‘dy staticr. pos
d be presented in a

i

infermation shi

xS in the workeard.
the task would £

&. Incorrect sequenc
che natural orde:

pages at
ger tasks

shosld

. Avoid car:
a

86


oo

Chapter Two Appendix 2-B Training Slides

@ Stands for: Disk Operating System
@ Sasic operating level
@ Runs programs and stores data

@ Hierarchical organization of data

-files: lowest element
i ~subdirectories: hierarchies of files

i ~both are limited to eight fetter names and
three letter extensions: eg. filename.txt

Training Slide &-:

i |
' DOS (cont.)
i
storage devices ea
{letters are only examples) subdirct <_
A: ir <———— filenametyxt
floppy disk enuekair a
e <i ~ file2.txt
. re
hard disk ~~~.
{ ifn ee
; ——
; E: ae
solid state _

Training Slide +0--: *.-

33

ANA2DO47TRLR


Chapter Seven

Correlates of Individual Differences in NDI Performance

with performance on a task as constrained
and repetitive as eddy-current testing.

© Cognitive Structure. A measure of the need to
make meticulous decisions based upon defi-
nite knowledge with a dislike of ambiguity
and uncertainty. It was felt that this trait
might be positively related to search time, i.e.
the time spent in searching each rivet for
possible faults.

« Autonomy. A. measure of the need to be inde-
pendent and not to be tied down, restrained,
confined, or restricted in any way. This trait
was mentioned in the previous review report
as characterizing the most proficient inspec-
tors (FAA/AAM & GSC, 1993). This trait
was also identified by some NDI instructors
interviewed.

© Change. A measure of liking for new and dif-
ferent experiences. with a dislike and avoid-
ance of routine activities. Inclusion of this
trait is self-evident, since NDI tasks are quite
often referred to as boring and monotonous.

© Impulsivity. A measure of the tendency to act
on the “spur of the moment” and without de-
liberation. This was included as an additional
measure of impulsivity to be compared with
the impulsivity measure derived from the
MFFT.

213,10 Figue: Preference Test

The Figure Preference Test was a paired
comparison version of the Munsinger and Kessen
(1964) test of preference for complex versus
simple perceptual stimuli. Subjects chose which
figure of each pair they prefer from a set of 66
pairs of figure drawings differing in complexity.
A recent study of industrial workers determined
that preference for simple stimuli on this test was
related to preference for repetitive. unchanging
work requiring a constant focus of attention
(Rzepa, 1984). Because of the apparent similarity
of NDI inspection to tasks of this type, it was de-
cided to add the Figure Preference Test to the
battery of predictors.

7.13.11 Summary of Tests and Measures

The tests and measures described above were
included because it was felt that cach might serve
to measure some aspect of the variables men-

123

tioned under Section 7.7.3 as predictors and/or
correlates of NDI performance. A number of
these tests and measures are similiar and may in-
deed measure the same trait, aptitude, or ability.
However, one cannot always tell from test titles
and descriptors whether they measure similar
things: some were included to determine empiri-
cally the extent of their interrelationships, or lack
thereof.

7.1.4 Procedure

Each subject was tested over two successive
days. The moming of the first day was devoted to
administration of the various tests and measures;
during the afternoon, subjects practiced using the
mouse, were required to read and be tested on a
document describing eddy-current testing and the
need for it, and practiced the NDI simulation task.
Afternoon training procedures were essentially
the same as those used in the earlier pilot study.

Trainicg in using the mouse was provided by
a display program consisting of a enlarged picture
of a rivet head with a craining circle surrounding
it. The subject practiced using the mouse and cur-
sor to circle the rivet while staying within the cir-
cle. After each pre-selected block of training
tials, each subject received feedback on the aver-
age times required to circle the rivet and the aver-
age number of times the cursor head touched the
Tivet or went outside the circle. Training contin-
ued until the subject reached a consistent ievel of
performance. This usually required 15 to 30
minutes of practice.

Task training began with a short (20-rivet)
demonstration session in which the basic ele-
ments of the NDI task were explained. This was
followed by three training sessions each 60 rivets
Jong. Thirty percent of the rivets in each of the
three training sessions contained faults (cracks).
In addition, the second and third sessions also
contained small, but visible (2 mm), “noise” spots
at various locations at or near a rivet. The fre-
quency of “noisy rivets" was alse thirty percent.
The location of faults and noise was randomly
assigned for each task session (both training and
subsequent test tasks). Performance feedback
was automatically provided after each block of 10

anannages


Ergonomic Factors Related to Posture

Chantor Five
Chapter Five

Meister, D. (1981). The problem of stress
definition. In G. Salvendy and M.J. Smith (Ed.}
Machine Pacing and Occupational Stress, Lon-
don: Taylor and Francis.

Mital, A., (1986). Subjective estimates of load
carriage in confined and open spaces. In W.
Karwowski (Ed.} Trends in Ergonomics/Human
Factors Hf, North Holland: Elsevier, 827-833.

Pearson. R.G. (1957). Scale analysis of a fatigue
checklist. Journal of Applied Psychelogy, 41.
186-191.

Pratt, L.I.. and Barling, J. (1988). Differing
between daily events. acute and chronic stres-
sors: A framework and its implications. In J.J.
Hurrell, L.R. Murphy. S.L. Sauter, C.L. Cooper
(Eds.} Occupatio. al Stress, Issues and Devel-
opments in Research, London: Taylor and
Francis.

Price, H. E. and Parker, J. F., dr. (1971). Fore-
cast of human factors technology issues and re-
quirements for advanced aero-hydro-space
systems. Arlington, VA: Office of Naval Re-
search (Contract #N0001 4-69-C-0327).

Reynolds, J. and Drury, C. G. (1993). An
evaluation of the visual environment in aircraft
inspection. Proceedings of the 37th Annual
Hianan Factors and Ergonomics Society Meet-
ing, Seattle, WA. 34-38.

Reynolds, J.L.. and Drury, C.G. (in press). A
field methodology for the control of muscu-
loskeletal injuries. Applied Ergonomics.

Reynolds, J.L.. and Drury, C.G. (1992). The ef-
fects of physical exertion on task performance in
modem manufacturing: A taxonomy, a review,
and a model. Paper submitted for publication in
Ergonomics.

Ridd, .E. (1985). Spatial restraints and in-
tra-abdominal pressure. Ergonomics, 28,
149-166.

106

Roebuck, J.A., and Levedahl, B.H. (1961). Air-
craft ground emergency exit design considera-
tions. Human Factors, 3, 174-209.

Rohmert, W. (1973). Problems in determining
test allowances. Applied Ergonomics, 4,91-95.

Rubin, T. and Thompsca, S. J. (1981). The ef-
fect of restricted workspaces upon maximal ex-
ertions in the sagittal plane. Ergonomics, 24,
240.

Shepherd. W.. Johnson, W. B., Drury, C. G.,
Taylor, J. C. and Berninger, D. (1991). Human
Factors in Aviation Maintenance Phase 1: Pro-
gress Report, DOT/FAA/AM-91/16, Spring-
field. VA: National Technicai Information
Service.

Stalhammer, H. R., Leskinen, T. P. J.. Kuorinka.
3. A. A.. Gautreau, M. H. J. and Troup, J. D. G.
{1986). Postural, epidemiological, and biome-
chanical analysis of luggage handling in an air-
craft luggage compartment. Applied
Ergonomics, 17, 177-183.

Sutherland, V.J., and Cooper, C.L. (1988).
Sources of work stress. In J.J. Hurrell, L.R.
Murphy, S.L. Sauter, C.L. Cooper, Occupa-
tional Stress - Issues and Developments in Re-
search, London: Taylor and Francis.

Underwood, C. (1993). Personal communica-
tion.

Van Wely, P. (1970). Design and disease.
Applied Ergonomics, 1, 262-269.

Westgaard, R.H., and Aaraas, A. (1984). Pos-
tural muscle strain as a causal factor in the de-
velopment of musculoskeletal illnesses. Applied
Ergonomics, 15, 162-174.

Wickens, C.D. (1992). Engineering Psychol-
ogy and Human Performance, 2nd Edition.,
New York, NY: Harper Collins.

Wiker, S.F., Langolf. G.D., and Chaffin. D.B.
(1989). Arm posture and human movement ca-
pability. Human Factors, 31(4), 421-441.


Chapter Six

Hypermedia Information System

6.6 REFERENCES

Federal Aviation Administration, Office of Avia-
tion Medicine (FAA/AAM) & Galaxy Scientific
Corporation (GSC). (1993a). Human factors in
aviation maintenance - Phase three, volume one
progress report. (NTIS No. DOT/FAA/AM-
93/15).

Federal Aviation Administration. Office of Avia-
tion Medicine (FAA/AAM) & Galaxy Scientific
Corporation (GSC). (1993b). Human factors in

mH

aviation maintenance - Phase three, volume two
progress Tepori.

Howell, G.T. (1992). Building Hypermedia
Applications: A Software Development Guide.
McGraw Hill, Inc.

Johnson. W. B. & Norton, J. E. (1992). Inte-
grated information for maintenance training, aid-
ing, and on-line documentation. Proceedings
36th Annual Meeting of the Human Factors So-
ciety. Atlanta,GA: The Human Factors Society.

ADA294756


Chapter Seven

Correlates of Individual Differences in NDI Performance

failure, (c) distraction, (d) social stress, and (e)
physical stress. In Thackray et al. (1973), two
groups of subjects were selected who scored ei-
ther high or low on the distractibility subscale of
this inventory. High scorers showed significantly
greater lapses of attention during performance of
a repetitive task than did low scorers. Because of
these findings, it was decided to examine the re-
Jationship of scores on this subscale to possible
performance decrement on the NDI task.

11.3.4 Arithmetic. Digit S 1 Dicit Sym
Tests of the Wechsler Adult Intelligence Scale
QWAIS)

Scores on these three WAIS subtests have
been shown in numerous factor analytic studies to
measute a factor that has been variously named
“Freedom from Distractibility", “Attention-
Concentration", or "Concentration-Speed" (c.g.,
Goodenough and Karp, 1961; Karp, 1963). Some
or all of these WAIS subtests have been found to
relate significantly to inspection performance
(Gallwey. 1982; Wang and Drury, 1989). Conse-
quently, these tests were included as another
measure of attention/concentration or, conversely,
distractibility.

7.1.3.5 Eysenck Personality Inventory (EPI)

The Eysenck Personality Inventory (EPI) is a
short inventory measuring extroversion and neu-
roticism. The extroversion dimension has been
studied extensively in the context of vigilance re-
search because of Eysenck’s (1967) hypothesis
that extroverts should have more frequent lapses
of attention and hence more omission errors than
introverts. Reviews of the use of this personality
dimension in vigilance research (Berch and Kan-
tor, 1984; Wiener, 1975) have lent some support
to the belief that extroverts generally do not per-
form as well on vigilance tasks as do introverts.
Much less research has been conducted on per-
sonality variables in the area of inspection, and no
studies of extroversion and inspection perform-
ance had been conducted at the time of Wiener’s
1975 review. Since then, the author is aware of
only one inspection study that has incorporated a
measure of extroversion. Using a visual search
task, Gallwey (1982) found that introverts. as

measured by the EPI scale, had fewer search er-
rors.

Koelega (1992) conducted a recent meta-
analysis of vigilance studies over a 30-year period
and concluded that evidence for the superiority of
introverts is considerably less than previously be-
lieved. Koelega feels that there is enough consis-
tency in the findings to warrant continued
tesearch. Because of this, it was decided to in-
clade extroversion as measured by the EPI in the
present study.

7.13.6 Boredom Proneness Scale (Life Experiences
Scale)

NDI inspection is typically repetitive and fre-
quently considered boring and monotonous
(Schroeder, Dunavant, and Godwin. 1988). While
the evidence relating experienced boredom to
poor performance is somewhat tenuous, at least
one study demonstrated a significant relationship
of reported boredom and monotony to vigilance
performance. As noted earlier, subjects falling at
the extremes of rated boredom following a simu-
lated radar monitoring task showed the greatest
decline in rated attentiveness and the largest dec-
rement in performance (Thackray et al., 1977}.

Boredom in ihe above study was measured
following task performance and thus can be con-
sidered a “state” assessment of boredom. Farmer
and Sundberg (1986) developed the only scale
specifically developed to assess the general con-
struct of boredom proneness (i.e. 2 “trait” meas-
ure of boredom susceptibility). To the author's
knowledge, this scale has not been used in studies
of inspection performance. For this reason, it was
included in the present study. In order to disguise
the scale’s intent, it was relabeled "Life Experi-
ences Scale.”

7.1.3.7. Matching Familiar Figures Test (MEFD

The Matching Familiar Figures Test (MFFT),
developed by Kagan and his associates (Kagan,
Rosman, Day, Albert and Phillips, 1964), consists
of a series of 12 “stimulus” pictures, each of
which is associated with 8 “response” pictures.
Except for one correct picture in each response
set, all differ from the stimalus picture in some

ADA294756


Results of the ECS Tutor Experiment at Clayton State Callege

Chapier Eight

THA. The most likely explanation for this result is
the smali number of mistakes subjects made dur-
ing the experiment. Because the IHA is error-
driven, it was not activated enough to have a sig-
nificant effect on subjects’ performance. If the di-
agnostic task had been made more difficult (for
example, by removing the FIM from the tutor}.
then the JHA would probably have had a more
significant impact on subjects’ performance.

The results of the experiment, data from the
poll, and researchers’ observations of the subjects
point to significant issues for applying ITS to
aviation maintenance training. The most signifi-
cant outcome of this study is that the use of an
THA in a computer training system should be
planned in the context of the rest of the training
system. For example, subjects may not use an
THA if the task is too simple or if there are job
aids decreasing the number of mistakes. Another
finding is that subjects need adequate background
knowledge both for the training task and the
taining software before they begin using the
training software.

Results of the polls given during the experi-
ment indicate that the ECS Tutor has evolved into
a user-friendly training system. Through repeated
usability studies with AMTs, we have been able
to identify problems in dhe user interface and to

146

make improvements. “": aso discovered that de-
signers should consider the tradcoff between
computer display resolution and system cost.
Choices should be made in the context of the
taining the ITS is intended to provide; the re-
quired display resolution depends on how much
picture detail is needed for adequate training. Fi-
nally, our last finding was that adequate, but not
excessive, feedback maximizes the quality of
training an ITS provides. Feedback should in-
clude how much time the student should spend on
each problem and how weil the student has
solved the problems in terms of mistakes, sim-
lated time, and cost.

8.7 REFERENCES

Pearce, M., “Advanced Technology Training for
Aviation Maintenance: An Evaluation.” Human
Factors in Aviation Maintenance - Phase Two
Progress Report, Federal Aviation Administra-
tion. DOT/FAA/AM-93/5, 1993. pp. 9-17.

Pearce. M., “Results of the Environmental Con-

trol System Tutor Experiment,” Human Factors
in Aviation Maintenance - Phase Three, Volume
1 Progress Report, Federal Aviation Administra-
tion, DOT/FAA/AM-93/15, August 1993, pp. 5-
23.


Reliability in Aircraft Inspection: UK and USA

Chapter Nine

responsibility for defect rectification and may not
be the inspector who does the buy-back inspec-
tion. Some airlines have an inspector specifically
assigned to perform only buy-back inspections.

Evaluation: The separating of the manage-
ment structure in the USA is dictated largely by
the existing Federal Aviation Requirements. The
notion of the need for checks and balances as an
error reduction mechanism is deeply felt. At the
bangar floor level the general view is that repair
and imaintenance would suffer if the maintenance
technician knew that certain inspectors were
*buying back’ the work. as some are thought to be
less stringent than others.

The general view in the UK was that the sys-
tem of having the same inspector responsible
throughout for any particular defect and its recti-
fication was preferable as the repair could be
monitored at appropriate stages ensuring that the
job had been performed correctly.

In the event of an inspection resulting ina
significant repair being nccessary, the supervisors
of both maintenance and inspection confer with
the inspector while, for a small item, the inspector
alone assumes responsibility. There must be a
point at which the inspector has to decide which
of these two courses is correct. although supervi-
sors on their own initiate a review of NNR cards
with inspectors. The decision might depend vari-
ously on safety, cost, time etc. but the crossover
point does not seem to have been well defined
and was seen to vary considerably between com-
panies.

9.4.2 The Superviser/Inspection
Dichotomy

Both Countries: The supervision of the air-
craft maintenance technician (AMT) or mechanic
is of primary importance. There is always the
need for monitoring their output whether for
quality or quantity. The responsibility for this su-
pervision varies both from operator to operator
and from country to country.

UK Variations: There is a tendency for the
supervision to come largely from the inspectorate

150

side in UK. Indeed, in many companies each in-
spector will be wholly responsible for a small
team of mechanics and the jobs to which they are
allocated. In any case it is common for the me-
chanic to be in close contact with an inspector
during a job, especially if it is a defect arising
from inspection.

US Variations: Due to the way that account-
abilities are allocated, the American system di-
vorces the inspection and maintenance
responsibilities at hangar level although some co-
ordination is still maintained. The system involves
inspectors locating defects and raising the appro-
priate paperwork as in the UK, but then the re-
sponsibility for the job becomes that of the
maintenance organisation and it is only after the
repair is complete that the inspectorate are asked
to re-inspect the area and *buy-back’ the com-
pleted job.

Evaluation: While the reasons for, and tech-
nical consequences of, the separation of respon-
sibilities were covered in 1 (above), there are stil!
issues of management and communications which
need addressing. First it should be noted that the
standards of repair deemed acceptable by the in-
spectors did not appear to differ between the two
countries. An aircraft was judged safe when it not
only met the written standards but also when, as
many expressed it “the plane is safe enough for
my family to fly in".

There are two sides to the question of
whether the inspector should act as supervisor or
have a team of mechanics. One has to weigh the
advantages of having close communication be-
tween the inspector and mechanic against the
continual interruption of the inspector’ train of
thought caused by requests to check current
situation of a repair or for further work. Some
companies use a leading hand (an long-
experience mechanic) as an intermediary and ina
large company, where there is sufficient work,
this seems a good altemative.

It is rare for an inspector/supervisor to have
any personnel-management training beyond a
couple of days. The tasks to be communicated
are frequently comptex: the difficulty of schedul-

ADA294756


Technical Report Documentation Page

iReport No. 2. Goverment Accession No. T Recipient's Catsiog No.
DOT/FAA/AM-95/14
This ana Subiie 5. Report Date
Human Factors in Aviation Maintenance — Phase IV Progress May 1995
Report

6. Performing Organization Code

1 Maents) & Periorming Orgaruzation Reson No.

William T. Shepherd, Ph.D., and Galaxy Scientific Corporation

SABES

70. Work Unt No. RAIS)

8. Performing Organizaios Name and AdGress: 2. WORK

Galaxy Scientific Corporazion
2310 Parklake Drive, Suite 325
Atanta, GA 30345

17, Contract or Grant NO
DTFA0!-94-C-01013

T2. Sponsoring Agency hams and Access 13. Type of Repon and Penod Covered

Office of Aviation Medicine Interim, April 1993 - April 1994
Federal Aviation Administration
800 Independence Avenue, S.W.
Washington, DC 20591

34." Sponsoring Agency Code

15. Supplemental Novas

76. Absiact

The fourth phase of research on human factors in aviation maintenance continued to look at the human's roie in the
aviation maintenance system via investigations, demonstrations, and evaluations of the rescarch program ourputs. This
report describes the field evaluation plan for the Performance Enhancement System, a computer-based too! designed
to aid Aviation Safety Inspectors in performing their oversight duties (Chapter 2). Chapter 3 describes che design of
a computer-based workcard system. The report also discusses the development of an ergonomic audit program for
visual inspection, which contains a method of choosing tasks to be audited, an audit checklist, and a computer
program to evaluate check-list response against national and international standards (Chapter 4). Chapter 5 reports on
an investigation of ergonomic factors chat may cause increased inspector stress, fatigue, and workload, particularly in
restrictive spaces that cause extreme postures. The continued development and expansion of the hypermedia
information system is reported on in Chapter 6. Chapter 7 describes an investigation of individual differences in
nondestructive inspection performance. Chapter 8 describes an investigation to determine the effect of an Intelligent
Help Agent on the effectiveness of computer-based training. Chapter 9 reports on a joint CAA/FAA investigation of
reliability in aircraft inspection in the United Kingdom and United States. Chapter 16 is a bibliographic overview of
selected issues in designing computer-based training systems.

17. Key Words 7. Distribution Statement

human factors, aviation maintenance hypermedia, Document is available to the public through the

NDI performance, computer-based training, ergo- National Technical Information Service,

nomic audit, aircraft inspection, restrictive spaces Springfield, Virginia 22161.

TS. Secunly C asst. (ol this Tepom 20, Secunty Classi" (of this page} Bi No of Pages BE Bice
UNCLASSIFIED UNCLASSIFIED 176

Form DOT F 1700.7 (8-72) Reproduction of co :

i

ADA294756


Results of the ECS Tutor Experiment at Clayton State Catlege

Chapter Eight

8.3.3 Data

Two types of data were collected: traces of
the subjects’ actions and a poll the subjects com-
pleted after finishing all simulated malfunctions.
Each tutor had a mechanism for tracking each ac-
tion a user performed, including the following:

« Going toa program screen
Inspecting/testing/replacing 2 component
Asking for help

eee

Along with recording each action, the tutor
tracked the components that the user acted on and
the time. This data allow’s the researchers to rec-
reate how each subject used the tutor and to de-
termine if subjects had any problems in using the
tutor. The data from the traces for the last prob-
Jem was lost on some computers, so the research-
ers analyzed only the data for the first 9 of 10
problems.

The researchers collected users’ opinions
about the ECS Tutor by using a short pall. We
also administered a background poll to determine
the distribution of skill levels for computer use
and ECS maintenance. After subjects finished the
simulation and polls. we asked them to write any
impressions or observations they had concerning
the tutor.

8.4 RESULTS

This section is divided into a trace. analysis
section covering analysis of profiles of how sub-
jects used the tutor, a poll results section deserib-
ing the poll results, and a post-experiment
comments section discussing remarks subjects
wrote on the poll forms.

8.4.1 Trace Anal

A trace was kept for each malfunction prob-
lem the subjects worked on. The trace consisted
of records that described the following:
© the action the user performed, e.g.. an inspec-

tion of a component
#7 the component that was acted on. €.g.. the

cockpit ECS control pane}

Accepting or rejecting help when offered.

So

¢ whether this action was an error, if so, of

what type, e.g., a procedural error
¢ the time that the action was performed.

From this data, the researchers could recreate
a.user’s responscs to the ECS Tutor. More impor-
tantly, we could infer some things about the
user’s mental processes. For example, if a user
completed a problem in a short time relative to
other users’ performance. we would infer that the
user has some knowledge about troubleshooting
the ECS. If the trace indicated that a user referred
to the FIM during the simulation, we would infer
that the subject used procedures describing how
to use the FIM. On the other hand, if a subject did
not use the FIM all during troubleshooting, we
would infer that the subject knew how to apply
troubleshooting principles to the ECS configura-
tion. The IHA performs similar inferences when
it analyzes a user's actions and calculates when to
give help and what type of help to give.

From the raw tutor usage data, we collected
data to measure subjects’ performance: the time
they needed to solve a problem and the number of
unnecessary part replacements. AJl data analyses
are either are either calculations of time subjects
needed to pertorm an action or counts of the
number of times subjects performed a particular
action {operate, inspect. test, or replace}. Al-
though not done in this experiment, another type
of data analysis would be fo look at patterns in the
way subjects used the ECS Tutor. Such patterns
could be measures of how quickly a user nar-
rowed down the possibilities of component fail-
ures or how long a user continued to work on a
problem after it was successfully solved,

A statistical analysis of the data did not indi-
caie any significant difference in performance
between the (we experimental groups. The types
of analysis performed on the data traces and the
average values for the two groups are shown in
Table 8.2.

ANAXOATERZL


Chapter Five

“|

1, Leg(s) Seraighr,
Trunk Bent and/or Twisted, and/or
Arm(s) Above Shouider

3. Leg(s), ‘frank, Arms Newral

2. Kneeling/Crouched,
Trunk Bent and/or Twisted, and/or
Amn(s) Above Shoulder

4. One Leg Straight,
Trunk Bent and/or Twisted, and/or
Arm(s) Above Shoulder

ADAZ94756


Chapter Three

Design of Portable Computer-bas

sed Workcards for Aviation Inspe.

guage that simplifies creation of detailed infor-
mation management applications by using links
between stacks of information. Eight different
inspection tasks were implemented into the sys-
tem. A-check inspection tasks for a B727-200
included log books, nose landing gear, main
landing gear. aircraft wings, aircraft empennage,
and aircraft fuselage inspection. Left wing and

System design adhered fo the lessons learned
from developing of the paper-based workcard
identified in Tables 3.1 and 3.2. The design also
followed design guidelines specific for computer
interfaces (Brown, 1988: Smith and Mosier,
1986). The specific guidelines which were used
to develop the computer-based systems are
identified in Table 3.3.

right wing inspection for a DC-9-30 C-check
were also implemented.

1. INFORMATION READABILITY

Use a fixed set of proportions/grids

Use spatial layout as a primary cue for object grouping
Use a consistent layout across fields

Use fixed size/iocation for “functional category fields”
Left justify the most important information

Use blank lines in place of graphic lines to reduce clutter

Use upper case only for short captions, labels, and headings
Use convertional punctuation and formalisms

1. Layout

eoeoeeee

2. Typography

oe

Be very explicit in the use of metaphors

Use explicit screen transitions, e.g., iris open vs. scroll
Use paper form metaphor for data input

Use soft button metaphor for all extemal links

Use contrast sparingly and as a last option
Use contrast to attract attention to select portions of text
| ¢ Use a maximum of three levels of contrast coding

3. Metaphors

eooee

4. Contrast

°

2. INFORMATION CONTENT

1. Input information

Use familiar mnemonics for input
Use congruent command pairs, e.g., RWrong, not R/Close
Use “radio buttons” for a!! multiple choice information

Use the display as an external working memory of the user
Provide screen identity information

Display only necessary information

Condense all unnecessary information into icons

Avoid a display density higher than 15%

Use the inheritance metaphor to identify position in hyper-
space

Use affirmative dialogue statements

Provide input acknowledgments and progress indicators
Use auditory feedback conservatively

System messages should be polite and instructive

Do not provide a system-initiated help feature

2. System output information

eeoeeeve

eevee

w
aa

ADA294756


Chapter Two Appendix 2-C Software User Manuals

Numeric Misc: Enter items for later mathematics manipulation. e.g., the number of records checked during
a records system inspection.

Local Use: Used for temporary tracking of selected activities.

Regional Use: Used for temporary tacking of selected activities. This block may be used by the DO on a
temporary basis and may be preempted by the region.

National Use: Used for temporary wacking of selected activities. This block may be used by the DO on a
temporary basis and may be preempted by the national headquarters.

Activity Time: Enter the time consumed in the performance of an activity (rounded to the nearesi hour)
when required in Appendices A through F or the PTRS Pocket Guide. Do not use otherwise.

Geographic Activity: Check this bo:

Travel Time: ! Do
management.

Travel Cost: Enter the travel cost. Do not use unless directed by management.

Triggers (Not Currently Functional): Used to automatically create new records containing some or all
information from Section I. It is usually used to trigger an enforcement activity or a follow-up activity.
INVS and REXM functions were used to generate letters of investigations and reexaminations, but are
ao longer available with the PENS software.

Activity #: Enter a new activity number to automatically create another record with this triggered
activity number. The new record will have OPEN status and will contain some information from
Section I.

R#(repeat): Enter an R and the number of identical records you want to create (up to 50). The new
records will contain all information from Section I.

3.2 Section Il ~ Personnel

Current Personnef: Lists afl personnel involved with the activity. Selecting an entry from the list will
display the data on that person and enable you to modify the data. The default list is empiy.

To record personne! information into the database, enter the information in the corresponding fields and hi

sponding f
SAVE ENTRY or NEW ENTRY button.

To erase an entry, select the desired entry from the Current Personnel list and hit CLEAR ENTRY.
Personnel Name: For an examiner's certification activity, enter the applicant’s or the recommending
instructor's name. For other activities, enter the name of any personnel involved with the activity. Enter one

person at a time,

Position: For an examiner’s certification activity, enter "APPL" (ior applicant} or "RI" (for recommending
instructor). Otherwise, enter the job title of the personnel.

Base: Enter the airport code for the location where f

43

ANADQATERL


Chapter Ten Guidelines for Designing and lniplementing CBT for Aviation Mainiénance

Greenstein, J.S., and Amaut, L.Y. (1987). Human
factors aspects of manual computer input devices.
In G. Salvendy (Ed.) Handbook of Human Fac-
tors. John Wiley & Sons, New York, pp.
507-548.

169

TUS. GOVERNMENT PRINTING OFFICE: 1998 - 60.057/00129

ADA294756


Ergonomic Factors Related to Posture ard Fatigue in tl

Inspection Environment

Chapter Five

factors identified in Section 5.2 which create, or
exacerbateing stress and fatigue etfects.

5.3.2.2 _Psychophysical Measures

Psychophysical techniques were used to
measure fatigue, physical discomfort, and work-
ioad. These techniques are particularly attractive
for field use because they are unrestrictive, re-
quire minimal instrumentation, are easy to
use/administer, and provide valid and reliable re-
sults.

The Feeling Tone Checklist (FTC), utilized to
measure fatigue effects over time, is an interval
scale that has been found to be a valid and reli-
able measure of subjective feelings of fatigue
(Pearson, 1957). The Body Part Discomfor: Chart
(BPD} was utilized to obtain postural discomfort
data (Corlett and Bishop, 1976). This chart cate-
gorizes the body into a number of functional areas
to allow the assessment of individual body areas.
A 5-point ordinal scale was utilized to solicit op-
erators’ BPD ratings. The MASA - Task Load In-
dex (TLX) is a multi-dimensional rating scale
measuring six workload-related factors (mental
demand, physical demand. temporal demand, per-
formance, effort, and frustration) and their asso-
ciated magnitudes to form a sensitive and
diagnostic workload measure (Hart and Stave-
land, 1988).

5.3.2.3. Experimental Protoco]
Postures were sampled every 30 seconds
throughout each task. Data were obtairy 1 on two

inspectors performing each task. The FTC and
BPD was administered before and after task per-
formance. In addition, the TLX was administered
after task performance. The FTC, BPD, and TIX
data were obtained on five experienced inspectors
per task.

5.3.2.4 Results

An adapted version of the Ovake Working
Posture Analyzing System (Louhevaara and Suvi-
nakki, 1992) postural recording scheme was util-
ized to classify whole body postures during task
performance. This system has been found to be
+ alid and reliable (Karhu, Kansi, and Kuorinka.
1977, 1981). It categorizes whole-body postures
into action categories based upon the severity of
different postures, making it useful in determining
which postures need to be addressed by work-
place changes. Table 5.4 lists the categorization
scheme and corresponding Action Categories
(AC). The postural data were categorized by ac-
tion categories and averaged across inspectors for
each task; results are presented in Figure 5.3.
These data indicate that AC frequency is depend-
ent upon task type (4 * = 140.23, p < 0.005} and
that inspectors adopted the largest percentage of
extreme postures, ie. AC2, AC3, and AC4, in the
aft cargo and tail interior areas. However, there is
a large percentage of extreme postures in the
other areas. The most typical working postuces
for each task are listed in Table 5.5 and illustrated
in Figures 5.4-5.7.

AR AANA


Chapter Two Appendix 2-A Evaluation Forms

Evatuation of Computer A
(Computers 8 and C used the same form)

Initials: FSDO:

Please rate the computer on the following factors:

Weight Too Heavy Adequate Too Light/Fragile
Size Too Large Adequate Too Small (eg. screen}
Speed Too Slow Adequate Fast

Display--inside Too Dark Adequate Too Bright
Display--outside Too Dark Adequate Too Bright

Pen Responsiveness Too Slow Adequate Too Fast

Pen Feel Too Slick Adequate Scratchy

Overall Comfort Not Comfortable Adequate Comfortabie

What were the environmental conditions j

snow drizzle rain heat cold frigid
Did you use the computer for five working days? Yes No
If not. why not? Broken On TravelV/V acatio/RDO Too difficult to use
Do vou prefer to have the pen tethered fo the unit? Yes No
Could you comfortably carry this unit thro: Yes No
Ifa neck, shoulder. or waist strap were available. would you use it? Yes No

Which would you prefer? Neck Shoulder Waist

What are the three largest drawbacks to this product? t.

te

Evaluation of Computer A 1/2

ADA294756


Chapter Two

What is your opinion of the following computer manufacturers:

Computer A.
Computer B
Computer C

Computer D

Favorable
Favorable
Favorable

Favorable

Untavorabie

Unfavorable

No Opinion

No Opinion

Personne! Background 2/2

ANADQATLEEL


spection E: Chapter Five

Ergonomic Factors Related to Posture and Fatigue in the Inspection En

|
1. Sitting, Trunk Suaight, 2. Sitting, Trunk Bent, '
Arms Below Shouiders Amns Below Shouider

3. Trunk Bent or Twisted,
Arm(s) Above Shoulder,
Legs Saraight

98

ADA294756


Chapter Nine

data if, on a subsequent inspection, a crack were
found.

Operators could utilise this information on all
their aircraft and, if it proved useful in early iden-
tification of future trouble, it might be even be
made a fleet-wide index. For any form of human
inspection, feedforward information such as pre-
viously-zeported sub-threshold defects, can sub-
stantially improve defect detection performance
(Prabhu and Drury. 1991).

9.4.9 Work Cards, Information and
Automation

Both Countries: The Work Card {aiso called
Job Card or Task Card) is the primary command
document for any inspection task. It is also the
primary record of work performed, being signed
and dated by the inspector and used as a reference
for all Non Routine Repair (NRR) cards raised
during its execution. As such, it must be well de-
signed from the inspectors perspective if it is to
be used without error. In both countries, many
types of card were seen, with differing degrees of
user-friendliness, and with differing levels of
automation. Also the integration of the work card
with other tools used by the inspector varied
widely. Further information on the shortcomings
of many work card systems can be found in
Drury, Gramopadhye, and Prabhu, 1991 (see Ap-
pendix I). Hence specific instances are selected
from cur observations to show how improve-
ments may be possible, rather than contrasting
systems between countries.

UK Variations: One airline visited had a
computer assisted method of job control and de-
fect reporting which was of general interest.
Work Cards had bar codes attached, as did in-
spectors badges. Thus to register that a job has
started, the inspector swipes the bar code reader
across the Work Card and across his badge. Then
after inspection is completed, all defects arising
are entered with a swipe of the work card, a swipe
of the badge, and swipes of each of a set of defect
bar codes located beside the reader. These defect
bar codes have names and illustrations of the
possible defects attached to them, and lead di-
rectly to computer generated NRRs.

US Variations: In two sites, the work card
was integrated into a carrying case which also
held the NRR forms, aircraft station diagrams,
pens, and even mirrors. At one site the work cards
were full size, approximately A4, while at the
other they were smaller, approximately AS, with
the carrying cases scaled appropriately.

Evaluation: Work cards will become more
automated. Portable computers with multi-level
task information have been proposed already
(Reference 1). The advantages of automation are
consistency, access to aircraft-specific informa-
tion, and a Jess error-prone human interface. But
automation must be undertaken correctly, or er-
rors and frustrations will result. For example,
work cards which were generated by early com-
puter systems (still in use) have low quality
dot-matrix printing, even in all capitals in places.
leading to low legibility. Moves towards “good"
automation need to be encouraged. Thus the use
of named examples of defects on the bar code
cards has the effect of reinforcing correct naming
of defects. NRRs are then raised with the appro-
priate and correct names on them, reducing the
possibilities of mis-interpretation by mechanics
and buy-back inspectors. One can foresee the use
of a portable computer containing the work card,
with the ability to read bar codes from the aircraft
smucture to ensure correct location of areas for in-
spection, and built in defect menus keyed to the
defect types possible in that inspection. Hyper-
media formats can be applied to the presentation
of knowledge and mules at multiple levels.

An integrated solution to the clutter of carry-
ing the work card, other paperwork, and small
toois is urgently required in many sites. Inspec-
tors access the inspection area along ladders and
scaffolds with their hands full of equipment,
adding to the hazard of the task. One inspector
entering a wing tank was observed as he removed
items from his pockets, belt and hands to be able
to fit through the access cover. There was a con-
siderable pile of equipment resting on the wing
after the removal was completed. New solutions
need to be devised, of which the quoted examples
are best considered as early prototypes.

ADA294756


Reliability in Aircraft Inspection: UK and USA

Chapter Nine

body would be the best source of such an agree-
ment.

9.5.5 Working Times

There is a great difference in the length and
rotation of shifts in both countries. In the USA.
there is a greater tendency for the older inspectors
to be given preference in a choice of shifts. The
effect of this in companies where no shift-rotation
occurs is often to condemn the younger, less ex-
perienced inspectors to nightwork with the con-
comitant difficulties of travel and social
problems. This is especially significant for the
married inspector with a family who, due to the
high housing costs around many airport locations,
has furthest 10 travel.

9.5.6 Demand and Supply of
Mechanics/Inspectors

An uptum in demand caused both by expan-
sion and retirement of the original generation of
aircraft maintenance personnel has resulted in a
resurgence of apprenticeship schemes in both
countries. In the USA, the onus of training to
AMT standard is on the worker whereas the UK
route has been predominantly based on day-
release to training centre or technical college.

Attraction of the high-grade personnel re-
quired could be improved by improvements in
low starting pay, poor working conditions and a
cessation of bonding.

An improved interface is recommended be-
tween military and civilian aircraft maintenance
employment.

95.7 Visual Inspection and Eye Tests

There are no mandatory requirements in the
UK or in the USA for annual checks of visual in-
spectors’ eyesight to specified standards. USA
operators tend to have an in-house requirement
and this is frequently financed by the company.
UK operators rarely have tests other than on ini-
tial entry into a company.

There is such a requirement for UK NDT
personnel: there should be for all inspectors.

Hangar lighting is frequently insufficient. es-
pecially secondary, portable lighting. Fluorescent
sources are to be preferred to bright, point-source
bulbs which can cause unnecessary glare either
directly or on reflection.

a eT ee
BGICAUOTS:

9.5.8 Reporting im

Where NRRs arise from a reportable level,
ihere could exist a secondary reporting system for
sub-zeportable, but still visible, indications. This
might be incorporated within the task card or
some other computer system to act both as a
highlight for future inspection, and a source of
daui for fracture mechanics analysis.

9.5.9 Work Cards, Information and
Automation

Increased use could be made of computer-
technologies in the near future to provide the in-
spector with enhanced on-line information of the
task in hand. This might be implemented as a
small portable computer indirectly accessing a
company mainframe. The information could
consist of a multiple choice level of presentation
of the task description to suit the inspector's ex-
perience, the past history of that particular aircraft
or of the relevant fleet statistics.

9.5.10 Access

There are no great regional differences in ac-
cess provision. The problem area is for the older
ageing aircraft which is unlikely to have custom-
built staging or docking and yet willl be liable to
extended smmuctural inspection. Indeed. even the
access stairs etc. available are frequently in very
poor condition through age and neglect.

Services are centrally located under the fuse-
lage more frequently in the USA, eliminating
much of the problem of trailing wires. cables and
hoses which can be a source of hazard in the
movement of wheeled access platforms.

ADA294756


Chapter Ter

for Designing aad implementing CB

Guidelines for Desi

poe mtn BT Fe
fi

have to repeat several times, ITS can provide
consistent training to a large number of students.

Bibliography:

Brown, J.S., Burton, R.R., and deKleer, J. (1982).
Pedagogical, natural language, and knowledge
engineering techniques in SOPHIE 1, H, anc itl.
In D. H. Sleeman and J. S. Brown, (Eds.), Inrelli-
gent Tutoring Systems.

Johnson, W.B. and Norton, J.E. (1992). Modeling
student performance in diagnostic tasks: A decade
of evolution. In V. Shute and W. Regian (Eds.),
Cognitive Approaches to Automated Instruction.
Hillsdale, NJ: Lawrence Erlbaum Associates,
Inc., 195-216. Also reprinted in Educational
Technology Research and Development, 404},
81-93.

Norton, J.E., Wiederholt, B.J., and Johnson, BJ.
(1991). Microcomputer intelligence for technical
training (MITT): The evolution of an intelligent
tutoring system. In Praceedings of Conference on
Intelligent Computer-Aided Training.

Polson, M., and Richardson, J., (Eds.). (1988).
Foundations of intelligent tutoring systems.
Hillsdale, New Jersey: Lawrence Erlbaum Asso-
ciates.

10.2.1.4 Psychomotor Training

Psychomotor training is used to teach physi-
cal skills. The task being taught should require
some sort of perceptual (usually visual or audi-
tory) or complex motor skills. For example, a
CBT system might be used to teach a technician
how to operate NDI equipment. The limitations of
current computer interfaces may require that spe-
cial equipment be used to provide a realistic
simulation of the actual environment.

Bibliography:

Gaines, B. R. (1972). The learning of perceptual-
motor skills by man and machines and its rela-
tionship to training. Instructional Science, I, pp.
263-312.

Lintern, G. Augmentation feedback for percep-
tuai-motor instruction. Paper presented at meeting

of the American Psychological Association,
Montreal.

10.2.2 Information Presentation Formats

The training and instructional analysis pro-
vides a functional description of what information
the CBT must provide to users. Presentation me-
dia affects a CBT’s cost so the media should be
selected based on instructional criteria, rather than
any aesthetic judgements or preferences.

10221 Text

Text is the most common CBT presentaticn
format, since all computers support text. Text can
be used to identify and describe processes, ob-
jects, and procedures. Designer should:

« Limit word use, be clear

+ Use large fonts and readable colors

Bibliography:

Bieger, G.R. and Glock, M_D. (1986). Compre-
hending spatial and contextual information in
picture-text instructions. The Journal of Experi-
mental Education, 54, 181-8

McTyre, J.H., and Frommer, W.D. (1985). Effect
of character/background color combination on
CRT character legibility. Proceedings of the
Human Factors Society, 31st Annual Meeting,
779-781.

10.2.2.2_Graphics

When a CBT program needs to show what a
piece of equipment looks like, or how a system is
organized, a graphic is the best presentation
method. Graphics can be pictures or line draw-
ings of equipment o schematics showing con-
nectivity and functionality of components.
Designers of CBT systems should:

e Make as simple as possible and do not

show unnecessary objects
¢ Consider display resolution of computers

Bibliography:

Hovy. E. and Arens, Y. (1990). When is a picture
worth a thousand words? - Allocation of modali-
ties in multimedia communication. AAAJ Sym-
posium on Interfaces at Stanford.

ARAPOIATSA


Appendix 2-A_ Evaluation Forms

Chapier Two

If any of the following need improvement, please
Section 1

PTRS Record ID function

Inspector ID, Inspector Type, Activity Number, and FAR screen
Status

Callup Date, Start Date. Completion Date

Designator

Airman Certification #

Airman Name/Other

Aircraft Registration #

Make-Model-Series

Loc/Departure Point, Arrival Point

Flight #

Investigation #

Tracking

PENS Software Evaluauon 2/6



END

FILMED

ADA294756



Hypermedia Information System.

Chapter Six

ies were created: one contains the Federal Avia-
tion Regulations; the other, the Inspector’s Air-
worthiness Handbook. The work described in this
chapter will be produced and distributed on CD-
ROM in early 1994.

The HIS reader interface maintains a book
paradigm and consists a navigation component
and a viewing component. The navigation com-
ponent combines the familiarity of traditional
book navigation, e.g., a table of contents, with the
power of hypermedia searching. The viewing
component allows the reader’ to read, print, and
ipulate the various media that make up the li-
brary.

6.1.1 Navigation

A traditional paper book provides several
navigation methods, including a table of contents,
an index, and simple page turning. Likewise, the
HIS supports a variety of access paths into and
within a document. Some readers seek specific
topics of interest and appreciate a powerful
method to browse through a complex document.
These readers find the hierarchical Outline
Viewer and powerful searching capabilities use-
ful. Other seaders may seek quick references to
standard information. Hot Links and Bookmarks
provide mechanisms for these readers to quickly
access frequently referenced places in a docu-
ment.

6.1.1.1 The Bookshelf

The first HIS component the reader encoun-
ters is the Bookshelf (Figure 6.1). The Bookshelf
graphically depicts libraries available to the
reader. The reader selects book icon to choose a
library. To change libraries. the reader returns to
the Bookshelf and selects another book icon.
Bookshelf icons can be customized to fit a spe-
cific application.

6112_ The Outline Viewer

Once a reader chooses a library from the
Bookshelf, the Outline Viewer appears to display

Reader denotes someone using the HIS to view
documents

the complete outline for the library. The outline is
similar to a Table of Contents and contains the
Topics defined for the library’s documents. A hy-
permedia author” specifies Topics within the
original digital documents and assigns a hierar-
chical order to them. By using the HIS Outline
Viewer. a reader is able to browse the outline of
all documents in the library and to expand and
collapse the Topics (Figure 6.2). Once a reader
finds and selects a Topic of interest, the part of
the document associated with the Topic appears
(Figure 6.3).

61.13 Hot Links

The HIS supports a variety of Hot Links a
reader can use to navigate through the library.
The Hot Links include both inter- and intra-
document links to text, as well as links to graph-
ics, animation, video, audio, definitions, and other
executable programs, Hot Links are denoted by a
rectangular box surrounding red text (Figure 6.3).

* Author denotes sorneone who puts a document or
collection of documents inte a hypermedia library for
use by the HIS.

108

ANnAANnRAIeS


Correlates of Individual Differences in NDI Performance

Chapter Seven

the sessions, and, except for change in interest,
were unrelated to performance error. With regard
to the change in interest, subjects showing the
highest levels of missed faults showed a greater
decline in interest during the sessions than did
subjects with the lowest numbers of missed faults.

In assessing the effects of sustained perfonn-
ance on error frequency, two aspects should be
emphasized. First, although significant perform-
ance declines occurred during the sessions, the
absoluie magnitude of the increase in errors was
relatively small. For missed fauits, mean percent
error for the first half of the sessions was 21 per-
cent, which increased to a mean percent error of
25.5 percent during the second half. For false
alarms, mean percentages of error for the first and
second half of the sessions were 1.8 percent and
2.2 percent, respectively. Also, the mean percent
error for false alarms during the first session was
Jess than 1 percent which increased to 3.7 percent
by the last session. Although these increases in er-
Tor were statistically significant. they may not be.
Jarge enough to be practically significant.

Second, the concomitant changes in such
subjective measures as tiredness, attentiveness.
interest, and strain, although statistically signifi-
cant, also represented relatively litle absolute
change in feeling states from the beginning to the
end of the sessions. As noted earlier. subjects
typically began each session feeling moderately
attentive, moderately relaxed, moderately inter-
ested, not annoyed. and having about their normal
fevel of energy. Post-session ratings deviated litle
from the initial feeling states. Except for change
in interest, which. as discussed above, was related
to frequency of missed faults, none of the changes
in feeling state was found to be reiated to meas-
ures of performance error. Had the sessions been
jonger or had they been conducted when subjects
were tired initially, greater changes in both per-
formance and feeling states might have occurred,
possibly resulting in significant relationships be-
tween subjective measures and task performance.

7.3.2 Performance Predictors

A factor analysis of the various predictor
variables employed yielded four factors: two cor-

130

related significantly with performance. Facto: 4
showed a significant negative correlation with
both missed faults and false alarms, while Factor
i showed a significant negative correlation with
the performance speed measure (mean
ume/rivel}.

Only two tests had substantial loadings (60
or greater) on Factor 4. These were the Bennett
Mechanical Comprehension Test and WAIS Digit
Span Test. As indicated earlier, mechanical abilin
has been frequently mentioned as possibly related
to inspection proficiency. Normative data shows
it to be significantly related to job performance of
various groups of aircraft factory empioyees
(Bennett. 1969). As previously noted, die Digit
Span Test appears to be a measure of alertness or
concentration. Several studies have shown it to
be related to inspection proficiency (Gallwey,
1982; Wang and Drury, 1989). Taken together,
these two tests seem to tap specific abilities relat-
ing to inspection errors the simulated NDI task
measured. It is interesting to note that while
missed faults and false alarms were essentially
uncorrelated, both were related to Factor 4. In
looking at individual Pearson correlations of each
test loading on Factor 4, Digit Span correlated
higher with false alanns than with missed faults.
The Bennett Test showed a higher correlation
with missed faults than with false alarms. This
suggests that the two tests may measure diff

ferent
aspects of task performance. A follow-up study
will examine this possibility further.

With regard to Factor 1. the tests loading
substantially on this facto: . EPI Extrover-
sion, PRF Impulsiviry, PRF Endurance) suggest
that this factor measures a rapid/impaticnt/impul-
sive cognitive style. It is not surprising that this
factor correlated significantly with the measure of
time taken to inspect the rivets (mean time/rivet).
The fact that mean time/rivet did not correlate
significantly with either of the two measures of
inspection error would indicate that subjects did
not necessarily lose inspection accuracy with in-
creased speed of inspection.

ADA294756


Chapter Two Appendix 2-C Software User Manuals

1

Hypermedia User Manual
for
FARS and Inspector’s Handbook

On-line Documentation

The PENS REFS button accesses the on-line versions of the Federal Aviation Regulations and the
Inspector’s Handbook. (Currently, only the Airworthiness Handbook is available.) These on-line documents
allow you to quickly find specific information without having to thumb through the bulky paper books. It
also eliminates the necessity to carry the FARs and the Handbooks to the field. Specific help for these on-
line reference systems can be found when you are using it.

Here are the necessary steps to access these documents:

1,
2.

Press the PENS REFS button. A separate Galaxy Hypermedia window appears on your screen.

Press the Bookshelf button. Three book icons: FARs, Handbook and ADs, appear on the screen.
(See Figure 1.) The ADs book icon is disabled because the ADs documents have not been
incorporated into this version.

Press the desired book icon to open the corresponding book. The topic outline of the book will appear
on the screen. (Figure 2 shows an example of the topic outline.)

When the Outline is first displayed, all topics are shown in a collapsed state with subtopics not shown.
The three-dots following a file icon indicates the topic contains hidden subtopics. To display hidden
subtopics either press the file icon twice, or select the topic and then choose the Expand menu item
from the Outline Menu.

All hidden subtopics can be displayed by choosing the Expand All menu item from the Outline
Menu.

To hide subtopics for a selected topic, either press the selected topic file icon wice, or choose the
Collapse menu item from the Outline Menu.

Subtopics for all topics can be hidden in one step by selecting the Collanse All menu item from the
Outline Menu.

To view a selected topic (or subtopic) either press the selected topic twice, or choose View Topic
from the Outline Menu. A Viewer window will appear, displaying the selected document. (See
Figure 3.)

‘You can also use the search function to quickly locate specific information. See the Search section for
more detailed information.

ADA294756


Chapter Five

Ergonomic Factors Related to Posture ar

a

Inspection Environment

Ki

Cox, T. (1990). The recognition and measure-
ment of stress: Conceptual and methodological
issues. In J.R. Wilson, and E.N. Corlett (Eds.)
Evaluation of Human Work, London: Taylor and
Francis.

Cox, T. (1985). The nature and measurement of
stress. Ergonomics, 28, 1155-1163.

Davis, P. R. and Ridd, J. E. (1981). The effect of
headroom on acceptable lifting capacity, Ergo-
nomics, 24, 239.

Dnury, C.G. (1987). The human as optimizer.
In Megaw, E.D. (Ed.), Contemporary Ergonom-
ics, Ergonomics Society Proceedings, 1987, 19-
29.

Drury, C.G. (1985). Influence of restricted
space On manual materials handling. Ergonom-
ics, 28, 167-175.

Drury, C.G. and Brill, M. (1983). New methods
of consumer product accident investigation.
Human Factors and Industrial Design in Con-
sumer Products, 196-229.

Drary, C.G., Montazer, M.A. and Karwan, M.H.
{1987). Self-paced path control as an optimiza-
tion task. Systems, Man, and Cybernetics, 17,
455-464.

Galaxy Scientific Corporation. (1993). Human
Factors in Aviation Maintenance - Phase Three,
Volume 1 Program Report. DOTIFAA/Am-
93/15, Springfield, VA.: National Technical In-
formation Service.

Grandjean, E., and Kogi, K. (1971). Introduc-
tory remarks. In K. Hashimoto, K. Kogi, and E.
Grandjean (Eds.) Methodology in Human Fa-
tigue Assessment, London: Taylor and Francis.

Hart, S.G, and Staveland, LE. (1988). Devel-
opment of NASA-TLX: Results and empirical
and theoretical research. In P.A. Hancock and
N. Meshbkati (Eds.) Human Menral Workload,
North Holland: Elsevier Science Publishers.

105

Hockey, G.R.J. (1986). Changes in operator ef-
ficiency as a function of environmental stress.
fatigue. and circadian rhythms. In K.R. Boff
(Ed.) Handbook of Perception and Human Per-
formance, Vol 2., New York: Wiley and Sons.

Hockey, G.R.J. and Hamilton, P. (1983). The
cognitive patterning of stress states. In R.
Hockey (Ed.) Stress and Fatigue in Human
Performance, New York, NY: John Wiley and
Sons.

Hunting, W., Grandjean, E. and Maeda, K.
(1980). Constrained postures in accounting ma-
chine operators. Applied Ergunomics, 11, 145-
149,

Karhu, O., Kansi, P. and Kuorinka, I. (1977).
Correcting working postures in industry: A
practical method for analysis. Applied Ergo-
nomics 1977, 8.4, 199-201.

Karhu, O., Kansi, P. and Kuorinka, I. (1981).
Observing working postures in industry: Ex-
amples of OWAS application. Applied Ergo-
nomics 198}, 12.1, 13-17.

Krenek, R. F. and Purswell, J. L. (1972). Auto-
mobile escape worthiness--an approach to a
predictive model. In Proceedings of the Human
Factors Society’s 16th Annual Meeting, Santa
Monica, CA, 46-57.

Kroemer, K.H.E., Kroemer, H.J. and Kroe-
mer-Elbert, KE. (1990). Engineering, Physiol-
ogy, 2nd Ed., New York: Van Nostrand
Reinhold.

Louhevaara, V. and Suurnakki, T., (1992).
OWAS: A method for the evaluation of postural
load during work (Training Publication 11).
Helsinki, Finland: Institute of Occupational
Health.

McDaniel, J.W., and Hofmann, M.A. (1990).
Computer-aided ergonomic design tools. in
H.R. Booher (Ed.) MANPRINT: An Approach
to Systents Integration, New York: Van Nos-
trand Reinhold.

ANANDOQATES


Ergonomic Audit for Visua! Inspection of Aircraft

Cheoter Four

TASK DESCRIPTION VISUAL EXAMPLE NDT EXAMPLE
1. Initiate Get workeard. Read and understand | Get workcard and eddy current
area to be “cvered. equipment. Calibrate.
2. Access Locate area o> aircraft. Get into cor- | Locate area on aircraft. Position self
rect position. and equipment.
3. Search Move eyes across a: *a systemati- Move probe over each rivet head.

cally.

Stop if any indication.

4. Decision-Making

Examine indication against remem-

Reprobe while ciosely watching eddy

bered standards. ,| Current trace.

5. Respond Mark defect. Write up repair sheet or “| Mark defect. Write up repair sheet, or
if no defect, return to search. if no defect, return to search.

6. Repair Brili cut and replace rivet. Drill out rivet. NDT on rivet noid. Drill

out for oversize rivet.

7. Buy-Back inspect

Visually inspect marked area.

Visually inspect marked area.

strategy for applying human factors principles
systematically. The audit programm developed in
this report is an essential step towards such inte-
gration.

Tn order to know where to apply human
factors, for example using the FAA/AAM-
developed Hiwnan Factors Handbook (Parker,
1992), it is first necessary to identify the mis-
matches between the human (inspector) and the
system (equipment, tools, environment). The
audit program provides a convenient, quantita-
tive way to identify these mismatches. It starts
from the common ergonomics basis of inspec-
tion as a task/operator/machine/environment
system. The audit’s output can be used to focus
design/tedesign efforts where they will have the
greatest impact on reducing human/system mis-
matches which cause inspection and mainte-
nance errors.

There have been previous ergonomics audit
programs for manufacturing (Mir, 1982; Drury,
1988; Kittusway, Okogbaa, and Babu. 1992),
but the problems of the aircraft hangar are dif-
ferent from those of the factory floor. In inspec-
tion and maintenance, the workplace is rarely
static; task, equipment, and environment can
change considerably throughout the course of a
single inspection task.

The original two-phase audit pregram (Mir,
1982) used outcorne measures in Phase I to
provide an overall context of the plant, foliowed
by a workplace survey (Phase It) of the depart-
ments selected in Phase I. Information from first
aid reports, medical records, OSHA reports of
accidents and injuries, workers’ compensation
payments, turnover rate, absenteeism frequency,
lateness reports, and productivity for the various
departments were used to identify the most rep-
resentative departments for conducting the
workplace survey.

Ergonomic Audit

The e: gonomic audit developed here pro-
vides an overview of the inspection system’ s er-
gonomics (human factors). It will not point out
specific human errors that might result during
the task; rather, it indicates the important hu-
man factors issues that need to be addressed to
improve the performance of the operator doing
the task. It compares the current conditions with
the standards prescribed by current human fac-
tors good practice. incorporating national and
international standards where appropriate. The
report the computer program generates gives
guidelines to prioritize and systematize the ap-
plication of human factors techniques, to im-
prove and to achieve the standards.

ADA294756



Chapter Two Appendix 2-A_Evaluation Forms

Evaluation of Computer D
Initials: _ FSDO:

Please rate the computer on the follow!

Weight Too Heavy Adequate Too Light/Fragile

Size Too Large Adequate Too Small (eg. screen)
Speed Too Slow Adequate Fast

Display--inside Too Dark Adequate Too Bright
Display--outside Too Dark Adequate Too Bright

Trackball Speed Too Slow Adequate Too Fast

Trackball Ease Too Cumbersome Adequate Easier than a Pen
Overall Comfort Not Comfortable Adequate Comfortable

What were the environmenta! cond! you used the computer?

snow drizzle rain heat cold frigid
Did you use the computer for five working days? Yes No
If not, why not? Broken On Travel/Vacatio/RDO Too difficult to use
Could you comfortably carry this unit throughout a typical day? Yes No

If a neck, shoulder, or waist strap were avai

6

Which would you prefer? Neck

What are the three largest drawbacks to this product? — 1.

Evaluation of Computer D 1/2

ANANOATIES


Chapter Five

Ergonomic Factors Related to

environment. They provide a starting point to fo-
cus these investigations.

Table 5:1: E’gonomc-Factors
Area/Volume of Workplace

Task Duration
Equipment/Tooling Used
Workplace Lighting

Social Factors, e.g., resource availability
Surface Condition of Adjacent Surfaces

5211 Ni Workn

Confined spaces normally associated with
whole-body restrictions eccur when an inspector
enters an intervening structure or works within an
area in which the entire body is confined to that
specific area, e.g. cargo hold. However. restric-
tive spaces are also created in areas where the
surrounding physical space is unlimited, but the
immediate working area is restricted. These pai-
tial-body restrictions result in limited movement
of a specific body part. For example, tasks aided
by access devices such as steps or cherrypickers
cause lower limb restriction, for the feet must re-
side within a limited area. Other examples include
reaching arms through access holes and position-
ing various body parts in and around fixed aircraft
components, ¢.g. inside a small access panel.
These partial-body restrictions may occur in ad-
dition to whole-body restrictions. Interior inspec-
tion of the tail compartment demands that the
inspector climb into the area (whole-body restric-
tion) place the head and arms through narrow
confines to check components (partial-body re-
striction).

Much research has examined te effects of
restricted space on access tasks. Access consists
of physically reaching the area to be inspected.
Access activities involve controlling the move-
ment of the body or body part(s) within a restric-
tive space. In aircraft maintenance/inspection this
may be an unaided human task (e.g. area inspec-
tion of lower fuselage skin), aided by access de-
vices (e.g. steps, scaffolding. cherrypickers). or
require access through an intervening structure
(e.g. inspection of wing fuel tank interiors
through access holes). Normally, aircraft are de-
signed to the anthropometric boundary, i.e. to the

minimum allowable requirements based upon
human body dimensions. However, designing to
this boundary does not ensure (optimal) perform-
ance. Mathematical models indicate that the
amount of space defines the accuracy require-
ments of a task. In turn, accuracy requirements
may dictate the speed of performance.

Numerous investigations have found a speed/
accuracy tradeoff in human performance; as accu-
racy requirements increase because of decreased
space, performance slows (see Bottoms, 1982;
Drury, Montazwer, and Karwan, 1987; Fitts in
Wickens, 1992). For example, the speed a hand
can be moved through an access hole depends
upon the hole’s size. Further performance
changes may depend upon the posture adopted
while the body part is restricted. Wiker, Langolf,
and Chaffin (1989) reviewed research which in-
dicated that there are only minimal differences in
rnanual performance for work heights up to
shoulder level. However, position and movement
performance decreased progressively when hands
were used above shoulder level. The production
of movement with pre-tensed muscles may serve
to increase tremor and decrease maximum muscle
contraction speed. Restricted entries and exits
have been found to affect whole-body ingress and
egress times (Drury, 1985; Krenek and Purswell,
1972; Roebuck and Levedahl, 1961), as well as
subjective assessments of accessibility (Bottoms,
Barber, and Chisholm, 1979).

These models indicate that the speed an in-
spector chooses increases until it reaches some
limiting speed. The point at which increases in
space no longer affect performance is the per-
formanze boundary (Drury, 1985}. However. de-
signing to this boundary does not ensure that
increased operator stress, fatigue, or workload
does not occur, merely that direct task perform-
ance is not affected,

Along with access, other aspects of the actual
inspection task may be affected by a restricted
space. Visial search requires the inspector's head
to be at a certain location to control the eyes and
visual angle. Thus. restncted areas frequently
force inspectors to adopt awkward head, neck.
and back angles induce stress and fatigue. Inspee-



List of Abbreviations

National Aeronautic and Space Administration

NDI. londestructive inspection
> . Nondestructive Testing
NRR ooo eecsssesesecsssseseecosssnsecenncssseeccssssnateenscsnnnanecssesauseeceassuaneccecssstunseseesnnarsecesssenseseeesunseceteste Non Routine Repair
OSHA wee ceteccecee ce cscceesseessasanaeassneenenecneneensanensanctnensentenees Occupational Safety & Health Administration
OND occ ccccececeeesteenessesecseesencotssennaessquassesenscansneesetenessesaressessuesessutencssesacsnesuesanesoeaneseceneerasienaes On-the-Job Injury

cousensteesassuesecsseceseuessegarsessenersessececssutesseatssnsesiesueseetessucanessecanecncenenneeesesnessee Personnel Certification in NDT

Performance Enhancement System
Personality Research Form

Speed/Accuracy Traceoff
ndard Generalized Markup Language
Subjective Rating Scale
tate University of New York

TIFF. Target Image File Format
seestereeeee Task Load Index

United Kingdom
Jnited States of America

. Wechsler Adult {Intelligence Scale
. What You See is What You Cet

aii



Chapter Four

Ergonomic Audit for Visual Inspection of Aircraft

_ As with the previous audit programs for
manufacturing (Mir, 1982), continuing observa-
tions of the task specify a series of measure-
ments that need to be made. Some are made
with the help of instruments such as light-meters
or tape measures; others are answers to checklist
questions. The audit program is modular so that
the auditor can apply the particular measure-
ments needed for each task.

4.2 REQUIREMENTS FOR AN AUDIT
SYSTEM

4.2.1 Deciding Which Tasks to Audit

Every auditor has to use a sampling process.
Any sampling strategy has to address the follow-
ing issues:

« how to sample

¢ how much to sample

© how to appraise sample results
(Bill, Roth, and Arkin, 1962).

For the ergonomics audit, how to sample is
more important than how much to sample. The
mechanics of sampling may well decide the suc-
cess or the failure of the test in providing the
auditor with valid, reliable information. First,
the auditor needs to identify the basic unit to be
audited. In a manufacturing environment, the
natural unit is the workplace. In inspection (or
maintenance) however, the task represented by
the workcard is more appropriate since all job
and quality control procedures are already based
on the task.

There are two possible sampling techniques:
judgment sampling and statistical sampling
(Willingham and Carmichael, 1979). Judgment
sampling selects items subjectively, without sta-
tistical considerations for sample size, method of
selection, or evaluation. Since selection criteria
are based on the auditor's subjective judgment,
one obviously cannot project the sample results
to the entire population. Statistical sampling, in
contrast, provides objective criteria for sample
selection and is more appropriate for quantita-
tive ergonomics audit. Of the various statistical
sampling techniques available, only two can be
effectively used to decide which task to audit:

random sampling and stratified random sam-
pling (systematic sampling).

In random sampling, all tasks (workeards)
have given an equal chance of being selected.
While ensuring that the sample selection is un-
biased, random sampling may require larger
sample sizes to provide appropriate coverage.

However, an important additional consid-
eration is the fact that all inspection tasks may
not be considered equally important. It may be
more appropriate to concentrate on sampling
those tasks considered most critical. Stratifica-
tion can be used to segregate items to be exam-
ined by sampling within pre-determined groups,
or strata, of tasks. Some care must be exercised
while establishing the strata. They should be
determined so as to form a group having similar
characteristics. The methods discussed below
provide one stratification strategy, although
other strategies can be adopted for screening
tasks.

Parallel to the development of audit systems,
there have been job analysis systems aimed at
evaluating the ergonomics and the technical de-
sign of working systems (Landau and Rohmert,
1989). The documentation and diagnosis of
working system involves describing and quanti-
fying the system's elements and their character-
istics, €.g. stresses they exert, deduction of
design needs, formation and verification of de-
sign properties, prevention of possible impair-
ments by detecting unsupportable stresses, and
purposeful reduction of stresses. Thus, job
analysis and ergonomic auditing share many
commonalities and have the same necd to iden-
tify critical tasks.

The technique for selecting tasks (work-
cards) in the ergonomics audit program used a
points system (Lanham, 1955) similar to those
used in job evaluation systems. Any sampling
system must be:

¢ able to provide a thorough study of all

jobs to be evaluated

ADA294756


Chapter Four

Ergonomic Audit for ¥

POWER PLANT TASKS

WING INSPECTION TASKS

1 i Power plant inspection (15.64)

Tee Cap inspection (14.1)

| Thruster-reverser drive link inspection (13.74}

Wing inspection (13.59)

Aft spar wing control inspection (12.89)

2
3 > Pylon inspection (13.17)
4 : Engine accessory inspection (12.16)

Flap hinge bracket penetrant inspection {10.97}

5 | Power plant check (11.43)

Flap hinge bracket inspection (10.66)

SIKORSKY S58T BELL 206.
Phase | (18.87) _| Phase Il! (20.23)

1

2 | Phase V(14.46) | Phase IV (15.49)
3 Phase §V (13.94) Phase I! (15.42)
4 Phase Ilf (13.71) Phase ! (13.18)
§ Phase {I (13.47)

The final result of these manipulations can
again be tested for its reliability. If the inspectors
are indeed judging consistently, then there should
be a high degree of agreement among the final
rankings of the tasks. Thus, the same inspectors
were asked to rank the criticality of the tasks
within each of the four sets ("fixed wing power
plant” to “Bell 2062"), and these rankings were
compared using the coefficient of concordance.
All four values were significant at p< 0.01, with
values as follows:

Fixed Wing, Power Plant 0.913

Fixed Wing. Wing Inspection 0.813

Rotary Wing, Sikorsky SS8T 0.910

Rotary Wing, Bell 2062 0.900
These results in fact do show a high and signifi-
cant level of agreement.

partners. The need for graphics was identified be-
cause of their greater comprehension capabilities,
Graphics were incorporated in Version 2.0.
Version 2.0 retained the same structure as the
previous checklist. A few questions were ap-
pended with self-explanatory diagrams while oth-
ers were rephrased to reduce ambiguity. This
checklist was then tested for reliability at two diz-
ferent sites.

43.3.1 Reliability of the Ergonomic Audit (Version
2

The ergonomic audit was administered simu!-
taneously by two trained auditors on the follow-
ing three tasks. spanning two aircraft types:

e Audit ] - Sikorsky S58T Phase IT! Main

Rotor wansmission inspection
*® Audit 2 - Wing Inspection on a DC-9
* Audit 3 - Lavatory Inspection on a DC-9.

The differences between the two auditors
were analyzed using the Cochran Q test. which is
a strong test to determine whether the same
treatment generates different responses between
subjects. The value of the test statistic X° for each
test is shown in Table 4,5; all differences are
significant at p < 0.05.

TASK AUDITED x

43.3 Audit Checklist

The Audit checklist evolved over three dif-
ferent versions. Version 1.0 contained questions
in 18 modules spread over the Pre-Inspection, In-

1 | Audit 1 SE8T Phase {If Main 7.14
Rotor inspection
2 | Audit 2 DC-9 Wing inspection 5.00

spection, aid Post-Inspection Phases. This ver-
sion was evaluated at the sites of both airline

3_| Audit 3 CC-9 Lavatory inspection 5.00

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Table of Contents

9.5.1 Maintenance/Inspection Responsibilities
9.5.2 The Supervisor/Inspection Dichotomy.
9.5.3 Non-Destructive Testing . 159
9.5.4 Bonding
9.5.5 Working Times.
9.5.6 Demand and Supply of Mechanics/Inspector:
9.5.7 Visual Inspection and Eye Tests ..
9.5.8 Reporting Imminent Indications...
9.5.9 Work Cards, Information and Automation
9.5.10 ACCESS .....eccceescetesseceneeecerecsnsereeeenes
9.6 BIBLIOGRAPHY OF COMPLEMENTARY

Chapter Ten - Guidelines for Designing and impiementing Computer-based

Training for Aviation Maintenance

10.0 ABSTRACT.......

40.1 INTRODUCTION ......0..20:-.

10.2 CBT SYSTEM DESIGN ISSUES
10.2.1 Instructional Approach
10.2.2 Information Presentaticn Formats
10.2.3 Screen Design and Layout

10.3 HARDWARE ISSUES
10.3.1 Computer Display Quality
10,3.2 Input Devices ... .

ANADOATESL


2 Exticue i

Ergonomic Factors Reiated to Posture and Fatigue i

hea Irena:
i the Tnspe

n Environment

Chanter Five

In the aft cargo area, due to the nature of the
task, much of the kneeling and Jaying cannot be
reduced. However, equipment would reduce
much of the stress caused by extreme postures.
In the stabilizers inspection task, the existing
light levels (Table 5.6) should be increased to
reduce visual fatigue caused when visual in-
spection is performed in non-optimum condi-
tions (Reynolds and Drury, in press). In
addition, the platform weight could be lowered
so that the underside of the horizontal stabilizer
could be inspected without inspectors having to
kneel or crouch (Table 5.5, Figure 5.4, posture
2). Due to aircraft constraints, there can be lim-
ited structural and access changes in the iail in-
terior. Thus, most of the solutions address the
environment, in an attempt to improve these
conditions. Access to the wheelwell could be
improved by a new step design and eliminate tne
bending and reaching into the wheelwell (Table
§.5, and Figure $.6, postures | and 4). Further-
more. a portable chair may be utilized to reduce
crouching during MLG inspection (Table 5.5.
and Figure 5.6 posture 2).

5.5.3 Ergonomic Program

This evaluation has only addressed a smal
subset of ergonomic problems in the aviation
maintenance environment, particularly those re-
lated to restricted space and posture. However,
we also considered other factors during the
evaluation and recommendation phases. This
work has revealed the need for a comprehensive
ergonomic program addressing all components
of the aviation maintenance environment. Many
issues were not addressed, e.g. safety concems,
but these issues could be evaluated and tm-
proved using proven ergonomic techniques and
tools. The techniques applied in this project
were found to be sensitive and could be adapted
and utilized in further investigations of the avia-
tion maintenance environment.

Ergonomic programs have been developed
for manufacturing environments with great suc-
cess (see. Reynolds anc Drury, in press). These
programs are based upon the idea of continuous
evaluation and intervention. using the tools and
techniques applied above. to improve the fit
between human and system. and hence to reduce

error-causing mismatches. In the 1994 plan,
such a program is being implemented as a
SUNY/FAA demonstration project.

5.6 REFERENCES

Alluisi, E.A. (1982). Stress and stressors, com-
monplace and otherwise. In E.A. Alluisi, and
E.A. Fieishman (Ed.) Human Performance and
Productivity, Vol 3: Stress and Performance
Effectiveness, Hillsdale, N.J.: Lawrence Erl-
baum Associates.

Astrand, P. and Rodahl, K. (1986). Textbook of
Work Physiology, New York: McGraw-Hill.

Bartlett, F. (1953). Psychological criteria of fa-
tigue. In W.F. Floyd and A.T. Welford (Eds.}
Symposium on Fatigue, London: H.K. Lewis
and Co.

Blair, W.C. (1969). Human factors in deep
submergence vehicles Marine Technology So
ciery Journal, 3(5), 37 45.

Boitoms, D.J. (19823. The wactor driver's
steering control task. Ergonontics, 25, 31-29.

Bottoms, D.J., 2scber. T.S. and Chisholm, C.J.
(1979). Improving access to the tractor cab: An
experimental study. Journal of Agricn sural
Engineering Research, 24, 267-284.

Cameron, C. (1973). A theory of fatigue.
nomics, 16, 633-648.

Corlett, E. N. (1983). Analysis and evaluation
of working posture. In Kvalseth, T. O. (Ed.)
Ergonomics of Workstation Design, London:
Butterworths.

Corlett, E.N. and Bishop, R.P. (1978). The er-
gonomics of spot welders. Applied Ergonomics,
9, 23-32.

Corlett, E.N. and Bishop, R.P. (1976). A tech-
nique for assessing postural discomfort. Ergo-
nomics, 19, 175-182.

ANADOQATGCE


Chapter Four

Ergonomic Audit for Visual Inspection of Aircraft

aircraft inspection is performed. The only Gif-
ference among the different versions of the audit
system is the choice of aircraft types in the ex-
amples and illustrations. Versions exist for air-
line jets, regional turdoprop airliners (or
corporate aircraft), light aircraft (general avia-
tion}, and rotary wing aircraft. It is worth repeat-
ing that the different versions exist solely to
make the auditors more comfortable by letting
them see familiar aircraft illustrated: the content
of each checklist (and of the computer analysis
program) is identical.

4.3.1 Sampiing Plan Evaluation - The
Point System

Before actually proceeding with the audit, it
is imperative for the auditor to identify the
task/tasks to be audited. The criticality of a task
does not necessarily indicate the magnitude of
its human factors mismatches. Those remain to
be assessed by the audit checklist and the pro-
gram itself. The Point Rating scheme identifies
tasks where the probability of error occurrence
is high and samples the likely problem areas.

43.11. Step L. Selecting Factors

The basis of the sampling system developed
was the experience and expertise of the employ-
ees who rate these tasks. We want to know
whether the component of the screening method
reflects the domain being tested and whether the
components taken as a whole cover it in a repre-
sentative fashion.

We employed a method of “Multiple
Judges" to enhance their confidence in judg-
ments of content validity. Eleven inspectors and
three auditors were each asked to

© study the definition of the aircraft in-

spection domain

© generate a pool of possible factors influ-

encing an inspection task

e refine that pool.

As a result of a survey study. the factors

listed below were identified:

* Mental demands: the amount of infor-
mation needed from documeats, refer-
ence manuals, and communication with
the supervisor and ce-worker

* Physical demands: the amount of
force/pressure to be exerted for task
execution

« Visual demands: iJivmination levels
required for the complete inspection

« Access demands: the space restrictions
for carrying out the task

* Postural demands: the awkward pos-
tures adopted to access and inspect)

¢ Temporal demands: time stress during
the inspection

¢ Safety: how safe the inspector feels
during the inspection.

4.3.1.2 Step 2, Ranking the Factors

Afier having identified the seven factors, the
inspectors were asked to rank order these factors
in terms of their “degree of importance and criti-
cality” with respect to the task. Ten inspectors
with three years or more experience on C-check
inspections were asked to rank these factors.
The average ranking for the seven factors is as
given below:

Most Important — Safety
Mental demands
Visual demands
Access demands
Physical demands
Temporal demands
Least Important —_—- Postural demands.

A correlation analysis was conducted of
these ten inspectors’ rankings. The correlations
of the individual subject readings with the aver-
age were relatively high, the lowest being 0.67.
‘A non-parametric measure of overall correla-
tion, The Kendal} Coefficient of Concordance
(W), measures the degree of association among
inspectors had the value W = 0.674. This result
was highly significant (p < 0.001). showing
considerable agreement among inspectors.

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Ergonomic Factors Related to Posture

cs

1
| i Kneeling, Truk Beat and/or 2. Laying, {
| Twisted, Ams Below Shouider Trunk Bent and/or Twisted, and/or;
: Arm(s) Above Shoulder i
i |
i
|

3. Sining,

Trunk Bent and/or Twisted, and/or

Amm(s) Above Shoulder H

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Chapter Five

Ergonomic Factors Related io Posture a

CHAPTER FIVE
INVESTIGATION OF ERGONOMIC FACTORS RELATED TO
POSTURE AND FATIGUE IN THE INSPECTION ENVIRONMENT

Jacqueline L. Reynolds and Colin G. Drury
State University of New York at Buffalo
Department of Industrial Engineering

Steve Eberhardt
Northwest Airlines - Adanta

5.0 ABSTRACT

Aircraft inspection tasks are often per-
formed under extreme conditions which may
cause increased operator stress, fatigue, and
workload. Several factors, particularly restric-
tive spaces that cause extreme postures, have
been identified as possible contributors to stress
and fatigue in the aviation maintenance envi-
ronment. These factors are dictated by design it-
self and by the access equipment employed.
Following the development of a methodology
for studying fatigue and restrictive spaces
(Phase II), a set of four tasks from the C-check
of a DC-9 were used to evaluate these effects.
Inspectors were observed performing each task
to collect posture! data, and psychophysical
scales were used to measure fatigue, postural
discomfort, and workload. All showed that the
same tasks have the greatest impact on the in-
stvctor. On the basis of _.ose findings, im-
provements were generated and are now being
implemented at the partner airline.

5.1. INTRODUCTION

Aircraft structures are designed as a com: *
promise asnong aerodynamics, strength, weight,
and access. Optimum access must be conceded in
order to meet other requirements, thus requiring
many aircraft inspection and maintenance tasks to
be performed in non-optimum conditions which
may lead to fatigue.

Ergonomic factors in aircraft inspection and
maintenance tasks may cause extreme working
conditions. One of the most noticeable deviations
from ergonomically optimum conditions is that
tasks must be performed in restricted spaces that

force awkward postures. Literature reviewed
during Phase II indicates that tasks possessing
excessive postural demands, e.g. cramped posi-
tions and maintenance of awkward postures, can
produce fatigue and ultimately affect both per-
formance and well-being (see Corlet, 1983,
Corlett and Bishop. 1978; Hunting, Grandjean,
and Maeda, 1980; Van Wely, 1970; Westgaard
and Aaras, 1984). The project reported in this pa-
per arose from a task statement to propose a
methodology to study extreme ergonomic condi-
tions. particularly restrictive or confined spaces,
and their effect(s) on human posture, perform-
ance, and stress.

Characteristics of the environment, operator,
and task may produce fatigue and stress. We
model to guide research in describing and predict-
ing the effects of extreme ergonomic factors and
associated postural, fatigue, and siress effects on
performance and workload. We undertook on-site
evaluation in order to 1) to measure and deter-
mine if increased stress and fatigue levels exist in
ths aviation maintenance and inspection environ-
ment; 2) io determine if techniques and methods
used successfully to measure fatigue and work-
Joad in non-aviation environments could be ap-
plied to this environment; and 3) if increased
levels of stress, fatigue, and workload were
found, to provide ergonomic interventions to im-
prove this environment.

5.2 RESTRICTIVE SPACE MODEL

The Restrictive Space Model (Figure 5.1)
systematically describes a space or task area in
terms of inputs, or ergonomic factors defining a
Physical or perceived space, and outputs allowing



Chapter Three

Design of Portable Computer-based Workcards for Aviation Inspection

CHAPTER THREE
DESIGN OF PORTABLE COMPUTER-BASED WORKCARDS
FOR AIRCRAFT INSPECTION

Swapnes Patel, Amy Pearl, Sanjay Koli, and Colin Drury
State University of New York at Buffalo
Department of Industrial Engincering

John Cunea
National Helicopter

Jay Lofgren
Continental Airlines

3.0 ABSTRACT

From the analysis of workcards performed
in Phase I, an improved paper-based workcard
was developed in Phase Hi. Issues raised and
designs developed all directly apply to work-
cards on a portable computer. Such a computer-
based workcard system was designed, using an
IBM ThinkPad and hypertext software. It was
implemented for eight tasks: five A-check tasks
on a B-737-200 and three C-check tasks on a
DC-9-30. We undertook a direct test of the
computer system against both the original and
improved paper-based systems, using cight in-
spectors performing an A-check task of the
landing gear of a B-737-200. Results show that
the superiority of the computer-based system
enabled rapid leaning by the inspector. Signifi-
cant savings can accrue from the use of such an
integrated, portable system.

3.1 INTRODUCTION

The workcard, as the primary document
controlling an inspection task, has a great influ-
ence on inspection performance. During Phase I,
many human-system mismatches were identified
which could contribute to errors. The costs of
undetectable faults or faulty detection when
weighed against those of providing quality
documentation make a strong case for develop-
ing optimum documentation and for developing
a methodology coupled with a set of guidelines
for designing such documentation. This study
develops such a methodology based on applying

$1

human factors knowledge to the analysis of air-
craft inspection tasks. In Phase II, a paper work-
card was designed as a replacement for the
current workcard. From this design, we devel-
oped a set of guidelines to improve workcard
design. This generic methodology can be ex-
tended to the design of portable computer-based
workcards.

Portable computer-based workcards can
overcome some limitations of paper-based
workcards. Feedforward and feedback infor-
mazion can be presented, in addition to tradi-
tional directive information. Access to detailed
information in attachments and maintenance
manuals is easier. The display can act as an ex-
ternal working memory keeping ali relevant in-
formation in front of the user at all times.
Computer-based information also provides ad-
ditional flexibility for organizing information
about the tasks. Multi-layered information usage
can cater to the needs of both experts and nov-
ices. As an example of these benefits, Glushko
(1989) described the advantages of using an
“intelligent electronic manual” in organizing the
information contained in maintenance manuals.
According to Higgins (1989}, there can be as
many as 70 manuals for one plane.

Advances ia portable computing systems
make it more feasible to realize these benefits.
The combination of inspectors’ increasing in-
formation needs and technological advances en-
sures that portable computer-based workcards
will replace traditional hardcopy workeards.

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Chapter Two Appendix 2-C Software User Manuals

Data Transter

Select faspocter Name _
[MCKEITHAN, CLIFFM Ts}

}APPTRS forms to FSAS a
; Select Rems Steet aT tnselect aa]

| OffiesID  Deaignator _Mk-MedSer__Statat Cell-Up/Stert/Cmpl

| sor7ssenss ACMNDR-iGA — Closed Wit
HSO17940008s FERPA ‘NA-BID-A Cited 42t

5.2. Types of Data Transfer

Data Transfer Utility provides the following types of data transfer:
PTRS forms to Supervisory Review: This function transfers your PTRS data to a temporary
storage location where your supervisor can review it before it is entered into FSAS.
PTRS forms from Supervisory Reviwe to PEN: This function transfers PTRS data from the
temporary storage to your computer.
PTRS forms from Archive: This function transfers PTRS data from the archive to your computer.
PTRS forms from FSAS to PEN: This function transfers PTRS data from FSAS to your computer.
PTRS forms to FSAS: This function transfers your PTRS data directly to FSAS.
Delete PTRS forms from PEN: This function erases PTRS data from your computer.
Delete PTRS forms from Archive: This function ezases PTRS data from the archive.
Handwriting files from PEN to TEMP: This function transfers handwriting recognition files from
your computer to a temporary network directory.
Handwriting files from TEMP to PEN: This function transfers handwriting recognition files from
the temporary network directory to your computer.

Note: Depending on your site’s policy, the options: PTRS forms to Supervisory Review, PTRS
forms from Supervisory Review, or PTRS forms to FSAS may not be available to you.
$3 Data Transfer Help

The Help function provides an on-line version of this manual.

ADA294756


Chapter Two

PENS Project Fiek

gjec ld Evaluation

off-the-shelf model (or its subsequent version)
and a custom design for final implementation.
The custom design will be specified becausz it is
unlikety that a commercial, off-the-shelf mode!
will incorporate all of the desired features.

2614 Training

The inspectors were trained for two days a8 a
group. The first day of training consisted of DOS
and Windows basics, the specifics of Windows
for Pen Computing. and training the pen comput-
ers to their individual handwriting. The second
day of taining consisted of using PENS and the
On-Line Documentation, the computer rotation
procedure, transferring field-collected data to the
FSDO database system (the Flight Standards
Automation Subsystem. FSAS), and training
specific to each of the computers. Appendix 2-B
contains copies of the training slides. Appendix
2-€ contains copies of the software user manuals.

2.6.2 Expected Outcomes of the
Evaluation

ASI activities are too diverse to expect that a
single approach will address all of the difficulties
that inspectors encounter in the field. Pen com-
puters wil] certainly be appropriate for some in-
spection activities. but it is highly unlikely that
they will be appropriate in all situations. For ex-
ample, cockpit enroute inspections are likely not
amenable to a computer tool for two reasons: 1)
airlines are becoming increasingly sensitive to
devices that emit radio frequency interference
(RFI) and the potential for resultant difficulties
with avionics; 2) cockpit environments are typi-
caily so small that an inspector has room for only
a very .mul} notepad, not a computer the size of a
clipboard or larger. But one shou!d not condemn
the approach just because it does not work in all
situations; ii just means that PENS tools will have
to be modified to meet the requirements of the
various environments in which they will be used.
For example, we are already investigating voice
recognition systems that would perinit nearly
hands-free operation.

Furthermore, inspectors have already identi-
fied specific activities in which PENS would be
invaluable even in its present prototype state. For

example, inspectors frequently go on week-long
trips to remote sites where they will inspect all of
the operators in that area. As another example, in-
spectors also perform in-depth inspections on
particular operators. They may spend several days
at a single site inspecting all of the maintenance
and training procedures. operations materials. and
the like to ensure that the operator is complying
with the regulations. in both examples, the inspec-
tors need to be able to quickly and accurately
collect such field data and they need access to
reference materials (FARs, Handbooks, etc.)
while they are in the field.

2.7 SUMMARY AND CONCLUSIONS

As discussed above, pen computers use
handwriting recognition software and a pen stylus
for input, rather then a keyboard. The user writes
on the screen and the handwriting recognition
software translates the written characters to typed
characters. The pen stylus also acts as a pointing
device, much like a mouse. The pen stylus and
handwriting recognition really make computers
viable field devices when they are combined with
a graphical user interface, such as Windows fer
Pen Computing. After extcrsive in-house
evaluations of pen computers, several models
were chosen for a field evaluation by Aviation
Safety Inspectors. Custom software ta support the
inspectors was also installed on the computers for
evaluation.

As with the introduction of any new tool into
an existing system, the effects are widespread.
The potential for enhancing the productivity and
job satisfaction of Aviation Safety Inspectors is
great. However. with that potential comes the
possibility of either having no effect (because of
rejection of the too]) or, worse yet, actually de-
creasing performance. Time and again. experi-
ence has shown that buying systems and
instatling them without consulting the individuals
who are supposed to use them does not work.
Such an approach results in user and management
frustration. as well as a waste of resources. Only
by developing prototype systems and testing them
in the field will the Flight Standards Service learn
what toois are necessary and viable to Aviation

ADA?94756



Appendix 2-C Software t'ser Manuals Chapter Two

PENS User Manual

PENS is 2 sunte of tools to assist Aviation Safety Inspectors (ASIs) in their daily activities. It primarily
addresses two main aspects of inspector activities: data collection via the PTRS form and accessing
ulatory documents. The current PENS softare provides these functions for airworthiness activities,
including an enhanced version of the PTRS form. Future development will include the forms, job aids. and
reference documents associated with all ASE activities,

1. Data Collection Procedure
Here are the necessary steps to mun the PENS software:
1. Start Windows. if you are not already in the Windows envrionment.

2. Start the PENS software located in the PENS group.

3. Fill out the information on the PENS Login Screen. This information is needed to identify the job aids,
forms. letters. and reports that are required for an inspection activity. (See PENS Login Section for detailed
information on how to enter this information.)

‘ou to the PT]

4. Press the OK button. This action br

5. The PTRS screen is divided into four sections. Boxes containing the required information for the
activity are surrounded with thick black boxes. Fill out these boxes accordingly. (See PTRS Section for
detailed information on how to enter this information.)

6. You can also access the FARs and Inspector's Handbook using the PENS Function buttons (the Job
Aid and Aircraft functions are not currently functional).

+ Sour data for
your data for

7. Choose either SAVE or SAVE VERIFY to save your data. SAVE VERIFY will revie:
consistency and completeness. SAVE will not make such checks. but it will save your data for later
verification. PTRS records cannot be transferred to FSAS dat.

8 Select EXIT when you are futished with the data collection.

2. PENS Login

The following paragraphs illustrate how to fill out information on the Login sercen:

{. Inspector {D: Enter your three character initials. (Oiher fieids will be t
filied in.)

2. Inspection Type, Section, Heading and Subheading fie!ds will help you select the proper activity
number. (These fields replace the small notebooks you currently use.) To supply this information press the
down-arrow on the corresponding list box and sclect one of the options. Once these fields are filled our, the

PENS will supply the relevant Activity Number.

38

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a cece eee ce

Appendix 2-C Software User Manuals Chapter Two

2. Press an INDEX button containing the first letter of the manufacturer and then use the scroll bar
wo find it. Tap the manufacturer name to select it.
Once the right manufacturer is highlighted, press OK. The cursor will change into an hour giass while
the software loads the models and series.

The Make/Model/Series button accesses the Make/Model/Series screen. This bution can be used instead
of the above method, provided that you know the aircraft popular name, model. or series. There are
several ways of finding the aircraft code in this screen:

1. Enter the first few letters of either the manufacturer, popular name, model, or series in the field
FIND. Then press either one of these buttons: SEARCH MAKE (search the manufacturer),
SEARCH NAME (search the popular name), SEARCH MMS (search the make. model and
series), or SEARCH ALL (search all information). The first matching entry containing these letters
will be highlighted. Additional aircraft may be found by subsequent pushing of the SEARCH
button.

2. Press an INDEX button coviaming the first letter of the manufacturer and then use the scroll bar
to find the aircraft. Tap the aircraft name to select it,

Once the right aircraft is selected, press OK. The cursor will change into an hour glass while the
software loads the make, model, and series.

lists. (These
t code.)

Model and Series: Select the appropriate Aircraft Mode] and Series from the correspondi
codes will automatically be entered if you used the Make/ModeV/Series screen to find the ai

Depart: Enter the code for the airport most proximate to the location of activities conducted outside of the
office (for En Route inspections. enter the code of the departure airport). If you do not know the code, hit the
SELECT bution to access the Airport Screen.
There are three methods to find the airport code in this screen:

1. Enter the first few letiers of the city, airport name or airport code in ihe field FIND and press the

SEARCH bution. The first matching entry containing these letters will be highlighted. Additional

manufacturers may be found by subsequent pushing of the SEARCH button.

2. Enter the state where the airport is located, in the ficld STATE: and press the SEARCH burton.

Use the scroll bar to find the airport. Then tap the airport name to select it.

3. Press an INDEX button containing the first letter of the state (INTL for international ai

and then use the scroll bar to find it. Tap the airport name to select it.

Once the right airport is selected, press OK.

Arrivai: Enter the code for the arrival airport. If you do not know the code, hit the SELECT button to
access the Airport screen. (See the above information for searching the arrival airport code.)

Flight #: Enter the flight number. if available.

nt.

investigation #: Enter the investigation file number assigned to the accident, vickition, incident, or
complaint associated with the activity.

Tracking: This field is only activated for certain activity numbers.

Miscellaneous: Enter misceljaneous information regarding a work activity. Enter “OBSVD" to document
examiner certification activities that are observed by inspector.

42

ARR XOATOS

an



Ergonomic Audit for Visual Inspection of Aircraft

Chapter Four

A. Pre-Inspection Phase

Tn this phase, the auditor collects informa-
tion on the ergonomic aspects of the task that are
not expected to change during the task sequence.
These are represented by questions on the fol-
lowing:

® documentation, communication during

shift changes, etc.

* visual and thermal characteristics of the
environment

© equipment design issues (NDT and ac-
cess).

This information is gathered before the ac-
tual inspection to keep the auditor's effort (and
any interference with the inspector) to a mini-
mum as the task progresses.

B. Inspection Phase
During this phase. the auditor evaluates the
main issues, i.e. information, environment,
equipment and physical activity. However, the
auditor's focus is the task at hand and the way
this task is completed. The issues are the follow-
ing:
* usage of documentation, communication
between workers/supervisor
© task lighting, noise levels. operator per-
ception of the thermal environment
© equipment availability and standards
*© access, posture. safety.

C. Post-Inspection Phase

This phase evaluates the maintenance ac-
tivities, i.e. repair and buy-back. Alihough us-
ing the same guidelines as the inspection task
and following the same structure and sequence,
some additional modules have been included te
address issues specific to maintenance activity.

42.3.2 The Computer Program (ERGO) for Audit
Analysis

Turbo Pascal 6.0 was chosen as the lan-
guage for developing the audit program. It is a
structured, high-level language with multiple
overlapping windows. mouse support, a multi-
file editar, and an enhanced debugging facility.

The audit analysis program has a data input
module and a data analysis module. These are
further divided into several independent mod-
ules addressing specific issues of the preinspec-
tion, inspection and the post-inspection stages,
e.g. documenis, communication, visual charac-
teristics, access, and posture. The fundamental
logic of both the programs is as follows:

*® opening the data file

accepting answers or values to the

checklist questions

updating the counter

writing the answers to a data file

accessing the data file

comparing values with the correct value

or answer

« setting flags and proceeding to the next
data set if the two answers are unequal

© checking the position of all flags at the
end of all data input

© printing recommendations or prescrib-
ing guidelines for all the flags set.

eee

A simple manual accompanies ihe pr
showing how to
© install the software onto a personal
computer
run the program
create and view data files
access data files for analysis
create and view output files
print data and output files
abort from in within the program.
The manual has been written so that even novice
computer users can install and run the program.

ogra,

4.3 EVALUATION AND EVOLUTION

It is only possible to refine and develop a
system such as this ergonomics audit program
through continual testing in operational envi-
ronments. Two airline partners were involved in
designing, evaluating and developing this sys-
tem. The first was a regional operation of pas-
senger helicopters; the second, a major national
airline. The requirements were initially per-
ceived to be quite different for each environ-
ment, but a common audit system was
eventually developed that is applicable wherever

ADA294756


Chapter Eight

Results of the ECS Tutor Experiment at Clayton State College

8.1.4 Intelligent Help Agent of the ECS
Tutor

The ECS Tutor offers two ways for a user to
get help. First, a user can ask for help by clicking
on one of the five help buttons on the bottom left
side of the screen. This help is continually avail-
able while the user is troubleshooting a malfunc-
tion. Four buttons providing help correspond to
the four types of knowledge used in troubleshoot-
ing, and one button explains hew to operate the
tutor. The five help buttons are described in Ta-
ble 8.1.

Second, a user gets help when he or she
makes mistakes. The ECS Tutor contains a
qualitative model of ECS’ components. The ECS
Tutor’s IHA can compare a user’s actions with
the model to determine if the user is making prog-
ress toward a solution. If the user performs an ac-
tion that does not make sense, e.g. replacing a
component that is working correctly, the IHA of-
fers the user some help. The type of help offered
depends on several factors, including the follow-
ing:

© the type of error the user made

the instructional strategy the tutor is using

* the number and type of mistakes the user

previously made

Purpose of Help

Help Type

Procedures ; Standard procedures
for troubleshooting

malfunctions

This Part | Component j{ Description of the com-
Porents and their sub-

components

Schematic of either the
ECS' control or pack
systems

Systems | Systems

Advice Principles Suggestion of what to

| do next

How To Operation General help with using

; the tutor

the threshold for offering help when
users make mistakes.

When a user make a mistake, the tutor offers
help that the user can either ignore or view. The
type of help offered will be one of the four
knowledge types described above: principles,
systems, components, or procedures. Figure 8,2
offers an example of a principle. It shows a gen-
eralized electrical control circuit and describes the
“backtrack” and “divide and conquer” strategies

part of a controller system, it & often the cause of
problems. The simplest test is to swap out the

the problem goes away. If a replacement is not

handy, check the test points on the board to see if it is
within specs. {f there is another fault in the system that

ADA294756


Chapter Seven

Correlates of Indi

cational level was coded "1", while the higher
Jevel was coded "2." Subjects in each category,
along with their expressed liking (or disliking) of
the inspection task, are shown in Table 7.6.

Like Dislike
Category Inspection Inspection
1 12 3
2 3 10

Ten out of 13 subjects (77 percent) who ex-
pressed a dislike of the inspection task or who
could not visualize themselves as inspectors were
in the higher educational level category, while 80
percent of subjects in the lower educational cate-
gory either liked the inspection task or could.
visualize themselves as inspectors. A chi-square
test of the data in this table revealed the relation-
ship between erjucational level and liking for in-
spection to be significant (p<.01}.

Correlational analyses revealed that neither
liking for inspection nor educational level were
significantly related (p>.05) to any performance
measures.

Although gender was not related to liking for
inspection and, as noted earlier, was not related to
any performance measures, gender was correlated
significantly (r=-.58, p<.01) with scores on the
Bennett Mechanical Aptitude Test. Males per-
formed better than females on this test. Because
the Bennett Test Joaded substantially on Factor 4,
which was significantly correlated with both
missed faults and false alarms, these data suggest
an indirect relationship of gender to performance.

7.3 DISCUSSION

The present study used a simulated eddy-
current inspection task to address two questions,
both of which are of concem to aviation mainte-
nance and inspection:

1. Does performance on this task over a pe-

riod of time simulating an 8-hour shift
show any evidence of decline (fatigue)?

ADA294756

2. Can tests and measures be identified that
will predict performance on this task?

7.3.1 Evidence of Fatigue Effects

Before considering possible fatigue effects,
the experiment’s procedure will be briefly re-
viewed. The first day for each subject was de-
vated to administration of the psychometric test
battery and to training sessions on the NDI task.
The second day simulated a work shift by having
subjects perform the NDI task over four succes-
sive sessions, two in the moming and two in the
afternoon. Each session was self-paced and Jasted
approximately 60 te 90 minutes. Fifteen-minute
breaks were given between the two morning and
afterncon sessions along with a 60-minute lunch
break. Attempts were made to make each session
as close to real life as possible by allowing sub-
jects to take brief “stretch” breaks as often as they
desired.

For purposes of data analysis, each session
was arbitrarily divided into a first and second
half. The results revealed a significant increase in
the number of both missed faults and false alarms
from the first to the second half of the sessions.
Further, while missed faults did not increase over
the four sessions, there was a significant increase
in the number of false alarms from session 1 to
session 4.

The increase in errors during sessions, where
no rest periods were allowed except for brief
stretch breaks, suggests a decline in performance
efficiency that may have been the result of a pro-
gressive increase in tiredness and/or a decrease in
attentiveness. Rating scale measures of attentive-
ness and tiredness both showed significant
changes from the beginning to the end of the ses-
sions, with attentiveness decreasing and tiredness
increasing. However, individual differences in the
magnitude of change in tiredness or attentiveness
were found to be unrelated to individual levels of
performance error (beth missed faults and false
alarms).

Changes in rating scale variables such as in-

terest, strain, annoyance, task difficulty, and task
effort were significant from beginning to end of



Phase (V Overview

Chapter Gre

differences in nondestructive testing (NDT) were
observed due to a difference in emphasis between
the two countries. The USA emphasized nule-
based performance: the UK, knowledge-based.
Chapter Nine documents the similarities and dif-
ferences and offers recommendations.

1.9 GUIDELINES FOR DESIGNING
AND IMPLEMENTING COM UTER-
BASED TRAINING FOR AVIATION
MAINTENANCE (CHAPTER TEN)

Chapter Ten is a bibliographic overview of
selected issues in designing computer-based
training (CBT) systems. Issues such as instruc-
tional design, information presentation formats.
screen design and layout, and hardware are cov-
ered. Over 60 references are included.

1.10 FUTURE PLANS

Capitalizing on a research team of scientists
and engineers from industcy, government and
academia, the research program will continue to
develop and implement tools and procedures for
human performance enhancement. Future phases
will increase field studies of research results. The
program will also continue to conduct research
with partners in both industry and government.
Ali research efforts will continue to emphasize
the measurable impact of the research program on
increasing maintenance effectiveness and effi-
ciency with resultant cost control.

1.11 REFERENCES

Shepherd, W.T.. Johnson, W.B.. Drury, C.
Taylor. J.C.. Beminger. D, (1991). Humana factors
in aviation maintenance phase !: Progress report.
Washington. DC: Federal Aviation Administra-
tion. (Report No. DOT/FAA/AM-91/16).

Federal Aviation Adminisiration Office of
Aviation Medicine (FAS/AAM) and Galaxy Sci-
entific Corporation (GSC). (1993a}. Human fac-
fors in aviation maintenance - Phase two progress
report. Washington, DC: Federal Aviation Ad
ministration. (Report Na, DOT/FAA/AM-93/5).

Federal Aviation Administration Office of
Aviation Medicine (FAA/AAM) and Galaxy Sci-
entific Corporation (GSC). (1993b). Human fac-
tors in aviation maintenance - Phase three.
volume | progress report. Washington, DC: Fed-
eral Aviation Administration. (Report No.
DOT/FAA/AM-93/15).

Federal Aviation Administration Office of
Aviation Medicine (FAA/AAM) and Galaxy Sci-
entific Corporation (GSC). (in press). Human
factors in aviation maintenance - Phase three,
volume 2 progress report. Washington, DC: Fed-
eral Aviation Administration.

ADA294756



Chapter Seven

Correlates of Individual Differences in NDi Performance

7.3.3. Gender, Liking for Inspection, and
Education Level

The previous pilot srudy suggested a possible
gender difference in inspection accuracy. For this
reason. this study examined possible male/female
differences in performance. The results did not
show differences between males and females in
either performance accuracy or in speed of in-
spection. This lack of a gender effect is consistent
with the findings of most previous studies of
vigilance and inspection (Wiener. 1975).

Liking for (or dislike of) inspection was re-
lated to educational! ievel. but not to any perform-
ance measures. Likewise, differences in subjects”
educational levels was also unrelated to perform-
ance. These findings are consistent with those of
Summers (1984) in his follow-up study of the
early Air Force “Have Cracks, Will Travel” study
(Lewis et al., 1978). The level of forma} educa-
tion (from less than high school to more than 2
years of college) was unrelated to technician per-
formance, as was expressed liking for {or dislike
of) inspection.

7.4 CONCLUSIONS

This experiment used a simulated eddy-
current inspection task (a) to determine the extent
of performance change, if any, over a simulated
day-shift work period and (b) to investigate the
relationships between various predictor variables
and performance on the eddy-current task. Many
of the findings, such as the lack of any relation-
ship among inspection performance and gender,
educational} level, and expressed liking for in-
spection, were generally consistent with previous
studies. Other findings, such as the relationships
between a number of psychometric tests and task
performance, are tentative and need fo be vali-
dated with a different group of subjects. This will
be accomplished in a planned foilow-up study. A
summary of the major findings of this study fol-
lows.

« There were statistically significant increases
in both missed faults and false alarms during
the 60-90 minute task sessions, but only false
alarms showed aay tendency to increase

across sessions. Increases in the percentages
of missed faults and false alarms, both within
and between sessions. ranged from only 0.8
to 4.5 percent, however, and may not repre-
sent performance declines of practical sig-
nificance.

* Accuracy of inspection (low numbers of
missed faults and false alarms) was found to
be positively related to mechanical ability, as
measured by the Bennett Mechanical Com-
prehension Test. and concentra-
tion/attentiveness, as measured by the WAIS
Digit Span Test. Tests and scales measuring
such waits as extroversion. impulsivity, and
lack of meticulousness (the Eysenck Extro-
version Scale and the PRF Impulsivity and
Cognitive Structure Scales) were significantly
related to speed of inspection.

* Speed of inspection was unreiated to errors
(missed faults and false alarms).

« There was a relationship between level of
educational achievement and liking for in-
spection. Subjects with higher educational
levels expressed a dislike for performing the
inspection task, while those with lower edu-
cational levels tended either to like the task or
not to find it unpleasant.

* Liking for inspection was unrelated to per-
formance (missed faults, false alarms, or
speed) on the NDI task.

© There were no differences between males and
females in either task performance or in lik-
ing for inspection.

7.5 REFERENCES

Bennett, G. K. (1069). Bennen Mechanical
Comprehension Test - Manual Forms § and T.
New York: The Psychological Corporation.

Berch, D. B. & Kanter, D. R. (1984). Individual
differences. In J. S. Warm (Ed.), Sustained at-
tention in human performance. New York:
Wiley.

Drury, C. G. (1992). Inspection Performance. In
G. Salvendy (Ed.}, Handbook of industrial engi-
neering, second edition. New York: Wiley.

ANADGATRSA


Appendix 2-C Software User Manuals Chapter Two

TOOLS: Accesses the standard windows for PEN computing tools:
] Gives you information on editing gestures

® Is not currenily useful for PENS software

Is the standard on-screen keyboard

Starts the handwriting recognition trainer

& Provides help for Windows for PEN Computing

HELP: Accesses PENS On-line Help File

EXIT: Exits the PENS software. If the changes in your PTRS form have not been saved,
PENS gives the following options before it exit
Verify and Save: Saves und verifies your file.
Save without Verifying: Saves your file.
Don't Save Changes: Exits PENS without saving the changes you made.
Return to Form: Cancels the exit comman:! and returns to the PTRS form.

5. Data Transfer Utility

The Data Transfer Utility allows you to transfer vour PTRS records either directly to the FSAS database or

to a temporary data storage. The purpose of the temporary data storage is to hold you

r data until your

supervisor verifies the data. When your facilities do not require this supervisor's approval, you can directly
transfer the data to the FSAS database. Figure 2 shows the Data Transfer Utility Screen.

5.1 Data Transfer Procedure

To transfer the data follow these steps:

1

yok wt

a

~o ge

Connect the Xircom Adapter to your computer. (Follow the steps for Connecting the Xircom
Pocket Ethernet Adapter in your computer user manual.)

Follow the prescribed network login procedure.

Start the Data Transfer Utility.

Select your name from the Select Inspector Name box.

Select the type of data wansfer from the Transfer... box. Files available from the selected data
transfer type will be shown in the Select Forms box. (See Type of Data Transfer section for
more detailed information.)

Tap the filets) you wish to twanfer with your pen. (Press the SELECT ALL button to select all
files: Press the UNSELECT ALL button to deselect all files.)

Press the Transfer Files button. (Messages about the transfer status will appear on the screen.}
Repeat steps 5 to 7. if you would like to transfer other files.

Choose DONE to exit from the Data Transfer Utility.

46

ADA294756


Tabie of Contents

3.2. METHODS
3.2.1 Hardware
3.2.2 Defining Design
3.2.3 Development of the System .
3.2.4 Usability Evaluation of the Computer-Based Workcar
3.3. CONCLUSIONS...
3.4 REFERENCES...

Chapter Four - Ergonomic Audit for Visual Inspection of Aircraft

40
4.1 INTRODUCTION
4.2. REQUIREMENTS FOR AN AUDIT SYSTEM...
4.2.1 Deciding Which Tasks to Audit
4.2.2 The Ergonomics Audit System
4.2.3 The Audit System Development
4.3 EVALUATION AND EVOLUTION...
4.3.1 Sampling Plan Evaluation - The Point System .
4.3.2 Results of Sampling Plan
4.3.3 Audit Thecklis
4.4 THE AUDIT SYSTEM IN PRAC-TICE

the Inspection Environment

5.0 ABSTRACT...
5.1 INTRODUCTION
5.2 RESTRICTIVE SPACE MODEL .
5.2.1 Ergonomic Factors
5.2.2 Physical and Perceived Spaces.
5.2.3 Stress .
5.2.4 Fatigue
5.2.5 Operator Response
5.2.6 Effects on Operator.
5.2.7 Framework to Measure the Effects on Performance/Workload
5.3. ON-SITE EVALUATION AND ANALYSIS 000 eeeeeceescecseeeres
5.3.1 Evaluation of Pre-Existing Conditions.
5.3.2 Evaluation of Existing Conditions
5.4 FINDINGS.
5.5 PRACTICAL INTERVENTION:
5.5.1 Ergonomic Audit Posture Module.
$.5.2 Design Requirements/ Interventions ............csccccescessesseeesesesesesecssesueeacaesessseseessesseseesnceeeesees 103

vi

ADA294756


Chapier Ten Guidelines for Designing and liplementing CB.

luplementing CBT for Aviation Maintenance

Greenstein, J.S., and Arnaut, L.Y. (1987). Human
factors aspects of manual computer input devices.
In G. Salvendy (Ed.) Handbook of Human Fac-
tors. John Wiley & Sons, New York, pp.
507-548.

69

AUS. GOVERNMENT PRINTING OFFICE: 1995 - 60-087/00129

ADA294756


Reliability in Aircraft Inspection: UK and USA

Chapter Nine

9.4.10 Access

Both Countries: The modes of access for in-
spection of aircraft have been greatly improved in
the past 10 years. This may be due to the fact that
wide-bodied jets cannot be inspected standing on
an oil dram or the top of a step ladder and that
enstom built docking is more efficient. Fortu-
nately. this attitude has spread to smaller aircraft
in a few companies although not down to the
older ageing aircraft such as the 707s and BAC
Ills where the extra heavy v..gineering occa-
sioned by the SSID programmes etc. render good
docking most advantageous.

UK and US Variations: There are no essen-
tially British or American variations although the
closer and more frequent contact with the gov-
ernment inspectorate (HSE) in the UK than with
the OSHA in the USA results in a safer environ-
ment with greater adherence to details such as
toe-boarding and piank ends in scaffolds. and
toxicity levels in composite repair work.

Evaluation: There is still a need for improved
access. Al} establishments visited had examples
of steps which were poorly designed or ed. Steps,
mobile staircases and Jadders vary enormously in
quality and safety. Most have wide bases to avoid
tipping and many have hand rails but there are
still too many that tip easily, that are rickety with
loose joints and that have wheels which do not
lock. One otherwise sturdy staircase had only one
wheel that was lockable and so moved around
gradually during inspection: others could not be
adjusted for foot height and rocked continually
during inspection. The worst case involved steps
that were ten feet tall with a top barely large
enough for two feet so that the inspection of the
fwd service door, an intricate enough task involy-
ing much torso movement to enable a close scru-
tiny of a complicated structure, necessitated one
foot on the steps and the other on the aircraft.

On top of the wing, there is still an unwilling-
ness to fence the perimeter yet the curve and
camber of the wing make it a genuine danger
where each succeeding step becomes the more
hazardous.

Particular problems, such as production break
inspection, can give rise to excellent access solu-
tions: the arced bridges used being perfect for that
particular job. However, they were extremely
awkward when used subsequently for a horizontal
lap joint.

The height of the platform is of some impor-
tance. The ideal eye position for visual inspection
and NDT probe manipulation are not the same
nor is that required for engineering work. There is
also the need for a place to conveniently locate
the NDT equipment itself. More adjustability in
heights is required, preferably power driven from
on board. It is very time wasting for the worker to
demount to adjust the jack-up leading to the
temptation to forego adjustment and work at a
non-optimal height. Tailplane vertical surfaces
are a particular case where this is required e.g. for
manipulation and alignment of an Xray set out-
board of the rudder. The popularity of the cherry-
picker is due largely to the independence and
variability of height and position even though it is
frequently far from being a stable platform.

The most frequent problem, however, was
simply of an insufficient supply of access equip-
ment with inspectors and mechanics continually
borrowing each others access stands. This wastes,
time and effort, suggests to an inspector the com-
pany’s lack of concem for the importance of the
job, and may be the cause of an incomplete in-
spection due to either forgetfulness or exaspera-
uon.

Despite the plethora of access aids, the in-
spector will still find himself in spaces where ac-
cess is difficult due to the overal! aircraft design.
Hatches can be too small to enter comfortably,
interna] spaces too small to allow for the focusing
distance of the eye: if one is already holding a
torch (flashlight) and a stick mirror then an addi-
tional magnifying lens becomes almost an im-
possibility.

Finally, the general clutter beneath and
around most aircraft needs eliminating. This is
generally a mix of portable work benches which
can easily be moved or avoided and services such

ananAAnaors


Chapter Three Design of Portable Computer-based Workcards for Aviation Inspection
ren
9 Point Rating Scale End
issues Addressed Points Workeard System

Q | 8 Current_| improved | Computer
Readability of text Terrible Excellent 4.0(2.1) 6.6(1.4) 6.5(0.76)
Task of reading Very difficult Very easy 3.9(2.0) : 6.5(2.3) 6.6(1.8)
Amount of information Too little Too much 4.8(1.8) 4.0(1.1) 3.5(1.8)
Flexibility of use Terrible Excetient 3.5(1.4) | 5.5(0.9) 5.6(1.8)
Ease of writing up a Non-Routine | Very difficult Veryeasy | 2.9(2.4) | 4.9(2.1) §.4(2.2)

Table 3.7 shows comparisons for each of
the 19 common questions made using the Wil-
cexon test. Note that 16 comparisons showed
that the computer-based workcard better than
the original paper-based system, reflecting the
results given in Table 3.6. The improved paper-
based system was better than the original paper-
based system in 17 comparisons, and the com-
puter-based system was only rated higher than
the improved paper-based system on 2 compari-
sons. It is interesting that the two comparisons
where the computer-based workcard was rated
higher than the improved paper-based workcard
measured the inspector's degree of interest in
the system and in using the system again.

Iniprovement appears to better layout, or-
ganization, end presentation of information,
whether on hard-copy or on computer. The
computer features add some benefit, but not
much, to the improved paper-based workcard.
indeed, of the total degree of improvement from
the original paper-based workcard to the com-
puter-based workcard, an average of 81.6%
across all rating scales was due to the improved
paper-based workcard. This re-emphasizes the
benefits of implementing good human factors
principles in workcard design, whether or not
the system is computerized.

Our conclusion is that many improvement
can be made without resorting to computer-
based systems. The text and graphics in our
computer-based hypertext system were the same
ones used in the improved paper-based system.
Thus, any company would be well-advised to

63

modify its paper-based system. as this completes
most of the work needed to implement any fu-
ture computer-based system.

All mechanics quickly became familiar with
the computer-based system: no mechanics took
mere than one hour to learn the system well
enough to go through the steps of single A-
check task. More time would obviously be re-
quired for mechanics to become fully adept at
navigating the system and using all of its fea-
tures, but the time and cost overhead associated
with introducing this system is very low. This
vindicates the design philosophy utilizes de-
tailed task analysis and human factors interpre-
tation of the mechanics’ jobs, and including
feedback from the mechanics themselves, to
produce the final design.

Despite the good rating of ease of physical
use (Tables 3.5 and 3.6), the computer-based
system will clearly benefit from improved
hardware. Weighing 6 pounds and requiring
both a keyboard and a pointing device, the cur-
rent system cannot be used as easily as, for ex-
ample, a future pen-based system. All features
of the current hypercard system can be used di-
rectly on a pen-based system, with the added
advantage of bit-mapped storage of signatures.
All that is required is better screens for pen-
based systems, and improved handwriting rec-
ognition for filling out Non-Routine Repair
forms rapidly. According to computer industry
sources (see Byte, October 1993) such systems
should be fielded within a year.



Appendix 2-4 Evaluation Forms Chapter Two

Would you use this computer in the field as part of your job? Yes No

If not, why not?

Evaluation of Computer A 2/2

ANADOATECS



A. Significantly Better Than Neutral Rating

p<0.01

p<0.05

eee

eoeeees

Readability of text

Readability of buttons and icons
Readability of graphics

Ease of understanding information
Ease of understanding symbols/icons
Chance of missing information

Degree of interest

Degree to which rater would like to use
workcard again

Degree to which workcards like these
should be used

Would rather rely on substituting computer
for paper-based workcard

Overall ease of usability

Degree of simpiicity

Degree of tension while using system
Usefulness of Global View feature
Usefulness of Home View feature
Usefulness of Automatic Non-Routine
Writeup feature

usefulness of direct access to ali refer-
ences

eoeoan

Task of reading

information covered everything for task
Separating information by frequency of use
Flexibility of use

Ease of referring to attachments or manuai
Often: confused about location

Often confused about how to retum to pre-
vious location

Degree of fatigue after using the system

8. Not Significantly Better Than Neutra! Rati

ng

er eroceeoree s

Tasks were well organized

Effort required in focating information
Consistency of organization

Ease of physical use

Ease of writing up an Accountability List
Ease of writing up a Non-Routine

Ease of learning to use the computer-based workcard

Need to refer to “Global View”

Performance rating using the computer-base workcard
Usefulness of Automatic Accountability List Generation feature

Usefulness of Writeup Note feature

C. Significantly Worse Than Neutral Rating

[ °

Usefulness of Time Overview feature

61



Chapter Eight Results of the ECS Tutor Experiment at Clayton State College

Measure

Time needed to solve a problem {secs.} 377
Problems completed (of the first 9) 8.7
Unnecessary part replacements 21
Component inspections per problem 6.7
Component tests per problem 62.4
Page navigations 122
Times help was asked for 0.4
Times the FIM was used 37

As shown in the performance measures, there
was little difference between the two groups. The
last two measures seem to be statistically signifi-
cant and require some explanation. The count of
the number of times that a subject asked for help
by clicking on one of the help buttons is much
higher for the group without the IHA. This is be-
cause two subjects in this group each asked for
help 18 times, thus skewing the average. (These
two subjects were sitting next to each other but
requested help mostly on different problems.) Of
the other subjects in the non-IHA group, two
asked for help only one time each, and the re-
maining four subjects did not request any help.

Figure 8.5 is a graph presenting the average
group time the two groups took to complete each
of the problems. Although the graph does not in-
dicate whether the problem was solved correctly,
only four problems of the total 150 were solved
incorrectly. This data and other analyses show
that the majority of students had little problem
solving the problems. As would be expected, the
first few problems took the longest, since the stu-
dents were getting familiar with using the ECS
Tutor. Similarly, for the measure of the number of
times the FIM was used, two subjects in the non-
THA group did not use the FIM at all to solve the
problems, thus pulling down the average. While
the first anomaly in the data was probably due to

—o-— Sees!

—*— Seties2

l4t



Design of Portable Computer-based Workcards for Aircraft Inspection Chapter Three

| Table 3.1 AC.
3. INFORMATION ORGANIZATION

A. Information Classification

no categorization or classification of tasks

notes, cautions, methods, directions, etc., not priori-
tized

no demarcation among directive information, refer-
ences, notes, methods, etc.

directive information is not broken up into command
verb, objects, and action quaiifiers

directive information includes more than two or three
telated actions per step

general and specific information chunked together
extemal and internal tasks not properly demarcated,
mixed

B. Information Layering

no fayering of information
not conducive to expert as well as novice usage
difficulty in writing such unstructured information

C. Other Organizational Issues

no use of naturally occurring page modules for fitting
in information
improper task sequencing

4. PHYSICAL HANDLING & ENVIRONMENT

physical handling difficult due to unwieldy size
excessively heavy, cannot be held continuously
usage in extreme environments difficult

not compatible with the other tools used during the
task

inadequate lighting conditions

No holder or place for holding the workcard while
using it

all these factors force inspectors to carry out the ex-
terna! inspection without the workcard, relying only
on memory.

Table 3.2 ck Workcar
1. INFORMATION READABILITY

A. Typographic Layout

» noconsistent typographic layout

« layout discontinuous, breaks within pages

* no usage ot secondary typographic cueing, e.g.. boldface,
etc.. in both text and graphics

* nouse Of full justification of typographic material

eoeee

B. Sentence, Word, and Letter

non-conformabitity with some of the printing conventions
use of ali capitals format, resulting in a low reading speed
ro room for selecting an appropriate typeface

use of a 5x7 dot matrix typeface

ADA294756


Chapter Two Appendix 2-A Evaluation Perms

Appendix 2-A Evaluation Forms

ersonnel Background
Post- Tra? sing Comfort Level
Evaluation Form Instructions
uation of Computer A {Computers B and C used the same form)
Evaluation of Computer D
Evaluation of Pen Computer Products
PENS Sottware Evaluation



Chapter Two

Appendix 2-A Evaluation Faris

Aircraft Graphic

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Save

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Reliability in Aircraft Inspection: UK and USA

Chapter Nine

A further grade, level 1, is also common
which qualifies the technician to make go/nogo
decisions. This is mostly used for simple MPI or
Dye Penetrant examinations in the workshops.

Some effort is being made to ensure that the
signatories for the operator under BCAR A8-6
are level 3. a supervisory grade.

US Variations: Here the reliance is on
task-specific instruction, being a combination of
teaching the techniques and general on-the-job
training although some organisations do require
ASNT level II certification. In essence. the train-
ing schedules and content are similar to the UK.
but without the outside qualifying body. This has
resulted in widely differing depth and duration of
the training. An especial example is that of im-
pedance plane eddy current methods where
training periods from a few hours to several days
were reported to the authors by inspectors, In
addition, sirlines in the USA have typically had
NDT as part of regular inspection duties, rather
than having a specialist NDT department or sec-
tion. This situation is now changing to some ex-
tent, with many operators establishing new NDT
sections and others reverting back in some in-
stances. There are regulatory moves towards
creating uniform and separate NDT qualifica-
tions.

Evaluation: There are fundamental differ-
ences between visual and NDT inspection tech-
niques. Foremost is the extra time spent setting up
and calibrating the equipment, and the actual in-
spection can take considerably longer. Then there
is the problem of validation of the techniques (i.e.
do they find the defects as designed and with
what reliability) as well as with confirming the
actual defect found by NDT, which may take
considerable maintenance time to uncover for
visual confirmation. Also, NDT is used at times
to confirm the extent of a visually-discovered
crack.

Between the UK and USA are two major dif-
ferences in philosophy, which can affect the
practice of NDT. First. the UK assumes a what
could be classified (Rassmussen, 1984) as a
knowledge-based inspector, i.e. one who has a

considerable depth of knowledge in the subject
and who is expected to use such knowledge rela-
tively frequently to solve problems from first
principles. The USA inspector is more frequently
expected to rely on rule-based reasoning, using
well-learned and (reasonably) well- documented
IF-THEN rules to complete the inspection. The
distinction is one of emphasis rather than bifurca-
Gon, with the UK inspector having reasonable
tules and the USA inspector having reasonable
knowledge, but the difference does exist. Inspec-
tors have to switch between these two levels of
abstraction at appropriate times. Thus, both forms
must be adequately supported by the system, for
example by training, clear documentation, and
explicit switching mules between the two. Both
operating philosophies can be expected to pro-
duce reliable results under ideal conditions, but
each has its characteristic errors. Knowl-
edge-based reasoning is difficult to reproduce in
different inspectors, and in the same inspector at
different times, whereas rule-based reasoning can
Jead to inappropriaie decisions if the situation
does not exactly match the niles. One observation
was made of an inspector mis-calibrating an eddy
current device by setting the frequency in Mhz
rather than in Khz, an error extremely unlikely for
a knowledge-based inspector. Rule-based reason-
ing in complex systems is often characterised as
“brittle”, while knowledge-based reasoning al-
lows more discretion, which can lead to errors
when the reasoning. or the perception of the
situation, is false.

Second in the differences of consequence is
the distinction between specialist NDT inspectors
and generalists. who perform NDT activities
along with visual inspection when needed. The
generalist has a broader knowledge of the particu-
far aircraft and its recent history such as indica-
tions of wear or unexpected service conditions.
Such an inspector is also able. and expected, to
use well-practised visual inspection skills to ob-
serve areas around the site of the NDT inspection
for other. non-NDT, indications. The specialist.
on the other hand. can be expected to be recently
practised in the NDT technique required at that
instant, and also to have a broader and deeper
knowledge of NDT methods as well as specific
techniques. Such an inspector will have less of a

ADA294756


Chapter Two

Appendix 2-C_ Software User Manuals

6. Supervisory Review Utility

The Supervisory Review Utility allows you to review your inspectors’ PTRS data before it is added to the
FSAS database.

6.7 Supervisory Review Procedure

You have indicated that you wish to review your inspectors”
database. Here are the necessary steps to run the utility:

J. Start Windows.

2. Start the Supervisor utility located in the PENS group. (When you start this program. it loads the most
recent record transferred by the Data Transfer Utility.)

3. Examine the PTRS record. (Use the scroll bar to move the record up and down.)

4. If you find exors or inconsistency in the record, write down the Record ID, the Inspector name, and
Activity Number. Notify the inspector about the errors or inconsistencies and ask him to resubmit the
revised record.

5. Select Next or Prev to examine other PTRS records.

6. Choose Transfer from the Form menu. (A transfer dialog box appears with a list of PTRS recards in
dic directory.) You can also select Print to print the current record.

7. Tap the record 1Ds to select the records you want to transfer to FSAS. You can select more than one
record. The selected records will be highlighted. You can also use the Select All button to select all
Fecords.

8. To deselect a record tap the highlighted file with your pen (or mouse). Use the Unselect Ail buuon to
deselect all records.

9. Press OK to transfer the selected records to FSAS and press Cancel to cancel the uansfer process.
10. Choose Exit! when you are finished.

6.2 Supervisory Review Help

The Help function provides an on-Jine version of this manual.

48

ADA294756


Appendix 2-A_ Evaluation Forms

Chapter Tee

Post-Training Comfort Level
Initials: FSDO:
Now that you have been trained...

How comfortable do you feel using a computer?

i 2 3 4 5
not at all comfortabie somewhat comfortable quite comfortable

How comfortable do you feel using a pen computer?

1 2 3 4 5
not at all comfortable somewhat comfortable quite comfortable

How comfortable do you fee!

] 2 3 4 5
not at all comfortable somewhat comfortable quite comfortable

How comfortable do you feel with the PENS PTRS?

not at all comfortable somewhat comfortable qui

I 2 3 4 3

How comfortable do you feel with the On-Line References (Hypermedia)?

i 2 3 4 5
not at all comfortable somewhat comfortable quite comfortabie
Do you have any other comments?

Post-Training Comfort Level 1/2

i4



Chapter Eight Results of the ECS Tutor Experiment ai Clayion Siaie Catlege
Used computer-
based training before
None
Computer experience
with mouse B Some |

Yes

8.3.2 Procedure

Subjects were randomly assigned to one of
the two experimental groups. The experiment was
divided into three phases: introductory lesson,
tutor usage, and testing (Figure 8.4) conducted
over two days. On the first day, all of the subjects
participated in an introductory lesson covering
general B-767 ECS operation; ECS modes of op-
eration; and functions of the ECS sensors, valves,
and electronics. The introduction covered mate-
tial needed by the subjects to oubleshoot mai-
functions, including how to use the FIM for the
B-767's ECS. Since some subjects had not used a
computer with a mouse before this experiment,
the introduction also covered how to use the
mouse and a graphical user interface. The course
instructor conducted the introductory lesson, de-
scribing the ECS Tutor by projecting iton an
overhead screen and then explaining the various

60% 190%

80%

buttons and how to use the program. All subjecis
went through this two-hour introductory Jesson
before participating in the troubleshooting portion
of the experiment.

On the experiment's second day, the re-
searchers randomly split the subjects into a “with
IHA" group and a “without IHA" group for the
troubleshooting portion of the experiment. The
subjects used the ECS Tutor on the school’s
training computers. Seven subjects used the ECS
Tutor with the IHA operational, and the remain-
ing eight subjects had computers with the IHA
tumed off. Help control was internal to the tutor,
so there was no way to distinguish the two con-
figurations, and none of the subjects said that they
noticed a difference. The subjects were allowed to
finish the simulated malfunctions at their own
pace and were given a poll after they had fin-
ished.

8-767 ECS introduction
2 hours, 15 students

Day 1: introduction

gure 8.4Experimert:

ECS Tutor without IHA
8 students

ECS Tutor with [HA
7 students

ADA294756


Appendix ~ Example Output from Ergonomic Audit Chapter Four

HUMAN FACTORS MISMATCHES/RECOMMENDATIONS IN INSPECTION/THERMAL CHARACTERISTICS

i. The current DBT is 31.00 degrees centigrade. The recommendec temperature is
between 20-26 degrees centigrade.

2. The current task has been identified as having MODERATE physical workload. The
current air velocity is LOW (less than 1.5 m/s), and the we: 29.06 cent.
fload and LOW air 30 deg.

9
4

The recommended WEGT values for MODERATE w
less.

D i
ning is 0.38 clo.

ad and clo values between 0.5-C.75 are
clothing.

3. The current task has been identified as hav
DET is 29.0C cent. and the clo value for clo’
The recommended D3T values for MODERATE w/1
18-22 degrees centigrade. Consider change

HUMAN FACTORS MISMATCHES/RECOMMENDATIONS IN INSPECTION/OPERATOR PERCEPTION OF THERMAL
av.

1. The cperator found the current workplace temperature te be slightiy warm.

2. Operator wanted the workplace

3. The opezator found the sumner temperature at workplace to be warm.

4. Operator wanted the summer temperature at the workplace to be ccoler than the current
temperature.
5. The operator found the winter temperature at the workplace to be cool.

. Operator wanted the winter temperature at the workplace to be warmer than the current

temperature.

on

EUMAN FACTORS MISNMATCHES/RECOMMENDATIONS IN INSPECTION/AUDITORY CHARACTERISTICS

1. The variance is high.

2. This task inveaves verbal communication. The average noise ievel is 65.00 dba.
The distance of communication is 25.€0 feet. The noise level for communication
at a distance of 10-2 feet should net exceed 5¢

HUMAN FACTORS MISMATCKES/ RE RATIONS IN INSPECTION/ACCESS EQUIPMENT USAGE

the correct access equipment ner the substitute access e

pment was

HUMAN FACTORS MISMATCHES/RECOMMENDATIONS IN INSPECTION/ACCESS - ACTIVITY
1. The operator felt that access was difficulc.

2. access equipment consumes 3 let of orerater

effort. Consider

3. Back bert enc twisted enc


Guidelines for Designing and Implementing CBT for Aviation Mainienance

Chapier Ten

Van Nes, F. L., (1986). Space, colour and typog-
raphy on visual display terminals. Behaviour and
Information Technology, 5(2), pp. 99-118.

10.2.3.4 Evaluation and usability

Evaluations are necessary to determine if any
changes are needed to fulfill the goals of the CBT
system, and to provide data for furare CBT sys-
tems. In the first case, the evaluation examines the
instructional features of the CBT system and how
the students use the system. In the second case,
the goal is to use what was learned during the de-
sign and implementation of one CBT system to
assist in the creation of other CBT systems.

Bibliography:

Jeffries. R.. Milter, J. R.. Wharton, C., and Uy-
eda, K. M. (1991). User interface evaluation in
the real world: A Comparison of four techniques:
Practical design methods. In Proceedings of ACM
CHI’91 Conference on Human Factors in Com-
puting Systems, pp. 119-124.

Kearsley, G. (1982). Costs, benefits, and produc-
sivity in training systems. Reading, MA: Addison-
Wesley Publishing Company, Inc.

Maddox, M.E.. & Johnson, W.B. (1986). Can you
see it? Can you understand it, does it work? An
evaluation plan for computer-based instruction.
Proceedings of the International Topical Meeting
on Advances in Human Factors in Nuclear Power
Systems (pp. 380-389), LaGrange, IL: American
Nuclear Society.

Sewell. D.R. and Johnson, W.B. (1990). The ef-
fects of rapid prototyping on user behavior in
systems design. Journal of the Washingion Acad-
emy of Sciences, 80(2), 71-89.

10.3 HARDWARE ISSUES

This section describes some of the issues in-
volved in choosing hardware to support CBT
hardware. The selection of hardware should be
driven by the type, amount. and quality of media
necessary for instruction.

162

19.3.1 Computer Display Quality

The computer monitor and ihe video adapter
card work together to display the text, graphics,
and video that the PC generates. There are several
dimensions along which the adapter/monitor
combination can vary, including resolution of the
video adapter, size of the monitor, and the num-
ber of colors. The appropriate combination de-
pends on the type of data the CBT displays. For
programs that display only text, the lower resolu-
tions are appropriate. If a program displays
graphics, video, and animation, then higher-end
equipment is necessary.

Bibliography:

Hazpster, J. L., and Freivalds, A. (1984). VDT
screen resolution and operator performance. In
Proceedings of IFIP INTERACT’84: Hu-
man-Computer Interaction, pp. 91-95.

Snyder, H. L. (1988). Image quality. In M.
Helander, Handbeok of Human-Computer Inter-
action. New York: North-Holland, pp. 437-474.

10.3.2 Input Devices

An input device is a computer peripheral that
allows users to enter data into the PC. The most
widely known input device is the keyboard which
allows users to enter text. However, most training
approaches and tasks do not require users to enter
large amounts of text. Keyboards are not widely
used in the newer CBT systems since it is easier
to interact with the computer through a
“selection” device such as a mouse, touchscreen,
or light pen.

Bibliography:

Card, S.K., English, W.K., and Burr, B.J. (1978).
Evaluation of mouse. rate-controlled isometric
Joystick, sap-keys, and text keys for text selec-
tion on aCRT. Ergonomics, 27, 601-613

Greenstein. 3.S.. and Amaut, L-Y. (1988). Input
devices. In Handbook of Human-Computer Inter-
action. North-Holland, New York, NY, pp.
495-519,


Appendix 2-B Training Slides

Chapter Two

DOS (cont.}

To get out of DOS and back te Windows:
| 4. Type exit <Enter>

2. Type win <Enter>

3. Restart the computer

Hold down <Ctr> <Aif and <Del> keys simuitaneousiy

Tum off the computer and turn it on again

Windows
¢ Graphical User interface (GUI)

+ Shows programs as screen objects

¢ Take action on screen objects
Point
Click
Double Click
Drag

Windows for Pen transcribes printed text to “typed” text

ta
&

ANASDOATES



Chapter Four

Ergonomic Audit for Visual Inspection of Aircraft

20

—
an

| gg aait 1 S58T phase tt!

BRE auctt 2 wing insp
audit 3 lavatory insp

percentage of total
5

o

Version 3.0 of the audit checklist incorpo-
tated all of the above recommendations and was
tested for reliability by having two auditors ad-
minister audits simultaneously on the task (Audit
4) of the Left Power Plant Inspection on a DC-9.
The differences between the two auditors were
analyzed using the Cochran Q test, referenced
earlier. The value of the test statistic X’ was now
not even significant at p < 0.10, showing that re-
sults did not change between the two auditors
(Table 4.6). Thus, Version 3.0 of the audit was
deemed to have proven reliable.

AUDIT TASK AUDITED xt
4 Audit 4 - Left Power 24
Plant Inspection/DC-9

4.4 THE AUDIT SYSTEM IN PRAC-
TICE

Both airiine parners have used the training
version of the checklist and the computer docu-
mentation produced, although each partner has

1
reading y operator auditor
errors perception judgement
errors errors

—

used the audit system in a rather different way.
The rotarv-wing operation performed several
audits, a _ che results were combined to guide
management in implementing changes. From this
compilation, it was determined that the major er-
gonomic necds were documentation redesign,
task lighting, and access equipment redesign.
Steps have now been taken to begin implement-
ing changes, based upon the findings. The audit
program will be used after implementation to
measure the effectiveness of the changes.

Our other airline partner has incorporated the
audit program into its on-going Quality Assur-
ance program. A single auditor has been trained,
and regularly uses the system to produce audit re-
ports on specific inspection activities. An exam-
ple of output from the program is Chapter 4
Appendix, obtained after an audit of a fixed-wing
aircraft late in 1993. Names, dates, and numbers
have been changed to preserve anonymity.

The audit evaluation takes the form of an
auditor's memo to a supervisor, using heading in-

=)

MYOGATRL.


Chapter Three

Design of Portable Computer-based Workcards for Aviation Inspection

3.2.2.2_Issues identified within the Taxonomy

In the Phase Ili report, issues highlighted by
the inspector responses and generic knowledge
of the tasks were compared against a taxonomy
of guidelines for designing of paper-based
documentation to identify paper-based workcard

issues for an A-check workcard; Table 3.2 does
the same for a C-check workcard. Computer-
based workcards give flexibility beyond any-
thing possible with paper-based systems; thus,
they are uniquely able to meet some of the re-
quirements in Tables 3,1 and 3.2.

design requirements. Table 3.1 presents design

1, INFORMATION READABILITY

A. Typographic Layout

no consistent typographic layout

layout discontinuous, breaks within pages

no usage of secondary typographic cueing, e.g., boldface,
etc.

no use of full justification of typographic material

B. Sentence, Word, and Letter

non-conformability with printing conventions

use of all capitats format, resulting in a low reading speed
use of a 5x7 dot matrix typeface, hence no choice of any
standard typeface

2. INFORMATION CONTENT

A. Appropriate Content

Ce 2 a

some inaccuracy in the information

incomplete information for certain tasks

language difficult to use and comprehend

syntax not standardized

directive information ambiguous

generalization across aircrait types causes confusion
not flexible for use by both novice and expert inspectors
use of difficult acronyms

logical errors and contradictory statements

tedundancy and repetition

not consistent with user training

does not foster generalizations across tasks, as every task
is described differently

B. Graphic information

system unsupportive of graphics

spatial information conveyed through text, resulting in the
use of complex, lengthy sentences thai are difficult to com-
prehend

53

ADA294756


Ergonomic Audit for Visual Inspection of Aircraft

Chapter Four

formation generated within the program. This
format can readily be changed, as the output file
is a simpie text file suitable for input into any
word processor. Aiso, the output does not simply
identify a mismatch. It provides some guidance as
to how corrections can be made, for example by
giving recommended illumination levels or rec-
ommended air temperatures. The audit pregram is
no substitute for a detailed ergonomic analysis,
but it does provide a rapid tool for identifying er-
ror-likely situations. For more detailed recom-
mendations, the FAA/AAM Human Factors
Guide should be consulted.

Finally, the audit program takes about 30
minutes to administer. As this is less than the time
typically required to type an audit report, the sys-
tem is time-saving and cost-effective in addition
to providing wider access to human factors tech-
niques in aircraft inspection.

45 REFERENCES

Drury, C. G. (1985). Stress and quality control
inspection. In Cooper, C. L. and Smith, M. J.
(Eds.), Job Stress and Blue Collar Work, 7,
Chichester, UK: John Wiley and Sons, Inc.

Drury, C. G. (1988). Inspection performance and
quality assurance: Job Analysis Handbook,
Chapter 65, New York: J. Wiley.

Drury, C. G. and Lock, M. W. B. (1992). Ergo-
nomics in Civil aircraft inspection. In Contempo-
rary Ergonvmics, London: Taylor & Francis,
316-123.

Eberhardt, S.. Reynolds, J.. and Drury, C. G.
(1993). Effect of working postures in confined
areas. FAA/AAM 7th Meeting on Human Factors
Issues in Aircraft Maintenance & Inspection (in
press).

Gramopadhye, A., Drury, C. G.. and J. Sharit
(1993). Training for decision making in aircraft
inspection. Proceedings of the 37th Annual Hu-
man Factors and Ergenomics Socier Meeting.

Seartle, WA, 1267-1271.

Guilford, J. P. (1954). The method of rank order.
Psychometric Methods, 8, New York: McGraw-
Hill, 178-196.

Hill, H. P., Roth, J. L., and Arkin, H. (1962).
Why statistical sampling? Sampling in Auditing -
A Simplified Guide and Statistical Tables, 1, New
York: The Ronald Press Company, 1-10.

Kitruswamy, N., Okogbaa, O. G., and Babu, A. J.
G. (1992). A preliminary audit for ergonomics
design in manufacturing environments. Industrial
Engineering, July 1992, 47-53.

Koli, S., Drury, C. G., Cuneo. J., and Lofgren, J.
(in press). Ergonomic audit for visual inspection
ef aircraft, Human Factors in Aviation Mainte-
nance - Phase 4 Progress Report.

Lankam, E. (1955). Selection of the rating plan.
Job Evaluation, 4, New York: McGraw-Hill
Book Company, 39-52.

Latorella, K. A. and Drury, C. G. (1992). A
framework for human reliability in aircraft in-
spection, In Meeting Proceedings of the Seventh
Federal Aviation Administration Meeting on Hu-
man Factors Issues in Aircraft Maintenance and
Inspection, Atlanta, GA, 71-82.

Mir, A. H. (1982). Develop:.zent of ergonomic
audi? system and training scheme, M.S. Thesis,
State University of New York at Buffalo.

Parker, J. (in press). Human Factors Guide, Bio-
Technology, Inc.

Patel. S., Prabhu. P., and Drury. C. G. (1992),
Design of work control cards. In Meeting Pro-
ceedings of the Seventh Federal Aviation Ad-
nunistration Meeting on Human Factors Issues in
Aircraft Maintenance and Inspection, Atianta,
GA, 163-372.

Prabhu, P. and Drury. C. G. (1592). A frame-
work for the design of the aircraft inspection in-
formation environment. In Meeting Proceedings
of the Seventh Federal Aviation Administration
Mecting on Human Factors Issues tn Aircraft
Maintenance and Inspection. Atlanta, GA, 83-92.

aN RAR IoeS


Hypermedia Information System

will enable virtually anyone to create a hyperme-
dia document.

6.4.2 Extended Document Types

fis also necessary to provide up-front sup-
port for existing source documents in formats
other than WordPerfect. SGML, and ANSI. An-
other goal is to develop filters for other word
Processing formats and documentation standards.
These other formats and standards might include
Microsoft Word and Interactive Electronic Tech-
nical Manual (IETM) specifications.

6.43 Increased Document Base

This past year’s work has already seen an in-
crease in the supported document base for the
HIS to include the Federal Aviation Regulations

(FARs), the Airworthiness Inspector's Handbook.

and recent research publications of the FAA/
AAM & GSC. This work is just the tip of the
iceberg so far as the HIS” documentation base is
concemed. Next year, the Human Factors Guide
that is currently in development under the Human
Factors in Aviation Maintenance research pro-
gram will be transformed into an HIS-accessible
hypermedia document. Also. Aviation Safety In-
spectors participating in the PENS project ure re-
questing Advisory Circulars and Airworthiness
Directives.

6.4.4 Enhanced Searching

Searching is a powerful means of navigating
a hypermedia document, enabling a reader to ac-
cess interesting information directly. By combin-
ing terms and phrases with Boolean operators, a
reader can refine a search that is too broad. How-
ever, it is stil] possible for a reader to end up with
seasch hits that are irrelevant or oniy vaguely re-
lated to the actual topic(s} of interest. Future re-
search wifi investigate several potential solutions
to this problem. A relevancy measure is one way
to prevent a reader from needlessly examining ir-
relevant hits by indicating the relative relevance
of a search hit to the topic in which it is found.

114

Arelevancy measure may not always be use-
ful, such as in situations when multiple hits have
similar relevance. A thesaurus will assist the
reader to focus a search. The thesaurus can be
customized by library; “plane” may have "air-
plane” as a synonym in an aviation library and
“shave” in a carpentry library.

6.4.5 Embedded Graphics

The HIS allows an author to present text to a
reader in the Document Viewer and to provide
Hot Links to graphics. Graphics are then dis-
played via the Graphics Viewer. The Graphics
Viewer may not be desirable for some types of
documents. For example, a document containing
pages with numerous icons, figures. or small ta-
bles might be clumsy if it requires frequent
opening and closing of graphics files via the
Graphics Viewer. To accommodate this type of
document, the HIS will add support for scrollable
embedded graphics and tables. This also allows a
reader to print text and graphics together. instead
of having to print them from their separate view-
ers.

6.5 SUMMARY

The AAM Hypermedia Information System
(HIS) research program continues to meet the
challenges of improving aviation information ac-
cess successfully. The HIS that has been devel-
oped allows a reader to navigate through huge
amounts information quickly and easily. By sup-
porting projects such as PENS and by creating
hypermedia documents such as the FARs, the
Airworthiness Inspector's Handbook, and re-
search publications of the FAA/AAM & GSC, the
HIS has proven its ability to support all facets of
the aviation community. The HIS is flexible in its
support of multiple document/graphic types and
standards and in its ability to accommodate new
types of media. With the advent of an authoring
system that will cnable virtually anyone to put
documents into the HIS, demand for the HIS will
only increase.

ADA294756


Correlates of individual Differences in NDI Performance

Chapter Seven

laboratory investigation of factors possibly influ-
encing NDI performance.

Neither of the two previous studies using this
task was concemed with extensive evaluation of
possible predictor measures or with possible fa-
tigue effects resulting from sustained perform-
ance over successive task sessions. Few studies of
inspection have examined performance over a
long enough period of time tc assess fatigue cf-
fects. Wiener (1984) concluded that the literature
docs not allow conclusions as to whether or not
there are time decrements in inspection perform-
ance. An earlier review suggested such fatigue ef-
fects, but most. if not all. of the “inspection”
studies reviewed were actually vigilance studies
using paced tasks, with brief stimuli presented
over relatively short sessions (Poulton, 1973).
Drury (1992) found only one study of “shop” in-
spection in which a giadual fall in performance
was reported. and that occurred over a two-hour
period. There is litte evidence relative to ex-
pected performance change over the simulated
day shift incorporated in the present stud

The total procedure of this study, including
the test and selection measures used, was tested in
a pilot study reported on previously (FAA/AAM
& GSC, in press). Since the purpose of the pilot
study was to examine the overall feasibility of the
approach used and to identify possible problems
with the procedure. minimal reference will be
made to this earlier study.

7.1 METHODOLOGY
7.LE Subjects

A total of 28 subjects. 15 males and 13 fe-
males, participated in the study. All were right-
handed. had normal near visual acuity (as deter-

1s

mined from an Orthorater screening test), re-
ported normal hearing. and were between 18 to
29 years of age. All had graduated from high
school, with most being full- or part-time em-
ployees concurrently attending a community col-
lege. technical school, or four-year college or
university. Subjects were obtained through an
existing Federal Aviation Administration (FAA)
subject contract and were paid $10.00 an hour for
their participation.

No subject was an aircraft mechanic or in-
spector and none had prior training or experience
in aircraft maintenance or inspection. This en-
sured a wider range of individual differences than
was likely if subjects had been selected from the
maintenancefinspection population. The inclusion
of college students appeared justifiable on the
basis of several recent studies of inspection per-
formance using both students and inspectors
(Gallway, 1982: Gallway and Drury, 1986). The
former study was reasonably similar to the pres-
ent one in that it involved selection tests and in-
spection performance. Neither study found any
significant differences between students and in-
spectors.

7.1.2 Apparatus

The basic apparatus for this study consisted
of a SUN SPARC Mode] 4/50GX-16-P43 work-
station, 19-inch color monitor, and 4 3-button op-
tical mouse. Since the nature of the task and its
physical characteristics have been described in
detail previously (Drury et al., 1991; Latorella et
at., 1992), only aspects relevant to the present
study will be reviewed here.

The display consisted of four basic task ele~
ments (windows). These are shown in Figure 7.1
and are described below.

ADA294756


Chapier Two Appendix 2-4 Evaluation Form:

s

Evaluation of Pen Computer Products
Initials: FSDO:

Please gather together all four of the evaluated compuiers, then circle ite desi compuier and draw an X
through the worst computer for each of the following characteristics:

Weight Computer A ComputerB ComputerC Computer D

Size Computer A ComputerB  ComputerC Computer D

Speed Computer A ComputerB ComputerC Computer D

Display inside Computer A  ComputerB  ComputerC Computer D

Display outside Computer A Computer Computer D

Pen Responsiveness Computer A Computer B

Pen Feel Computer A  ComputerB  ComputerC Computer D (trackball)
Handwriting ComputerA ComputerB ComputerC Computer D

Comfort Computer A ComputerB ComputerC Computer D

Which product do you prefer?
ComputerA ComputerB ComputerC  ComputerD No preference
Do you think you could carry any of these units for a significant period of time? Yes No
Which one? Computer A ComputerB ComputerC Computer D
If a neck, shoulder, or waist strap were available, would you use it? Yes No

Wraice
Waist

Which would you prefer? Neck

Would you prefer a very rugged unit, even though it weighs nine pounds? Yes No

ne



Chapter Nine

Reliability in Aircraft Inspection: UK and USA Perspectives

ing and supervising several different simultane-
ous maintenance activities and the communica-
tion skills required to secure proper repairs should
not be underestimated.

Not all tasks are straightforward or even re-
peats of those previously performed so that it will
probably be quicker and more accurate for the
mechanic to be informed directly by the inspec-
tor/supervisor than by documentation and a third
party. However, freedom from the supervisory
role enables the inspector to assume the role of fi-
nal arbiter at buy-back.

If the potential difficulty with the UK system
is in ensuring an ability to lead as well as inspect,
the potential difficulty in the US system is with
communication.

There is a need to communicate both within a
single shift and across shifts between the follow-
ing groups:

Inspectors

Maintenance technicians
Inspection management
Maintenance management

Quality control
Planning

Some of this communication is written, for
example, in job cards and NRRs, and some is
verbal. The quality of written NNRs had consid-
erable variability between inspectors, between
companies and between countries. In the US, this
assumes more importance as not only the main-
tainer has to understand the NRR to carry out the
{often complex) repair, but so must the buy-back
inspector to ensure that the original fault has in-
deed been eliminated. Little formal training in
written or verbal cornmunication was seen.
While formal coordinators were seen at some
companies, and other companies were small
enough that direct communication was inevitable,
there is still a need for formal training of inspec-
tors and maintenance technicians.

Inter-shift communications varied widely by

company. Some had an informal talk between
equivalent supervisors at shift change, some had a

1§1

written checklist, while one company had a for-
mal half-hour combined written report and tour of
the on-going jobs by both supervisors. At the in-
dividual inspector and mechanic level, shift
change ranged from merely receiving the supervi-
sors’ instructions to formal start-of-shift meetings.
With many maintenance operations, and even
some inspection jobs, covering multiple shifts,
systems are needed to ensure that the complex
communications required do indeed take place. It
is vitally important that the incoming shift have
complete information on the status of each re-
pair/inspection. A failure of such information
flow was recently cited as being causal in a recent
accident in the USA.

94.3 Non Destructive Testing

Both Countries: The 1980's saw a large in-
crease in the application of NDT to aircraft in-
spection practises and this rise has been
continued. The situation is largely manufac-
turer-driven so that a similar situation exists in all
maintenance/inspection shops.

In many applications, the bulk and weight of
the NDT electronics box is such as to make loca-
tion of it within easy visual range, difficult. More
use of secondary visual or aural device’ is.re-
quired. Such devices are small repeater screens.
LEDs on probes, and earphone systems
(especially where the tone changes with the size
of the ultrasonic or eddy current parameter).

UK Variations: Training is currentiy based on
the PCN (Personnel Centification in NDT)
scheme monitored by the British Institute of NDT
and the industries it serves.

In the aircraft industry, training corresponds,
in the main to PCN level 2, with the necessary
endorsements, which allows the inspector to per-
form NDT tasks and to define new methods
which are used subject to manufacturer’s ap-
proval. Training to this level can be done in-house
or through a registered and certified establishment
specific to aircraft NDT. This is followed by a
penod of about 6 months on-the-job instruction.

ANAMOAVES


List of Tables

LIST OF TABLES

TABLE 2.1 FEATURES OF EVALUATED COMPUTERS
TABLE 2.2 EVALUATION SITES

TABLE 3.1 A-~CHECK WORKCARD: ISSUES IDENTIFIED WITHIN THE TAXONOM
TABLE 3.2 C-CHECK WORKCARD: ISSUES IDENTIFIED WITHIN THE TAXONOMY
TABLE 3.3 DESIGN GUIDELINES FOR THE COMPUTER-BASED WORKCARD SYSTEM
TABLE 3.4 PERSONAL DATA ON MECHANICS USED TO EVALUATED WORKCARDS ...
TABLE 3.5 CLASSIFICATION OF EVALUATION FACTORS AS BETTER THAN, NOT DIFFERENT FRO!
WORSE THAN NEUTRAL RATING.. votes
TABLE 3.6A ISSUES ON WHICH SYSTEMS Wi VERE SIGNIFICANTLY DIFFERENT ...
TABLE 3.6B ISSUES ON WHICH SYSTEMS WERE NON-SIGNIFICANTLY DIFFERENT
TABLE 3.7 PAIRWISE COMPARISONS AMONG ORIGINAL PAPER-BASED, IMPROVED PAPER-BASED, AND
COMPUTER-BASED WORKCARDS, SHOWING SIGNIFICANCE LEVEL ON THE WILCOXON TEST ....64

TABLE 4.1 GENERIC TASK DESCRIPTION OF INSPECTION WITH EXAMPLES FROM VISUAL AND NDT
INSPECTION . .
TABLE 4.2. DEVELOPMENT OF FACTOR WEIGHTINGS FROM AVERAGE RANK V ALUES ..
TABLE 4.3 FINAL CRITICALITY RATINGS OF POWER PLANT AND WING INSPECTION TASKS
TABLE 4.4 FINAL CRITICALITY RATINGS OF INSPECTION TASKS ON SIKORSKY S58T AND BELL 206L
TYPE AIRCRAFT..
TABLE 4.5 TEST FOR SIGNIFICANCE OF DIFFERENCES BETWEEN AUDITORS
TABLE 4.6 X? TABLE TO TEST FOR SIGNIFICANCE

TABLE 5.1 ERGONOMIC FACTORS .
TABLE 5.2 PERFORMANCE, WORKLOAD, AND STRESS DEFINED WITHIN RESTRICTIVE SPACE
FRAMEWORK...
TABLE 5.3 SUMMARY OF SPACE-RELATED HANGAR OII'S.
TABLE 5.4 OWAS CLASSIFICATION TABLE ....
TABLE S.S TYPICAL WORKING POSTURES BY TASK.....

TABLE 7.1 MEAN PERCENT OF FAULTS MISSED ACROSS PERIODS AND SESSIONS
TABLE 7.2 MEAN PERCENT OF FALSE ALARMS ACROSS PERIODS AND SESSIONS.
TABLE 7.3 MEAN PRE- AND POST-SESSION RATINGS..
TABLE 7.4 LOADINGS OF EACH PREDICTOR VARIABLE ON THE FOUR FACTORS ceeeeeee
TABLE 7.5 NUMBER OF MALES AND FEMALES EXPRESSING A LIKING FOR OR DISLIKE OF THE
INSPECTION TASK...
TABLE 7.6 NUMBER OF EACH EDUCATI
THE INSPECTION TASK...

TABLE 8.1 TYPES OF HELP AVAILABLE IN THE ECS TUTOR
TABLE 8.2 AVERAGE PERFORMANCE MEASURES FROM THE EXPERIMENT .
TABLE 8.3 WRITTEN COMMENTS FROM THE POLL...

137

143

xi



Chapter Seven

‘orrelates of Individual Diffe

epoge fn NDE Do fone as
ences th ves c eRpOTMANCE

Sanders, M. G., Halcomb, C. G., Fray, J. M., &
Owens, J. M. (1976). Intemal-external locus of
control and performance on a vigilance task.
Perceptual and Motor Skills, 42, 939-943.

Schroeder, J. E., Dunavant, D. W., & Godwin, J.
G. (1988}. Recommendations for improving Air
Force nondestructive inspection technician pra-
Siciency. SwRI Project No. 17-7958-845, San
Antonio Air Logistics Center, Air Force Logistics
Command, Kelly Air Force Base. Texas.

Schurman, D, L. Personal communication, Sep-
tember, 1993.

Schurman, D. L. Personal communication,
March, 1994,

Spencer. F. Borgonovi, G.. Schurman, D., &
Smith, R. (1992). Proposed reliability assess-
ment for eddy current inspection of lap splice
Joints in airline maintenance and inspection fa-
cilities. Final draft report prepared for the FAA
Technical Center, Atlantic City, New Jersey.

Summers, R. H. (1984). Nondestructive inspec-
tion: Improved capabilities of technicians: Final
Report. AFHRL-TP-83-63, Training Systems
Division, Air Force Human Resources Labora-
tory, Lowry Air Force Base. Colorado.

133

Thackray, R. I., Bailey, J. P., & Fouchstone, R.
M. (1977). Physiological, subjective, and per-
formance correlates of reported boredom and
monotony while performing a simulated radar
control task. In R. R. Mackie (Ed.), Vigilance:
Theory, Operational Performance, and Physio-
logical Correlates. New York: Plenum.

Thackray, R. I., Jones, K. N., & Touchstone, R.
M. (1973). Self-estimates of distractibility as re-
lated to performance decrement on a task requir-
ing sustained attention. Ergonomics, 16, 141-
152.

Thackray, R. I. & Touchstone, R. M. (1991). Ef-
fects of monitoring under high and low taskload
on detection of flashing and coloured radar tar-
gets. Ergonomics, 34, 1065-1081.

Wang, M. J. & Drury, C. G. (1989). A method of
evaluating inspector's performance differences
and job requirements. Applied Ergonomics, 20.3.
181-190.

Wiener, E. L. (1975). Individual and group dif-
ferences in inspection. In C.G. Drury & J. G.
Fox (Eds.}, Human reliability and quality control.
New York: Taylor & Francis.

Wiener, E. L. (1984). Vigilance and inspection:

In J. S. Warm (Ed.), Sustained artention in human
performance. New York: John Wiley, 1984.

ADA294756



Results of the ECS Tutor Experiment at Clayton

Catt

ster Bick:

Hose
ei hapter Eight

rat
La

personal cognitive styles. the second anomaly
was most likely the result of a misunderstanding
of the tutor’s features.

8.4.2 Poll Results

The poll contained nineteen questions about
various aspects of the tutor. Questions were either
general questions dealing with the nutor’s usabil-
ity and general behavior of the tutor or questions
about several of the tutor’s features of the tutor.
Subjects were asked to rate their agreement with
each statement, using the scale “agree strongly,”
“agree.” “no opinion,” “disagree,” and "disagree
strongly.” The questions were equally mixed be-
tween positively and negatively phrased sen-
tences. Figure 8.6 show the distribution of
responses for the subjects in the individual-use
group.

Overall. subjects’ satisfaction with the tutor
was high. No statistic for any of the nineteen
questions indicated any weak points in the ECS
Tutor. There were only two questions for which
responses were not closely clustered. Question 9
asked if hints the nutor provided were useful; re-
sponses were Spread between "strongly agree"
and “no opinion.” Question 15 concemed the
resolution of the tutor’s component pictures; re-

sponses were also more varied than for other
questions. This issue: is discussed in Sections
8.4.3.2 and 8..

These results can be compared with those
from an earlier study done at Clayton State Col-
lege. In the earlier study, the first fifteen questions
of the poll used in this experiment were given to
six subjects at Clayton State after they had solved
two malfunction problems (Pearce 1993a). A
comparison between the twa evaluations indicates
a more positive response to the current version of
the ECS Tutor. This increased acceptance is most
likely due to changes made in response to prob-
lems users pointed out in the early usability stud-
ies.

8.4.3 Post-Experimeni Coiiimi

is

The poli asked subjects to write down any
comments not covered by the multiple choice
questions. Only four subjects (of fifteen total} re-
sponded to this section. Table 8.3 lists all of the
subjects’ written comments.

After the experiment was finished, several
subjects told the instructor that their biggest
problem using the ECS Tutor was to decide how
much time to spend on each problem. Even

2

5. The tulor benaved in

Pace
49. Tne nelp bu"

“8 The fsecback ar the end heired me

1. The system commancs ate easy tc use. ——nfim
|—_—_-

i Jee! competent with the system: commands
3. When t get an error message. it #5 net heiptet in identifying the problein
4, There afe 199 “Many ocbons ard special cases.

€. s Nave Voubie temembering tne commands urd options

7 The system was net innre:dating, | fet comforabie using 4.
8, | often knew what to do, ut t dian’: know Tow to do ft

cnts” that suggested parts 1 teSt OF fep)
proviced uselut infermation in sowing the preclems,
11 The tesson intreductons renews helped me undetsiaad the malunctons.
12, 124 rot know what te do ater repracing a come:

13. The “Info” bar at the sottem of screen helped me understarc
14 The FIM 156 was easy 10 use arc helped in sobv.ng

15. coud not tel wrat tre pictures of ECS pans were supposes

18. The computer's mouse was easy

17, The computer was slor. m resperging 10 my choices,

i terstand the maltunctions
19 The tutor was too compt cated ang! v 23 never sure what ‘0 Jo

142

atl dign’t expect,

were uselu.



Rekabitity in Aircraft Inspection: UK and USA

Chapter Nine

9.1 OBJECTIVES

‘The first objective of this study was to com-
bine into a single concise document material col-
lected jointly and separately by the investigators
so as to highlight the similarities and differences
in aircraft inspection between the UK and the
USA.

The second objective was to draw any con-
clusions which would allow the transfer of tech-
niques or information relating to human factors in
aircraft inspection between the wo systems to the
benefit of airworthiness.

$.2 BACKGROUND

The application of Human Factors techniques
to aircraft inspection is relatively recent on both
sides of the Atlantic. A major 1981 UK study
{Lock and Strutt, 1985) was not complemented
by equivalent work in the USA until after the in-
terest in continuing airworthiness spurred by the
Aloha incident in 1988. Because of the com-
monality of interest in improving inspection reli-
ability in the two jurisdictions, the FAA and the
CAA signed a Memorandum of Cooperation in
April 1990 to cover joint work in this fieid. This
would build on the then-current human factors
work in both countries, as well as various studies
of structural mechanics and flight loads.

Since that date, M. W. B. Lock and C. G.
Drury have been co-operating specifically on
cross comparisons of USA and UK practice as
part of theix contract work with the FAA and
CAA respectively. The aim was to take two sci-
eatists whe had studied aircraft inspection from a
practical viewpoint, but from different academic
backgrounds, and have them jointly observe a
nuraber of inspection operations in both countries
in addition to their other contractual observations.
The disciplines of the two participants were
complementary in that Dr. Lock is an applied
physicist with a particular expertise in Non De-
structive Testing (NDT) while Dr. Drury is a
Human Factors (HF) engineer with a particutar
expertise in industrial inspection.

This report is intended to be complementary
to the reports issued by the two participants sepa-
rately as part of their contract work. These other
reports are listed in Section 9.6. In particular, the
site visit - based work described here is also re-
ferred to in the following reports:

1. Human Factors in Aviation Maintenance:
Phase One Progress Report. FAA Office
of Aviation Medicine, September 1991
Inspection Reliability for Transport Air-
craft Structures: A Three-Part Study:
Part 1 Initial Investigations. CAA Paper
90003, April 1990
3. Inspection Reliability for Transport Air-
craft Structures: A Three-Part Study:
Part 2 The Current Situation. CAA Draft
Paper. May 1991

iy

9.3 METHODOLOGY

A number of visits were undertaken by each
participant in each country, either separately or
together. There was no attempt at comprehensive
sampling: rather the knowledge of each partici-
pant was used to select sites which would be illus-
trative of various features. For exanple, in the
UK visits were made to specialist third-party
NDT companies which serviced civil aviation as
they represent a major source of NDT expertise
utilised by some airlines.

At each site, the visit was divided into two
sections, although these often overlapped in cov-
erage:

Systems Overview: First the management of
the maintenance of the site was probed in man-
agement interviews. The structure of the mainte-
nance and inspection organisation(s) was elicited
during discussions with managers, shift supervi-
sors, foremen, and often with staff who were
outside the line management siructure. These
could include training personnel, archive keepers.
work card preparers, planners, and so on depend-
ing upon the initial discussions with management.
The aim was to be able to write a short descrip-
tion of how the system should operate, and the
management philosophy behind this system
structure and functioning.

ADA294756


Chapter Two Appendix 2-C Software User Manuals

Appendix 2-C - Software User Manuals

PENS User Manual
HyperMedia User Manual for FARS and Inspector’s Handbook

ced

ADA294756


List of Figures

LIST OF FIGURES

FIGURE 1.1 THE RESEARCH PROGRAM...
FIGURE 1,2 PERFORMANCE ENHANCEMENT SYSTEM (PENS).
FIGURE 1,3 HUMAN FACTORS ISSUES IN AVIATION MAINTENANCE AND INSPECTION, CD-1
FIGURE 1.4 ECS TUTOR -

FIGURE 2.1 COMPARISON OF DESKTOP AND PEN COMPUTERS........ssscsessssecsscssesoneeesvecseeerreancensessuressenerseseesi

FIGURE 4.1 STRUCTURE OF THE CHECKLIST, SHOWING ITS RELATIONSHIP TO THE FOUR GROUPS OF

FACTORS AND THREE PHASE DEFINED IN SECTION 4.2.1...
FIGURE 4.2 FREQUENCY OF MISMATCHES FOR THE THREE AUDITS BY MODULES
FXGURE 4.3 PERCENTAGE OF EACH ERROR TYPE ON EACH TEST .....cssssssssssessssesssssveesssesesssneceecsaneasessesseneeeee

FIGURE 5.1. RESTRICTIVE SPACE MODEL
FIGURE 5.2 OJI REPORT SUMMARY ..
FIGURE 5.3 POSTURE ANALYSIS ..
FIGURE 5.4 STABILIZER POSTURES..
FIGURE 5.5 TAIL INTERIOR POSTURE!
FIGURE 5.6 WHEELWELL/MAIN LANDING GEAR.
FiGuRE 5.7 CARGO POSTURES......
FIGURE 5.8 BODY PART DISCOMFORT OVER TIM
FIGURE 5.9 FATIGUE OVER TMi
FIGURE 5.10 TLX WorKLOAD Dat

FIGURE 6.1 THE HIS BOOKSHEL!
FIGURE 6.2 COLLAPSED AND EXPANDED TOPICS .
FIGURE 6.3 THE OUTLINE AND DOCUMENT VIEWERS.
FIGURE 6.4 SEARCH QUERY DIALOGUE Box.
FiGuRE 6.5 SEARCH HITS
FIGURE 6.6 BOOKMARKS.

FIGURE 7.1 NDI TASK SIMULATION (DRURY ET AL... 1992) ....ceccsesssessseesscessscsssecsnecaeesnsesereaveestessessersenes LED

FIGURE 8.1 SAMPLE SCREEN FROM THE ECS TUTOR
FIGURE 8.2 EXAMPLE OF A PRINCIPLE.
FIGURE 8.3 COMPUTER EXPERIENCE
FIGURE 8.4 EXPERIMENT DESIGN ..
FIGURE 8.5 AVERAGE GROUP TIME TO COMPLETE EACH PROBLEM
FIGURE 8.6 DISTRIBUTION OF POLL RESPONSES.

ANAANRsURKS


Appendix 2-B Training Slides Chapter Two
> The Peyormance |}
PENS =| PENS atest er
___ CS CTimetable for eigen

4993 : 1994 14995

| Field Evaluation of =

Airworthiness Prototype :
" « Complete Airworthiness!

and Avionics PENS !

«Prototype Operations | i

PENS |

«Field Evaluation of i

Operations Prototype i H

«Compiete Operations
| PENS
| * Prototype General
| Aviation PENS }
| «Field Evaluations of ;
| Generat Aviation {
| Prototype i
, ! «Complete General |

Aviation PENS

i The Performance |
ENhancement System i
i

Schedule __?74vation sate
Day One

|

|

| « Demo

| ¢ Background information
| « Introduction to Computer
¢ Windows Tutorial

{

|

|

¢ Windows Practice
« Pen Computer Tutorial

30

ADA294756



Chapter Six

Hypermedia Information System

completely automated. The SGML language is
used to mark up documents by inserting tags in
the text. Basically, these tags describe the docu-
ment’s structure, such as which text is chapter ti-
tles (Topics), which is references (Hot Links),
which is paragraphs, etc. The hypermedia re-
search project has developed a translation pro-
gram to convert SGML tags into their HIS
counterparts. This makes documentation trans-
formation-a smooth process, with no need for in-
tervention by an author.

An ANSI document requires the most cum-
bersome transformation process. Since an ANSI
document is flat text with no fonts, boldface,
links, etc., it is the hypermedia author’s zespon-
sibility to provide these details. Fortunately, an
authoring system is under development to make
this task intuitive. With this authoring system, a
computer novice will be able to turn a digital
document into a hypermedia document easily.
Once a document is displayed in the HIS, an
author can pui the Document Viewer into “authcr
mode." By using the mouse to highlight text, the
author can use menu options to specify the text’s
appearance (bold, italics, etc.) or function (link to
graphics, link to text, etc.). The information the
author provides is part of the hypermedia docu-
ment, even after the author exits from the HIS.

6.3 REAL-WORLD HIS APPLICATION

Now that the HIS itself has been described in
detail, it is beneficial to describe a situation in
which it is being used. The HIS has proven its
ability to support all facets of the aviation com-
munity. The previous version of the HIS on CD-
ROM addressed the needs of researchers. It was
also successfully integrated into several mainte-
nance training systems. During the last year, the
current HES (described above) was incorporated
into a job aid for Aviation Safety Inspectors.

The Performance Enhancement System.
(PENS) (see FAA/AAM & GSC, 1993a) applies
pen computer and hypennedia technology to
provide real-time job aiding and information re-
trieval for Aviation Safety Inspectors. Aviation
Safety Inspectors nist have access to large

113

amounts of information, including Federal Avia-
ton Regulations, Airworthiness Directives, and
Advisory Circulars. The Federal Aviation Regu-
lations and the Inspector’s Airworthiness Hand-
book have been put into a library for inspectors’
use. As the inspectors use PENS, they can di-
rectly access the HIS to reference and search for
information. The initial PENS system is being
distributed for use and evaluation to Aviation
Safety Inspectors in nine U.S. locations. During
the formal evaluation, feedback provided regard-
ing the HIS will be used to make future PENS
enhancements. Initial, informal feedback indi-
cates that inspectors find it extremely valuable to
have access to the documents through the HIS.
Inspectors are looking forward to having other
documents such as the Airworthiness Directives
incorporated into the system.

6.4 FUTURE DIRECTIONS

As demand continues to increase, the HIS
will continue to evolve. Specifically, the goals for
developing the HIS further include the following:

¢ Complete the development of easy-to-use

authoring tools

* Support a wider variety of document

* Increase the document base to include
other aviation documents
* Enhance the searching mechanism to
provide “smarter” searching
* Support embedded graphics and tables.
The following sections describe plans to enhance
the HIS in support of these goals.

6.4.1 Authoring Tools

Given that it is necessary for an author to
transform a digital document into a hypermedia
document, it is desirable to make the process for
doing so as easy and intuitive as possible. As
mentioned previously, development is under way
to provide such an authoring system. Anything
the author needs to add, such as Hot Links and
Topics, will be added ina WYSEWYG (“what
you see is whai you get") environment. The
author will be able to modify text, ¢.g., to correct
spelling exrors, and even to type a document from
scratch. This powerful authoring environment

ADA294756


PENS Project Field Evaluation

Chapter Tie

Safety Inspectors and their supervisors. The
PENS project is taking just such an approach.

2.8 REFERENCES

Gery, G. J. (1992). Electronic performance sup-
port systems (2nd ed.}. Boston: Weingarten.

ARADOATESL



Chapter Two

PENS Project Field Evaluation

CHAPTER TWO
PENS PROJECT FIELD EVALUATION

Charles F. Layton, Ph.D.
Galaxy Scieniific Corporation

2.1 PENS: A PERFORMANCE
ENHANCEMENT SYSTEM

The Performance ENhancemient System,
PENS, is a tool designed to aid Aviation Safety
Inspectors (ASIs) in performing their oversight
duties. Aviation Safety Inspectors (ASIs) make
up the inspection team for the Flight Standards
Service (FSS), which is the regulatory branch of
the Federal Aviation Administration (FAA).
They perform a variety of tasks. in both com-
mercial and gencral aviation areas, including:
inspecting aircraft «nd equipment, reviewing
manuals and records. certificating pilots, and
evaluating training programs.

There are approximately 2,600 ASJIs in the
nine regions of the FAA. The initial target of
PENS is an ASI performing an airworthiness
(maintenance) inspection. PENS is an electronic
performance support system (Gery, 1991) that
combines a "smast” forms application and an on-

line documentation system. PENS capitalizes on
recent advances in pen computer technology.

2.2 A BRIEF INTRODUCTION TO PEN
COMPUTERS

Pen computers use handwriting recognition
software and a pen stylus for input, rather then a
keyboard. The operator writes on the screen and
the handwriting recognition software translates
the written characters to typed characters. The
pen stylus also acts as a pointing device. much
like a mouse. When combined with a graphical
user interface, such as Microsoft Windows for
Pen Computing, the pen stylus and handwriting
recognition software hold the promise of making
computers easier to use than traditional desktop
computers. A comparison of typical desktop and
pen computers is shown in Figure 2.3.

|

j
|
j
{

ADA294756



Table of Contents

5.5.3 Ergonomic Program .......csssssssssssesssssssssesesnscanstseecsssssersesssnnnieesesstee

=
=}

Chapier Six - Hypermedia Information Sys

6.0 INTRODUCTION .....
6.1 THE HYPERMEDIA INFORMATION SYSTEM FEATURES
6.1.1 Navigation ..
6.1.2 Viewing...
6.2 HYPERMEDIA DOCUMENT CREATI
6.3. REAL-WORLD HIS APPLICATIO!
64 FUTURE DIRECTIONG.............
6.4.1 Authoring Tools ........0
6.4.2 Extended Document Types .
6.4.3 Increased Document Base
6.4.4 Enhanced Searching ..
6.4.5 Embedded Graphics .
6.5 SUMMARY ..
6.6 REFERENCES.

Chapter Seven - Correlates of Individual Differences in Nondestructive Inspection
Performance

70 INTRODUCTION
7.1 METHODOLOGY .
7.1.1 Subjects...
7.1.2 Apparatus
7.1.3 Predictors and/or Task Correlates
7.14 Procedure.
7.2. RESULTS.........
7.2.1 Task Performance..
7.2.2 Rating Scale Variable:
7.2.3 Predictor Variables and Performance...
7.2.4 Gender, Liking for Inspection, and Educati
7.3. DISCUSSION
7.3.1 Evidence of Fatigue Effects .
7.3.2 Performance Predictors...

74
75

vii

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Correlates of Individual Differences in NDI Performance

Chapter Seven

Variable Min Pre-Session Ratings | Mn Post-Session Ratings
Attentiveness 68 5.3
Tiredness 46 5.6
Strain 37 47
interest 5.8 4.2
Annoyance 1.3 21
Effort 3.5 48
Difficulty 2.3 3.2

Separate ANOVAs revealed significant pre-
to post-task decreases in attentiveness
(F(1/27}=37.15, p<.01) and interest
(F(1/27}=48.83, p<.01). along with significant
increases in tiredness (F(1/27)=30.39. p<.01),
strain (F(1/27)=15.75, p<.01), and annoyance
(FQ27}=11.77, p<.01). Ratings of task diffi-
culty increased significantly from the beginning
to the end of the sessions (F(1/27)=8.27, p<.01)
as did the ratings of effort required to remain
attentive (F(1/27)=22.39, p<.01).

Verbal labels associated with numerical val-
ues on the rating scales revealed that none of the
feeling states represented extreme levels. Sub-
jects typically began each session feeling mod-
erately attentive, moderately relaxed. moderately
interested, not annoyed. and having about their
norma! energy level. Each variable was rated on
a 9-point scale, with 5 representing the midpoint
or middle value. Post-session levels for most
variables were near this midpoint value. Pre- to
post-session changes for all variables were rela-
tively small, representing minor shifts in feeling
state from pre-sess‘on levels. For difficulty and
effort, subjects initially perceived the task to be
slightly difficult, requiring slight effort. Ratings
of perceived difficulty and effort at the end of
the sessions. although increasing significantly
for both variables, revealed relatively minor
changes in cach variable.

7.22.2_Conclations of Rating Scale Data with
Performance

To investigate the relationships, if any, be-
tween rating scale data and performance. differ-
ence Scores (post minus pre Jeveis) were

126

obtained for each subject for each rating scale
variable. These were separately correlated with
missed faults, false alarms, and mean time/rivet.
No correlation reached significance (p>.05},
with the exception of an association of atten-
tiveness change with missed faults (r=-.40.

ps<.05). This relationship, as explained in the
next section, was apparently the result of differ-
ences in initial rather than final levels of atten-
tiveness.

7.2.2.3 Analyses of Variance of Rating Scale Data and
Performance

In addition to the correlational analyses,
separate ANOVAs were conducted to compare
rating scale changes for extreme groups of sub-
jects (the best and the worst 9 subjects) formed
on the basis of total scores on each performance
variable. It was felt that eliminating subjects in
the middle range of score distributions might
provide a more sensitive approach to analyzing
relationships. Only one of the ANOVAs, how-
ever, suggested a possible zelationship of per-
formance scores to ratings; this was an
interaction between interest change and missed
faults (F(1/16)=3.88, p<.06). Examination of
mean vajues revealed that subjects in the poorest
group showed a greater decline in interest dur-
ing performance than did those in the better
group. The analysis comparing the best and
worst groups’ missed faults with attentiveness
change yielded an interaction effect that, like
that shown above for interest change, ap-
proached significance (F(1/16)=3. 71, p<.7}.
Examination of the mean values, however. re-
vealed the reason for the significant correlation
reported in Section 7.2.2.2. While the best and
worst groups had similar post-session ratings of



Chapier Five

Ergonomic Factors Related to Posture and Fatigue in the Inspection Environment

FINDINGS

Although performance measures could not
be obtained, as noted in previous work
(Shepherd, Johnson, Drury, Taylor, and Bern-
inger, 1991) as well as in this work, inspectors
are highly motivated to perform accurately. We
assume that inspectors were taking the steps
necessary to ensure that their performance was
not affected by the conditions. However, the
above analysis and results indicate that inspec-
tors often experience increased levels of stress,
fatigue, and workload. Based upon these data,
inspection work in the tail interior can be classi-
fied within Zone 2 of the framework (Section
5.2.7). That is. task performance is acceptable,
but operators’ workload and stress are increased
because of their compensating for extreme
conditions. Inspection of the stabilizers and
wheelwell/MLG can be classified within Zone
3; acceptable task performance can be obtained
without any Significant increases in workload or
stress imposed by the task conditions. Work in
the aft carge falls somewhere on the boundary
between Zones 2 and 3. If more data were col-
lected reduce variability in this real-world data,
it is predicted that work in this area would be
found to be in Zone 2.

5.4

The psychophysical data shows a consistent
pattern of stress experienced during task per-
formance in different areas. Generally, fatigue,
body discomfort, and workload were judged
higher in the aft cargo and tail interior areas, as
compared to the other areas. There was some
disassociation between the postural and the psy-
chophysical data. The stabilizers and wheel-
well/MLG were not rated as extremely
fatiguing, although many extreme postures
{AC3 and AC4) were noted while inspectors
worked in these areas. This indicates that pos-
ture may be just one factor contributing to fa-
tigut and that other factors such as space and
lighting, in combination with extreme postures,
play a role in eliciting fatigue. These results are
to be as expected from the discussion in Section
$.2.1.

i103

PRACTICAL INTERVENTIONS

Based upon the above evaluation, 2 pos-
ture/fatigue module has been developed and in-
tegrated into the ergonomic audit program (Koli,
Drury, Cuneo, and Lofgren, Chapter 4 of this
report). In addition, specific ergonoinic inter-
ventions were provided for each task analyzed.
These were generated from a logical analysis of
factors contributing to fatigue in each area and
the possible ergonomic interventions that could
impact upon these factors. Furthermore, the
techniques and tools used for this analysis can
be applied and used in developing and guiding a
comprehensive ergonomic pregram.

5.5

§.5.1 Ergonomic Audit Posture Moduie

A module has been developed and inte-
grated inio the ergonomic audit program that can
be used to recognize extreme postural and spa-
tial demands possibly causing fatigue and dis-
comfort. This module snould assist in
eliminating misinatches, specifically these re-
lated to postural and spatial requirements, be-
tween the inspector’s capabilities and the task
demands.

5.5.2 Design Requirements/
Interventions

For each task, design requirements were
stated. They are presented in Table 5.6. Design
requirements are positive statements about what
needs to be accomplished during redesign.
These design requirements were geared towards
eliminating or reducing extreme working pos-
tures (Table 5.5 and Figures 5.4-5.7) and im-
proving the overall inspection environment.
Notice that these are not solutions, but require-
meats. There may be several altemative solu-
tions for each requirement. Formally stating
design requirements can assist in generating so-
lutions and reduce the probability of overlook-
ing potential solutions (Drury, 1987). In
addition, design requirements were prioritized
according to the OJI’s that occurred in each
area. This assists in selecting interventions
maximizing injury reduction for a given budget.

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Subject Characteristic Mean Standard Deviation
Age (years) 38.4 13.8 ~
Years in civil aviation : { 9.9 8.8
Level of experience on A-checks (years) 46 Ww
Average number of A-checks performed every month ; 3.8 44
Years of computer experience 3.5 1.9

Two analyses of the evaluation response

data are of interest:

1, Whether the features of the computer-
based workcard were judged better or
worse than a neutral rating.

How the computer-based workcard was
evaluated in comparison with the exist-
ing paper-based workcard and the redes-
igned paper-based workcard.

we

Results of the first analysis are presented in

Fable 3.5. The three parts of this table identify
issues that were rated significantly better than
neutral (A), not significantly different from
neutral (B). and significantly worse than neutral
(C). Of the 39 issues, 25 are in (A); 13, in (B);
and 1, in (C), showing that mechanics were
highly enthusiastic about most aspects of the
system. Many items judged better than neutral
were overall evaluations such as the degree to
which workcards like those shouid be used, but
some were for very specific features such as
readability of buttons and icons. beth the overall
concept and detailed design. Most of the neutral
responses (B) were for completeness and or-
ganization, or for features such as automatic
generation of Accountability list and Non-
Routine Repair forms. The only feature mechan-
ics significantly disliked was one which showed
what percentage of the standard time had been
spent. As has been found consistently in earlier
phases of this project. mechanics strenuously
resist implications of time pressure in their jobs.
The time feature has now been removed.

The computer-based workcard compared

favorably against both the current and propased

paper-based workcards. Tables 3.6A and 3.6B
show the mean ratings and standard deviations
for the three workcards on each issue the com-
puter- and the paper-based systems.

As in Table 3.5, results have been divided
into those where there was a significant differ-
ence among the three systems (Table 3.6.4) and
those where there was no difference (Table
3.6B). The mechanics did not rate the computer-
based system worse than the paper-based system
on any issue. Fourteen of the nineteen issues
were judged significantly in favor of the com-
puter-based system, including all issues asking
for an overall evaluation of the system, overall
ease of usability of workcard. The amount of in-
formation provided was judged almost the same
in all three systems. This result was expected
since no information was added to or subtracted
from the original warkcard to develop the two
new systems.

Although the main comparison was between
the original paper-based workcard and the com-
puter-based system, the inclusion of an im-
proved paper-based workcard was instructive. In
addition to the omnibus test of difference among
the three mean ratings used in Table 3.6, it is
possible to perform three pairwise tests of the
three workcards:

¢ Original paper-based versus computer-
based

¢ Original paper-based versus improved
paper-based

« Improved paper-based versus computer-
based.


Chapter Two Appendix 2-A Fvaiuatian Forms

If there is anything you feel the least bit uncomfortable about, or if you have any questions, please
bring them to our attention now. We are here to address your concerns and ensure that PENS meets
your needs. PENS wiil only be as good as you personalty make it. Please take the time to bring your
concerns to our attention.

Post-Training Comfort Level 2/2



Results of the ECS Tutor Experiment at Clayton State College

Chapter Eight

for troubleshooting electrical circuits. The user
can click on a component to see how the system
behaves when that component malfunctions.

8.2 PURPOSES OF THE EXPERIMENT

One goal of our research is to evaluate the ef-
fectiveness of ITS technology as applied to AMT
training. We produced the ECS Tutor, an ITS
that teaches troubleshooting skills in the context
of aviation maintenance. The research conducted
so far has included several usability snudies and a
smail-scale evaluation (Pearce 1993a, Pearce
1993b).

The experiment described in this paper was
designed to determine the effectiveness of an JHA
in a computer-based training system. Although
much research has addressed designing and im-
plementing ITSs, little has evaluated ITS" etfec-
tiveness in a classroom setting. Researchers often
assume that adding intelligence to a computer-
based training system will automatically improve
students” performance. Our experiment was spe-
cifically desigacd to allow quantitative measure-
ment of an THA's effect.

We also wanted to determine which ITS is-
sues are important for AMT training. Although
many issues are similar to those of other instruc-
tional settings, there are also specific aviation
maintenance issues. For example, the availability
of BITE in newer commercial aircraft requires the
technician to understand the abilities and limita-
tions of such equipment. By observing students
using the FCS Tutor in an aviation maintenance
classroom setting, we examined how they use the
software to learn about troubleshooting. Data
from these observations were used to discern in-
structional. implementation, and pragmatic issues
related to using the software in an aviation main-
tenance classroom setting.

138

8.3 METHOD

The experiment was designed primarily to
determine the effect of including an IHA ina
CBT program. We measured the performance
difference between students using a tutor with an
THA and students using a tutor without an IHA.
The two ECS Tutor versions were identical ex-
cept for availability of an |HA. Therefore, stu-
dents in both experimental groups could ask for
help by clicking on ene of the help buttons, but
students in the “without JHA” group did not get
help when they made rnistakes. The subjects were
not told that there were two ITS programs, and
none notified the experimenters of any difference
between the two versions of the nutor.

8.3.1 Subjects

The subjects consisted of 15 A&P students in
the Aviation Maintenance Technology Depart-
ment of Clayton State College. All subjects were
enrolled in the Winter 1993 course “Cabin At-
mosphere” (AVMT203) and had been at Clayton
State College for at least one year. The “Cabin
Atmosphere” course covers operation of the DC-
9°s ECS, which is less complicated (because of
the limited use of electronic control) than the B-
767's FCS. Before participating in the experi-
ment, subjects had spent approximately seven
hours of class time learning about the DC-9°s
ECS. No subject had worked on the Boeing 767's
ECS, or seen the ECS Tutor before the experi-
ment. No subject had used a FIM to troubleshoot
aircraft malfunctions. The subjects’ computer ex-
perience ranged from none to 3 years. As shown
in Figure 8.3, a poll given after the tutor usage
portion of the experiment indicated that while
more than 80% of the subjects had used a com-
puter before the experiment, only about 20%. had
previously used a CBT system.

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Chapter One

Phase IV Overview

CHAPTER ONE
PHASE IV OVERVIEW

1.8 INTRODUCTION

Since 1989. the Federal Aviation Admini-
stration (FAA) Office of Aviation Medicine
(AAM) has conducted research rejated to human
factors in aviation maintenance and inspection.
The research has been well received by FAA, the
scientific community. and the airlines. This re-
search program has sponsored eight workshops
on human factors issues in aviation maintenance
and inspection. These workshops have been at-
tended by more than 8) participants. The 8th
workshop was conducted during this phase of the
research program. The theme for this meeting
was "Trends and Advances in Aviation Mainte-
nance Operations.” The proceedings were dis-
tributed in April 1994 and were aiso included on
the second FAA/AAM CD-ROM, produced in
May 1994.

Figure 1.1 outlines the research plan for this
program. The first phase consisted of extensive
investigations of airline maintenance organiza-
tons in order to gain a better understanding of the
problems/needs of the “real world" of airline
maintenance (Shepherd et al. 1991). The second
phase developed a number cf human performance
enhancements based on the findings from Phase }
fe.g., the Environmental Control System (ECS)
Tutor, NDI Simulation, etc.] (FAA/AAM &
GSC, 1993a}. The third phase continued the in-
vestigations and demonstrations of various human
performance enhancements. Examples are the
FAA/AAM CD-ROM 41, improved workcards
for inspection, and the Performance ENhancment
System (PENS) for Aviation Safety Inspectors
(ASis). The third phase also began evaluating the
effects of the research program outputs (ECS
Tutor evaluations) (FAA/AAM & GSC, 1993b;
FAA/AAM & GSC. in press). The current phase
(Phase IV) also continued with investigations.
demonstrations. and evaluations. Phase IV also
included fielding of research results. Feedback to
all stages of the research program is provided by
industry adoption of the research products. All
products, procedures, and ideas that have been

generated contribute to the continued safety and
iniprovement of operational efficiency through
improved human performance.

An Cngoing Research &
Development Program

>. 'molementation/Evaluation -—

~reaemee!
Industry Adoption of

As with the other reports from this research
program, this volume begins with 2 sincere thanks
to and acknowledgement of the many government
and industry personne! who continue to cooperate
with the research team. As the work continues
the number of contributors (FAA entities, ar car-
Tiers, and consortiums of industry groups} has
grown beyond a reasonable size to individually
list all those who have provided guidance and co-
Operation.

The remainder of this chapter describes each
chapter in this report.

1.1 PENS FIELD EVALUATION
(CHAPTER TWO)

Chapter Two reports on the Performance En-
hancement System (PENS) field evaluation plan.
PENS (Figure 1.2) is a computer-based tool de-
signed to aid ASI» in performing their ove:
duties (FAA/AAM & GSC. 1993b). For the
evaluation. PENS will be fielded in all nine re-
gions of the FAA, using four different portable
computers (three pen-based systems, one track-
ball system). Approximately 36 ASIs will partici-
pate in the evaluation. four at each FSDO. Testing



Resuits of the ECS Tutor Experiment at Clayton State College

Chapter Eight

tion of system components and schematics. Fig-
ure 8.1 is a sample screen from the ECS Tutor.

The tutor allows four types of actions on ECS
components: operating, inspecting, testing, and
replacing. In operating ECS equipment, a user,
for example, can change the switch settings for
the cockpit control panels. Inspecting a compo-
nent includes reading display values on control
equipment or looking for visible failures in pack
components. Testing differs from inspection be-
cause an AMT has to perform some action; usu-
ally, it is to operate some internal or external test
equipment. One example of testing occurs when
an AMT tests the pack controller by operating the
BITE. Replacing allows users to swap out Line
Replaceable Units (LRUs) with working compo-

nents.

Renaeang:
| No fimit

|; Sesto B-767-300 ECS Systems Overview By 767-300 ECS Systems Overview

8.1.3 Knowledge for Diagnosis

An AMT needs several types of knowledge
to diagnose malfunctions. The ECS Tutor con-
tains knowledge about principies. systems, com-
ponents, and procedures. Principles can be either
physical laws governing the behavior of systems
or rules-of-thumb useful for diagnosing malfunc-
tions. Systems are groups of connected compo-
nents that interact to perform some function: a
system can contain other subsystems. A compo-
nent is a elementary part of a system that trans-
forms material or energy. Finally. procedures are
lists of actions performed to achieve a goal. For
example, the troubleshooting steps a FIM expli-
cate procedures for certain tasks. Knowledge
types differ in their levels of abstraction. Princi-
ples. the most abstract, apply to many situations
but may be difficult to apply to a specific situa-
tion. Procedures, the most concrete, are used only
in specific situations.

136

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Appendix 2-A Evaluation Forms Chapter Two

Wou!d you use this computer in the field as part of your job? ~=-Yes == No

Tf not, why not?

Evaluation of Computer D 2/2



Chapter Nine

Reliability in Aircraft Inspection:

9.6 BIBLIOGRAPHY OF
COMPLEMENTARY

(Reports by Participants)

Lock MWB. (CAA paper in draft, May. 1991). In-
spection Reliability for Transport Aircraft Struc-
tures Pt 2 ‘The Current Situation’. This report is
an update of a similar survey completed in 1981
(CAA Paper 85013 and in abbreviated form,
CAA Paper 90003).

Drury. CG et al. (1991). Human Factors in Avia-
tion Maintenance, Phase I: Progress Repart. Re-
port No. DOT/FAA/AM-91/16. Springfield
Va:National Technical Information Service.

In association with Galaxy Scientific Corporation,
Atlanta, GA.

Drury, CG (1992). Errors in aviation mainte-
nance: taxonomy and control. In Proceeuings of
the Human Factor Society 35th Annual Meeting,
San Francisco, CA. pp42-46.

Drury, CG (1990). Design for inspectability. In
Proceedings of the IEA Human Factors in Design
for Manufacturability and Process Planning
Honolulu, Hi.

161

Drury, CG (1990). Exploring search strategies in
aircraft inspection. In Proceedings of the Second
International Conference on Visual Search
University of Durham, England.

Drury, CG, Prabhu P and Gramopadhye, A
(1990). Task analysis of aircraft inspection ac-
tivities: methods and findings. In Proceedings of
the Human Factors Society 34th Annual Confer-
ence, Santa Monica, CA

pp.1181-1185.

Deury, CG and Gramopadhye, A (1990). Train-
ing for Visual Inspection. In Proceedings of the
Third Federal Aviation Administration Meeting

on Human Factors in Aircri,: Maintenance and
Inspection Training Issues. Atlantic City, NJ.

Additional References

Shepherd WT and Parker JF (1991). Future avail-
ability of aircraft maintenance personnel. In Pro-
ceedings of the Human Factors Society 35th
Annual Meeting, Volume i, pp 33-36.

Taylor JC (1990). Organizational context for air-
craft maintenance and inspection. In Proceedings
of the Human Factors Society 34th Annual
Meeting, Volume 2, pp.1176-1180.

ADA294756


Chapter Five

Ergonomic Factors Related to Posture and Fatigue in the Inspection Environment

craft, an initial physiological response to the pos-
tural demands such as lack of blood flow to the
leg muscles. In tura, this response causes a behav-
ioral response such as posture shifting and/or a
subjective response perceived discomfort. A re-
sponse may alleviate one component of the stress
response while causing another. Continuing the
example, while a change in posture may reduce
the physiological response, the new posture may
make the task more difficult to perform, causing
feelings of frustration.

5.2.6 Effects on Operator

In order to describe, or possibly to predict,
the effects of operator response on performance
and workload, there is a need to understand the
effects of stress and fatigue on the operator.
These effects were cited previously in their re-
spective sections (Sections 5.2.3 and 5.2.4). If
performance is affected, it may be possible to
specify the affected subsystem and why it is af-
fected. For example, perception may be affected
by the inability to obtain an adequate visual angle.
attention may be distracted by discomfort due to
postural stress, or decision-making may be
speeded up in an effort to finish the task and
eliminate the stressor, i.e. to leave the environ-
ment.

5.2.7 Framework to Measure the Effects
on Performance/Workload

Performance and workload will ultimately be
affected by any changes in operator function
forced by working conditions and associated
stress and fatigue. Drury (1985) advances a
three-level framework attempt to describe task
performance with respect to the working arza.
The following proposed framework includes an
additional zone to better predict inspector stress,
workload, and performance. This framework pre-

sents four zones that specifically define perform-
ance, workload, and stress (Table 5.2).

5.2.7.1 Zone 0 - Anthropometrically Restricted
Zone

The task cannot be accomplished in Zone 0
because the working conditions or postures are
too extreme for the operator to function. The
boundary between Zone 0 and Zone | is normally
determined by anthropometric data, i.e. by human
dimensions. These minimum criteria are only
used if space is a critical commodity such as in an
aircraft. Under normal conditions, larger spaces
are recommended. These type of data are limited
wecause they are normally based on static sitting
or standing. They do not account for normal
working postures, do not allow for special equip-
ment, and represent a young population. Hence,
anthropometically defined spaces underestimate
minimum space requirements (Drury, 1985).
There are computer-aided systems such as
CREWCHIEF (McDaniel and Hofmann, 1990)
that account for some of these limitations. How-
ever, Boeing, which has developed and utilizes a
simiiar computer-aided human modeling system,
admits that, "{these] systems [have] limits, and
some mock-ups still will be required. ‘Human.
models....can’t do all the interface work.’"
(Underwood, 1993).

Even if “minimum allowance models’ could
ensure that individuals can work in a given space.
they do not account for fatigue, workload, or
stress effects.

5.2.7.2. Zone 1 - Performance Restricted Zone

Task performance is possible, in Zone 1, but
performance is not optimum because ergonomic
conditions still interfere with the task. This zone
ranges from allowable access for task perform-

ZONE PERFORMANCE WORKLOAD STRESS
i) None possible W....0 §....0
1 Proposiional to space W oaks comseratonss Ds ccovenastanty > HOC
2 Acceptable W ssaceccnserticrss D ser nengaentern > HOC
3 Acceptable W D ... <HOC

91

ADA294756


Chapter Eight

Results of the ECS Tutor Experiment at Clayton State Coilege

CHAPTER EIGHT
RESULTS OF THE ENVIRONMENTAL CONTROL SYSTEM TUTOR
EXPERIMENT AT CLAYTON STATE COLLEGE

Michael Pearce
Galaxy Scientific Corporation

William Beyer
Department of Aviation Maintenance Technology
Clayton State College

8.0 INTRODUCTION

The study described in this paper investigates
the effect of an Intelligent Help Agent (THA) on
the effectiveness of computer-based training. The
experiment was conducted February 16-17, 1993,
at the Aviation Maintenance Technology De-
partment of Clayton State College in Morrow,
Georgia. Subjects used the Environmental Con-
trol System Tutor, a simulation-based twainer, ei-
ther with or without an error-driven IHA. There
was no significant difference in overall perform-
ance between the two groups: 80% of all subjects
made two or less errors diagnosing ten system
malfunctions.

8.1 ENVIRONMENTAL CONTROL
SYSTEM OVERVIEW

AI modern airliners use the Environmental
Contro! System (ECS) to control the aircraft's air
pressure and temperature. The ECS Tutor simu-
lates an ECS with three contro! and display panels
in the cockpit, electronic modules in the avionics
bay, and two cocling packs in the fuselage. The
ECS is acomplex system. Electrical, mechanical.
and airflow subsystems interact to provide cool,
pressurized air to the cabin and cockpit. We chose
the ECS as the training domain for the tutor be-
cause it is fairly similar across airliner types: ECS
training would not be specific to one airliner.
Built-In Test Equipment (BITE) makes the tech-
nician’s job easier since it tests some components
with the push of a button. However, BITE does
not test all ECS’ components. A technician must
know when and how to use external test equip-
ment to isolate malfunctions.

8.1.1 The Aviation Maintenance
Technician

Aviation Maintenance Technicians (AMTs}
must quickly diagnose and repair malfunctions on
the aircraft they are certified to work on. AMTs
must know about the systems of several types and
models of aircraft. Their task is time-constrained
since there is about 40 minutes between a flight's
landing and takeoff. Since some repairs require
more than 40 minutes, AMTs must find the faults
quickly if they are to minimize delays in the flight
schedules.

It is standard procedure for AMTs to use the
Fault Isolation Manual (FIM), a logic tree used to
diagnose malfunctions. AMTs follow the FIM's
“pranches” based on outcomes of their tests and
inspections. The FIM specifies a “minimal path”
of actions necessary to repair a failure, from a
high-level description of the malfunction to the
malfunctioning component. Since it is sometimes
possible to diagnose malfunctions with a single
test (for example, by operating the BITE), AMTs
do not always use the FIM.

8.1.2 Overview of ECS Tutor

The ECS Tutor is a intelligent tutoring system
(ETS) that allows AMTs to improve their diag-
nostic skills through simulated ECS’ malfunctions
of the Boeing 767. The ECS Tutor contains a
deep-simulation ECS model that allows users to
see the consequences their actions have on the
simulated ECS. Users can change the switch set-
tings and observe values of various system pa-
rameters. The tutor is also highly graphical,
allowing direct manipulation of ECS" compo-
hents. and contains realistic pictures and anima-

ADA294756


Chapter Four Appendix - Example 0:

HUMAN FACTORS MISMATCRES/RECONMENDATIONS If PRE-INSPECTION/ SAFETY

1. No safety attachments provided when operator performs inspecticn at heights.
Consider using safety screens on stair landings, rails, cages etc.

HUMAN FACTORS MISMATCHES/RECOMMENDATIONS IN 5OST-INSPECTIGNH/ FEEDBACK

1. Consider inclusion of standard information like ATA codes, station #, sup.#,
employee #, etc. in the workcard. This considerably reduces the cognitive lcad on

the inspector.



Phase IV Overview

Chapter Gne

the PENS prototype in the field will identify tre
tools necessary and viable to ASIs and their su-
Ppervisors.

1.2 DESIGN OF PORTABLE
COMPUTER-BASER WORKCARDS
FOR AIRCRAFT iNSPECTION
(CHAPTER THREE)

Chapter Three discusses a computer-based
workcard system developed during Phase IV.
using a portable computer and hypertext software.
This system was based on the improved paper-
based work ard developed in Phase HI

“AA/AAM & GSC. 1993b). Fight tasks were
ented on the computer-based system (five
A-checks and three C-checks). Results from tests
se IV show that the com-
better than the paper-based.
sysiem. even though the computer-based system
could benefit from improved hardware.

13 ERGONOMIC AUDIT FOR
VISUAL INSPECTION OF AIRCRAFT
(CHAPTER FOUR)

in order for airlines to determine which hu-
man factors inte: ons are most urgently
in their own operations. an ergonomics
audit was developed to help evaluate potential
human/machine mismatches in any inspection
tasa. Chapter Four d} $ this audit which
contains a method of choosing tasks to be audited.
un audit checklist. and computer program evaluat-

nee

ta

ing checklist response against national and inter-
national standards to produce an audit report. An
evaluation conducted in Phase IV showed that
while the audit program is no substitute for a de-
tailed ergonomics analysis, it is a useful tool for
identifving error-prone situations. Chapter Four
Appendix is an example output from the program.

1.4 INVESTIGATION OF
ERGONOMIC FACTORS RELATED
TO POSTURE AND FATIGUE IN THE
INSPECTION ENVIRONMENT
(CHAPTER FIVE)

Chapter Five reports on an investigation of
ergonomic factors which may cause increased in-
specior stress. fatigue and workload, particularly
Tesiriclive spaces that cause extreme postures.
Phase {II developed a methodology for studying
the effects of these cestrictive spaces on inspector
fatigue (FAA/AAM & GSC.1993b). Phase IV
evaluated these effects using a set of four tasks
from the C-check of a DC-9. Inspectors were ob-
served and tests were taken to measure fatigue,
postural discomfort and workload. The results
showed that the same tasks have the greatest im-
pact on the inspector. Based on this evaluation, a
posture/fatigue module has been developed and
integrated into the ergonomic audit program
(Chapter Four). Also several improvements/ in-
terventions were implemented at the partner air-
line to reduce the effects of restrictive spaces.

1.5 HYPERMEDIA INFORMATION
SYSTEM (CHAPTER SIX)

Phase IV continued to expand the Hyperme-
dia Information System (HIS). Research during
Phase IV continued to make the tools generic and
enhance their functionality. The current HIS
contains eight conference proceedings and three
phase reports. It also contains one complete
training simulation (ECS Tutor) as well as a com-
puter-based workcard system and an ergonomics
audil for inspection. The HIS also contains the
Performance Enhancement System (PENS). Two
new libraries used in conjunction with PENS
were added: one contains the Federal Aviation
Regulations: the other. the Inspector's Airworthi-

ADA294756


Ergonomic Factors Related to Posturi

Chapter Five
Chapter Five

more clearly to define and understand individ-
ual’s various stress responses. Physical stress is
directly perceived by an individual's involved
physical subsystems, e.g. biomechanical or
physiological, due to a discrepancy between the
environmentai/task demands and the individual's
physical ability to meet these demands. An indi-
vidual perceives this type of stress through a spe-
cific, or localized, experience of discomfort.
Thus. an individual's response can be specifically
aimed at eliminating or alleviating the stressor,
when possible. There also is an overall physio-
logical response to bodily requirements. For ex-
ample, space restriction may cause postural stress
and discomfort in various muscle groups, result-
ing in increases in heart rate and blood pressure
(Astrand and Rodahl, 1986).

Cognitive stress results from an individual's
perception of the discrepancy betw zen perceived
eavironmentaV/task demands and the individual’s
perceived ability to meet those demands (Cox,
1990, 1985). Since this mismatch eventually de-
termines the stress reaction, the operator's per-
ceptions play 2 key role. This stress is
experienced as negative emotion and unpleasant-
ness (Cox. 1985; Sutherland and Cooper. 1988)
and may be difficult to localize.

We hypothesize that whole-body confine-
ments, as opposed to partial-body restrictions. are
more apt to produce cognitive stress effects. In-
spectors may feel that they have less contol io
adapt or to adapt to the perceived space. For ex-
ample, when an inspector is totally enclosed in an
area, there may be fewer opportunities to elimi-
nate the stressor, c.g. through frequent rest breaks
outside the space. Both whole-body and par-
tial-body space restrictions are hypothesized to
cause physical stress effects, particularly postural,
due to the body positions which these restrictions
demand. These physical stress effects most likely
lead to cognitive stress effects if task completion
is compromised.

in summary, the effects of stress on human
performance provide the basis for investigation.
These effects include increased arousal, increased
processing speed, reductions in working memory,
reduced attentional capacity and attentional nar-

rowing, and changes in the speed and accuracy of
performance (Hockey and Hamilton, 1983;
Hockey, 1986; Reynolds and Drury, 1992; Wick-
ens, 1992).

5.2.4 Fatigue

As discussed above, task performance under
exireme conditions can resu!t in both physical and
cognitive stress; in tur, it can induce physical or
cognitive fatigue. Physical fatigue may be defined
as a state of reduced physical capacity (Kroemer,
Kroemer. and Kroemer-Elbert, 1990). An indi-
vidual can no longer continue to work because the
involved physical subsystems are not capable of
performing the necessary functions. For example,
a posture can no longer be maintained due to ex-
ceeding the endurance limit of the muscles (see
Rohmert, 1973).

Cognitive fatigue is normally associated with
stress and may be broadly defined as a general-
ized response to stress over time. The effects may
reside as a psychological state within the individ-
ual or extend to affect performance. Symptoms of
fatigue include reswicted field of attention:
slowed or impaired perception: decreased mcti-
vation; cognitive subjective feelings of fatigue
and task aversion; and decreased performance in
the form of irregularities in timing, speed, and ac-
curacy (Bartlett, 1953; Grandjean and Kogi,
1971).

5.2.5 Operator Response

An operator’s response is a function of the
perceived space and associated stress and fatigue
effects. Operator response cannot generally be
described by one variable. as it is manifested in
various physiological. psychophysical, and behav-
ioral patterns.

An individual may respond to or cope with 2
stressful situation in order to lessen the effect of
or eliminate the stressor (Cox, 1985). A depend-
ency may exist among the different modes of re-
sponse: psychophysical, physiological. and
behavioral. Any mode(s) of response may in tum
elicit another mode(s} of response (Meister,
1981). For example, while performing mainte-
nance or inspection in a cramped area of an air-

ADA294756


Chapter Five Ergonomic Factors Related to Posture and Fatigue in the Inspection Environment

Upper Lower Limbs
Trunk [Limbs [| 28 | is | 2B | 1] Kiwis fel s
Straight 2 Below AWW AW | A
1Above | AWW | AW WW
2 Above AW] AW AW Ws
Bent 2 Below ARN AWWA sera [pee POL A] eee fo eee
1 Above AWA EW || ese | eee | ae | dere [ene
2 Above | sess | NN | aati | dee Wut
Twisted 2 Beiow CHER
[3 Above } Wii) j ee
2 Above WA, Wi
Bent & 2 Below AWWW. = AW
Twisted | 1 Above AW _| eee Ze WW
2 Above AAW | eee =. NN

S=Straight 8=Bent K=Kneel W=Walk S= Sitting L=Laying C=Crawt

Action Category 1. = The overall pasture is ordinary and narmal. No action is necessary. These
postures are marked with a blank square.

Action Category 2. The foad imposed by the overall posture is of some significance and slightly
harmful. A better working posture should be sought in the near future. These
postures are shown with a WW.

Action Category 3. The strain imposed by the overall posture is significant and distinctly harmful. A
better working posture should be sought as soon as possible. These postures
are marked with ##%.

Action Category 4. The strain imposed by the overall posture is greatly significant and extremely
harmful. A better working posture should be sought immediately. These postures
are marked by shading.



Hypermedia Information System

ojo

‘Oklahome City, Okda. 73125. The letter mrust--

and the ratings on it; and

§1438 Change ef mame; replacernent of lestor destroyed certificate.

(a) An application for a change of name ona Certificate issved under
this part must be accompanied by the applicant's current certificate
and the marriage license, court order, or other document verifying the
change. The documents are returned to the applicant after inspection.

(0) An application for a replacement ofa lost or destroyed certificate
is made by letter to the Department of Transportation,
REA. Aicrran Cerssfication Branch, Post Office Box 25082,

(1) Contain the name in which the certificate was issued, the permanent
maiting address (including ip code), social security number (if ary),
and date and place of turth of the rerificate holder, and any available
information regarding the grade, number, and date of :ssue of the certificate, i

(2) Be accompanied by a check or money order for $2, payable to the
(c) A person whose certificate issued under this part has been lost

fray obtain a telegram from the SAME confirming that 1 was issued The
telegram may be carried as a certificate for a period not to exceed +

ao

oan

Fie

S115 5
It is sometimes desirable for a reader to mark
a place in a document. The HIS provides a book-
marking capability and enables a reader to create
multiple Bookmarks for a document. When creat-
ing a Bookmark, the HIS uses the current Topic
as the Bookmark’s target destination. To use a
previously created Bookmark, the reader chooses
one from che Est of active Bookmarks (Figure
6.6). The Topic coniaining the Bookmark does
not have to be in the current library; the HIS
automatically switches libraries, if necessary.

6.1.2 Viewing

The HIS provides three distinct tools viewing
the various media comprising a hypermedia li-
brary. The Document Viewer has multiple entry
mechanisms: the Outline Viewer, the Search
Query Dialogue Box, Bookmarks, and Hot Links.
The Graphics Viewer and the Multimedia Viewer
are accessible only through Hot Links.

iy

6.L2.1_The Document Viewer

The Document Viewer, shown in Figures 6.3
and 6.5, allows a reader to scroll through and read
a hypermedia document, as well as to investigate
search hits. Text formatting such as boldface,
italics, underlining, and multiple font sizes and
typefaces, enables the on-line document closely to
resemble the original. Any headers and footers
are also displayed.

6.12.2 The Graphics Viewer

Readers use the Graphics Viewer to view and
print graphics. It appears when a reader clicks on
a hot word that links to a static graphic image.
Supported graphics formats include, among oth-
ers, bitmap (BMP), encapsulated postscript
(EPS), graphics interchange file (GIF), target im-
age file format (TIFF). and Joint Photographic
Experts Group (JPEG). The Graphics Viewer
determines the graphics file's format and dis-



Design of Portable Computer-based Workeards for Aircraft laspection

Copatt Insnection

Table 3

B. Information Layering .

no layering of information
Rot conducive to expert as well as novice usage
difficulty in writing such unstructured information

C. Other Organizational issues °

no use of naturaily occurring page modules for fitting in
information

improper task sequencing

no consistency in the number of signoffs across the task

4. PHYSICAL HANDLING & ENVIRONMENT

am

size of attachments different from the workcard, causing
inconvenience in usage

inadequate lighting conditions in certain work areas

no holder or place for holding the workcard while using it

3.2.2.3 Hypertext

Many advantages computer-based informa-
tion have over paper are due to hypertext. Hy-
pertext is a technology cf nonscquential writing
and reading: it is also a technique, a data-
structure, and a user interface (Berk and Devlin.
1991), Hypertext systems split documents into
components or nodes connected by machine-
supported links or relationships. Conklin (1987)
summarized the operational advantages of hy-
pertext as follows:

1. Information structuring: Both hierar-
chica] and non-hierarchical organization
can be imposed on unstructured infor-
mation.
Global and focal views: Browsers pro-
vide table of contents-style views, sup-
porting easier restructuring of Jarge or
complex documents: both global and Jo-
cal views can be mixed effectively.
Modalarity of information: Since the
same text segment can be referenced
from several places, ideas can be cx-
pressed with less overlap and duplica-
tion.
Task stacking: The user can have sev-
eral paths of inquiry active and dis-
played on the screen simultaneously;
any path can be unwound to the original
task.

These hypertext features solve many desi
issues identified in the taxonomy given in Ta-

bles 3.1 and 3.2. For example. computer-based
information provides a consistent typographic
layout and a continuous layout with no page
breaks. It also reduces redundancy and repeti-
tion, fostering generalizations across tasks.
Computer-based systems are more supportive of
graphics than paper-based systems. Hypertext
easily allows for categorization and classifica-
tion of tasks and information so that general in-
formation can be separated from specific
information. Layering of information is condu-
cive to expert and to novice usage. Hypertext
should make accessing and referring to infor-
mation such as attachments and manuals consid-
erably easier. In addition, the inspector can sign
off tasks after completing them, write notes For
non-routine maintenance in the computer-based
system, and then easily return to the correct
place in the task list to continue inspection.

Thus, we hypothesize that hypertext can
solve many de«1gn issues associated with paper-
based workcards. The next step is to design
specific examples of computer-based workcards,
using the lessons learned from designing paper-
based workcards, knowledge of hypertext, and
inforriation on inspection tasks.

3.2.3, Development of the System

A prototype computer-based workcard sys-
tem was developed on an 1BM Think Pad 700
PS/2 using Spinnaker PLUS. This hypenext
object-oriented programming Jan-

ADA?94756


Design of Portable Computer-based Workcards for Aircraft Insi

Chapter Three

issue Addressed § Point Rating Scale End Workeard System Significance
Points
0 8 Current improved Computer
Ease of understanding Very diffi- Very easy 44 (1,1) 6.25(1.7) 7.1(1.6) 0.02
cuit
information covered every- Disagree { Agree fully 15(1.4} 4.4(2.4) 6.6(2.1) 6.01
thing for task fully
Tasks were well organized Disagree Agree fully 1.9(1.6) 5.52.1} 6.1(2.4) 0.02
fully
Effort required in tocating Very diffi. Very easy 1.8(1.4} 5.52.0) 5.82.0} cokers
information cult
Consistency of organization Terrible Excetient 3.4(0.9) 5.3(4.0) 5.4(1.8) 0.05
Separating information by Terrible Excellent 3.3(1.6) 5.9(1.4) 6.1(1.6) 0.05
frequency of use
Chance of missing informa- Always Never 44(0.7) 651.7) 650.9) 0.01
tion
Ease of physical use Very diffi: Very easy 3.0{0.9} 5.5(2.4) 6.4(2.5) 0.05.
cult
Ease of referring to attach- Very diffi- Very easy 1.8(1.7) 45(2.3) 7.0(1.9} 0.07
ments or manual cult
Ease of writing up an Ac- Very diffe | Very easy 1 24(t3) 4.82.3} 5112.0) 0.05
countability List cult
Degree of interest Very boring 2.3(1.7) 4.81.0) 6.8(1.2} 0.61
esting
Degree to which rater would Detinitely Definitely 3.0(1.1) 5.8(1.3) 7.40.9) 0.01
iike to use W/C again not yes
Degree to which W/C like Definitely Definitely 3.4(1.0} 5.9(4.4} 6.3(1.2} 0.01
these should be used rot yes
Overali ease of usability of Terrible Excellent 2.50.9} 5.9014} 6.5{1.4} 0.01
wit i



Chapter Two

PENS Project

ing seal on the wing of an aircraft, the inspector
could annotate a line art drawing of that aircraft
on the computer. This graphic could then be
stored along with the completed form.

2.6 EVALUATION AND
IMPLEMENTATION

There are a number of issues that can affect
the success of introducing new technology into
the AST work environment. Many inspectors do
not have experience using computers. Of those
inspectors, some are willing to try the new tools
based on promised increased productivity, while
others think that using computers is not part of
their job description. Some inspectors are even
concermed with how they will be perceived by the
operators when they are carrying a pen computer.

We are capitalizing on constraints built into
the forms and data to make the system easy to
use. For instance, because many fields on the
forms require one item out of a finite set of pos-
sible entries, one can display that set and select an
item from it. This approach has the added benefits
of reducing memory demands on the inspectors
and of increasing data reliability.

Pen computer configurations and durability
must also be considered, as there are significant
tadeoffs in these areas. Questions that should be
asked include: Is it better to have a lightweight
unit without a keyboard, or a slightly heavier unit
with a keyboard? Which is more important to in-
spectors, weight or mggedness? Is battery life
sufficient to even consider using such a device?

PENS is undergoing a field evaluation in one
Flight Standards District Office (FSDO) in each
of the nine FAA Regions in order to answer the

Table. 2.

Computer C

above questions and to determine whether pen
computers arc a viable solution to the FSS infor-
mation management needs.

2.6.1 Design of the Evaluation

Four models of portable computers, each
from a different manufacturer. have been fielded
in one office in each of the nine FAA Regions.
These computers were selected because each one
had a particular differentiating characteristic that
may be important to ASIs. For example, three of
the computers were pen computers, while the
fourth used a trackball. The latter computer was
fielded to address the following question: Is a pen
computer necessary or will inspectors benefit
simply from having a portable computer? This
and similar questions have been raised. and rather
than dictate an answer and force inspectors to
adapt to our decisions, we deemed it more appro-
Pfiate to provide the inspeciors the opportunity to
tell us what were their requirements.

The following sections address the details of
the evaluation.

2.6.1.1 Evaluated Computers

A total of thirty-six computers (nine units of
each of four models) are were fielded. These
computers were selected based on their particular
combination of features and differentiating char-
acteristics. That is, the computers were sclected
because they had certain features in common, but
they also had a particular feature that made them
unique compared to the others. These features are
described in Table 2.3.

Computer 0

Computer A
486/25 Mhz CPU 486/25 Mhz CPU
200 Mb Hard Drive 80 Mb Hard Drive

Built-in Keyboard Separate Keyboard

Pen Pen

386/25 Mhz CPU
200 Mb Hard Drive

| 486/25 Mhz CPU

! 420 Mb Hard Drive

; Built-in Keyboard

ADA294756



Chapter Nine

Reliability in Aircraft inspection: UK and USA Perspectives

aircraft (or continuing airworthiness) considera-
tions, both supply of new inspectors and loss of
existing inspectors are critical issues for the pres-
ent and the future. Recent studies in the USA and
Canada (Shepherd, 1991) have documented that a
crisis may soon be reached.

UK Variations: Here the tradition has been to
apprentice a school-leaver to a company to leam
the job of mechanic, with CAA examinations and
company examinations both being given at regu-
lar intervals throughout the apprenticeship. When
mechanics are certified, after a certain time, and
more training, they can be recertified as inspec-
tors. Not all who are qualified are given inspec-
tion jobs, depending upen current employment
opportunities within that company. Other ways of
entry are via the services (RAF, Army, Navy).
which accounts for a large proportion in some
fields (e.g. up to half of NDT inspectors), and oc-
casionally from the shop mechanics. Leaving is
often to other airlins companies (see Bonding
above), but does occur to other industries at
timies. Pay is considered to be poor, but rarely
poor enough to cause a move. The typical grum-
ble is that the job status is not perceived highly
outside the aircraft industry.

US Variations: Most mechanics attend an
A&P School after leaving high school, to be
trained at their own expense for approximately
two years. The output from these schools has a
high wastage (perhaps up to 50%) to other indus-
tries, such as automobile mechanic or dental
equipment technician. There is some recruiting
from the services, but the numbers are too small
to provide a large fraction of inductees. At the
same time, retirements are increasing due to pre-
vious cycles of hiring and freezing. Over the next
ten years there is predicted to be a severe shortfall
between the demand for mechanics and the sup-
ply, even with relatively optimistic assumptions
about recruiting, retention, and productivity.

Evaluation: Apprenticeship schemes are
starting in the USA after a considerable lapse, and
are being revitalised in the UK after considerable
recent neglect. Such schemes hold promise for in-
creased supply, as trainees are paid during train-
ing. and have a strong company identity after

a

certification. However, they represent a consider-
able cost outlay for the company; an outlay which
may not always be repaid (see Bonding above).
Joint ventures between companies, high schools
and junior colleges have been tried with some
success both in USA and Europe as a way to ex-
pose more people to careers in aviation. Similar
schemes between companies and A&P schools
are now under way, with results which appear to
be encouraging. Low pay and poor working
conditions must also be addressed. Pay rates in
the starting jobs are particularly low. This is even
more of a factor at the second-level companies,
who are often considered as "holding areas’ for
staff by the major carriers, leading again to a high
rate of leaving in the industry.

Working conditions such as shift work, dirt,
confined spaces, and lack of amenities can be
changed only by action on many of the human
factors points made in this and previous reports.
Such conditions are not acceptable in the current
market place, and indeed would not be tolerated
by most of the office staff in many of the compa-
nies visited. If the mechanics who will become
the inspectors are to be recruitec and retained in
sufficient numbers to ensure continued safety, the
conditions will have to improve.

When inspectors rather than mechanics are
considered, there are additional problems. If a
mechanic chooses to become an inspector he will
move from the top of the seniority levels in one
group to the bottom in another. This often entails
a reversion to an unpopular shift, and more isola-
tion from the management function (who are of-
ten concentrated on the day shifts), before
seniority in the new occupation is established.
The inspectors studied for this report had all, by
definition, survived these problems. Maintaining
adequate future supplies requires similar studies
of those who chose not to continue to inspector
level.

The route into civilian inspection, especially
for NDT, from a military background is unneces-
sarily difficult. A joint committee on training
would benefit both parties: morale would be
boosted for those in a service environment and
the civilian sector could have a ready supply of

ADA294756


Ergonomic Factors Related to Pasture and Fatigue in the Inspection Environment

Chapter Five

ance up to acceptable task performance. As
conditions improve. performance increases. The
total workload is equal to the workload associated
with the task plus the workload associated with
the operator compensations caused by the work-
space. There is increased stress present in this
zone, for the task demands exceed the operator
capabilities. Workload and stress most likely de-
cTease within the zone, as ergonomic demands
decrease. the compensations should also decrease.

5.2.7.3, Zone 2 - Workload/Stress Restricted Zone

Task performance is acceptable. in Zane 2. at
least in the short term. However, operators'
workload and stress are increased because com-
pensate for ergonomic conditions and/or extreme
postures. As ergonomic conditions improve
within this zone, operator compensation(s} or 7e-
sponses should decrease, causing the total work-
load and stress to decrease.

5.2.74 Zone3- Unrestricted Zone

Zone 3 allows acceptable task performance
without additional operator compensation: thus,
there is no additional workioad or stress imposed
by the working conditions.

§.3 ON-SITE EVALUATION AND
ANALYSIS

Experimentation utilized the restrictive space
model to assist in understanding and describing
the relationships between the task conditions and
the operator's compensations, fatigue, stress, and
workload. The framework used categorizes the
task spaces based upon the measured stress and
workload effects.

The knowledge of the effects ergonomic
factors have on the operator was applied within
the methodology to develor the following:

1. A recognition guide, integrated within the
ergonomic audit, allowing users to pre-
dict which tasks will have a performance
decrement and/or stress increase due to
posture.

A set of interventions keyed to task. op-
erator. and environment factors reduce
stress and fatigue.

is

The maintenance facility where data were ob-
tained possesses four bays and services only DC-
9°s on all three shifts. i.e. day, aftemoon, night.
On-site evaluation was two-pronged and included
analysis of 1) pre-existing conditions in terms of
¢cn-the-job injuries (OJI's) and 2) existing condi-
tions in terms of direct and indirect data collection
techniques.

5.3.1 Evaluation of Pre-Existing
Conditions

Evaluation of pre-existing conditi
sist in determining if there is any need for ergo-
nomic intervention and. if there is, to focus
analysis towards the problem areas. in addition. it
can guide the implementaion process by empha-
sizing and prioritizing interventions. OJI’s were
reviewed in an effort to provide this information,
as these data were already collected and thus eas-
ily accessible. OJI's represent an extreme hu-
man/system mismatch leading to an error severe
enough to cause injury.

53.L1 OM Analysis

We reviewed OJI reports from 1/1/92 to
6/30/93. The procedure outlined by Drury and
Brill (1983) was employed to identify accident
patierns. Accidenvinjury data were separated in
order to identify OJI's that occurred in the hangar
and OJV’s specifically related to restricted space.
The OJ1’s identified space-related were then
grouped based upon age, job, years on the job,
area, activity being performed. days out, type of
injury, and body part injured. Thus, we were able
to develop a small number of repetitive scenarios
or pattems.

33.1.2 Results

The percentage of space-related OJI's in the
hangar was 20.4% (Figure 5.2). This finding in-
dicates that ergonomic interventions, particularly
those related to space, should be addressed. Fig-
ure 5,2 also shows other data that were meaning-
ful in this analysis. Most injuries were sprains to
the lower limbs or back/neck, primarily occurring
during repositioning. working. and access type
activities, e.g. climbing and slip/trips. Table 5.3
presents a summary of the most predominant sce-
nar1os.

ADA294756


Appendix 2-A_ Evaluation Forms

Chapter Two

Personne! Background

initials: FSDO:

Age: Years as ASI:

Type of operator you inspect reguiarly: 12h 125) 129433) 135) 137
other

Type of operator you inspect most frequently: 121 12509 1291330 135
other

Have you ever used a computer before? Yes No How many years?

What type of computer have you used?

Do you own acomputer? Yes

What type of computer do you own?

Have you ever used a "Mouse" before?

Have you ever used a “Trackball” before?

Have you ever used a “Pen Computer” before?

Do you currently use the PTRS Transmittal System (Paradox }?

IBM PC Compatible (eg. AT&T/NCR OATS)
Apple Macintosh

Other: ___

How many years?

IBM PC Compatible (eg. AT&T/NCR OATS)

At this point, how comfortable do you feel using a computer?

i 2 3
not at all comfortable

somewhat comfortabie

Apple Macintosh
Other:
Yes No
Yes No
Yes No
Yes No
4 5
quite comfortabie

Personne! Background i/2


Chapter Two Appendix 2-C Software User Manuals

Assistance: Used to prevent recording more than one unit of work for an activity when inspectors of
the same specialty combine their effort to.accomplish an activity.

Satisfactory: Used to close out Surveillance activities and indicates the activity was in fuil compliance.
This code should only be used when no comments are made.

information: Indicates that the result of the inspection was satisfactory in the Flight Standards program
area, but there is information in the PTRS Section IV that is pertinent to future surveillance of the
activity. Additional information must be provided in Section IV.

Follow up: Used in two ways. either to indicate that a corrective action was taken prior to completing
the Surveillance activity, or that 2 re-inspection was opezed for completion in the future to confirm
continued compliance. Additional information must be provided in Section IV.

Enforcement: Indicates that a violation was found and an enforcement action opened. Additional
information must be provided in Section IV.

X(Canceled): Indicates a Surveillance activity has been canceled. A planned activity should be
canceled when the scheduled date exceeds 60 days, if the same activity is scheduled at a later date. Do
not use X to cance! an NPG Required Surveillance, except when the DO's division grants a deviation
from the required Surveillance in accordance with FAA Order 1800.56.

Terminate: Indicates that a certification activity was aborted or that an NPG required surveillance was
terminated because the subject of i oe longer was active wi the region.

pection ceased op:
Pass or Fail: Check either box to indicate the result of certification activity or the conclusion of various
evaluation activities.

Designator: Enter the designator code for the subject. if you do not know the code, hit the SELECT button
to access the Designator Screen.
The Designator screen will help you select the appropriate designator code for an operator. One way to
find the code is using the search function: Enter a portion of the operator name or the designator code in
the FIND field, then press the SEARCH button. The first matching data will be highlighted. You may
need to press the SEARCH button repeatedly until you find the right operator.
An alternative method is to use the INDEX buttons (A-G to 0-9). Push the INDEX button that contains
the first letter of the operator name and then scroll until you find the desired operator.
Once the right designator code is selected. press OK.

Airman Cert #: Enter the applicable certificate number.

Airman Name/Other: Enter the name of airman, non-certified organization, training course, or topic of a
special project as applicable, which is not associated with an Air Operator or an Air Agency.

Make: Enter the manufacturer of the aircraft. If you do not know the manufacturer, press either the
SELECT button or the Make/Model/Series button.
The SELECT button will access the Make screen. There are two ways to find the aircraft
manufacturer in this screen:
I. Enter the first few letters of the manufacturer name in the field FIND and press the SEARCH
button. The first matching entry containing these letters will be highlighted. Additional
manufacturers may be found by subsequent pushing of the SEARCH button.

31

ADA294756


Ergonomic Factors Related to Posture and Fatigue in the Inspection Environment

‘

hag

¢

tors are forced to either search an area at
less-than-optimum viewing angles or work indi-
rectly, using a mirror. Although both methods can
produce acceptable performance, inspector
workload and stress are increased; performance is
Jess efficient than under unrestricted conditions.

Restricted areas may also prohibit inspections
from having any extraneous miaterial easily ac-
ces” bie in the immediate working area (e.g.
workcards on the illustration). This forces inspec-
tors to make decisions without comparison stan-
dards, increasing memory Joad. or additional time
to obtain information from the workcard, a man-
ual, or a supervisor. Moreover, less-than-
optimum viewing angles may further decrease
sensitivity and increase the difficulty of decisions.
Thus, restricted spaces can force the decision-
making task to be more memory-intensive, more
jength, and more difficult.

Conversely. pressures for cursory decision-
making may encourage the inspector to get out of
the space quickly. Decision-making tasks exhibit
a speed/accuracy tradecff (SATO), with speedy
performance associated with inaccurate deci-
sion-making. However, inspectors are highly mo-
tivated to perform accurately (Shepherd, Johnson.
Drury. Taylor, and Beringer. 1991). Thus, we
predict that while accurate decision-making per-
formance may not be compromised by even the
mosi extreme space conditions. workload and
suess may increase.

The inspectiun task aisa requires that detected
detects be marked and documented. As discussed
above, restricted areas ray not allow additional
material such as non-routine repair forms in the
workspace. The inspector must then remember
all defects within an area. only later documenting
on the appropriate forms. This situation can add
to the high memory load requirements on inspec-
tors and present the potential for an inspector to
forget 10 note a defect.

Finally, extreme space conditions allow i
spectors (0 adcpt only a limited mimber of ineffi-
cient postures. Thus, their physical work
capacity may be reduced in restrictive spaces. as
indicated by research in the area of manue! mate-

&

rial handling (Davis and Ridd, 1981; Mital, 1986;
Ridd, 1985; Rubin and Thompson, 1981; Stal-
hammer, Leskinen, Kuorink, Gautreau, and
Troup, 1986). Under unlimited space conditions,
operators are able to adept efficient postures or
switch postures and use other muscle groups,
enabling primary muscle groups to be rested
(Drury. 1985). However, the frequent breaks
from restrictive areas common during mainte-
nance/inspection activities allow relief from sus-
tained task performance and allow the primary
muscle groups to be rested.

5.2.1.2. ‘Task Duration

Some inspection tasks and many repair tasks
require mechanics to be in a confined or restricted
area for prolonged periods. Increased task dura-
tion forces an inspector to spend longer periods of
time in a restrictive area and could psychologi-
cally affect his or her perception of space. Habi-
tability literature, concemed with the study of
manned underwater vessels and space vehicles.
indicates that internal space requirements vary as
a function of duration (Blair, 1969; Price and

Parker, 1971}. Furthermore, Cameron (1973) in-
dicates duration to be the primary variabie asso-
ciated with fatigue effects.

The equipment and tooling utilized during
access and task performance can contribute to
stress and fatigue effects and may further physi-
cally restrict the area. Furthermore. the equipment
may not be des:ened optimally for a given task.
For example, ratchets used to loosenftighten a bolt
may not have attachments which allow inspectors
to reach an area without placing their arms in an
awkward position. forcing them to creute torque
in an inefficient posture. Similarly. eddy-current
devices used to inspect rivets have no convenient
resting place, Icading to a less-than-optimal rela-
Gonship amor ispector. the probe. and the
eddy-c

sin aircraft inspection have shown that
poor iHumination and other adverse lighting
conditions could be important reasons for eve
strain or visual fatigue. fi



Chapter Two

PENS Software Evaluation
Initials: FSDO:

Now that you have used PENS for a sig

{enjoyed using PENS. True
Tam eager to see PENS evolve to meet my additional needs. True

I would like all of my forms linked together so that I don’t have to fill in the same

information on multiple forms. True
I will continue to use PENS after the evaluation period. True
I would rather use paper in the field and ir: Tre
T would rather use the current transmi True
I like the On-Line References (Hypermedia), such as FARS and Handbooks. True
I would like more On-Line References (Hypermedia), such as ADs, ACs, etc. True
The On-Line References (Hypermedia) aré the best part about PENS. True
Thad difficulty transferring my files from the computer to the network. True

PENS Software Evaluation 1/6

23

False
False



Guidelines for Designing and Implementing CBT for Aviation Maintenance

Chapter Ter.

propriate for teaching the physical and coordina-
tion skills necessary for safe driving. Note that a
CBT program may combine several of these ele-
ments,

Bibliography:

Cohen, V.B. (1985). A reexamination of feedback
in computer-based instruction: Implications for
instructional design. Educational Technology,

25, 33-7.

Flexman, R. E. & Stark, E. (1987). Design of se-
lection and training systems. In G. Salvendy (Ed.)
Handbook of Human Factors. New York: John
Wiley & Sons, pp. 1012-1038.

Golas, K.C. Estimating time to develop interac-
tive courseware in the 1990s (Technical Report).
Southwest Research Institute, San Antonio, TX.

Goldstein, L L. (1987). The relationship of train-
ing goals and training systems. In G. Salvendy
(Ed.) Handbook of Human Factors. New York:
John Wiley & Sons. pp. 963-975.

Reigeluth. C. (1983). Instructional design: What
is itand why is it? In C. Reigeluth (Ed.), Instruc-
tional Design Theories and Models: An Overview
of their Current Status. Hillsdale, NJ: Lawrence
Erlbaum Associates.

10.2.1.1_Linear/Tutonal Training

‘The linear training method of CBT presents
the material in much the same way as a book. Us-
ers can "step" forward and backward through the
material, and possibly jump to other topics and
subjects. Linear training differs from a book in
that the program can use multiple types of presen-
tation methods, including graphics, audio, and
video.

Bibliography:

Alessi, Stephen M.. and Troilip, Stanley R.
(1985). Computer-based instruction: Methods
and development. Prentice Hall. Inc: Englewood
Cliffs, NJ.

Black, J., Bechtold, J., Mitrani, M.. & Carroll, J.
(1989). On-line tutoria!s: What kind of inference

Icads to the most effective learning? ACM CHI 89
Proceedings.

Chamey, D. H., and Reder, L. M. (1986). Design-
ing interactive tutorials for computer users. Hu-
man-Computer Interaction 2(4), pp. 297-317.

10.2.1.2 Simulation-hased Training

A simulation-based CBT system simulates
some type cf task through dynamic interaction.
The software provides a realistic imitation of the
necessary equipment and activities and behaves
like the “reai" world. For example, the CBT may
require the student to troubleshcot a piece of
equipment by inspecting, testing, and replacing its
components.

Bibliography:

Harri-Augstein, S., and Thomas, L_ F. (1984).
Simulators which invite users into learning con-
versations. Proceedings of IFIP INTERACT'84:
Human-Computer Interaction, pp. 785-793.

Hollan, J. D., Hutchins, E, L., and Weitzman, L.
(1984) STEAMER: An interactive inspectable
simuiation-based training system. AJ Magazine, 2.

Jchnson, W.B. & Norton, .E. (1991). Using in-
telligent simulation to enhance human perform-
ance in aircraft maintenance. Proceedings of the
1991 International Conference on Aging Aircraft
and Structural Airworthiness (NASA Conference
Publication 3160). Washington, DC: Federal
Aviation Administration and National Aeronau-
tics and Space Administration, 305-313.

Wiederholt, B.J., Norton, J.E., Johnson, W.B.,
Browning, E.J. (1992). MITT writer and MITT
writer advanced development: developing
authoring and zraining systems for complex
technical domains (AL-TR-1991-0122). Brooks
AFB, Texas: Air Force Systems Command.

10.2.1.3 Intelligent Tutoring

An intelligent tutoring system (ITS) mimics
the instructional strategies of an instructor or do-
main expert. An ITS can give advice, provide
feedback, and explain mistakes. By automating
some of the assistance that instructors usually

ADA294756


Chapter Seven

Correlates of Individual Differences in NDI Performance

attentiveness. better performers had a higher
initial level of attentiveness, thus showing a
greater pre to post change than did the poorer
performers.

7.2.3 Predictor Variables and
Performance

A large number of exploratory analyses
were conducted using discriminant function
analysis and factor analysis. In general, the
clearest relationships were found using factor
analysis. A principal components analysis using

varimax rotation and sclved for four factors
seemed to yield the best, most interpretable re-
lationships. Loadings of each predictor variable
on the four factors are shown in Table 7.4. A
cut-off criterion of .60 was used to select thase
variables contributing to factor interpretation.

This means that a variable would have to
explain at least 36 percent of a factors variance
for it to be included in a factor’s interpretation.
The factors were identified with the labels listed
below.

Variable 14 2 3 4
Typ Exp Inve tory 0.046! 6.473/ -0.128| -0.276
Benneit Mech Tes! 0.209; 0.103) -0.257| 0.612
LES Boredom Frone 0.358; 0.378! -0.582| -0.052
Maich Fam Fig Error 0.257| 0.722} 0.096! -0.291
Match Fam Fig Time 0.975 | 0.049} -0.639} 0.222
Eysenck Extroversiori 0.644 -0.398 0.222 { 0.203
WAIS Dig Symbol 0.208/ 0.175{ 0.697{ -0.156
WAIS Dig Span 0.114 0.105 0.106 0.828
WAIS Arithmetic 0.057 0.600 0.129 0.500
PRF Achievement 0.553] 0.308} -0.029| 0.241
PPF Autonomy 0.059 0.738 3.213 0.028
PRF Change 0.075{ 0.073{ 0.754] 0.296
PRF Cog Structure 0.807; 0.016] -0.186| 0.051
PRF Endurance -0.717| -0.282| 0.055] -0.084
PRE imputsivity 0.741| 0.250} 0.1701 0.074
PRF Understanding -0.143| 0.644| 0.075} 0.152
Rotter i-E Scaie 0.584 0.085 0.491 | -0.026
Fig Preference 0.105} 0.016| 0.359} 0.282
127

ADA294756


PENS Project Field Evaluation

Chapter Two

These computers allow us and inspectors to
address the following questions:

1, sa field computer a viable solution?

2. Isa pen computer required, or will any
portable computer work?

3. Is a 486 processor required?

4. Isa separate or built-in keyboard prefer-

able (given that it adds weight)?

5. The 80 Mb Hard Drive limits the func-
tionality of the computer, but it also
weighs less. Which is preferable: A
lightweight machine with limited func-
tionality or a slightly heavier machine
with increased functionality?

The following fearures common to all four
computers:

8 Mb RAM

Backlit LCD Monochrome display
PCMCIA Data Storage Card

DOS 6.0

Windows (Windows for Pen Computing
or Windows 3.1: functionally equivalent
except for handwriting recognition)

© PENS Software

The PENS software is common to all four
computers and nuns nearly identically on each of
the three pen computers. (Computer B does not
have sufficient hard disk space to contain all of
the FARs or the Airworthiness Inspector's Hand-

book.) It nuns essentially the same way on the
trackbal} computer, with the exception that there
is no handwriting recognition on that computer.

2.6.12 ._ Evaluation Sites

Units were fielded in all nine FAA Regions. This
scope gives the project broad exposure to field in-
spectors and it subjects the hardware to a range of
environmental conditions. The nine FSDOs were
selected based on the worst-case environmental
conditions present in those regions. The FSDOs,
environmental conditions, and installation dates
are listed in Table 2.2,

2.6.1.3. Experimental Design

A team of four inspectors in each FSDO is
evaluating these units. These inspectors represent
a cross-section of the inspector population in
terms of age. sex, work experience. and computer
experience. Each inspector is using one of the
computers for a week and then switching to a dif-
ferent model. The rotation is counterbalanced to
eliminate order effects. This rotation will continue
until each inspector has had an opportunity to use
each model. At the end of the rotation, each in-
spector will complete an evaluation form that re-
quests himrher to rate each unit and answer some
general questions. Appendix 2-A contains a
compicte set of evaluation forms. The inspectors
still have access to the units at this time to refresh
their memories of the specifics of cach unit. From
these data, we will recommend one commercial,

Fabte 2:2° Ev.

i Re FSDO Environment | Installation Dates

| Great Lakes Milwaukee ! Cold, snow | November 15-16, 1993
Centra! i St Louis i Average i November 16-19, 1993
Southwest Ft. Worth i Warm, dry | November 21-24, 1993
Western Pacific Long Beach i Warm, humid | November 29-30, 1993
Northwest Mountain Seaittie | Average, humid i December 2-3, 1993
Alaska Fairbanks | Extrerne cold. dry | December 6-7. 1993
New England Boston | Cold, snow : December 13-14, 1993
Eastem | Harrisburg ] Cold, snow i December 16-18. 1993
Southern i San Juan | Het. humid, rainy | January 10-11, 1994

ADA294756



Design of Portable Computer-based Workcards far

Chapter Three
Chapter Three

Specialized computer hardware and software
systems have been designed to automate com-
plex diagnostic tasks (maintenance) such as the
Air Force's Integrated Maintenance Information
System (IMIS) (Johnson. 1989). There remains
a need for a simpler, less-expensive system us-
ing off-the-shelf components. Such computer-
based systems have been aimed at diagnostic
tasks, but here they are applied to more infor-
mation-intensive procedural .asks that form a
major portion of aircraft inspection activity. The
objective of this study is to develop and test a
prototype of a simple, inexpensive inspection
workcard implementation on a lap-top com-
puter. Specifically, the design had to be effective
for both A-checks and C-checks.

3.2 METHODS

The computer-based workcard’s design used
and extended guidelines developed for the pa-
per-based workcard. Computerization of infor-
mation solves some problems and opens 4 new
set that this project had to identify and resolve.
The computer-based workcard’s design was
compared against the paper-based workcard’s to
determine if these issues were properly identi-
fied and resolved.

3.2.1 Hardware

The choice of hardware for the computer-
based workcard was a critical issue. The original
paper-based system studied lacked a convenient
hand-held integrated workcard holder. although
one was designed for the improved paper-based
system. Current lap-top systems are inexpensive
and are getting smaller while adding new sets of
features and sacrificing little in computing
power. Key breakthroughs in technology are
feeding this process: storage devices are getting
smaller; IC designs supporting fewer chips are
lowering power requirements {Linderholm, O.,
Apiki, S., and Nadeau, M., 1992). Also, designs
are getting more mgged. inspiring confidence
when a computer is intended for field usage.
Using these systems is stil] inconvenient. due to
keyboard and pointer interfaces. Systems oper-
ated by keyboards and mice purtially defeat
goals of accessibility and connectivity

(Meyrowitz, 1991). Pen-based computing allows
links between information to be created by a
mere pointing gesture, but this technology is still
a year or so away from field use without special
support. Thus, the first step in implementing
computer-based workcards is to define the
hardware requirements as part of the overall de-
sign requirements.

3.2.2 Defining Design Requirements

During Phases I, 11. and WI of this project.
we conducted field visits at various A-check and
C-check inspection sites. An A-check is a more
frequent. less-detailed inspection. A C-check is
a less-frequent, more detailed inspection sched-
uled according to zones. Field visits included di-
rect observations. observational interviews, and
personal interviews of inspectors (inexperienced
as well as experienced), technicians, and super-
visors. Inspector’s perceptions of workcard us-
ability were obtained from various inspection
sites within the airline.

During Phase H. mechanics’ responses
about using the A-check workcard usage indi-
cated a moderate level of satisfaction with the
current workcard, as well as a number of users
needing different information. There was sub-
stantial agreement that the. current order of in-
formation was incorrect and that the sign-off
procedure was not performed after every step.
An analysis of the task sequence preferences
obtained from inspector's responses gave an op-
timal task sequence (Galaxy Scientific Corpora-
tion, 1993).

Information readability and organization is-
sues are similar for the C-check and the A-
check. The information content issue, however.
is different so far as requirements for graphic in-
formation are concerned. Most C-check inspec-
tors seem to be troubled about information
content, pointing at a scarcity of information and
their need for more and better quality graphic in-
formation. As far as information organization
was concemed, most users felt that there was no
clear differentiation between general and spe-
cific information.

us
m

ADA294756


Correlates of Individual Differences in NDI Performance

Chapter Seven

rivets. In the first session, taining circles around
each rivet assisted the subject to keep the cursor
in the appropriate region while circling the rivets;
no training circles were used in the second and
third sessions.

On the morning of the second day, subjects
performed a short (20-rivet) “refresher” version
of the NDI task and then two lengthy (180-rivet)
test sessions. These sessions were self-paced, and
test durations for each subject varied from a
Minimum of about 60 minutes to the maximum
allowable duration of 90 minutes. There was a
fixed 15-minute rest break between sessions, al-
though subjects were told that they could take
short (10-20 second) "stretch" breaks as needed
during any session. Following a 60-minute lunch
break, this same procedure (two 180-rivet ses-
sions), minus the short practice session, was fol-
lowed in the afternoon. No feedback was
provided following test sessions, and the fre-
quency of both fauits and noise was held at 30
percent each.

Subjective rating scales were administered at
various times during the course of both days.

At the end of the second day, subjects were
debriefed and questioned about their various atti-
tudes and approaches to the NDI task.

7.2 RESULTS

7.2.1 Task Performance

1.2.1.1 Performance Measures: Reliabiliny,
Tntercorelations, and General Observations

As mentioned earlier, 30 percent of the rivets
in each 180-rivet session contained cracks
(faults). Of the two types of error (failing to de-
tect a faulty rivet or calling a good rivet bad).
missed faults were by far the most common. On
the average. approximately 23 percent of faulty
rivets were missed. while only about 2 percent of
good rivets were marked faulty. These mean error
fates, incidently, are remarkably close to those

noted in preliminary analyses of the recently
completec Sandia/FAA field study (Schurman,
1993). Comparisons of the sum of the first two
sessions with the sum of the last two sessions
yielded correlations (reliability estimates) of
r=.84, p<.01 and r=.82, p<.01 for false alarms
and missed faults, respectively. Total errors (false
alarms plus missed faults) correlated r=.51, p<.01
with false alarms and r=.91, p<.01 with missed
faults. Since false alarms and missed faults were
essentially uncorrelated (r=.09), missed faults ac-
counted for most of the variance in total errors.

The remaining measure of performance,
mean time per rivet, measured speed of inspec-
tion; it represented the mean time a subject exam-
ined rivet before arriving at a decision. A negative
correlation of missed faults with mean time per
rivet would suggest that subjecis traded speed for
accuracy. However, the obtained correlation of
missed faults with speed, although negative,
failed to reach statistical significance (r= -.22,
p>.0S).

7.2.L2 Performance Change Across Periods and
Sessions

. One of the purposes of this study was to ex-
amine the data for evidence of progressive
changes across periods and sessions. Such data
might suggest a fatigue effect. Changes indicative
of fatigue were suggested from the findings of the
earlier pilot study. Tables 7.1 and 7.2 show mean
percentages across sessions of missed fauits and
false alarms, respectively. To allow intra-session
comparisons of performance not separated by rest
breaks, each session was divided into two 90-rivet
segments, referred to as periods in the tables. Al-
though each session contained an equal number
of total faults, arbitrarily breaking each into
halves resulted in slightly differing proportions of
faults in the first and second halves of the four
sessions. Consequently. the data shown in Tables
7.1 and 7.2 show percentage data, and all subse-
quent analyses of variance were conducted on
these data.


Chapter Six

CHAPTER Six
HYPERMEDIA INFORMATION SYSTEM

Karin M.Hartzell and Leo G. Utsman
Galaxy Scientific Corporation

6.0 INTRODUCTION

The aviation industry manages large quanti-
ties of documentation for purposes including
training, research, maintenance, and safety in-
spection. Paper or microfiche documents include
fault isolation manuals, maintenance manuals,
federal aviation regulations, and research re-
ports. Timely and convenient access to these
documents is important, but currently document
access can be quite cumbersome. For example,
safety inspectors and aviation maintenance
technicians roust carry literally stacks of docu-
ments to the flightline when they inspect or
work on an aircraft. Finding the desired infor-
mation in cumbersome documents is not always
easy; therefore, the results are not always accu-
rate. Improvements in the way aviation person-
nel access information will lead to more reliable
and more cost-effective aircraft maintenance.

Toward this end, the Federal Aviation Ad-
ministration (FAA) Office of Aviation Medicine
{AAM) Human Factors in Aviation Maintenance
research program is studying the challenges as-
sociated with creatin, accessing, and maintaining
digital documentation using a Hypermedia Infor-
mation System (HIS). This paper discusses the
current state of the HIS, including the interface
features, integration into a job aiding system, and
future plans.

6.1 THE HYPERMEDIA
INFORMATION SYSTEM FEATURES

The goal of the AAM Hypermedia Informa-
tion System research program is to use hyperme-
dia technology to improve access to aviation
information. Hypermedia technology makes it
possible to establish links between a document
and other documents, graphics. animation, video,
and audio. This makes a hypermedia document
far more powerful and meaningful than a digitci

107

document that is strictly text. With hypermedia
technology, information can be stored, searched,
and retrieve by referential links for fast and in-
tuitive access. This reduces the time spent looking
for information and allows a more thorough,
meaningful search. Hypermedia technology al-
lows users to make faster and more intelligent
decisions. Naturally, the technology offers other
benefits such as reduced costs for inspecting and
maintaining aircraft. For more information on hy-
permedia, see Howell, 1992, and FAA/AAM &
GSC, 1993b.

Initial research program efforts concentrated
on demonstrating the feasibility of a hypermedia
system for aviation personnel. Team members
designed a digital library system and imple-
mented rudimeniary tools for storing the infor-
tation. The bulk of the impiementation effort
was focused on information retrieval tools and the
hypermedia reader interface. Federal Aviation
Administration research reports were used as a
testbed for creating the digital library. This proof-
of-concept hypermedia viewer (FAA/AAM &
GSC, 1993b) proved to be a flexible, powerful
way for researchers to view hypermedia docu-
ments. The HIS can be used solely as a tool to ac-
cess information, as well as integrated with
training and job-aiding systems (Johnson and
Norton, 1992).

Both the viewer and the library were distrib-
uted on compact disc, read-only memory (CD-
ROM) to the aviation maintenance community in
early 1993. As with many proof-of-concept sys-
tems, this one was geared toward a specific appli-
cation area. The viewer interface was tailored to
the FAA research reports, making its broad-scale
applicability limited. Over the last year, research
has continued to make the tools more generic and
enhance their functionality. The digital library
containing FAA research reports was expanded to
include new reports. Additionally, two new librar-

ADA294756


Chapter Six

Hypermedia Information System

i Topics [-f+

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...PART 65-CERTIFICATION: AIRMEN OTHER THAN FLIGHT CREWMEMBERS
@...PART 67-MEDICAL STANDARDS AND CERTIFICATION

@...PART 71--DSSIGNATION OF FEDERAL AIRWAYS, AREA LOW ROUTES. CONTROLLED
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PART 95-IFR ALTITUDES

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PART §5-CERTIFICATION: AIRMEN OTHER THAN FLIGHT CREWMEMBERS
SFAR No. 58
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Subpart A-General
Subpatt B--Air Traffic Control Tower Operators
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65.71 Eligbitty requiements: General

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Section 14515 appropriate to the rating and class specified in § 245.47) for the rating he
Seater ie % seeks. However, he need not be equipped for a function that does not im
Seaiicn 14521 apply to the particular make ar model article for which he seeks 2 rating, if
Section 145.23 sf he shows that itis not necessary under the recommendations of the H
Section 145.25 manufachrer of the article.
Section 146.31 (b) An applicant for a rating for specialized services or techmepss
Seong | || eral mx
Section 145.37 (1) For magnetsc and penetrant snspection, have the equipment and materials
Section 145.33 for wet and dry magnetic inspection techmques, residual ans continuous
Section 145.41 it methods, and portable equipment fer the inspection of welds both on
Section 145.43 and off the aircraft;
Section is & Hil (2) For emergency equipment maintenance, have the equipment and matenals 4
; “ to perform inspections, repairs. and tests of all kinds of inflated {
Section 145.51 equipment, the re-packing, re-marking, re-sealing, and ze-stocking of |
Section 145.53 life rats, and the weighing, refiling, and testing of carbon dioside
Section 145.55 2 extn suis containers: *)
ion 145.57 Shils +} i
Rea

ANAXOQATRL


Table of Contents

Chapter Eight - Results of the Environmental Control System Tutor Experiment at
Clayton State College

8.0 INTRODUCTION
8.1 ENVIRONMENTAL CONTROL SYSTEM OVERVIEW.
8.1.1 The Aviation Maintenance Technician .
8.1.2 Overview of ECS Tutor
8.1.3 Knowledge for Diagnosis.
8.1.4 Intelligent Help Agent of the ECS Tuto:
8.2 PURPOSES OF THE EXPERIMENT.
8.3 METHOD.....
8.3.1 Subjects
8.3.2 Procedure.
8.3.3 Data
84 RESULTS........
8.4.1 Trace Analys
8.4.2 Poll Results
8.4.3 Post-Experiment Commen:
8&5 IMPLICATIONS AND RECOMMENDATIONS.
8.5.1 Use of Intelligent Help ...
8.5.2 Ensuring Adequate Background Knowledge
8.5.3 Usability of the ECS Tutor.
8.5.4 Graphicai Resolution......
8.5.5 Providing Adequate Feedback .
8.6 CONCLUSION
8.7 REFERENCES..

13S

145
145
146

Chapter Nine - Reli>hility in Aircraft Inspection: UK and USA Perspectives

$3.0 ABSTRACT.
9.1 OBJECTIVES
9.2 BACKGROUND
9.3 METHODOLOGY ...............
9.4 RESULTS AND DISCUSSION
9.4.1 Maintenance/Inspection Responsibilities
9.4.2 The Supervisor/Inspection Dichotomy.
9.4.3 Non Destructive Testing
9.4.4 Bonding...
9.4.5 Working Times.
9.4.6 Demand and Supply of Mechanics/Inspectors
9.4.7 Visual inspection and eye tests.
9.4.8 Reporting imminent indications ....
9.4.9 Work Cards, Information and Automation .
9.4.10 Access ....
9.5 CONCLUSIONS.

viii

ADA294756


Ergone:tic Factors Related to Pasture and Fatigue in the Inspection Environment

an

Restrictive Space Factors

Environment
Operator

Task

i

Physical Space

Perceived Space

Stress

1

Fatigue

C Physical >
— Cognitive

+

Physiological

Operator Response

Behavicral

Phenomencicgica!)

clog

Effects on Operator
Senses, Perception, Atte:

nition,

Memory, D-M, Contro! |
mi

t

Effects on Performance/Workload

the effects of the space to be understood and pre-
dicted.

5.2.1 Ergonomic Factors

In order to describe and eventually to predict
the effects of operator response on performance
and workload, we must understand the effects
stress and fatigue have on the operator. During.
Phase II, ergonomic factors which may produce
fatigue and ultimately effect performance and

ace Madet

86

well-being were identified: these factors are listed
in Table §.1 (Galaxy Scientific Corporation,
1993). This compilation of factors is not exhaus-
tive. There are a number of other (lesser) envi-
ronmental, task, and operator characteristics
which could contribute to fatigue effects, e.g.
iemperature, gender. and age. However. the listed
factors have been identified as being the most sa-
lien and prominent possible contributors to fa-
tigue in the aviation inspection/maintenance.


Appendix 2-A_ Evaluation Forms

Chapter Two

Copying

Other

Data Transfer

Inspector Name

Transfer List

Record List

Supervisory Review

Previous

Next

Transfer

Print

Delete

PENS Software Evaluation 6/6

28


Chapter Nine

Reliability in Aircrafi inspection: UK and.

Perspectives

problem of skill maintenance under Jong periods
of disuse, and thus be less prone to the errors as-
sociated with jack of recent practice. A number of
occasions were observed where a generalist in-
spector had to seek help from others who had per-
formed the particular NDT inspection recently, as
the instructions on the work card or in the manu-
als were ambiguous.

9.4.4 Bonding

Both Countries: In both countries there is a
projected lack of trained inspection staff: indeed
of all maintenance staff, (Shepherd, 1991). It is
inevitable that there will be some movement of
staff from one operator to another; this happens in
all industries and is quite acceptable. However on
occasions, when a new repair station is set up or
an operator expands quickly, there have been as
many as 100 maintenance staff ‘poached’ in a
short time.

In an effort to stop this, many companies
have implemented policies of bonding in one
form or another. This usually takes the form of
requiring personnel who are taking a taining
course to sign a declaration to the effect that they
will not leave the company for a period of time,
or that if they do they will repay a proportion of
the training costs. The repayment is usually
scaled from the full cost immediately following
qualification and reducing, on a sliding scale, to
zero after 1-3 years.

UK Variations: Only one company visited
had a current bonding policy and that only asked
for proporiional repayments for lodging and
travel etc. when they were on a course at another
site. No training costs were included even though
these could be as high as £40k. In only one case
had this policy been implemented in recent mem-
ory and that involved the sam of under £2k.

Many other companies had such a policy and
the main reason thai they had abandoned it was
that legal advice suggested it to be untenable and
‘binding in honour only’,

USA Variations: In the USA, bonding is the
rule rather than the exception at the engineering

153

sites visited. In one company, staff were even
bonded for a first-aid course.

Evaluation: In any industry a pool of skilled
personnel is necessary. The time for inspectors to
reach fruition is longer than for most skilled
technicians and they therefore have a rarity value.

It is reasonable that employers should want to
protect their investment in time and money. How-
ever, it is also reasonable that any person should
be able to sell themselves freely in the market
place.

Due to legal uncertainties, especially in the

UK, it may no longer be realistic to bond employ-
ees but the industry needs a stable work-force.
One solution offered to some industries in the UK.
was the government-sponsored training boards.

” Here, there was some sharing of training costs by
an industry-wide levy which was redistributed to
companies who provided training themselves.

It would act as a deterrent for mass poaching
if the operators had a common agreement; per-
haps not to have a general levy but to repay
training costs if personnel changed employment.
This could be done on a reducing scale, as in the
bonding agreements.

It would do several things:

1. It would compensate the previous em-
ployer to some extent, and not penalise
employers who run extensive training
Programs.

2. It would act as a deterrent to large
poaching operations. .

3. It would not prevent staff movement
completely but would act as a brake on
the recently qualified who are, as far as
the operator is concemed, an important
investment.

4. Abuse of the mutual repayment system
might be thought to be a potential prob-
lem but withdra+al of cooperation when
the abuser has an aircraft on the ground
in need of parts could atiay that.

ADA294756


Chapter Seven

Correlates of Individual Differences in NDI Performance

U. B. Airlines
oQoQocd:

g

ca

teft

Wher
jar?

° } Fight!

Hl

om | [work |) 80m
won]

f
break

H
clock i \ \
i Jy \

212.1 Inspection Window

The lower left portion of the screen was the
inspection window displaying the rivets to be in-
spected. Although it is possible to present a sub-
ject with multiple six-rivet rows, this study used a
single row. The subject used the optical mouse to
move the cursor around each rivet's circumfer-
ence. The subject could examine the rivet until
deciding if it was cracked. When the subject de-
cided that a rivet was cracked, he or she pressed
the right mouse button. A red cross appeared over
this rivet, and “rivet marked bad" appeared on the
screen. If the subject decided the rivet was not de-
fective, he or she pressed the middle button.
“Rivet marked good" then appeared on the
screen. A subject could correct a mistake by
Pressing the appropriate button.

When a subject had inspected all six rivets, he
or she pressed the left mouse button on the direc-
tional block labeled “right.” A black marker ring
circled the last rivet inspected, and the next six
rivets in the row appeared in the inspection win-
dow.

119

7.1.2.2 Macto- View and Directionais

A macro-view in the upper left portion of the
screen displayed a side view of the aircraft fuse-
lage and the row of rivets being inspected. Since
only a small portion of this row was being in-
spected at any given time, the subject could move
the cursor over the words “Where am I" and a
momentary circle then appeared over the portion
of the rivet row currently being examined.

7.1.23 Eddy-Current Meter

The upper right portion of the screen con-
tained a simulated analog meter serving as the
eddy-current output indicator. Meter deflections
beyond a set point produced an audible alarm and
ared flash on an indicator light. The following
actions caused meter deflections:

¢ touching a rivet’s edge with the cursor or
moving the cursor onto a rivet
passing the cursor over a crack (All
cracks were invisible and of varying
length.}
passing the cursor over or near simulated
corrosion, scratches, or paint chips

ADA294756


Chapter Five

Ergonomic Factors 8

Type of Injury

e Repositioning in cramped cr dirty piaces.
e.g.. the fuei tank, tail interior, and bag bin,
often causes sprains or strains

* Head lacerations are associated with
walking in the cabin or around the fuse-
tage exterior

e Kneeling causes knee bruises or strains

* — Lifting in confined spaces can result in
back strain

* Falls on stairs and access stands are
common

e Most injuries occur during access or
maintenance subtasks

5.3.2 Evaluation of Existing Conditions

Four inspection tasks were selected for
analysis: aft cargo compartment. horizontal/

vertical stabilizers, tail interior, and wheelwell/
muin landing gear. These tasks provided a repre-
sentative sample of tasks with regard to varying
environmental conditions such as the amount of
space. lighting. Both behavioral (direct recording}
und psychophysical (indirect recording) data were
collected to assess the effect of the aviation
maintenance and inspection environment on in-
spector fatigue, discomfort, and workload.

5.32.1 Behavioral Measures

Whole-body postures were recorded through-
out task performance. Positions of the upper
limbs. lower limbs, and trunk were recorded con-
tinuously for two inspectors performing each
task. In addition. detailed descriptions of each
task. This included having human factors analysts
work with inspectors during the completion of
workcards. While obtaining task descriptions, we
placed emphasis on documenting the ergonomic

ADA294756


Chapter Two

| PENS | ENhancenent System |
| | Schedule | sven seey |
Day Two

| ¢ PENS Training

¢ PENS Practice

¢ Data Transfer Training

¢ Data Transfer Practice

¢ Evaluation Forms

¢ Rotation Schedule

¢ Specific Computer Training

Trainigg Side 5... ~

You cannot harm the
computer by using it!

een nnd

Training Stide’6..

31

ADAZ9OATSE