RESEARCH TRIANGLE INSTITUTE 

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March 1988 

Development of a 

Multipurpose Smart Recorder 

for General Aviation Aircraft 

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bY .' 

J. H. White 

J. F. Finger 

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Prepared for 

National Aeronautics and Space Administration 

Wallops Flight Facility 

Wallops Island, Virginia 

POST OFFICE BOX 12194 RESEARCH TRIANGLE PARK, NORTH CAROLINA 27709 

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March 1988 

DEVELOPMENT OF A 

MULTIPURPOSE SMART RECORDER 

FOR GENERAL AVIATION AIRCRAFT 

s 

3. H. White 

J. F. Finger 

Prepared for 

National Aeronautics and Space Administration 

Wal lops F1 ight Faci 1 i ty 

Wallops Island, Virginia 
CONTENTS 

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Executive Summary .......................................... 1.1 Background ............................................ 1.2 Present Effort ........................................ 1.3 Program Accomplishments ............................... 

Introduction ............................................... 2.1 Background ............................................ 2.1.1 Previous Work and Scope ........................ 2.1.2 Motivation for Present Effort .................. 2.2 Purpose and Objective of Project ...................... 

Development of Recorder .................................... 3.1 Requirements for Recorder ............................. 3.2 Initial Hardware Design ............................... 3.2.1 System Configuration ........................... 3.2.2 Recorder Design ................................ 3.3 Software Development for Recorder ..................... 3.3.1 Software Development Environment ............... 3.3.2 Functions of Software .......................... 

3.4 Recorder Characteristics and Capabilities ............. 3.5 Verification of Performance ........................... 

3.3.3 Software Organization .......................... 

4 Recorder Installation on Charter Aircraft .................. 

5 Data Analysis ............................................... 

5.2 DVGH Processing ....................................... 5.1 Ground-Based Data Processing System ................... 

Data Summary and Conclusions ............................... 6.1 DVGH Data Summary ..................................... 6.1.1 DVGH Goals ..................................... 6.1.2 Perflight Data ................................. 6.1.3 Cumulative Statistics .......................... 6.2 Trend Monitoring Data Summary ......................... 

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7 Development of Second Generation Recorder .................. 

Additional Applications of the Smart Recorder .............. 8.1 Transportation Environment Monitoring ................. 8.1.1 Introduction ................................... 

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CONTENTS 

Section 

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8.1.2 Transportation Payload Monitoring 

Requirements ................................... 8.1.3 Data Acquisition in the Transportation 

Environment .................................... 8.1.4 Conclusion ..................................... 8.2.1 T-38 Crash Recording ........................... 8.2.1 Approach ....................................... 8.2.2 Data Recovery .................................. 8.2.3 Conclusions .................................... 

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FIGURES 

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Number 

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I. Smart Recorder System Concept ............................... 

Block Diagram of Prototype Smart Recorder.. ................. 

Physical Layout of Prototype Smart Recorder.. ............... 

Organization of Prototype Smart Recorder Software. .......... 

17 

21 IO 

Interconnection of Smart Recorder to Sensors on 

King Air Aircraft.. ......................................... 33 

6 Microprocessor-based System for Retrieval and 

Processing of Smart Recorder Data... ........................ I. 36 

7 Plot of Pressure Altitude Representing a Typical 

F1 ight Profile.. ............................................ 40 

a Plot of Indicated Airspeed for a Typical Flight * (2-second Sampled Data). .................................... 41 

9 Plot of Vertical Acceleration Data Including Positive 

Peak, Raw and Negative Peak Determined for Each Minute 

Interval .................................................... 44 

10 Delta Internal Turbine Temperatures Taken from 

Smart Recorder Data with In-Flight Variability 

Shown with Error-Bars ....................................... 54 

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Comparison of (A) ITT for Manual and Automated 

Trend Monitoring ............................................ 56 

Comparison of (A) NG for Manual and Automated 

Trend Monitoring ............................................ 57 

Comparison of (A)WF for Manual and Automated 

Trend Monitoring ............................................ 

Block Diagram of Second Generation Smart Recorder ........... 

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15 Description of GSFC Transportation Environment 

Measuring and Recording System (TEMARS) ..................... 69 

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FIGURES (continued) 

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16 An Example of TEMARS Data. .................................. 

17 Transportation Environment Monitoring Concept ............... 

18 Functional Block Diagram of Transportation Environment 

19 

Monitoring Recorder ......................................... 

Example Presentation of Detected Impulse Event .............. 

20 Proposed Location of Smart Recorder and Epams on T-38.. . . . . . 

21 Configuration of Smart Recorder Suitable for 

Installation on T-38 at "Data Case" Location ................ 

22 Possible Graphical Presentation of Crash Memory Data 

Recovered with Automated Process (Simulated Data). . . . . . . . . . . 

23 Tabular Presentation for Detailed Examination of Crash 

Memory Data Recovered with Automated Processing 

(Simulated Data). . . . . . .. . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

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TABLES 

Number Page 

1 8 Original List of Parameters to be Monitored by the 

Smart Recorder .............................................. 10 

26 

27 

32 

Smart Recorder Specifications ............................... 

Description of Stored Data in Smart Recorder... ............. 

Parameters Monitored by the Intelligent Flight Recorder.. ... 

Example of Statistical Summary Generated for 

Individual Flights .......................................... 42 

6 Processed Acceleration Data for Group of Flights 

Recorded on One Cartridge ................................... 45 

7 Percent Time of Indicated Airspeed versus A1 ti tude 

Bins for All Flights Conditions Derived from 

Onboard Processing .......................................... 46 

8 Percent Time of Indicated Airspeed versus Altitude 

Bins for Climb Derived from Onboard Processing .............. 47 

9 Percent Time of Indicated Airspeed versus Altitude 

Bins for Level Flight Derived from Onboard Processing ....... 48 

10 Percent Time of Indicated Airspeed versus Altitude 

Level Crossing Counts per Hour versus Altitude Bins 

for Longitudinal (Axial) Acceleration.. ..................... 

Level Crossing Counts per Hour versus Altitude Bins 

for Vertical Acceleration (Gravity Removed). ................ 

Bins for Descent Derived from Onboard Processing ............ 49 

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Level Crossing Counts per Hour versus Altitude Bins 

for Lateral Acceleration .................................... 13 

52 d 

14 Standard Deviation for the A Values for Automated 

and Manual Trend Monitoring ................................ 60 

15 66 

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Specifications of the Second Generation Smart Recorder ...... 

Analysis of Memory Capacity Required for Storage of 

Parameters Required Under the SAE Standard for 

General Aviation Flight Recorders ........................... 80 

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SECTION 1 

EXECUTIVE SUMMARY 

1.1 BACKGROUND 

An intelligent flight recorder, called the Smart Recorder, was fabricated 

This recorder was used for collection of data toward two objectives: 

and installed on a King Air aircraft used in standard commercial charter 

service. 

(1) the characterization of the typical environment encountered by the 

aircraft in terms of: velocity, V; acceleration, G; and altitude, H (collectively referred to as DVGH for Digital VGH data), and (2) research in the area 

of trend monitoring--the reliable detection of engine malfunction precursors 

allowing the maintenance-by-indication rather than by regular schedule. 

effort is a continuation of NASA aircraft measurement programs which had as 

their objective the characterization of the environment seen by commercial 

aircraft. 

formats were defined that are applicable to the commuter size aircraft and 

thus establishing the requirements for the instrumentation system described 

herein. 

application of the Smart Recorder.112 

This 

During that effort, data processing routines and data presentation 

The purpose of this report is to summarize the development and 

1.2 PRESENT EFFORT 

A prototype recorder was fabricated using commercially available 

components augmented by custom hardware for the performance of specialized 

functions required for this recorder. The initial recorder configuration 

included a custom 50-channel, analog-to-digital conversion board, a fast, 

single-board microcomputer to provide processing capability and a removable 

1. J. Finger, L-1011 Interim Report #1, March 1978-August 1978, prepared by 

Research Triangle Institute for NASA-LRC under NAS1-16098, October -7, 

1981. 

8 2. J. Finger, L-1011 Interim Report #2, March 1978-February 1979, prepared by 

Research Triangle Institute for NASA-LRC under NAS1-16098, February 9, 

1982. 

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bubble memory unit to provide non-volatile data storage. 

package developed for the recorder monitored analog inputs from sensors, 

determined the aircraft situation (e.g. , takeoff , level flight, landing, or 

taxiing) and stored the data appropriate for that situation. Later, 

processing routines were added for on-board statistical processing of acquired 

data from the aircraft (especially accelerometer data). 

The intelligence of the recorder provides the capability for adaptive 

sampling where the sampling of input signals may be modified in real-time in 

response to changes in aircraft situation. 

trend monitoring by switching to a high- speed recording mode for engine 

parameters during engine start-up. 

used to detect the aircraft situation (e.g., climbing, level flight , descent , 

or on-ground) so acquired data may be processed and tabulated accordingly. 

service by Airlift Associates at Raleigh-Durham Airport. 

aircraft systems and installed sensors were connected to the recorder to 

provide information on aircraft altitude, airspeed, acceleration, and engine 

The initial software 

This capability is used to support 

Also the intelligence of the recorder is 

The recorder was installed on a King Air aircraft used for charter 

Signals from 

performance. 

Data stored in the bubble memory are recovered and plotted using a 

laboratory microcomputer system equipped with a bubble memory cartridge 

interface. Software for archiving data and generating plots was written 

FORTRAN, except for fundamental 1/0 rout nes which were written in assemb 

1 anguage. 

1.3 PROGRAM ACCOMPLISHMENTS 

The feasibility of a cost-effective, multipurpose recorder for gener 

aviation aircraft has been successfully demonstrated. Operation of the 

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recorder was verified by comparison of acquired data from the Smart Recorder 

with manually acquired data both by pilots during normal flights and by 

engineers during test flights. Automatic acquisition of trend monitoring 

data was performed simultaneously with the acquisition of DVGH data and the 

operation of a crash recording memory. 

Pratt and Whitney manual engine trend monitoring data processing techniques 

showed less variability in the trend plots when compared against plots of the 

manual data. The lower variability allows earlier detection of a change in 

Trend monitoring algorithms based on 

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engine performance that could indicate the necessity of engine maintenance. 

The trend monitoring function of the recorder is especially important because 

the cost savings associated with a trend monitoring capability could partially 

offset the cost of the recorder and its installation on the aircraft. A 

significant reduction in per-unit cost would make possible a large-scale study 

to install the recorder in numerous aircraft for acquisition of DVGH data from 

a significant sample population of general aviation aircraft. 

Implementation of on-board DVGH processing increased the number of 

flight-hours that could be stored on a single data cartridge and simplified 

the data management problem by reducing the volume of data to be processed in 

the laboratory. After on-board processing was implemented, 207 hours of DVGH 

data were collected and tabulated. These tabulations are presented in Section 

6 of this report. 

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SECTION 2 

I NTRODUCT I ON 

2.1 BACKGROUND 

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2.1.1 Previous Work and Scope 

The effort described in this report is the culmination of an effort begun 

in 1980 in response to a need for aircraft use data identified by NASA Langley 

Research Center. 

digital flight recorders on air transport aircraft operated by commercial 

airline companies were analyzed to characterize typical aircraft use. The 

objective of the effort was to produce a data set and statistics describing 

utilization of aircraft and the acceleration loading encountered by those 

aircraft during normal use. Such data would be useful in validating design 

requirements for the aircraft already in service and establishing requirements 

for new ai r-transport aircraft. 

The processing of the flight recorder data consisted of converting the 

data to engineering units, validating the data, editing to remove bad data, 

and analyzing the data statistically. 

complicated because of the lack of independent supporting data. Consequently, 

where inconsistencies were identified in the data (out-of-range values or 

contradictory measurements), the data usually could not be corrected. Instead 

it was often necessary to discard the questionable data before performing any 

statistical analysis on the entire data set. 

validation and editing of the data was labor intensive. 

computer programs were written to check for anticipated data problems. 

However, since not all problems could be anticipated, an extensive manual 

review was still necessary. 

the need for an improved data collection method Wti.Lh would acquire and store 

data more reliably to reduce the data management effort associated with the 

processing of the data on the ground. 

which would use microprocessor technology to provide the necessary 

In the early phases of the project, data collected on 

The validation of the data was 

The effort required for 

Data screening 

The difficulties associated with the data processing effort pointed out 

An in-flight recorder was proposed 

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intelligence to screen and preprocess data before storage, reducing both the 

quantity of data to be processed and the complexity of the data validation and 

editing to be performed on the ground. This recorder would make the maximum 

utilization of existing data sources on the aircraft such as the digital data 

busses and existing sensors analog outputs, but could also accommodate new 

sensors or existing sensors whose outputs were not presently connected to 

aircraft data systems (e.g. , the aircraft integrated data system, AIDS). 

Ultimately, statistical tabulation of the data could be performed in the 

recorder, greatly reducing the volume of data which must be managed on the 

ground thereby reducing the attendant effort. 

would allow the collection of data from a large sample of aircraft, paving the 

way for collection of data from a variety of aircraft types, aircraft operated 

in different geographical areas, and aircraft operated for different purposes 

(e.g., charter, freight, or corporate use). 

the data collection with a Smart Recorder would broaden the data base of 

characterized aircraft, offsetting the development and installation costs of 

the recorder. 

using existing commercial electronics technology. 

identified which would be capable of performing the necessary functions and 

timing studies were conducted on time-critical software functions. The 

conclusion of this study was that a recorder could be fabricated using boardlevel components available at the time (1981) that could satisfy the 

processing requirements within time constraints imposed by the required data 

rates. 

significant data base was developed for air transport aircraft. 

information was accumulated for the general aviation aircraft which 

significantly outnumber the air transport aircraft. 

scarcity of typical use and loading data for these smaller aircraft, the 

emphasis of the recorder development effort was shifted to the implementation 

of a recorder on GA aircraft (recognizing that much of the experience gained 

The reduction in manual effort 

Thus the cost of automation of 

An informal study was conducted to determine if a recorder could be built 

Single board computers were 

During the data collection effort using commercial airline data, a 

However, no 

In recognition of the 

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in the development of an intelligent, GA aircraft VGH recorder would be 

directly transferable to the development of recording equipment for the more 

sophisticated air transport aircraft). Shortly after the decision was made, 

the NASA responsibility for the Smart Recorder development effort was 

transferred to the Wallops Flight Facility of Goddard Space Flight Center 

because of the executive size aircraft based at Wallops that were considered 

as potential test beds for the recorder. 

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2.1.2 Motivation for Present Effort 

In addition to the VGH data collection effort, there are other NASA 

research and operational interests which could be served by the development of 

an airborne flight recorder with a data processing capability. 

interests include engine trend monitoring, ground-mobile or aircraft internal 

environmental monitoring, meteorological data collection (in situ), and crash 

recorder development. For the effort recently completed, support was obtained 

from within NASA toward the accomplishment of the following objectives: 

These 

The development and demonstration of feasibility of an economical 

crash recorder for general aviation aircraft. 

applications included, initially, the NASA executive fleet with 

potential expansion to all general aviation aircraft. This 

application was driven by the NASA decision to equip their fleet 

with crash recorders in the wake of accidents involving those 

aircraft. 

Specific target 

Demonstrate the feasibility of VGH data collection and on-board 

processing on GA aircraft through implementation of a microprocessor-based recorder. 

to extend the VGH data base to GA aircraft which comprise the 

majority of aircraft in operation. 

This task was based on the NASA requirement 

Investigate engine trend monitoring using a flight recorder. 

Determine the improvement that may be realized using electronic data 

acquisition over traditional manual logging techniques. Trend 

monitoring capability allows the aircraft maintenance to be 

performed on the basis of indicated need rather than schedule, 

allowing the periods between required maintenance operation to be 

extended. 

maintenance operations would provide an economic incentive for the 

fixed base operator to install recorders on his fleet. If at some 

time in the future, NASA elects to install flight recorder on one or 

more commercial GA aircraft, the cost savings realized by the fixed 

The cost savings associated with the less frequent 

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base operators might be used to reduce the cost to the government of 

installing and operating the recorders. 

by the interest and support from Pratt and Whitney Aircraft of 

Canada, Ltd. (Montreal , Canada) who provided technical information 

on processing of engine trend data and test facilities for 

evaluation of engine recorder performance. 

This effort was encouraged 

2.2 PURPOSE AND OBJECTIVE OF PROJECT 

The main objective of the effort described in this report is the development of a multipurpose recorder that may be cost-effectively applied to GA 

aircraft for DVGH data collection, crash survivable recording and engine trend 

monitoring. On-board processing was a requirement to maximize the use of onboard memory and reduce the amount of data to be processed on the ground. A 

removable non-volatile memory cartridge was required for the transfer of data 

from the recorder to a ground-based data processing for final processing and 

archival of the data. 

The effort was conducted as a logical sequence of activities that 

together led to the implementation of a Smart Recorder capable of collecting 

and processing VGH, engine trend data and which provides a crash survivable 

recording capability. The specific phases were: 

Design and fabricate a microprocessor-based recorder that would 

monitor and store a small number of aircraft parameters. 

would be limited to recognizing aircraft situation (takeoff, climb, 

cruise, descent, or landing) and modification of sampling strategy 

based on the perceived aircraft situation. 

Processing 

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Develop software on laboratory computer to statistically process the 

aircraft VGH data collected. The development of these routines in 

the laboratory allowed their refinement in an environment where they 

could be easily modified and verified until the desired performance 

was achieved. 

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Implement DVGH processing software in programmable-read-only-memory 

(PROM) and installation in the aircraft. 

Process engine trend monitoving data and compare with manually 

acquired data to determine if trends could be detected earlier in 

electronically acquired data than in the manually acquired data 

(i.e., can the sensitivity of the detection process be improved 

through electronically monitoring and processing the engine 

pa ramet ers ? ) 

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Study various data storage requirements developed for crash 

survivable recorders to determine if the appropriate data can be 

collected and stored in a crash survivable memory for the desired 

time interval. 

Procure a crash survivable memory and construct the required 

interface for the Smart Recorder. 

The parcelling of the overall effort into these segments reduced the scope and 

complexity of the development effort at any time. 

developed during each phase were completely tested and evaluated before 

proceeding to the next phase. 

Hardware or software ' 

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SECTION 3 

DEVELOPMENT OF RECORDER 

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3.1 REQUIREMENTS FOR RECORDER 

The requirements for the Smart Recorder were dictated by the stated 

objectives of acquisition and statistical tabulation of VGH data, acquisition 

of engine trend monitoring data, and the demonstration of a crash recording 

capability n an economical recorder. The recorder was intended for 

application in general aviation aircraft (business charter or executive 

service) wh ch meant that the required information would have to be derived 

from analog signals from aircraft sensors or from sensors installed to monitor 

the desired parameters where no existing sensor was installed. 

the required parameters to be monitored in the first application. 

The recorder was being designed to acquire data for a program that had 

dynamic goals which could only become completely defined Once preliminary 

results were received. Hence, the recorder had to be reconfigurable, being 

designed to initially to accommodate the parameter list given in Table 1 with 

provision for accommodating additional sensors as the need arose. There were 

no stringent requirements on the form or packaging of the recorder as the 

purpose of this prototype recorder was simply to demonstrate the feasibility 

of a monitoring concept. 

production aircraft flight recorder. However, it was required that the 

recorder be able to serve functionally as a flight recorder in an operating 

aircraft without degrading the integrity of any of the aircraft systems to 

which it is connected. 

The general requi rements for the prototype Smart Recorder are described 

below. 

Table 1 lists 

As such, the recorder did not have to resemble a 

Low Cost--Since the recorder was intended to demonstrate the 

feasibility of a cost-effective flight recorder, the recorder 

should be constructed in such a way that it could be massproduced economically. Although the prototype was intended only 

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TABLE 1. ORIGINAL LIST OF PARAMETERS TO BE 

MONITORED BY THE SMART RECORDER 

Parameter Abbrevi at i on Sample rate 

Indicated Airspeed I AS 1 

Engine Inlet Temperature T2 

Engine Inlet Pressure p2 Propeller Speed NP 1 

Torque TQ 1 

Gas Generator Speed NG 1 

Interturbine Temperature I TT 1 

Fuel Flow WF 1 

Bleed Valve Position 1 

Acceleration (3-axis) G 4 

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to fit the function of a GA flight recorder and not necessarily the "form," 

it was recognized that the recorder should employ the same electronic 

architecture and logic types as the mass-produced units could employ. 

use of esoteric, high cost components in the prototype recorder would not 

demonstrate the feasibility of producing a low-cost recorder even if the 

functions of the expensive items could be reproduced in inexpensive 

components. To accomplish this requirement, the recorder was built using 

commercially available components at the highest level of integration 

available--typically commercially printed circuit boards. 

The 

Intel ligent--The necessity of adaptive sampling (varying the 

group of parameters sampled based upon the sensed aircraft 

situation--i .e. , takeoff , climb, cruise, descent, or landing) 

requires that acquired sensor data be processed in real time to 

determine aircraft situation and the sampling strategy be 

modified in a predetermined, appropriate manner based upon those 

determinations. 

programmable logic functions such as a microprocessor. 

requirement for an on-board microprocessor is further supported 

by the requirement for on-board tabulation of VGH data, 

establishing the necessity for a computational capability within 

the recorder. 

This processing is most easily performed through 

The 

Reconfi urable--Since the recorder is to be used in a program 

mtions of the recorder are defined based on previous 

experience, it is necessary that the recorder be reconfigurable 

to provide for the evolutionary development of the recorder. 

Both functions which are inherent in the software and hardware 

must be upgradable. 

exchanging the memory elements (e.g: , programmable read only 

memories--PROMS) with units containing the rep1 acement code. 

Provision for hardware modification may be made through use of a 

standardized bus on a motherboard (e.g. , multibus, standard bus) 

for interconnection of plug-in processor and peripheral interface 

cards. 

cards at the time of development and the replacement of these 

with more capable versions as they become available 

Capable of Unattended Operation--The recorder must operate in the 

aircraft environment with no required attention from the pilot. 

Operation should begin with an automatic initialization upon 

power-up. Any determination of aircraft situation (climb, 

descent, cruise, taxiing, etc) must be made based on sensor 

inputs and not from pilot input. 

Software, of course, may be easy modified by 

This allows the use of existing commercially available 

Compatible with Aircraft Sensors--The recorder (or associated 

signal conditioning electronics) must be capable of extracting 

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information from sensor signals in the normal forms found on 

aircraft. For instruments listed in Table 1, electrical signals 

will have the information encoded in the frequency of an 

sinusoidal source, the relative phase of a multiphase signals 

(synchro signals), voltage level, or resistance. 

Operate from Aircraft Power--The recorder must operate from the 

power source for the aircraft it is to be used on. 

aircraft have 110-VAC, 60- or 400-Hz power available, smaller GA 

aircraft have only 28 Vdc. 

variations, depending on a the type of battery available and 

maximum electrical bus loading. Voltage drops in excess of 50% 

during engine start-up are normal. 

Although some 

This voltage level is subject to wide 

3.2 INITIAL HARDWARE DESIGN 

3.2.1 System Configuration 

To take advantage of commercially avai 

existing signal conditioning equipment, the 

Figure 1 was selected for the prototype imp 

able, single-board computers and 

system configuration shown in 

ementation. In this configuration, all signals are converted to voltage signals (with a uniform range of 0 

to 10 Vdc) by signal conditioning modules mounted external to the recorder. 

The recorder module then has only to perform the functions of voltage measurement, data manipulation (data analysis or data compression), and storage. 

These functions are performed by a single-board computer, a multichannel 

analog-to-digital converter system, and a removable cartridge data storage 

system. 

laboratory computer for further processing and data archival. 

memory which is mounted external to the recorder. Conventionally, these 

The removable cartridge allows the transfer of monitored data to a 

A crash-survivable recording capability is provided by a crash survivable 

memory units are mounted in 

physical shock or risk of f 

section). For this system, 

Hami 1 ton Standard which had 

TSO451a.3 For this feasib 

an aircraft location where there is the least 

re in the event of a crash (e.g., the tail 

a crash survivable memory was obtained from 

been certified to meet the criteria specified in 

lity demonstration, this memory unit, herein 

cal led the Environmental ly Protected Auxi 1 i ary Memory (EPAMs) was mounted 

adjacent to the recorder. 

made with a multiconductor cable. 

Connection between the EPAMs and the recorder was 

3. U.S. Federal Aviation Regulation, Part 37.150, AIRCRAFT FLIGHT RECORDER 

TECHNICAL STANDING ORDER, TSO-C5la. 

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3.2.2 Recorder Design 

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The Smart Recorder is essentially a microcomputer-based data acquisition 

system with a removable bubble memory for transfer of the acquired data to a 

ground-based processing unit. 

Figure 2. 

The recorder is shown schematically in 

Components within the recorder are listed below: 

Microprocessor Board--Control and on-board processing is performed 

on an SBC 86/14 sinqle board computer (Intel). This board contains 

the 8086 microproceisor running at 5 or 8 Mhz, up to 32K of random 

access memory, up to 64K of programmable read only memory, a serial 

1-0 port, timers, and a 24-parallel-line 1/0 interface. The 

interface for the environmentally protected auxiliary memory (EPAMS) 

was built on the patch area of this board provided for the 

fabrication of custom interfaces. The board is a Multibus 

(Registered Intel Trademark) board. 

Analog-to-Diqi tal Converter Board--The custom-fabricated A/D board 

contains a single 8-input, 12-bit analog-to-digital conversion 

module with six 8-input, analog multiplexers to provide 50-channel 

capability. 

programmable gain, selectable bipolar/unipolar inputs, and 

selectable single-ended/differential inputs. In this application, 

the A/D was set up for 0 to 5 Vdc input with differential inputs. 

Eight-input, differenti a1 CMOS mu1 tiplexers (Date1 MXD-807) were 

used to allow connection of 48 inputs to six of the A/D modules 

inputs. 

connected to reference signals (0 and 5 Vdc) to provide a convenient 

means for verifying the A/D zero and span settings on a routine 

basis. Control signals for multiplexer input selection and sampling 

were supplied through the parallel 1/0 port on the microprocessor 

board. 

The A/D converter is a Data Translation DT5712 with 

The two A/D inputs not connected to multiplexers were 

Filter/Isolation Board--A filter/isolation board containing RC 

filters for each channel is connected between the input connectors 

and the multiplexers to reduce the effects of induced electrical 

noise on measured values and to provide electrical isolation to 

protect monitored circuits from short circuits in the unlikely event 

of an internal multiplexer failure. 

Bubble Memory Holder--The bubble memory holder serves as the 

mechanical and electrical interface for the Intel Plug-a-Bubble 

memory cartridge. The holder is mounted so that the cartridge may 

be inserted into the holder through an opening in the front panel. 

Once installed, the cartridges are retained by a cover fastened to 

the panel with quarter-turn fasteners. 

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Power System--0vercurrent protection, filtering, and voltage 

translation are provided by the power system. The major components 

in this system are dc-dc switching converter modules which convert 

the nominal 28 Vdc aircraft power to levels need by the solid-state 

circuits (+5V, +12v and +15V). A critical selection criteria for 

the power converters was-input voltage range. The selected units 

could function with input voltages from 9V to 40V, a requirement if 

the recorder is to continue to operate while the engine startup. 

Other components in the power subsystem include a circuit-breaker 

(with backup fuse) and transient suppressors. 

The recorder was packaged in a commercial instrument cabinet, reinforced 

to withstand the aircraft environment and to facilitate mounting of internal 

components. 

Figure 3. 

controlled-fans. 

power down the system when temperature limits are exceeded. 

adapt the outputs of the various sensors to the 0-5Vdc input range of the A/D 

converter. Signal conditioning circuits included frequency-to-voltage 

conversion, synchro-to-voltage conversion, resistance-to-voltage conversion, 

contact sensing, and simple voltage scaling (voltage division and 

amplification). 

The layout of components in the enclosure is illustrated in 

Cooling of electronic circuits is done with thermostatically 

Additional protective temperature limit switches are used to 

External signal conditioners were installed in two instrument boxes to 

3.3 SOFTWARE DEVELOPMENT FOR RECORDER 

3.3.1 Software Development Environment 

Software for the recorder is ROM based and uses the 32K of random access 

memory for the storage of dynamic data (acquired data, calculated results, and 

any other data which may change). Since the software does not require the 

services normally provided by an operating system (program loading, input/ 

output to conventional peripherals, etc) , the software was written as a selfcontained module. Logic was included to schedule function performance, handle 

1/0 with the A/D system and the memory unit, and perform the necessary 

calculations. 

Software was developed on a Zendex laboratory microcomputer, a multibus 

based system using the Intel 8086 processor. This system includes two 8-inch 

16 
0 

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floppy drives and runs under the CPIM-86 operating system. 

backplane is the same used in the Smart Recorder, so the processor and 

peripheral boards could be plugged into the Zendex system for testing in the 

laboratory environment. More importantly, many of the existing tools used for 

software development on the Zendex microcomputer could be used for development 

of software for the recorder, including assemblers, editors, utilities for 

linking and library management and source/object file management utilities. 

assembler. Code was modularized to provide a clear software organization and 

to facilitate software updates (only the modules associated with the function 

to be updated have to be modified). Software debugging was carried as far as 

practical on a laboratory development system which utilized the same processor 

and bubble memory storage system as the Smart Recorder. Program modules were 

tested individually or in small groups using simulated data to verify the 

module's function. 

module which generated a data stream simulating the output of A/D interface 

routines. 

supplemental CRT-display routines were used to present data concerning the 

operation of the software system. 

easily evaluated and debugged through use of the debug utilities and display 

devices available only on the development system. Once testing was carried as 

far as possible on the development system, the executable image was burned 

into PROMS and installed for testing on the target system--the Smart Recorder. 

Software was incorporated in the Smart Recorder for recognizing if a CRT were 

connected to the recorder, and if found, to allow an operator to control 

software execution from the keyboard, and display interim results on the 

screen, thus providing a mechanism for monitoring and verifying software 

operation both before and after installation. 

in the laboratory with artificially generated signals simulating those from 

aircraft sensors. 

display. Overall program execution was finally verified by dumping the memory 

cartridge and comparing the data with the manually calculated values. 

The Multibus* 

All code was written in assembly language and compiled using the an Intel 

Next all the modules were linked with a dummy data input 

Both the standard bubble-memory data storage routines and 

In this manner, software could be more 

Next, the recorder was operated 

Operation was monitored with a logic analyzer and CRT 

e 

*Registered Trademark Intel Corporation. 

18 
3.3.2 Functions of Software 

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Within the constraints of the hardware, all recorder performance 

characteristics are determined by the software, including data sampling rate, 

number of channels sampled, averaging interval, etc. Under the original 

version of the software, the acceleration data (3 channels) were sampled at 

every 0.25 sec and the remaining channels are sampled once per second. One 

minute averages for each channel are computed, and the positive and negative 

peak values for each minute are found for the three acceleration channels. 

Data stored in the bubble memory cartridge included 1-minute averages for each 

of 26 channels, the positive and negative peak values within the one-minute 

interval for the three acceleration channels, and 0.5-Hz samples for 8 

selected channels. 

special processing such as that required for off-line determination of 

acceleration level crossings. 

imp1 emented, addi tional acceleration data consi sting of 24 "level -crossing" 

values were stored each second in the bubble memory cartridge along with the 

raw data. In this configuration, the 128-kbyte bubble memory is capable of 

storing approximately 4.5 hours of data. Once DVGH processing was verified, 

the amount of stored time-series data was further reduced to extend the 

recording interval for one cartridge to 15 hours. 

described in Section 3.2.3. 

accommodate changes in sensor configuration, desired processing, etc. A 

configuration table, loaded into the bubble memory cartridge by the ground 

base unit, is read by recorder software upon power-up. 

determine sampling and recovery strategy, i .e., which channels are timeaveraged, which are stored as raw sampled values, and which are processed in a 

special or unique way such as generation of maximum or minimum values for 

specified periods. 

this table (using the ground base bubble memory cartridge access utilities 

operating in the ground base unit) thus eliminating the need for removing the 

recorder from the aircraft to make changes. 

The 0.5-hz data provide the fine time resolution data for 

Later, when on-board DVGH processing was 

The modifications are 

The processing performed by the recorder may be readily reconfigured to 

Entries in this table 

The functions of the recorder may be modified by editing 

Modiffcations made through this 

0 

19 
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e 

0 

process are limited to changing options and enabling/disabling features 

incorporated into the software stored in PROMs. 

still necessary to replace the PROMs to implement major changes. 

With this arrangement, it is 

3.3.3 Software Organization 

As mentioned previously, software for the smart recorder was written as 

modules, each designed to perform a function or group of related functions. 

Modules were written to control the data acquisition process, to process the 

acquired data, and to perform the services normally provided by an operating 

system such as input/output control and task scheduling. 

integrated into a single module which does not require the services of 

external software to execute. Hence it can be "burned" into PROMs and will 

begin execution in the Smart Recorder upon application of power to the 

processor. 

the flowchart in Figure 4. 

the recorder software are briefly described below: 

The modules are 

The software executing in the Smart Recorder is functionally described in 

The functions of each of the modules that comprise the current version of 

e 

SYSMANGR--Control program which schedules execution of all other 

modules. 

0 

c 

e 

RAMTEST--Writes and reads pattern to test RAM. 

PROMTEST--Computes checksum on contents of PROMs and checks against 

stored value to verify integrity of stored code. 

CPUTEST--Verifies operation of the 8086 CPU by comparing results of 

large number of instructions with the expected results. 

BUBTEST--Tests the ability to read and write to a page in bubble 

memory reserved for this purpose (does not overwrite existing data). 

ADBTEST--Tests analog board by verifying that ground and reference 

analog inputs return the expected values. 

SYSSETUP--Initializes interrupt vectors, timers and peripherals. 

Checks to see if CRT terminal is connected to the system for on-line 

testing. 

c 

20 
INTERRUPT 

e 

c 

a 

0 

RESTART 

I 

INITIALIZATION: 

SET VARIABLES, 

INTERRUPT VECTORS 

HARDWARE, AND 

INITIATE 

QUARTER-SECOND 

SAMPLING INTERRUPT 

BEGINNING 

,& SECOND 

DESIGNATED 

"HIGH-SPEED" 

SAMPLE 

DESIGNATED SAMPLE 

ALL CHANNELS CHANNELS 

UPDATE POINTERS 

I I 

'S

FIRST 2501c OF SECOND: 

ACQUIRE DATA 

ADD TO TABULATIONS 

WAIT FOR SECOND QUARTZR-SECOND INTERRUPT. THEN: 

IF SECOND #I OF MINUTE, THEN 

COMPWE PEAK ACCELERATIONS. WRITE QUARTERSECOND DATA TO BUBBLE MEMORY 

ELSE IF SECOND 12 OF MINUTE. THEN 

PERFORM DVGH PROCESSING ON PREVIOUS MINUTES DA?A 

ELSE IF SECOND 63 OF MINUTE. THEN 

COMPRESS PREVIOUS MINUTES DATA AND WRITE IT TO BUBBLE MEMORY 

ELSE - comm 

STORE DATA AND 

UYDArE DATA POINTERS IN BUBBLE-MOKY. END PROCESSING 

Figure 4. 

INTERRWT - THEN WRITE DATA TO EPAMS (CKASH MEMORY) 

I 

MINUTE POINTERS 

Organization of Prototype Smart Recorder Software 

21 
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BUBCONST--Loads configuration data from bubble memory into memory 

and tests to see if bubble memory can accept additional data (i.e., 

cartridge is not full). 

POWERDWN--Adds end-of-fl ight marks to stored data and saves pointers 

in the non-volatile memory for reloading upon power-up. 

DIAGNOS--Cal led upon detection of error condition to log information 

about the error in the bubble memory for later interpretation. 

DELAY5M--Provides a 5-minute delay. 

during delay period and, when input is detected, calls routine to 

service the entered request. 

Checks for input from terminal 

LITPANEL--Controls status lights on the front panel of the recorder. 

SETVAR--Initializes program data. Called during power-up sequence. 

RECORDLP--Manages the data recording tasks including engine startup 

recognition, one-second sampling, calculation and storage of oneminute averages, data compression and analysis and flight 

status/sensor checks. 

ENGSTART--Recognizes engine start and acquires engine data with fine 

time resolution during engine startup. 

FRAMERCD--Records all channels and store results in buffer for 

access by averaging and other processing routines. . 

FRAMEAVE--Processes the one-second scan data acquired by FRAMERCD, 

averaging all channels which contain data from the same source to 

remove redundant data. 

produced from an original set of 50. 

Final result is a set of 38 data points 

SENSORCK--Checks sensors for out-of-range values. 

FLIGHTST--Determines the flight status or mode: taxi, takeoff, 

landing or in-flight. 

TAXIMODE--Used by FLIGHTST to determine if the aircraft is taxiing. 

TAKEOFFM--Used by FLIGHTST to determine if the aircraft is taking 

off. 

LANDMODE--Used by FLIGHTST to determine if the aircraft is landing. 

DATACOMP--Computes minute averages of sampled data put in buffer by 

FRAMEAVE. 

verification of DL&i processing. 

Also merges selected raw data with the averages for 

22 
k 

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I 

~ 

DATSTORE--Wri tes data buffer to bubble memory. 

HIGHSPD--Wri tes raw (unaveraged) data to bubble memory. 

SAMPLEAD--Subroutine which controls the A/D converter and 

multiplexer to acquire the data for the specified channel. 

TRENDS--routine for in-flight analysis of trends in data. This 

routine is provided for future expansion. 

SAMPACC--Sampl es acceleration data and stores them separately from 

the data to be averaged. 

ACCPEAK--Determines positive and negative peaks of acceleration data 

during 1-minute period. 

INTERCD--Interacts with operator through CRT while in the 

interactive mode. 

calls appropriate routine to execute that function. 

Prompts operator to enter operation desired and 

MPUCHECK--Performs CPU check and informs operator of result (if 

terminal is connected) . 

PROMCHCK--Performs PROM check and informs operator of result (if 

terminal is connected). 

BUBCHECK--Performs bubble memory check and informs the operator of 

the result (if terminal is connected). 

MEMCHECK--Informs the operator of the results of the memory power-up 

memory test (if terminal is connected). 

CHANSCAN--Reads all 50 analog inputs and displays values on CRT. 

MONITOR--Reads a single channel once per second and displays the 

reading on the CRT. 

CRTCAL--Calls MONITOR to acquire and display input data for 

determination of calibration data. 

BUBCRT--Reads page specified by operator from bubble memory and 

displays it on CRT. 

LEDCHECK--Cycles front-panel LEDs upon operator command. For use as 

a lamp-test routine. 

ABCHECK-Performs analog input system check and reports results to 

operator. 
EPAMDUMP--Retrieves 16 bytes from EMAM and displays it on the 

screen. 

0 BUBBLE--Utilities to perform low-level 1/0 functions for bubble 

memory including controller initialization, input and output. 

SERIAL--Driver for serial port (used to communicate with CRT). 

PARALLEL--Driver for parallel port (used for lamp control and A/D e 'input). 

TIMERS--Loads registers in system timers for establishing the serial 

port baud rate and hardware time delays. 

INTRCTRL--Sets interrupt controller used for bubble memory 

transfers. 

MISC--Miscellaneous data conversion utilities, e.g., binary-to-hex 

conversion, decimal-to-binary conversion. 

INTERUPT--Interrupt service routines used for bubble memory 

transfers. 

TABULATE--Computes and tabulates statistical parameters for the DVGH 

data analysis. 

BINPOS--Determines appropriate bin for altitude, airspeed, and 

acceleration from monitored data. (Used in DVGH processing). 

FLTMODE--Determines whether aircraft in ascending, descending or 

flyinglevel when in flight. 

MAXVAL--Determines maximum and minimum values and accelerations 

throughout a flight. 

TABLESUM--Sums tabulated DVGH data throughout a flight. 

DVGH--Complete DVGH processing upon landing and stores the results 

in the bubble memory. 

LOADDVGH-Re1 oads cumul at i ve DVGH data from bubble memory and checks 

against values already in memory to verify their accuracy. 

PERFLT--Formats and stores "per-flight" data in bubble memory. 

ACCUMFLT--Adds current "per-f 1 ight" data to cumulative data taken 

from bubble memory and writes result to bubble memory. 

STOREP--Writes data to EPAM, observing 10 ms write speed duration 

requirement of the EARAM chips. 

24 
LOADDEP--Puts data in buffer for use by STOREP to load into EPAM. 

a 

e 

t 

- EPAM--low-level functions for EPAM including read, write, 

initialize, and 10-ms delay. 

3.4 RECORDER CHARACTERISTICS AND CAPABILITIES 

The maximum performance characteristics are determined by the capabilities of the hardware comprising the Smart Recorder. 

characteristics of the recorder hardware. 

software operating within the constraints imposed by the capabilities and 

limitations of the hardware discussed in the previous paragraphs. System 

capabilities provided by the current version of software residing in the 

recorder are summarized in Table 3. 

Table 2 summarizes the 

The capabilities of the Smart Recorder are determined primarily by 

3.5 VERIFICATION OF PERFORMANCE 

Once construction of the Smart Recorder was completed, several tests were 

Initially laboratory testing was used in 

Simulated sensor signals were applied to the recorder for critical 

performed to verify its performance. 

conjunction with the software debugging process to verify proper software 

execution. 

parameters such as static and differential pressure, engine speed, etc. The 

response of the recorder to various signal profiles was compared with the 

expected response to verify that the algorithms used were correctly 

determining the state of the aircraft and that the recorded data agreed 

quantitatively with predicted values. 

performed to verify the reasonableness of the acquired data. 

retrieved from the bubble memory were examined for consistency with pilot logs 

to verify system operation under actual operating conditions. Also test 

f 1 ights were conducted where engineers , flying as passengers, recorded values 

from cockpit displays for quantitative comparison with data stored on the 

bubble memory cartridge. 

the tests conducted on an engine test cell at the Pratt and Whitney facilities 

in Montreal, Canada. 

Once the recorder was installed on the aircraft, additional testing was 

Plots of data 

Perhaps the most comprehensive evaluation of recorder performance were 

The primary objective of these tests was to verify the 

25 
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TABLE 2. SMART RECORDER SPECIFICATIONS 

Input Characteristics: 

Total Input Channels 50 

Available for connection to sensors 26 

Number used for "housekeeping" functions 6 

Number used for reference monitoring 18 

e 

0 Input range 0 - 10 Vdc 

Max sample rate (per channel) 1000 sampl es/second 

Resol uti on 12 bits 

(1 part in 4096) 

Processor Intel 8086 @ 

Integral Memory: Random Access Memory 32 or 64 Kbytes 

up to 64 Kbytes 

Removable Memory: Bubble Memory Cartridge 

(Intel Plug-a-Bubble) 

Weight: 20 pounds Power Requirements: 72 W (3A at 28V nominal) 

Programmable Read Only Memory 

e 

Capacity 128 Kbytes 
f 

TABLE 3. DESCRIPTION OF STORED DATA IN SMART RECORDER 

Data Stored in Bubble Memory Cartridge: 

One-minute averages 

Max-min data 

c 

High-speed data 

Average values calculated from 60 

1-second samples for 26 channels. 

Configuration Options (Specific data stored determined by configuration 

information stored in the 10 pages of bubble memory by the ground-based 

data processing system) 

0 

Maximum positive and negative values 

for three selected channels. 

Values are determined from 

quarter-second data. 

Startup channels 

8 

Raw (unaveraged) data for two 

selected channels. Values 

are obtained by abstracting 

every second data value 

from the one second data 

before averaging. 

Analog channel map 

Sensor pointers 

Threshold levels 

Channel numbers for six channels 

to be monitored and recorded 

during engine startup. 

Multiplexer and gain settings for 

each of the available 50 analog 

channels. 

Channel numbers of sensors inputs 

to be used in specific on-board 

calculations (i.e., static 

pressure, pitot differential 

pressure, accelerometers, 

engine generator speed, and 

engine torque) 

Levels used by on-board processing 

routines to "bin" the data or to 

determine mode of the aircraft 

(e.g., rate of descent or ascent 

beyond which the aircraft is 

declared to be descending or 

ascending). 

Mode flags Used to turn on/off optional modes 

such as high speed data 

storage and DVGH processing. 

(continued) 

27 
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TABLE 3. DESCRIPTION OF STORED DATA IN SMART RECORDER (continued) 

Data Stored in Bubble Memory Cartridge: 

Data limits 6 channels and the respective limits 

for data in each. Acquired 

voltages outside the stated range 

are flagged as suspect. 

Bubble Memory Allocation by Page: e 

Memory Page Use 

d 

a 

1 

2 

3 

4 

5- 15 

16- 75 

76- 135 

136- 195 

196- 200 

20 1-2047 

Read/Wri te test page (scratch area) 

Not used 

Diagnostic error message log 

Data page pointer and misc. variables 

Configuration data 

Cumulative flight statistical tables 

Backup statistical tables 

Perflight statistical tables 

-- spare -- 

Data -- startup, high-speed, and 

average data pages in order 

that they are acquired. 

Data from different flights 

separated with file marker-- 

a page filled with distinct 

characters. 

e 

28 
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electrical and mechanical compatibility of the Smart Recorder with the engines 

and associated instrumentation in an environment where noted incompatibilities 

could be safely and completely investigated. 

recording system calibration, determination of measurement sensitivities, 

determination of specific recorder response to engine anomal ies and unusual 

operating conditions, and investigate the feasibility of on-line engine 

diagnostics using the Smart Recorder. 

The recorder was removed from the King Air aircraft and additional 

interfaces and cabling were fabricated for compatibility with the engines when 

operating on the test stand at the P&W facility. The planned, one-week test 

scenario included one day for connection of the recorder with the engine and 

test cell instrumentation, two days for acquisition of data from the engine 

(two shifts per day), an additional day for resolution of anomalies in the 

data, and a final day for dismantling, packing, and shipping. Tests were 

conducted during the week of January 15, 1984 in a production test cell at the 

P&W Montreal facility. 

instrumentation. 

the data acquired and stored in the Smart Recorder bubble memory cartridge. 

On-line observations and comparisons were made from data present on a terminal 

temporarily connected to the Smart Recorder for the duration of the tests. No 

discrepancies were noted between the Smart Recorder data and the P&W data 

verifying the fidelity of the Smart Recorder data acquisition process. 

quently, the third testing day was used to acquire additional data on the 

engine while operating under a variety of induced conditions. 

those were corrected through wiring changes in the recorder/engine 

interconnection. 

problems saved considerable time in troubleshooting the interface with the 

engine on the aircraft. 

the NASA Smart Recorder is well within the tolerances of the system being 

monitored by it. Also, the relatively low speed of engine operation and the 

accuracy of the NASA recorder make on-1 ine diagnostics realizable. 

Additional objectives included 

The Smart Recorder was operated in parallel with standard test cell 

P&W supplied their data on strip charts for comparison with 

ConseDuring the entire test period, only minor anomalies were observed, and 

The experience gained in the discovery of these minor 

The conclusions of the test were that the dynamic range and resolution. of 

29 

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The conclusions of the test were that the dynamic range and resolution of 

the NASA Smart Recorder is well within the tolerances of the system being 

monitored by it. 

accuracy of the NASA recorder make on-line diagnostics realizable. 

Also, the relatively low speed of engine operation and the 

a 

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SECTION 4 

RECORDER INSTALLATION ON CHARTER AIRCRAFT 

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The recorder has been installed and operated on a King Air Aircraft used 

for commercial charter service by Airlift Associates based at Raleigh-Durham 

Airport. The recorder is connected both to existing aircraft sensors and to 

sensors installed on the aircraft to provide data not available from existing 

sensors. Table 4 lists the parameters monitored on the aircraft along with 

the signal source. 

aircraft, their interconnection, and the approximate location. 

itself and two interface units. 

conditioning necessary to make the sensors or transducer outputs compatible 

with input capability of the recorder. 

amplification, and conversion from frequency, resistance, or synchro signais 

to dc voltage required by the recorder analog-to-digital converter. 

Sensors for data acquisition included both sensors which were a part of 

the original aircraft systems and additional sensors, installed when no 

suitable signal was available for the parameter to be monitored. 

transducers were used to sense altitude and indicated air speed (IAS) since no 

analog voltage proportional to these parameters was available outside the 

cockpit indicators. 

static system in parallel with the aircraft transducers. 

most of the engine parameters were derived by tapping into cables between the 

cockpit indicator and the aircraft sensor. 

the appropriate cable from the back of the indicator and inserting a short 

extension cable between the instrument and the cable originally connected to 

it. This extension cable was constructed with a pair of wires permanently 

connected to appropriate contacts of the .cable connectors to "tap" the 

necessary signals for routing to the recorder or appropriate interface unit. 

(The extension cable/signal tap arrangement was used to ease installation in a 

Figure 5 illustrates the components installed on the 

The major electronic components in this installation are the recorder 

The interface units provide the signal 

Functions performed include filtering, 

Pressure - 

The transducers were connected to the aircraft pitotSignals representing 

Connection was made by removing 

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TABLE 4. PARAMETERS MONITORED BY THE INTELLIGENT FLIGHT RECORDER 

Parameter Sensor Location 

A1 t i tude 

Airspeed 

Accel erat i on 

~~~ ~ ~~~~~ ~~ 

Sensym Forward Baggage Compartment 

P/N LX1802AZ (Connected to A/C 

Pitot Static System) 

Sensym Forward Baggage Compartment 

P/N LX1802DZ (Connected to A/C 

Kist ler Below Floor in Cabin 

3 ea. P/N 303B (Near aircraft CG) 

Pitot Static System) 

Torque Ai rcraft Sensor Rear of Cockp 

Fuel Flow Aircraft Sensor Rear of Cockp 

Squat Switch Aircraft Sensor Rear of Hobbs 

Propel 1 er Speed Aircraft Sensor Rear of Cockp 

t Indicator 

t Indicator 

Meter 

t Indicator 

Compressor Speed Aircraft Sensor Rear of Cockpit Indicator 

Internal Turbine Aircraft Sensor Rear of Cockpit Indicator 

Temperature 

Engine Inlet 

Temperature 

Engine Inlet 

Pressure 

Lewis Eng. Co. A/C Inlet Screen 

P/N 56B4A 

Kul i te Behind Engine Firewall 

P/N XTM-190-25 w/Tube to Inlet Screen 

Bleed Valve Lewis Eng. Co. Adjacent to Engine 

Exhaust Temp. P/N 56B17 Bleed Valve 

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32 
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cramped cockpit and to allow the instruments to be easily returned to original 

configuration at the end of the measurement program.) Additional engine data 

necessary for trend monitoring was obtained from pressure and temperature 

sensors installed at the engine inlet screen and a temperature sensor at the 

exhaust port for the engine bleed valve. 

necessary for DVGH data acquisition, 3 single-axis accelerometers were 

installed at the aircraft center of gravity (CG), under the floor in the 

passenger compartment. 

the FAA covering the recorder and installation on September 25, 1984. 

To provide the acceleration data 

A supplemental Type Certificate for the installation was obtained from 

a 

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34 
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SECTION 5 

DATA ANALY S I S 

5.1 GROUND-BASED DATA PROCESSING SYSTEM 

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A laboratory microcomputer system is used to support the Smart Recorder 

by providing those functions which cannot practically be supplied by the 

recorder which is installed in the aircraft, namely: 

Processing of collected data 

Retrieval of data from bubble memory cartridges 

Maintenance of a data base for the collected data 

Production data plots 

Initialization of the bubble memory cartridge prior to reuse. 

The microcomputer system purchased for this system is a Comark Diskstor 

unit, which uses standard Multibus boards. The system, illustrated schematically in Figure 6, consists of processor, memory, two 8-inch floppy disk 

drives, and power supplies housed in a single enclosure. Peripherals for the 

system include a CRT terminal/console, Epson FX-80 dot matrix printer, and an 

Intel Plug-a-Bubble cartridge interface. 

and MS-DOS 1.25 operating system, allowing it to execute IBM-PC code. 

ever, there are differences between this system and the PC: (1) the system 

speed of the Comark System is approximately four to six times that of the IBMPC, allowing faster processing and manipulation of data, and (2) the bus 

structure and peripheral interfaces of the two machines differ so peripheral 

interface boards and software which accesses those boards directly (instead of 

through the operating system) may not be transferred from one system to the 

other. Therefore, slight modifications in the software will be necessary 

before the software could be transferred to contemporary MS-DOS or PC-DOSbased systems. 

This system uses the 8086 microprocessor operating at 10 Mhz clock rate 

How35 
INTEL PLUGA-BUBBLE 

0 

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I CARTRIDGE I INTERFACE 

(ISBX BOARD 

II 

IL 

8086 CPU BOARD 

WITH 128K MEMORY 

8- INCH 

DISK CONTROLLER FLOPPY 

DRIVES 

r 

PARALLEL INTERFACE - 

I.------ --------- 

* 

COMARK 

DISK STOR 

SYSTEM 

--------- I 

1 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

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DOT-MATRIX PRINTER 

(FOR TEXT AND GRAPHICS) 

Figure 6. Microprocessor-based System for Retrieval 

and Processing of Smart Recorder 9ata 

36 
5.2 DVGH PROCESSING 

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Software developed for DVGH processing the data from the Smart Recorder 

includes the following programs: 

Data Input Program--A program to retrieve data from the 

cartridge, check for format errors and store the resulting data 

in files for subsequent processing. 

Database Management Program--A set of programs designed to 

gather data into individual files for each monitored parameter, 

catalog the data, and retrieve upon request for processing by 

other programs. 

Plotting Package--A set of programs which allows generation of 

two-dimensional X-Y plots of the data with appropriate labeling 

on both the axes and plotted contours. Plot images are formed 

in the computer memory and passed to the Epson printer for 

generation of hardcopy. The plots shown in this report were 

generated using this capability. 

Main Processing Software--Programs which analyze the collected 

data to first determine the per-flight tabulated characteristics 

and then combine those with cumulative statistics tabulated from 

previous processing to produce the updated cumulative 

characteristics 

Most of the software was developed in FORTRAN with assembly language used 

for certain low-level input/output routines. The developed processing 

capability was confined to the Comark microcomputer so it could be easily 

relocated to a NASA facility if desired. 

Software was validated by inspection of plots of processed data, 

comparing indicated levels with manually recorded data from cockpit indicators 

during flight and data taken from pilot logs. Later, when on-board processing 

of DVGH data was implemented, the processing routines that classify and 

tabulate data were transferred from the ground base unit to the Smart Recorder 

to eliminate the need for recording the raw time series data in the bubble 

memory cartridge. 

cartridge from 4.5 hours to 30 hours. The implementation was carried out in 

two phases: (1) modification of Smart Recorder software to add processing 

required for on-board DVGH processing extending the recording time to 15 

hours, and (2) at a later time, removal of time-series data storage to 

This change extended the data storage capacity of the 

e 

37 
0 

0 

0 

0 

I) 

increase the recording time 

simultaneous storage of raw 

phase made possible the Val 

comparison of the results w 

original software. 

for a single cartridge to 30 hours. 

dation of the in-flight processing routines by 

th data processed in the laboratory with the 

The 

time-series data and processed data in the first 

The implementation of DVGH processing of the record was more than simple 

transfer of processing routines from the ground-based system to the recorder. 

Minor logic changes for real -time processing were necessary because the data 

is available serially and must be processed as it is acquired. In contrast, 

during ground-based processing, system the data for an entire flight is 

available to the processing routine and may be accessed randomly or 

sequentially in multiple passes. 

assembly language to optomize execution speed and reduce memory requirements 

for the processing code. All numerical computations were implemented in 

integer arithmetic, with appropriate scaling to minimize errors due to 

overflow and roundoff error. 

A/D "counts," leaving the final conversion of data to engineering units until 

the final ground-based processing. 

stored in the bubble memory and handled on the ground is achieved irregardless 

of whether the data is stored in "counts" or in engineering units, so there is 

no disadvantage to performing the final conversion to engineering units on the 

ground-based processing .) 

the cumulative data until it can be ascertained that the data represent a 

complete flight from take-off to landing. 

included in the cumulative statistics. 

incomplete data set caused by interruption of the Smart Recorder operation at 

some point during the flight.) 

tion and ground base generation of tables encompassing large numbers of 

flights. Examples of these tables are: (1) percentage of flights of indicated 

duration versus altitude bands, (2) percentage of flights to maximum altitude 

band versus duration, and (3) percentage of flights where maximum positive and 

negative acceleration occur versus altitude. 

The FORTRAN routines were converted to 

Data were processed and stored on the basis of 

(The goal of reducing the amount data 

Tabulated data are accumulated for individual flights but not added to 

Data from partial flights are not 

(A partial flight refers to an 

Per-flight data are stored far the purpose of individual flight valida0 
a 

a 

SECTION 6 

DATA SUMMARY AND CONCLUSIONS 

6.1 DVGH DATA SUMMARY 

0 

6.1.1 DVGH Goals 

The purpose of the collection of DVGH data was to continue and extend the 

NASA Langley aircraft measurement program whose objectives were to characterize the environment seen by commercial aircraft. 

of the Smart Recorder, data had been collected primarily on large commercial 

air transport aircraft. The objective of this hardware development effort was 

to demonstrate the feasibility of collecting DVGH data for general aviation 

aircraft in a cost effective manner, i.e., using equipment which would provide 

some economic payback to the operator to offset the expense of equipment 

installation and operation. 

demonstration of an inexpensive, multipurpose recorder which could provide the 

operator with engine maintenance information while acquiring the environmental 

data desired by NASA. 

The data objective for the DVGH monitoring program is a statistical 

description of aircraft loading (acceleration). Toward this goal , acceleration data was collected along with supporting aircraft flight data to allow 

the tabulation of acceleration data vs. altitude and under various flight 

conditions (i .e., climb, level flight and descent). Statistical summaries of 

this data were then computed on the data set. 

Prior to the development 

This objective was achieved by the successful 

6.1.2 Perfliqht Data 

Examples of data produced on a perflight basis for the purpose of examining and validating the data are shown in Figures 7 and 8 and Table 5. These 

data include both plots of key parameters such as altitude and acceleration. 

The altitude plots were used to to verify that recorded data was consistent 

with actual take-off, landing and cruise altitude and to verify that the data 

39 
a 

0 

0 

a 

! 

I I I I I 

aJ 

cc 

0 

L 

n 

C, 

r 

ET) 

LL 

rrJ 

V 

P 

1, 

IrrJ 

ET) 

c 

C, 

c 

a, 

v) 

aJ 

L 

n 

aJ 

cy: 

aJ 

-0 

3 

C, 

C, 

a 

aJ 

L 

3 

v) 

v) 

aJ 

L 

4- 

0 

C, 

0 

7 

-I- 

.f7 

7 

.I- 

.I- 

.I7 

n 

- 

a 

h 

aJ 

L 

3 

m 

LL 

.I40 
41 
e 

a 

0 

a 

TABLE 5. EXAMPLE OF STATISTICAL SUMMARY GENERATED 

FOR INDIVIDUAL FLIGHTS 

PER-FLIGHT STATISTICAL SUWlCIRY ***************************~**. 

DATA RETRIEVED ON: 9/12/1984 

FLIGHT 

NO 

34 

55 

36 

57 

38 

------ 

FL IGHT 

NO 

34 

35 

36 

37 

38 

------ 

FLIGHT 

NO 

54 

35 

36 

37 

38 

------ 

TRIP TIME 

(MINS) 

68 

29 

64 

95 

67 

--------- 

TRIP LENGTH 

MILES (EST) 

209 

68 

194 

162 

-217 

----------- 

CKTITUDE (FT) IAS 

WE MLIX WE (KT) 

--- --- -------- 

?470 16970 151 

St70 8210 168 

7610 14810 164 

6020 12750 169 

12300 17020 145 

VCTRUE) INLET 

MAX (KT) MIN 

230 -4 

223 14 

230 12 

237 19 

203 0 

-------- --- 

TERM I NAL 

AREA 

7.3 

12.1 

12.1 

6.8 

-------- 

9. a 

-500 

TO 

4300 

12.7 

7. e 

9.4 

11.5 

4.2 

---- 

4500 

TO 

95w 

9. 5 

11.4 

13.3 

9.4 

5. s 

-- 

9500 14500 

TO TO 

14500 19500 

l0.B 27.0 

.o .0 

11.8 17.4 

22.1 .Q 

6.9 43.6 

---- ----- 

19500 

TO 

24500 

.O 

.o 

.0 

.Q 

.0 

--- 

24500 

TO 

29500 

.o 

.o 

.0 

.o 

.o 

-I_ 

29500 

TO 

34500 

.o 

.o 

.u 

.0 

.Q 

----- 

-5I:N:t 

TO 

4900 

141 

158 

13s 

165 

135 

---- 

4C'. J.W 

TO 

9500 

159 

175 

175 

174 

142 

---- 

~45l:ic:i 

TO 

19500 

IS! 

Q 

1 S9 

0 

149 

----- 

TOT& 

TIME 

(MINI 

------ 

68 

29 

64 

5s 

67 

PER-FLIGHT 

AVERAGE 

(KTS) 

151 

168 

164 

169 

145 

----- 

a- 

* 

e 

42 
I) 

e 

e 

0 

0 

0 

e 

a 

e 

any out1 

data. 

Tab 

recorded 

data and 

did represent a complete flight from take-off to landing without interruption. 

This verification is actually a check of the automated processing which 

recognizes the beginning and end of each flight, and verifies that data have 

been acquired without interruption over the flight, incorporating the 

statistics for the flight into the cumulative statistics. 

acceleration data. 

reasonableness. 

plot provides an indication of variability of the data and the existence of 

Other plots, such as Figure 9, show a time series presentation of 

These plots allow the manual examination of data for 

The maximum and minimum envelope surrounding the time series 

ers which would not otherwise be easily seen on a plot of 0.25 second 

e 6 shows calculated acceleration statistics for a group of flights 

on a single cartridge. These data are used for verification of the 

the processing routines prior to combining the data with that from 

other flights to produce the cumulative statistics. 

6.1.3 Cumulative Statistics 

Initially cumulative statistics were produced by analyzing the acquired 

time-series data in the laboratory. Later, after on-board processing was 

implemented, statistical data were accumulated in the bubble memory, retrieved 

and formatted by the ground-based processing system, and printed for interpretation and dissemination. 

produced for the 180 hours of data acquired by the Smart Recorder after onboard processing was implemented. These data represent typical use of the 

King Air aircraft operated by Airlift Associates out of the Raleigh-Durham 

Airport . 

Tables 7 through 13 show the cumulative statistics 

6.2 TREND MONITORING DATA SUMMARY 

An analysis of trend monitoring feasibility was performed by processing 

data recorded by the Smart Recorder and comparing the results with data 

acquired and processed manually by the aircraft operator. The processing in 

both cases consisted of using monitored flight conditions (e.g., pressurealtitude, temperature, engine power) to correct monitored values of NG, ITT, 

and WF to a specified set of standard flight conditions using compensation 

equations provided by Pratt and Whitney for the specific engine used. This 

43 
a 

0 

0 

a 

0 

a 

e 

a 

a 

44 
a 

TABLE 6. PROCESSED ACCELERATION DATA FOR GROUP OF FLIGHTS 

RECORDED ON ONE CARTRIDGE 

0 ACCELERATION LEVEL CROSSING TABLE ++**++ +** ****************~**+ 

DATA RETRIEVED ON: 11/16/84 FLIGHTS NO. 69 THRU 77 

TOTALS 

3 

186 

992 

13363 

12767 

612 

97 

3 

28023 

------ 

------ 

TOTALS 

0 

149 

1895 

283 1 

3514 

1874 

66 

0 

10329 

------ 

TOTALS 

0 

5 

95 

14123 

14668 

135 

4 

0 

29030 

------ 

------ 

267 

VERTICAL ACCELERATION 

PER FLIGHT COUNTS ..................... 

BIN RANGE 

--------- 

? .5 G'r 

.2 TO .S 

.1 TO .2 

.O TO . 1 

-. 1 TO .O 

-.2 TO -.l 

-.S TO -.2 

< -.5 

FLT 1 

0 

16 

94 

242 

229 

2s 

3 

0 

609 

----- 

FLT 2 

0 

2 

29 

1795 

1749 

14 

1 

0 

3590 

----- 

FLT 3 FLT 4 FLT 5 FLT 6 FLT 7 FLT 8 FLT 9 

0 0 0 

1s 3 6 

07 67 09 

1270 1516 1390 

1191 1429 1279 

40 33 37 

4 4 0 

0 0 0 

2607 3050 2801 

----- e---- 

CI 

----- ----- ----- 

0 

41 

20 1 

1571 

1544 

162 

16 

0 

353s 

----- 

3 

178 

642 

625 

139 

43 

3 

1690 

57 

----- 

0 

44 

188 

21 13 

206 1 

132 

28 

0 

4566 

----- 

0 

2 

59 

2824 

2660 

30 

0 

0 

5575 

--I 

a 

TOTALS 

0 LONGITUDAL ACCELERATION 

PER FLIGHT COUNTS ....................... 

BIN RANGE 

> .S G'r 

.2 TO .5 

.1 TO .2 

.0 TO .1 

-.l TO .o 

-.2 TO -.l 

-.5 TO -.2 

< -.5 

--------- 

FLT 2 

0 

24 

463 

376 

384 

106 

10 

0 

1363 

----- 

----- 

FLT 3 FLT 4 FLT 5 FLT 6 

0 0 0 0 

27 15 26 15 

176 4 274 336 

478 215 263 541 

603 247 356 726 

326 30 486 323 

4 7 7 11 

0 0 0 0 

1614 518 1412 1952 

----- ---e- ----- ----- 

-e--- ----- -e--- ----- 

FLT 7 FLT 8 FLT 9 

0 0 0 

1s 15 12 

178 285 179 

336 309 295 

409 398 370 

280 90 210 

10 4 10 

0 0 0 

1228 1101 1076 

----- ----- ----- 

e--- ----- e---- 

a 

TOTALS 

0 

LATERAL ACCELERATION 

PER FLIGHT COUNTS .................... 

BIN RANGE 

--------- 

? .5 0's 

-2 TO .5 

-1 TO -2 

.0 TO .1 

-.l TO .o 

e.2 TO -. 1 

-.5 TO -.3 

c:. - . 5 

FLT 4 FLT S FLT 6 

0 0 0 

0 0 4 

24 6 11 

470 2051 2760 

466 2169 2958 

33 25 29 

0 3 0 

0 0 0 

993 4254 5762 

----- ----- ----- 

----- ----- ----- 

0 

TOTALS 

a 

FLIGHT MINUTES S 41 33 11 37 50 30 31 29 

0 

45 
TABLE 7. PERCENT TIME OF INDICATED AIRSPEED VERSUS 

ALTITUDE BINS FOR ALL FLIGHT CONDITIONS 

DERIVED FROM ONBOARD PROCESSING 

Altitude Bins (ft) 

-500 4,500 9,500 14,500 19,500 -500 

IAS (Kts) to to to to to to 

4,500 9,500 14,500 19,500 24,500 24,500 

100 to 120 

120 to 140 

140 to 160 

160 to 180 

180 to 200 

200 to 220 

220 to 240 

240 to 260 

260 to 280 

280 to 300 

Percent all 

modes vs. 

A1 ti tude 

Flight Time 

in All Modes 

(hours) 

Total Flight 

Time per Bin 

(hours) 

Percent Time in 

Altitude Bin 

10.91 .3a .ll .91 

23.51 11.66 8.89 13.68 

26.47 21.37 14.00 62.64 

18.51 18.51 41.83 20.34 

16.31 35.73 32.27 2.40 

4.25 12.29 2.87 .03 

.04 .06 .02 . 00 . 00 .01 . 00 . 00 

. 00 . 00 . 00 . 00 

. 00 . 00 . 00 . 00 

22.80 22.23 23.20 25.81 

41.90 40.83 42.63 47.42 

41.90 40.83 42.63 47.42 

1.53 2.92 

25.46 15.06 

1.16 23.36 

.oo 19.77 

.oo 4.37 . 00 .03 . 00 . 00 

. 00 . 00 . 00 .02 

71.85 34.48 

5.95 100.00 

10.93 183.72 

10.93 183.72 

100.00 100.00 100.00 100.00 100.00 100.00 

Number of flights 252 

Average flying time 0.82 

46 
[o 

c 

P 

TABLE 8. PERCENT TIME OF INDICATED AIRSPEED VERSUS 

ALTITUDE BINS FOR CLIMB 

DER I VED FROM ONBOARD PROCESS I NG 

Altitude Bins (ft) 

- 500 4,500 9,500 14,500 19,500 -500 

IAS (Kts) to to to to to to 

4,500 9,500 14,500 19,500 24,500 24,500 

100 to 120 8.23 .07 . 00 .oo . 00 3.20 

120 to 140 18.62 .23 , 00 .24 1.92 7.30 

140 to 160 12.72 1.66 .40 8.78 47.60 6.42 

160 to 180 16.60 7.27 11.42 56.41 50.48 15.54 

180 to 200 33.64 55.12 73.28 34.14 . 00 48.38 

200 to 220 10.51 35.48 14.77 .43 . 00 19.02 

220 to 240 .ll .16 .14 . 00 . 00 .13 

240 to 260 . 00 .02 . 00 . 00 . 00 .01 

260 to 280 . 00 . 00 . 00 . 00 . 00 . 00 

280 to 300 . 00 . 00 . 00 . 00 . 00 .05 

Percent Climb 38.69 34.23 19.16 7.48 .43 100.00 

vs. Altitude bin 

e 

e 

Flight Time 15.48 13.69 7.67 2.99 .17 40.00 

in Climb 

Total Flight 41.90 40.83 42.63 47.42 10.93 183.72 

Time 

0 

Percent Total 36.94 33.54 17.98 6.31 1.59 21.77 

Time in Climb 

47 
TABLE 9. PERCENT TIME OF INDICATED AIRSPEED VERSUS 

ALTITUDE BINS FOR LEVEL 

FLIGHT DERIVED FROM ONBOARD PROCESSING 

0 

Altitude Bins (ft) 

-500 4,500 9,500 14,500 19,500 -500 

4,500 9,500 14,500 19,500 24,500 24,500 

IAS (Kts) to to to to to to 

0 

100 to 120 

120 to 140 

140 to 160 

160 to 180 

180 to 200 

220 to 240 

240 to 260 

260 to 280 

280 to 300 

vs. Altitude bin 

0 200 to 220 

# Percent Climb 

Flight Time 

in Climb 

Time 

0 Total Flight 

Percent Total 

Time in Climb 

22.06 .12 . 00 .02 .10 

14.08 1.91 .01 9.65 25.03 

20.47 1.91 5.74 70.38 74.49 

30.70 41.75 62.74 19.67 .38 

11.39 53.16 31.16 .29 . 00 

1.30 1.14 .34 . 00 . 00 . 00 . 00 . 00 . 00 . 00 

. 00 . 00 . 00 .oo . 00 

.oo .oo . 00 . 00 . 00 

.10 . 00 . 00 . 00 . 00 

13.19 12.72 25.20 38;85 10.04 

13.62 13.13 26.02 40.12 10.37 

41.90 40.83 42.63 47.42 10.93 

32.50 32.16 61.05 84.61 94.87 

2.94 

8.37 

39.22 

32.84 

16.23 

.40 

. 00 

. 00 

.oo 

. 00 

100.00 

103.27 

183.72 

56.21 

48 
TABLE 10. PERCENT TIME OF INDICATED AIRSPEED VERSUS 

ALTITUDE BINS FOR DESCENT 

DERIVED FROM ONBOARD PROCESSING 

Altitude Bins (ft) 

-500 4,500 9,500 14,500 19,500 -500 

IAS (Kts) to to to to to to 

4,500 9,500 14,500 19,500 24,500 24,500 

100 to 120 

120 to 140 

140 to 160 

160 to 180 

180 to 200 

200 to 220 

220 to 240 

240 to 260 

260 to 280 

280 to 300 

2.28 .94 .52 9.85 

39.41 31.97 42.35 60.59 

49.48 58.88 49.70 27.97 

7.87 7.71 7.05 1.55 

.94 .42 .35 .05 

.02 .07 .02 . 00 

. 00 . 00 . 00 . 00 . 00 . 00 . 00 . 00 

. 00 . 00 . 00 . 00 . 00 .oo . 00 . 00 

40.53 2.60 

47.56 39.82 

11.91 50.13 

. 00 6.89 

. 00 .53 

. 00 .04 

. 00 . 00 

. 00 . 00 

. 00 . 00 

. 00 . 00 

Percent Climb 

vs. Altitude bin 

Flight Time 

in Climb 

Total Flight 

Time 

Percent Total 

Time in Climb 

31.65 34.64 22.10 10.65 

12.80 14.01 8.94 4.31 

41.90 40.83 42.63 47.42 

30.55 34.30 20.97 9.08 

.96 100.00 

.39 40.44 

10.93 183.72 

3.54 22.01 

49 
B 

I' 

TABLE 11. LEVEL CROSSING COUNTS PER HOUR VERSUS 

ALTITUDE BINS FOR LONGITUDINAL (AXIAL) ACCELERATION 

Altitude Bins (ft) 

Longitudinal On -500 4,500 9,500 14,500 19,500 -500 

Acceleration the to to to to to to 

(G) ground 4,500 9,500 14,500 19,500 24,500 24,500 

0.75 to 1.00 

0.50 to 0.75 

0.40 to 0.50 

0.30 to 0.40 

0.25 to 0.30 

0.20 to 0.25 

0.15 to 0.20 

0.10 to 0.15 

0.05 to 0.10 

0.00 to 0.05 

-0.05 to 0.00 

-0.10 to -0.05 

-0.15 to -0.10 

-0.20 to -0.15 

-0.25 to -0.20 

-0.30 to -0.25 

-0.40 to -0.30 

-0.50 to -0.40 

-0.75 to -0.50 

-1.0 to -0.75 

Average cts/hr 

F1 ight time/bin 

2.5 

4.2 

4.6 

11.0 

15.1 

12.4 

10.3 

37.9 

149.2 

1349.8 

1352.5 

209.9 

107.4 

64.3 

17.6 

5.5 

.1 

.1 

.o 

.o 

167.8 

23.16 

.o 

2.6 

3.4 

27.8 

69.6 

118.4 

245.1 

402.5 

111.4 

348.7 

347.9 

495.7 

417.0 

64.5 

8.1 

.7 

.1 

.1 

.1 

.1 

133.2 

41.90 

.o 

1.9 

2.8 

8.1 

3.6 

5.4 

53.5 

532.2 

225.5 

417.8 

419.1 

489.3 

432.8 

26.9 

1.5 

.2 

.1 

.1 

.1 

.1 

131 .O 

40.83 

.1 .1 .o 

2.5 .o .o 

2.6 .o .o 

6.0 .o .o 

6.8 .o .o 

6.4 1.3 .o 

20.7 3.4 .o 

263.2 58.7 20.2 

209.3 119.8 67.1 

969.0 2965.0 3485.2 

971.2 2965.8 3486.1 

429.1 126.0 25.9 

115.9 11.3 .2 

6.0 .o .o 

.1 .o .o 

.1 .o .o 

.1 .o .o 

.1 .o .o 

.1 .o .o 

.1 .o .o 

150.5 312.6 354.2 

42.63 47.42 10.93 

.o 

1.6 

2.0 

9.5 

18.3 

30.0 

73.4 

287.5 

159.0 

1370.0 

1370.9 

355.4 

221.1 

22.1 

2.2 

.2 

.1 

.1 

.1 

.1 

217.3 

183.72 

IO 

0 

50 
TABLE 12. LEVEL CROSSING COUNTS PER HOUR VERSUS 

ALTITUDE BINS FOR VERTICAL ACCELERATION (GRAVITY REMOVED) 

0 

Altitude Bins (ft) 

Vertical On -500 4,500 9,500 14,500 19,500 -500 

Accel erat i on the to to to to to to 

(GI ground 4,500 9,500 14,500 19,500 24,500 24,500 

a 

e 

- 

0.75 to 1.00 

0.50 to 0.75 

0.40 to 0.50 

0.30 to 0.40 

0.25 to 0.30 

0.20 to 0.25 

0.15 to 0.20 

0.10 to 0.15 

0.05 to 0.10 

0.00 to 0.05 

-0.05 to 0.00 

c -0.10 to -0.05 

-0.15 to -0.10 

-0.20 to -0.15 

-0.25 to -0.20 

-0.30 to -0.25 

-0.40 to -0.30 

9 -0.50 to -0.40 

-0.75 to -0.50 

-1.0 to -0.75 

Average cts/hr 

F1 ight time/bin 

.o 

.3 

.9 

3.7 

8.3 

23.1 

69.9 

232.2 

970.6 

3951 .O 

3955.5 

590.5 

141.2 

39.9 

11.9 

3.8 

1.9 

.2 

.1 

.o 

500.3 

23.16 

.o 

1.4 

5.0 

21.9 

45.2 

100.8 

225.9 

489.3 

1114.2 

2244.8 

2245.4 

811.5 

312.7 

134.2 

56.4 

25.1 

12.7 

2.9 

.9 

.2 

.o .o .o 

.4 .2 .1 

1.2 .7 .3 

4.1 1.9 1 .o 

8.3 3.4 1.8 

17.9 6.8 4.0 

42.1 16.2 10.8 

108.9 53.4 34.2 

438.2 336.8 241.0 

2655.2 2871.7 3346.3 

2655.4 2871.2 3346.1 

358.9 272.4 165.8 

83.1 44.8 26.4 

31.6 14.4 8.9 

14.0 6.2 3.5 

6.9 2.8 1.7 

3.4 1.7 .8 

1.1 .6 .3 

.5 .3 .1 

.2 .1 .o 

392.5 321.6 325.3 359.7 

41.90 40.83 42.63 47.42 

.o 

.o 

.o 

.1 . 

.4 

1.6 

7.6 

34.6 

316.8 

3298.7 

3299.0 

162.7 

25.7 

6.4 

1.6 

.6 

.1 

.o 

.o 

.o 

.o 

.5 

1.6 

6.6 

13.4 

29.7 

67.9 

159.1 

510.7 

2828.5 

2828.6 

380.5 

108.5 

43.7 

18.4 

8.4 

4.3 

1.1 

.4 

.1 

357.8 413.7 

10.93 183.72 

51 
TABLE 13. LEVEL CROSSING COUNTS PER HOUR VERSUS 

ALTITUDE BINS FOR LATERAL ACCELERATION 

Altitude Bins (ft) 

Lateral 

Accel erat i on 

(GI 

0.75 to 1.00 

0.50 to 0.75 

0.40 to 0.50 

0.30 to 0.40 

0.25 to 0.30 

0.20 to 0.25 

0.15 to 0.20 

0.10 to 0.15 

0.05 to 0.10 

0.00 to 0.05 

0 

-0.05 to 0.00 

0 -0.10 to -0.05 

-0.15 to -0.10 

-0.20 to -0.15 

-0.25 to -0.20 

-0.30 to -0.25 

-0.40 to -0.30 

-0.50 to -0.40 

-0.75 to -0.50 

-1.0 to -0.75 

0 

Average ctslhr 

On 

the 

ground 

-500 4,500 9,500 14,500 19,500 -500 

to to to to to to 

4,500 9,500 14,500 19,500 24,500 24,500 

.o 

.1 

.2 

.7 

2.2 

9.7 

35.8 

90.7 

360.5 

2298.7 

2303.3 

289.1 

47.6 

11.6 

2.9 

.6 

.o 

.o 

.o 

.o 

272.7 

.o 

.o 

.o 

.1 

.2 

.6 

6.9 

28.5 

355.9 

2792.5 

2794.1 

312.3 

21.5 

3.2 

.6 

.2 

.1 

.1 

.1 

.1 

315.8 

.o 

.o 

.o 

.1 

.2 

.o 

.2 

2.8 

250.4 

3376.5 

3376.3 

163.5 

1.7 

.3 

.2 

.1 

.1 

.1 

.1 

.1 

358.6 

.o 

.o 

.o 

.o 

.o 

.o 

.1 

2.4 

232.2 

3514.2 

3514.0 

117.7 

1 .o 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

369.1 

.o 

.o 

.o 

.o 

.o 

.o 

.o 

.5 

138.0 

4213.4 

4213.2 

53 .O 

.4 

.1 

.o 

.o 

.o 

.o 

.o 

.o 

430.9 

b 

.o 

.o 

.o 

.o 

.o 

.o 

.o 

.o 

91.2 

4352.4 

4352.5 

49.7 

.3 

.o 

.o 

.o 

.o 

.o 

.o 

.o 

442.3 

.o 

.o 

.o 

.o 

.1 

.2 

1.6 

7.8 

231.7 

3549.4 

3549.6 

151.5 

5.6 

.8 

.2 

.1 

.1 

.1 

.1 

.1 

409.3 

c Flight time/bin 23.16 41.90 40.83 42.63 47.42 10.93 183.72 

52 
0 

0 

W 

oi 

* 

correction is necessary to remove the expected variability in measured engine 

parameters due to variability in engine operating conditions. Next, the 

nominal expected values for the engine parameters under standard conditions (a 

constant value for each parameter) is subtracted from the corrected data to 

produce a A value. 

that indicate a change in engine performance. The level of the A values is 

not as significant as changes (slow or rapid) which might indicate a change in 

engine condition and could be a precursor for necessary corrective action to 

avoid a more costly repair or engine failure. 

In order to compare the manual and automated approaches for trend 

monitoring, ANG, AITT and AWF were calculated for each flight. 

approach was to select a point 5 to 10 minutes after the aircraft reached the 

cruise altitude and calculate the A values from instantaneous measurements 

made at that time. 

averaging measured values over the entire cruise portion of a flight. 

averaging process removes variability in A values due to short-term variations 

from random measurement errors and changes in engine operating conditions. 

Flights with cruise duration less than 5 minutes or cruise altitudes less than 

8,000 feet were not included in the analysis. Processed data from the 

remaining flights are plotted for comparison with manually acquired data. 

The A values calculated from the Smart Recorder data using the Pratt and 

Whitney supplied compensation equations was plotted for verification prior to 

comparison with the manually derived data. 

variability in calculated A values between flights was far greater than the 

variability in values calculated during the cruise portion of any given 

flight. 

AITT for all flights over the study period. 

plot represent the one-sigma variance about the mean value calculated for the 

flight. Note that this variance is small in comparison to the point to point 

variation in the plot. Consultations with the engine manufacturer, Pratt and 

Whitney (Montreal, Canada) revealed two possible causes for the flight-toflight variation. First, cabin pressurization introduces a loading on the 

engine which is dependent on the altitude of the aircraft and, if not 

These A values are plotted against time to observe trends 

The first 

However, more consistent results were obtained by using 

The 

In the original data, the 

This is shown by the data in Figure 10 which shows the raw data for 

The "error bars" shown on the 

53 

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accounted for, would introduce an error in the compensation calculations for 

the A parameters. Secondly, the electrical loading of the alternators would 

also cause a loading on the engine which would impact the compensated results 

in a similar manner. An analysis of the data revealed that the A values 

showed a strong correlation with altitude even though the compensation 

equations account for variation in engine performance with environmental 

pressure. It is thought that, while the A-value/altitude correlation could be 

produced by inaccuracies in the equation coefficients, they are more likely to 

be produced by the altitude dependence of the engine loading of the cabin 

pressurization system (Altitude dependence of electrical loading is thought to 

be negligible). To resolve this problem, an empirical relationship was 

determined from a portion of the data to account for the altitude dependency 

of engine loading, and applied to the data set in addition to the standard 

compensation equation prior to the comparison with the manually acquired data. 

This reduced the flight-to-flight variability significantly (as shown by 

comparing Figure 10 with Figure 11) but did not reduce it to a level 

comparable with the data variability within a flight. 

ability farther, it will be necessary to more closely monitor engine loading. 

(The manual method overcomes the engine loading problem by requiring that the 

pilot shift loads to the opposite engine while measurements are being made. 

This approach is not appropriate for the automated,systems because the 

ultimate application would be for continuous engine monitoring with real-time 

pilot notification upon detection of a significant trend in the observed 

data.) 

empirically-derived altitude relationship, the trend monitoring data from the 

Smart Recorder was compared against data taken using manual techniques (from 

data logged by pilots). To perform this comparison, values for each A 

parameter from both the automated and the manual processes were plotted 

together against time for the period of May through August 1985. 

through 13 show the three resulting plots, one for each of the calculated A 

values. 

pilots and 32 observations were taken from the Smart Recorder data. 

To reduce the variAfter application of the Pratt and Whitney compensation equations and the 

Figures 11 

During this time interval, 25 data observations were collected by the 

The 

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difference in number of observations was due to the fact that the pilots do 

not record data during every flight and some flight data was missing from the 

recorder because of full data cartridges or the pilot turning it off during 

flight. 

First, 

the magnitudes of the various A parameters differ somewhat between the manual 

and automated procedures. 

the magnitude of the measured parameters, particularly NG, ITT and WF and 

torque. These recorder measurements for these parameters were calibrated 

against known or expected sensor outputs and are not calibrated directly 

against the cockpit indicators. 

automated results. However, a constant bias is not detrimental to the 

detection of trends or changes in the data, so no effort was made to reduce 

the bias. 

Several observations may be made from the data presented here. 

The difference is primarily due to differences in 

This results in a bias between manual and 

Table 14 compares the variability of the manual-processing and automatedprocessing techniques. Comparison of the two AITT values finds only a small 

decrease, from 7.4 to 5.14, in the standard deviation of between flight data 

using the recorder data. ANG and AWF both exhibit improvements in their 

respective standard deviations for the two methods; from 0.49 to 0.29 for ANG 

and 5.15 to 3.1 for AWF. 

values. 

the three delta values during this period. 

this: (1) the propeller speed transmitter was replaced during the "hot 

section" which may have biased the data from that point in time and 

effectively hidden the change in the delta values, and (2) the expected 

changes may be smaller than the typical measurement errors. In the data 

recorder results, the delta values do appear to change for AITT and ANG. 

Excluding the three performance flights, the mean before an after the "hot 

section" for AITT changes from approximately -41.0 to -34.0 "C. 

the mean for ANG changed from -1.91 to -1.49 percent. 

not as visually apparent in AWF, the mean does change from 14.15 to 12.58 

1 b/hr. 

A final observation involves the effect of the "hot section" on the delta 

The pilot data do not appear to exhibit any marked change in any of 

There are two possible reasons for 

Similarly, 

Though the change is 

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59 
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TABLE 14. STANDARD DEVIATION FOR THE b VALUES FOR 

AUTOMATED AND MANUAL TREND MONITORING 

Standard deviation 

Manual Automated 

(Calculated from (Calculated by 

Parameter information in processing data 

pilot logs) from Smart Recorder) 

AITT 7.40 5.14 

ANG 0.49 0.29 

AWF 5.15 0.90 

a 

60 
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In summary, the advantages gained by performing trend monitoring use data 

recorder continuously during a flight are as follows: 

A larger number of flights are recorded during a given period. 

A large number of data samples can be taken and averaged 

improving data quality. 

An improvement in the standard deviation (variability) between 

flights is realized. 

Events such as "hot section" repairs may be more apparent. 

Frees pilot time for other functions and thus eliminates the 

human factor. 

61 
SECTION 7 

DEVELOPMENT OF SECOND GENERATION RECORDER 

0 

0 

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a 

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Th prototype Smart Recorder was 

commercial components and hardware to 

developing the appropriate configurat 

fully demonstrated the feasibility of 

aviation aircraft, it was not package 

fabricated using off-th- -shelf 

minimize initial equipment cost while 

on. While the initial device successapplying flight recorders to general 

in a standard aircraft enclosure and no 

attempt had been made to make the recorder and its ancillary equipment 

compact. 

a recorder that could be installed in standard aircraft racks and that would 

impose minimal logistical requirements on the aircraft (minimal size, weight, 

and power). 

Figure 14. Like the initial version, this recorder uses a bubble-memory 

cartridge system for transfer of data between the recorder and the laboratory 

data-processing faci 1 ity. However, since the Intel Plug-a-Bubble was no 

longer available, a Targa unit was used instead. Other design enhancements 

over the original Smart Recorder include: internal interface to the 

environmentally protected auxiliary memory (EPAM); internal signal 

conditioning for synchro, frequency, and variable resistance sensors; and a 

real-time clock to provide actual date and time. 

construction. These boards are 4.5 x 6.5 in. overall and are commercially 

available for a wide variety of microcomputer related functions. 

their smaller size, the functions available in the single board computer used 

in the original recorder required several STD-Bus boards to implement. 

However, the overall size of the recorder was reduced to that of an ARINC 600 

LRU-6 case (equivalent to an ATR-5/8 short case if that designation existed 

officially). 

The purpose of the development of the second recorder was to develop 

The second-generation Smart Recorder functional configuration is shown in 

The second recorder utilizes STD-Bus boards allowing a more compact 

Because of 

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An advantage to the use of the smaller STD-Bus boards is the increase 

flexibility in configuration because of the increased modularity of the 

design. 

conditioning capabilities that are required. The characteristics of the 

system may be modified by changing boards. A wide variety of boards are 

commercially available including processor, memory, special function and 

peripheral interface boards. The existing configuration of the secondgeneration Smart Recorder includes eight boards: 

Boards may be selected which provide the specific processor or signal 

1. 

2. 

3. 

4. 

5. 

6. 

7. 

a. 

Four of 

8088 Processor Board 

Memory Board 

Bubble Memory and EPAM Interface Board 

Analog-to-Digital Converter/ Multiplexer Board 

RTD Input Card 

Synchro Input Card 

Frequency Input Card 

Bus Terminator/Real Time Clock Board. 

these boards are off-the-shelf, commercial boards. On 

Memory Interface, Synchro Input, Frequency Input, and Bus Term 

Clock boards were custom fabricated for this project. 

y the Bubble 

nator/Real Tim 

Like the original Smart Recorder, the second generation Smart Recorder 

was designed to be powered from an unregulated 28 Vdc power bus. Power 

modu 

with 

SUPP 

- +12 , 

es capable of operating from 9 to 40 Vdc input were used for supplying 

- +15, and 5 Vdc to internal electronics. An additional supply located 

the EPAM interface electronics was used to provide the 21 Vdc programming 

y voltage used for writing data to the EPAM. 

Software for the second recorder consists of a general utility data 

acquisition program containing many of the capabilities of the software for 

the original recorder. 

rate sampling of input parameters, and interactive mode using external 

terminal wei2 implemented on this system. 

Configuration data read from the bubble memory, dualNew software includes drivers for 

64 
e 

the internal signal conditioning boards and the real time clock/calender. 

Software for on-board processing was not implemented on the second recorder 

because the specific application for the recorder has not been defined. 

technical characteristics of the recorder are summarized in Table 15. 

The 

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65 

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TABLE 15. SPECIFICATIONS OF THE SECOND GENERATION SMART RECORDER 

TY Pe Number Range Comments 

Voltage(High Level) 16 0 to 10 v Range of individual 

channels may be 

changed by 

rep 1 acing res i stor 

a 

Inputs: 

0 

Vol t age (Low Level ) 8 0 to 500 mV 

RTD 

a 

Synchro 

e 

Frequency 

8 -200 to 800OC Linearization done 

on the interface 

board 

0 Processor: 8088 

4 0 to 360° 26V ref with 11.8V 

line-to-line 

voltages for 

synchro input 

channel may be 

altered by changing 

component value. 

8 0 to 500 Hz Range of individual 

Memory: RAM,Static 32K 

ROM 32K 

EPAM (external) 16K 

e Removable storage Media 128KB Cartridge 

Cool 

0 

Phys cal Size 

Forced Air suppl ied 

through rack 

7.5 x 7.64 x 12.5 

LRU #6 (ARINC 600) 

Expandable to 128K 

Hamilton-Standard 

512 KB cartridges 

available from 

manufacturer 

(Targal 

Weight 19 lb 

Power 3.5A at 24 V (80W) 

a 

-- 

e 

66 
0 SECTION 8 

ADDITIONAL APPLICATIONS OF THE SMART RECORDER 

0 

0 

0 

During the development of the Smart Recorder, certain applications within 

NASA were identified which required or could benefit from a compact data 

acquisition system that could process data as it is acquired to compress the 

data, select data of interest for retention, or provide real-time notification 

upon determination of specified conditions. Two representative applications 

are described here. 

monitoring environmental exposure of Shuttle payloads while being transported 

to the lauch area. 

aircraft is more in keeping with the original design objectives of the Smart 

Recorder, although the logistical constraints for this application are 

considerably more severe because of the compact construction of this aircraft. 

The first is a transportation environment recorder for 

The second application, a flight recorder for a T-38 

8.1 TRANSPORTATION ENVIRONMENT MONITORING 

8.1.1 Introduction 

The Transportation Environment Measurement and Recording System (TEMARS) 

is an instrument used to record shock and vibration levels induced by 

transportation vehicles on payloads being transported from the point of 

assembly to the launch site. 

alternative data acquisition concept for monitoring the transportation 

environment , recording statistics which characterize the environment, and 

selective detailed recording of critical parameters at time when exceedances 

were noted that could be dangerous to the load. In this application, the 

Smart Recorder is used to eliminate the need for an in-transit operator/ 

controller and for tedious, post-trip data analysis. 

also provide real-time notification of the shock and vibration exceedances. 

The Smart Recorder concept was evaluated as an 

The Smart Recorder could 

67 

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8.1.2 Transportation Payload Monitoring Requirements 

The TEMARS, described in Figure 15 consists of standard instrumentation, 

The associated sensor set consists of two 

including an analog magnetic tape recorder, controlled remotely by an operator 

riding in the cab of the vehicle. 

tri-axial accelerometers, plus payload container temperature and humidity 

sensors. 

plate (force input) and second is located near a region of probable force 

amplification. All sensors are monitored on operator demand. Normal 

accelerometer scaling is 10 G maximum, and frequencies of interest are dc to 

200 Hz. Some typical TEMARS data are represented by Figures 16. The data 

represent force inputs ranging from single-episode short-duration shock inputs 

to long-duration inputs with occurrences of regular frequency features and 

envelope modulation effects. 

TEMARS recorder. Since the on-board operator must anticipate occurrences, the 

operator tends to be conservative and records many non-occurrences. Emergency 

situations such as an accident or flat tire may either distract the operator 

or be of such short duration as to be missed by the operator. Additionally, 

the fact that an exceedance has occurred is not available until the data have 

been analyzed after the trip. 

8.1.3 

One of the accelerometer systems is located near the object mounting 

A normal trip might contain 30 to 50 turn-on cycles (-1 min) of the 

Data Acquisition in the Transportation Environment 

The critical parameter to be monitored in the transportation environment 

is acceleration, a measure of shock and vibration to which the payload is 

subjected. 

acceleration data is driven by three factors unique to this application: 

The design of a system for measurement and recording of 

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The wide bandwidth of the signal to be recorded 

The relatively long duration of the desired recording period 

The need for processing the data both for impulse information and 

for steady state information. 

Spectral analysis of acceleration measurements from vehicular environment 

shows significant e.iergy from below 1 Hz to above 300 Hz. 

0 

6% 

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GSFC TEMARS OPERATOR 

SPACECRAFT WITH REMOTE CONTROL 

SHIPPING UNIT IN TRACTOR 

CONTAINER PASSENGER'S SEAT TEMARS 

INSTRUM. ' 

KISTLER 303B 

ACCELEROMETER 

TRACTOR/TRAILER FOR TRANSPORTING SPACECRAFT 

TpiARs INSTRUMENTATION CART 

CONTAINS : /T-f A) TAPE RECORDER 

TEMARS INSTRUM. 

CART 

GROSS WEIGHT: 

700 LBS. 'I 

I, 3 .-5 ' 4.5 ' ,-a 

a 

SPECIFICATIONS FOR TEMARS : 

8 

e 

I B) AIRCRAFT BATTERIES 

3.5' C) JUNCTION BOXES 

D) OSCILLOSCOPE 6. VOLTMETER 

E) SUPPORT HARDWARE & SOFTWARE 

NUMBER OF CHANNELS - 12 ACCELEROMETERS MAXIMUM 

g RANGE 

FREQUENCY RESPONSE - dc to 200 HZ 

RECORDING TIME 

- 0 TO 40 g PEAK 

- UP TO 3 HOURS PER TAPE; UP TO 6 HOURS 

PER BATTERY CHARGE 

OVERALL INSTRUM. 

CART DIMENSIONS - 4.5' x 3.5' x 3.5'; GROSS WEIGHT 700 LBS. 

AND WEIGHT 

POWER REQUIRED - 24 to 30 VDC (USES 12 VDC, 80 AMP-HR, 

AIRCRAFT LEAD-ACID BATTERIES) 

TAPE RECORDER - HONEYWELL 5600C, 14-TRACK, FM ANALOG 

ACCELEROMETER TYPE - KISTLER SERVO, MODEL 303B 

ACCELEROMETER 

DIMENSIONS AND - 1.5" x 1.5" x 2.5''; 6 OUNCES 

WEIGHT 

Figure 15. Description of GSFC Transportation Environment 

Measuring and Recording System (TEMARS) 

69 
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Figure 16. An Example of TEMARS Data 

70 
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* 

If conventional recording techniques are used, (e.g., magnetic tape 

recorders), then only a few hours of data may be recorded unless high 

frequency information is sacrificed. With existing systems the only means of 

acquiring data may be acquired over a long period is to either (1) turn the 

recorder on only during periods of interest and (2) or to periodically change 

the recording media. The first procedure requires that an instrument operator 

anticipate stimuli which will induce shock or vibration in the vehicle 

payload. If stimuli such as grooves in the pavement, potholes, etc. are not 

spotted, the event will not be recorded. The second procedure results in high 

quantities of acquired data, creating a monumental data processing problem. 

Either procedure requires that an operator travel along with the recording 

equipment. 

how it should be acquired and stored. 

vibration induced by the vehicle rolling over regular features of the road-- 

such as expansion cracks or pavement grooves generally is analyzed in terms of 

spectral characteristics. Impulse acceleration data from shock or random 

variations from random sources generally is characterized by the time domain 

characteristics (e.g., pulse height, duration, and waveform), although fourier 

analysis techniques may be used to determine the spectral characteristics of 

isolated pulses as well. 

usually present in the acceleration data, then data must be encoded in such a 

manner that both temporal detail and frequency fidelity are preserved. These 

factors impose a major constraint on the design of a data acquisition system 

for the transportation environment. 

The intelligence of the Smart Recorder could be used to reduce the data 

storage requirements through on-board processing. Figure 17 illustrates the 

monitoring concept using this recorder. 

other single-chip microprocessor) is not sufficiently fast to acquire 6 

channels of data and perform a spectral analyses on it, a separate preprocessor would be used to determine the spectral characteristics of each of the 

six signals from the two three-axis accelerometers. The signal from each axis 

The nature of the data determines how the data should be processed and 

Stationary acceleration data from 

Since both impulse and continuous signals are 

Since the 8088 processor (or any 

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would be passed through a series of filter banks (shown in Figure 18) to 

determine the energy between 0 and 1 Hz and in each of 8 octaves between 1 Hz 

and 256 hz. Integrators and sample-and-hold units would be used to determine 

average values representing each one-second i nterval . negative, would operate on each filter band output and the "raw" 

data to "freeze" the spectral content of transient 

cs of impulse data, e.g., measured shock upon impact with 

Peak detectors , both 

positive and 

(unf i 1 tered) 

characteri st 

pot hol e. 

The ana og output signals from the preprocessor would be passed over 

multiple signal paths to the Space Recorder where it would be digitized and 

tested to determine if the data are worthy of retention--i.e., if the data 

contain indications of significant acceleration levels. Once a significant 

event is detected, data would be stored over successive sample intervals until 

the observed shock or vibration decreases to a the nominal background level or 

until it reaches a new steady-state value and remains there for a specified 

period. These long duration events, such as these produced by sections of 

grooved pavement or by concrete highways with raised expansion joints, would 

be detected by the testing for variability in successive data records. Once 

it is determined that the event is a long duration event, representative data 

for the period would be tabulated and stored along with information about the 

duration of the period, eliminating the possibility of filling the memory with 

data which essentially describes only one condition. 

data describing impulse type events, the stored data would consist of a series 

of data records containing the peak and average values for acceleration in 

each of the frequency "bins" (including the unfiltered channel) for each 

accelerometer output. 

speed (distance traveled) would be stored also. 

would be implemented in the recorder whereby data would be buffered so that on 

the detection of a valid trigger, data that slightly precedes the trigger 

could be stored. 

from the early part of a long duration event in a manner resembling the 

Data describing two different situations would be stored in memory. For 

Other parameters such as temperatures and integrated 

A pretriggering technique 

In the case of long duration events, initial records would describe data 

73 
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impulse event format, with additional records relating the remainder of the 

event to the initial portion by concise, statistical terms such as means and 

standard deviations 

Numerous design options are available for this configuration. Three 

parameters which must be selected are: 

Spectral resolution--full-octave, half-octave, or third-octave or 

constant - w i dt h spec t r a1 'I b i ns I' 

Temporal resolution--sample rate of stored data 

Criteria for retention of data. 

All three parameters must be chosen based on the expected nature of the 

acquired data, the monitoring period, and the capacity of the storage media. 

Increasing temporal and spectral resolution directly increases the storage 

requirements for a given number of events, while changing the criteria for 

retention of data effects the quantity of data which is retained. Thus to 

obtain the capacity of longer operation periods, spectral or temporal 

resolution may be reduced or the criteria for data retention tightened such 

that only high-acceleration events are retained. 

Data capacity of the bubble memory cartridge used with the recorder is 

128 Kbytes. If 10 spectral bands for each of 6 accelerometer outputs are 

recorded along with 15 bytes of date/time, distance, and miscellaneous data, 

then 195 bytes will be required for each sample interval. 

once each second, approximately 11.2 minutes of data may be stored in each 

cartridge. Assuming a nominal event duration of 20 seconds, 33 events may be 

stored in the cartridge. 

had been filled, and the events have greater acceleration levels than those in 

memory, then the new data would be written over the old data. Thus, the most 

significant events would never be missed due to a full memory. 

may be recorded by using a longer sample interval (e.g., sampling data every 2 

seconds instead of the 1-second interval assumed above). Provision would be 

made for changing the sample rate by switch to provide flexibility in 

selecting that parameter. 

* 

If data are stored 

If additional events are detected after the memory 

More events 

Larger data capture may be obtained by dividing the 

*256 Kbyte cartridges are presently available. Higher capacity cartridges, 

512 kbyte and one megabyte, are under development. 

75 
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0 

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frequency spectrum into larger bins hence storing data from a smaller number 

of frequency ranges. 

use must be decided at the time the preprocessor is fabricated and is not 

easily modified. 

minutes using the same procedure used for the flight recorder--reading data 

from the bubble memory cartridge into a microcomputer through a cartridge 

holder/interface which is similar to the one used in the recorder. Once data 

are read into the microcomputer they may be manipulated either with new 

routines written especially for this application, or with existing routines 

prepared for the flight monitor ng application. The data may be presented in 

several graphical formats using plotting routines already developed on the 

Ground Base microcomputer for processing flight recorder data. An example 

data presentation from a single shock event is given by Figure 19. 

possible formats include: 

However, the decision of the number of frequency bins to 

Printed summaries of data from the recorder may be generated within 

Other 

Spectral plots portraying the peaks and rms magnitudes of all 

spectral bins in a histogram manner 

A family of time series plots showing all frequency bands associated 

with a particular accelerometer axis 

A false 3-dimensional plot showing the frequency and time on the 

horizontal x and y axis with acceleration (peak or rms) plotted on 

the z axis. 

Tabular listings could also be used for review of data and determination of 

representative acceleration levels. 

would have the recorder and the data preprocessor mounted inside an enclosure 

with shock mounts to isolate and protect the electronics from the vibrations 

being monitored. 

include the following three items: 

The anticipated implementation of the transportation environment recorder 

Connections between the recording system and the vehicle 

Output from a speed sensor on the vehicle 

0 Power -- 12 or 24 Vdc, unregulated 

Inputs from payload sensors. 

c 

76 
TRANSPORTATION ENVIRONMENT MONITORING SYSTEM 

EVENT REPORT 

2- 

x-nxis 0 

2- 

y-Axis 1- 

2- 

Z-Axis 1- 

DATE/TIME: 12 JUN 1987 16:32 

ESIrlATED MILEAGE: 437 

EVENT TYPE: Impulse 

DURATION: 5 secs 

-4 

0- 7 

0- 

ACCELERATIONS (Gravity Corrected) 

+Peak, -Peak, g rms, g 

W 

e 

0 

UPPER ACCELEROMETER - x-Axi s 1.31 1.00 0.69 

y-Axis 0.45 0.36 0.22 

z-Axis 0.73 0.67 0.43 

LOWER ACCELEROMETER - x-Axis 1.67 1.56 0.78 

z-Axis 0.59 0.41 0.34 

y-Ax i s 0.24 0.38 . 0.10 

Energy Spectrum at Peak, g 2 

Frequency, Hz 

UPPER ACCELEROMETER 

21 

0 

co~cubco .. 

d 

Frequency , Hz 

Figure 19. Example Presentation of Detected Impulse Event 

77 
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Utilization of the vehicular power would eliminate the need for internal 

batteries (and the associated recharging procedure) 

to function for longer periods without attention. Preliminary estimates for 

this configuration are that it would weigh approximately 55 pounds and would 

use approximately 120 watts from an unregulated 24 volt supply. The system 

may also may be powered directly from an unregulated 12 volt supply, also but 

would consume slightly more power. 

and permits the recorder 

8.1.4 Conclusion 

An accurate, cost-effective, approach to the transportation environment 

measurement requirement has been proposed. 

application permits continuous monitoring of all parameters, portal to portal, 

including 1 oading , transportat ion and unloading , without operator assi stance. 

A real-time exceedance indicator can be included in the system capability. 

Rapid and automated post-trip data analysis, as well as statistical evaluation 

of transportation environment, are within the capabilities of the Space 

Recorder. The "ground" station also has the capability of reprogramming the 

recorder "EPROM," thereby creating modified software for specific changing 

measurement requirements. 

With the advent of the STS and commercial use of shuttle, two factors 

have become increasingly important. 

responsibility associated with the handling and transporting very expensive, 

delicate, time-critical payloads. A system to continuously prove that 

payloads have not been subjected to excessive environmental input would be of 

great value during an insurance claim litigation. 

improvement in the launch environment produced by the maturing space 

technology. Man-rated launch environments have become so benign that typical 

transportation induced stresses may fall outside the payload design envelope 

specified for shuttle flights. 

The Smart Recorder technology 

The first factor is the financial 

The second factor is the 

8.2.1 T-38 Crash Recording 

The application of the Smart Recorder technology to crash recording on 

the T-38 was investigated to determine if a cost-effective multipurpose 

e 

78 
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a 

recorder could be fabricated for that aircraft. The T-38 aircraft was chosen 

for two reasons: (1) because it is representative of the "fighter-type" 

aircraft which comprise a significant portion of the total NASA aircraft 

fleet, and (2) because the physical requirements (i.e. size and mounting 

provisions) are more severe for the T-38 so that a flight recorder which could 

be installed in the T-38 could be used in most other aircraft as well. 

The Smart Recorder appeared particularly appropriate for this application 

because the intelligence of the recorder could be used to advantage for data 

compression and automatic recognition of significant events suitable for 

storage in memory. For the crash-survivable memory unit, an existing unit 

manufactured by Hamilton Standard was considered. This unit represents an 

existing memory technology which is electrically compatible with the Smart 

Recorder and which has already been qualified for crash memory application 

under TSO-C5la. (This study was conducted prior to the EPAM acquisition and 

its installation with the prototype Smart Recorder on the King-Air aircraft. 

The procurement of the EPAM was done primarily to demonstrate the feasibility 

of interfacing a crash survivable memory system with the Smart Recorder and 

therefore was an extension of this study.) 

8.2.1 Approach 

The establishment of feasibility of a crash recorder for the T-38 using 

the Smart Recorder interfaced to an EPAM was dependent on the answer to two 

fundamental questions: 

Could the data storage requirements for crash recorders as specified 

by pertinent standards and regulations be satisfied with the 

existing 128 kbyte size limitation of the Hamilton Standard EPAMS? 

Could the "Smart Recorder" be reconfigured such that it could be 

mounted in a T-38 aircraft in a suitable location? 

The first question was addressed by analyzing the monitoring requirements 

as specified by the SAE, determining the storage (number of bits) 

to accommodate each measurement considering the specified requirements for 

accuracy and precision. Table 16 summarizes this analysis. Data could be 

maintained for the most recent 15 r.!nutes, the minimum period required by the 

necessary 

79 
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TABLE 16. ANALYSIS OF MEMORY CAPACITY REQUIRED FOR STORAGE OF PARAMETERS 

REQUIRED UNDER THE SAE STANDARD FOR GENERAL AVIATION FLIGHT RECORDERS 

Pa ramete r 

Re1 ative time 

Airspeed 

A1 ti tude 

Magnetic Heading 

Vertical 

Acceleration 

Pitch Attitude 

Roll At t i t ude 

Fan or N1 Speed 

or EPR or PROP 

Speed 

Engine Torque 

A1 ti tude Rate 

Angle of Attack 

Radio Transmitter 

TE Flaps 

(Di screte) 

LE Flaps 

(Di screte) 

Thrust Reverser 

Spoil er/Speed 

Autopi 1 ot 

Brake 

SA€ Sampl i ng 

Storage Mi nimun Rate Storage 

Range Resolution Accuracy (seconds) IBits) 

9 Hours 1 sec 0.125 Hrs 1 15 

0-1024 KtS 2 Kts 10 Kts 1 9 

-1000 ft to 50,200 ft 50 ft 100 ft 1 10 

360" 3.0" 5" 1 7 

-39 to 69 0.lg 0.29 4 4*7=28 

a0 " 

*180° 

Max Range 

1.5" 2" 1 7 

1.5" 2" 1 8 

5% 5% 1 5 

Max Range 5% 5% 1 5 

232000 fpm 250 fpm 250 fpm 1 8 

t90" 1.5" 2" 1 7 

On/Off 1 1 

Each discrete position 1 2 

Each discrete position 1 2 

Stowed or Full 1 1 

Stowed or Up 1 1 

- - 

- - 

(U,D,T/O, APP) 

(U,D,T/O, APP) 

- - 

- - 

- - 

Engaged - - 1 1 

- 

Total 117 

Sampl i ng Interval 

Total Storage 

Record Size 

Total CSMM Storage 

1 Second 

117 Bits at 1 engine 

127 Bits at 2 engines 

128 Bits (stored each second)' 

- 

- 

- 128 K Bits 

Available Storage Time - 16 Minutes 

80 
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specification, with approximately 6 percent of the memory remaining. An 

innovative use of this remaining memory would be to store information on 

"exceedances", i.e., a situation where one or more of the monitored parameters 

exceeds the normal operating envelope for that aircraft. 

information would provide significant information concerning the history of 

the aircraft outside the 15-minute recording period. 

The second question, concerning the installation of the crash recorder on 

a T-38 aircraft was addressed by conversations with NASA personnel responsible 

for T-38 aircraft at NASA-LaRC and an inspection of the aircraft. Appropriate 

mounting locations were identified for both the recorder and the EPAMS. 

recorder could be mounted in place of a "data case" normally used for carrying 

papers for the aircraft but seldom used. This location, illustrated in Figure 

20, is readily accessible through a door on the underside of the aircraft 

allowing maintenance and periodic checkout of the recorder from outside the 

aircraft. 

vertical stabilizer. This location would provide the greatest protection for 

the memory in the event of a crash. Very little room is available at the 

proposed recorder location, necessitating the reconfiguration of the Smart 

Recorder to take maximum advantage of the available space. 

illustrates the a configuration of the smart recorder, which includes the 

appropriate signal conditioning circuitry for processing the signals from 

available sources on the T-38 aircraft. 

Exceedance 

The 

The EPAMS could be mounted at the base of the forward edge of the 

Figure 21 

8.2.2 Data Recoverv 

The utilization of an electronic memory provides the advantage of automated data recovery capability. 

The EPAMS unit recovered from a crash site would be taken to a central 

laboratory. After removal of the protective casing, the memory unit would be 

connected through an EPAMS interface'to a computer which would non-destructively interrogate the memory. 

engineering units and plotted for fast visual interpretation of the data. 

Figure 22 shows an example plot format of simulated data which might be 

The recovery scenario would be as follows: 

Recovered data would be converted to 

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€PAM Mounted At Bare 

of Vertical Stabilizer 

Figure 20. Proposed Location of Smart Recorder and Epams on T-38 

Enclosure 

Out1 inc 

0 

Mother Board '* 

-- 

Power supp 1 i es 

i 

NOTE: Actual enclosure would have sligh t curve to fit available space. 

e Figure 21. Configuration of Smart Recorder Suitable for Installation 

on T-38 at "Data Case" Location 

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- CKTITUDE 

- - AIRSPEED 

A ALTITUDE RATE 

0 2 4 b e 10 12 14 16 

TIHE (MINUTES REFERENCED TO 10804r17) 

WWERUP WAS AT TIHE 09: 16142 

=O 1 'i 

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- PITCH 

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TIflE (HINUTES REFEREW.FD TO 10:04: 17) 

POWERUP WAS AT 1 :&E 09: 16: 42 

z 

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ua 

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Figure 22. Possible Graphical Presentation of Crash Memory Data 

Recovered with Automated Process (Simulated Data) 

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AUTOPILOT ON 

TE FLAPS 

f SPEED BRAKE ON 

THRUST REVERSER 

360 

c 

lao 0 e 0 2 4 6 a 10 12 14 16 

MAD I m3 

(EO) 

TIME (MINUTES REFERENCED TO 101041 171 

WUEAIJP WAS AT TIME 09: 16142 

KEY 

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0 2 4 6 a 10 12 14 16 

TIK (MINUTES REFERENCED TO 101041 17) 

WUERUP WAS AT TIME 09116142 

Figure 22 (continued) 

84 
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appropriate for the presentation of crash data. The tabulated data in Figure 

23, more tedious to examine, might be more appropriate for closer scrutiny of 

selected intervals within the 15-minute recorded data period. 

8.2.3 Conc 1 us i ons 

The study of the applicability of the Smart Recorder to the T-38 revealed 

that the existing design of the Smart Recorder could be physically modified to 

satisfy the requirements of the SAE standard for General Aviation Flight 

Recorders. Conventional processing and data "packing" is sufficient to record 

the required 15 minute period in the memory. Increased performance may easily 

be obtained using "exceedance" monitoring to store information concisely on 

events outside the 15-minute recording interval. Additional capability may be 

obtained through the use of sophisticated data compression techniques to 

expand the data capacity. 

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