Federal Register / Vol. 65, No. 188 / Wednesday, September 27, 2000 / Proposed Rules 58203

alternative method of compliance in

accordance with paragraph (i) of this AD. The

request should include an assessment of the

effect of the modification, alteration, or repair

on the unsafe condition addressed by this

AD; and, if the unsafe condition has not been

eliminated, the request should include

specific proposed actions to address it.

Compliance: Required as indicated, unless

accomplished previously.

To prevent opening of the cargo door while

the airplane is in flight or collapse of the

main deck cargo floor, and consequent rapid

decompression of the airplane including

possible loss of flight control or severe

structural damage, accomplish the following:

Actions Addressing the Main Deck Cargo

Door and Associated Fuselage Structure

(a) Accomplish the actions specified in

paragraphs (a)(1) and (a)(2) of this AD in

accordance with a method approved by the

Manager, Los Angeles Aircraft Certification

Office (ACO), FAA.

(1) Within 1 year or 1,200 flight cycles after

the effective date of this AD, whichever

occurs first, incorporate inspections into the

operator’s FAA-approved maintenance or

inspection program that ensure the continued

operational safety of the airplane. These

inspections should be based on a damage

tolerance assessment that identifies any

principal structural element (PSE) associated

with the STC modification and should

include associated inspection thresholds,

inspection methods, and repetitive

inspection intervals.

(2) Within 3 years or 4,000 flight cycles

after the effective date of this AD, whichever

occurs first, accomplish the actions specified

in paragraphs (a)(2)(i) and (a)(2)(ii) of this

AD.

(i) Modify the main deck cargo door

structure and fuselage structure immediately

surrounding the main deck cargo door to

comply with the applicable requirements of

Civil Air Regulations (CAR) part 4b.

(ii) Incorporate inspections into the

operator’s FAA-approved maintenance or

inspection program that ensure the continued

operational safety of the airplane. These

inspections should be based on a damage

tolerance assessment that identifies any PSE

associated with the STC modification

required by paragraph (a)(2)(i) of this AD and

should include associated inspection

thresholds, inspection methods, and

repetitive inspection intervals.

Actions Addressing the Main Deck Cargo

Floor

(b) Within 2 years or 2,000 flight cycles

after the effective date of this AD, whichever

occurs first, perform an inspection and

evaluation of the cargo handling system to

determine if the side restraints provide the

support required by the unit load device

(ULD), in accordance with a method

approved by the Manager, Los Angeles ACO.

If any vertical side restraint does not provide

the required support, within 2 years or 2,000

flight cycles after the effective date of this

AD, whichever occurs first, modify the

vertical side restraint to provide the support

appropriate to the ULD’s compatible with the

cargo handling system, in accordance with a

method approved by the Manager, Los

Angeles ACO.

(c) Within 3 years or 4,000 flight cycles

after the effective date of this AD, whichever

occurs first, modify the main deck cargo floor

to safely carry the applicable FAA-approved

payload limits for above and below the main

deck cargo floor. The modification and

payload distribution shall be accomplished

in accordance with a method approved by

the Manager, Los Angeles ACO. The

modification must comply with the

applicable requirements of CAR part 4b for

the FAA-approved payload distribution.

(d) Except for those airplanes that have

been modified in accordance with paragraph

(c) of this AD, within 1 year or 1,000 flight

cycles after the effective date of this AD,

whichever occurs first, perform an inspection

and evaluation of the venting system of the

main deck cargo floor to determine if the

system limits decompression loads to a level

that can be carried by the floor structure

without failure, in accordance with a method

approved by the Manager, Los Angeles ACO.

(e) If, based on the evaluation required by

paragraph (d) of this AD, the venting system

does not limit decompression loads to a level

that can be carried by the floor structure

without failure, within 2 years after the

effective date of this AD, modify the venting

system, as necessary, to limit the

decompression loads to a level that can be

supported successfully by the existing floor

structure, in accordance with a method

approved by the Manager, Los Angeles ACO.

Actions Addressing Main Deck Cargo Door

Hinge

(f) Within 250 flight cycles after the

effective date of this AD, perform a detailed

visual inspection to detect cracks of the

exposed surfaces of the main deck cargo door

hinge (both fuselage and door side hinge

elements), in accordance with a method

approved by the Manager, Los Angeles ACO.

If any crack is detected, prior to further flight,

repair in accordance with a method approved

by the Manager, Los Angeles ACO, or replace

the cracked hinge element with a new, like

part.

Note 2: For the purposes of this AD, a

detailed visual inspection is defined as: ‘‘An

intensive visual examination of a specific

structural area, system, installation, or

assembly to detect damage, failure, or

irregularity. Available lighting is normally

supplemented with a direct source of good

lighting at intensity deemed appropriate by

the inspector. Inspection aids such as mirror,

magnifying lenses, etc., may be used. Surface

cleaning and elaborate access procedures

may be required.’’

(g) Within 3 years or 4,000 flight cycles

after the effective date of this AD, whichever

occurs first, accomplish the actions specified

in paragraphs (g)(1) and (g)(2) of this AD in

accordance with a method approved by the

Manager, Los Angeles ACO.

(1) Perform a detailed visual inspection to

detect cracks or other discrepancies (i.e.,

double or closely drilled holes, corrosion,

chips, scratches, or gouges) of the mating

surfaces of the main deck cargo door hinge,

skin of the main deck cargo door, and

external fuselage doubler underlying the

hinge. If any discrepancy is detected, prior to

further flight, repair the discrepant part.

(2) Install a main deck cargo door hinge

that complies with the applicable

requirements of CAR part 4b, including failsafe requirements.

Actions Addressing Main Deck Cargo 9g

Crash Barrier

(h) Within 3 years or 4,000 flight cycles

after the effective date of this AD, whichever

occurs first, install a main deck cargo 9g

crash barrier that complies with the

applicable requirements of CAR part 4b, in

accordance with a method approved by the

Manager, Los Angeles ACO.

Alternative Methods of Compliance

(i) An alternative method of compliance or

adjustment of the compliance time that

provides an acceptable level of safety may be

used if approved by the Manager, Los

Angeles ACO, FAA. Operators shall submit

their requests through an appropriate FAA

Principal Maintenance Inspector, who may

add comments and then send it to the

Manager, Los Angeles ACO.

Note 3: Information concerning the

existence of approved alternative methods of

compliance with this AD, if any, may be

obtained from the Los Angeles ACO.

Special Flight Permit

(j) Special flight permits may be issued in

accordance with sections 21.197 and 21.199

of the Federal Aviation Regulations (14 CFR

21.197 and 21.199) to operate the airplane to

a location where the requirements of this AD

can be accomplished.

Issued in Renton, Washington, on

September 21, 2000.

Donald L. Riggin,

Acting Manager, Transport Airplane

Directorate, Aircraft Certification Service.

[FR Doc. 00–24747 Filed 9–26–00; 8:45 am]

BILLING CODE 4910–13–U

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000–NM–283–AD]

RIN 2120–AA64

Airworthiness Directives; McDonnell

Douglas Model DC–8 Series Airplanes

AGENCY: Federal Aviation

Administration, DOT.

ACTION: Notice of proposed rulemaking

(NPRM).

SUMMARY: This document proposes the

adoption of a new airworthiness

directive (AD) that is applicable to

certain McDonnell Douglas Model DC–

8 series airplanes that have been

converted from a passenger- to a cargocarrying (‘‘freighter’’) configuration.

This proposal would require, among

58204 Federal Register / Vol. 65, No. 188 / Wednesday, September 27, 2000 / Proposed Rules

other actions, modification of the main

deck cargo door structure and fuselage

structure; replacement of fasteners in

the two door-side hinge elements;

modification of the main deck cargo

floor; and installation of a main deck

cargo 9g crash barrier. These actions are

necessary to prevent opening of the

cargo door while the airplane is in

flight, and consequent rapid

decompression of the airplane including

possible loss of flight control or severe

structural damage. These actions are

intended to address the identified

unsafe condition.

DATES: Comments must be received by

November 13, 2000.

ADDRESSES: Submit comments in

triplicate to the Federal Aviation

Administration (FAA), Transport

Airplane Directorate, ANM–114,

Attention: Rules Docket No. 2000–NM–

283–AD, 1601 Lind Avenue, SW.,

Renton, Washington 98055–4056.

Comments may be inspected at this

location between 9:00 a.m. and 3:00

p.m., Monday through Friday, except

Federal holidays. Comments may be

submitted via fax to (425) 227–1232.

Comments may also be sent via the

Internet using the following address: 9-

anm-nprmcomment@faa.gov. Comments

sent via fax or the Internet must contain

‘‘Docket No. 2000–NM–283–AD’’ in the

subject line and need not be submitted

in triplicate. Comments sent via the

Internet as attached electronic files must

be formatted in Microsoft Word 97 for

Windows or ASCII text.

Information pertaining to this NPRM

may be examined at the FAA, Transport

Airplane Directorate, 1601 Lind

Avenue, SW., Renton, Washington; or at

the FAA, Los Angeles Aircraft

Certification Office, 3960 Paramount

Boulevard, Lakewood, California.

FOR FURTHER INFORMATION CONTACT:

Michael E. O’Neil, Aerospace Engineer,

Airframe Branch, ANM–120L, FAA, Los

Angeles Aircraft Certification Office,

3960 Paramount Boulevard, Lakewood,

California 90712–4137; telephone (562)

627–5320; fax (562) 627–5210.

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to

participate in the making of the

proposed rule by submitting such

written data, views, or arguments as

they may desire. Communications shall

identify the Rules Docket number and

be submitted in triplicate to the address

specified above. All communications

received on or before the closing date

for comments, specified above, will be

considered before taking action on the

proposed rule. The proposals contained

in this notice may be changed in light

of the comments received.

Submit comments using the following

format:

• Organize comments issue-by-issue.

For example, discuss a request to

change the compliance time and a

request to change the service bulletin

reference as two separate issues.

• For each issue, state what specific

change to the proposed AD is being

requested.

• Include justification (e.g., reasons or

data) for each request.

Comments are specifically invited on

the overall regulatory, economic,

environmental, and energy aspects of

the proposed rule. All comments

submitted will be available, both before

and after the closing date for comments,

in the Rules Docket for examination by

interested persons. A report

summarizing each FAA-public contact

concerned with the substance of this

proposal will be filed in the Rules

Docket.

Commenters wishing the FAA to

acknowledge receipt of their comments

submitted in response to this notice

must submit a self-addressed, stamped

postcard on which the following

statement is made: ‘‘Comments to

Docket Number 2000–NM–283–AD.’’

The postcard will be date stamped and

returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this

NPRM by submitting a request to the

FAA, Transport Airplane Directorate,

ANM–114, Attention: Rules Docket No.

2000–NM–283–AD, 1601 Lind Avenue,

SW., Renton, Washington 98055–4056.

Discussion

The FAA has conducted a design

review of McDonnell Douglas Model

DC–8 series airplanes modified in

accordance with STC SA1802SO

(originally issued to Rosembalm and

currently held by National Aircraft

Services, Inc. (NASI)) and has identified

several potential unsafe conditions.

[Results of this design review are

contained in ‘‘DC–8 Cargo Modification

Review Team Review of Rosenbalm

Supplemental Type Certificate

SA1802SO—Installation of a Cargo Door

and Interior, Final Report, Revision A,

dated November 29, 1999,’’ hereinafter

referred to as ‘‘the Design Review

Report,’’ which is included in the Rules

Docket for this notice of proposed

rulemaking (NPRM).) The modification

defined by STC SA421NW (also held by

NASI) is nearly identical to that defined

by STC SA1802SO; therefore, STC

SA421NW has the same potential unsafe

conditions. STC’s SA1802SO and

SA421NW specify a design for

installation of a main deck cargo door,

associated door cutout in the fuselage,

door system hydraulics, door indication

system, Class E compartment with a 9g

crash barrier, and cargo handling system

on McDonnell Douglas Model DC–8

series airplanes.

On June 28, 2000, the FAA issued

airworthiness directive (AD) 2000–09–

01 R1, amendment 39–11809 (65 FR

41869, June 7, 2000), which identifies

corrective action for the unsafe

conditions that relate to the hydraulic

and indication systems of the main deck

cargo door and provides for a means to

prevent pressurization to an unsafe level

if the main deck cargo door is not

closed, latched, and locked.

In the preamble of the NPRM for AD

2000–09–01 R1, the FAA indicated that

further rulemaking action was being

considered to address the potential

unsafe conditions on Model DC–8 series

airplanes modified in accordance with

STC’s SA1802SO and SA421NW that

relate to the unreinforced main deck

floor, main deck cargo door hinge,

fuselage structure in the area modified

by installation of a main deck cargo

door, 9g crash barrier, and fire/smoke

detection system. The FAA now has

determined that further rulemaking

action is indeed necessary, and this

NPRM follows from that determination.

Other Related Rulemaking

The FAA is considering further

rulemaking to address the remaining

potential unsafe condition that relates to

the fire/smoke detection system.

Cargo Modification Concerns

In early 1989, two transport airplane

accidents were attributed to cargo doors

coming open during flight. The first

accident involved a Boeing Model 747

series airplane in which the cargo door

separated from the airplane, and

damaged the fuselage structure, engines,

and passenger cabin. The second

accident involved a McDonnell Douglas

Model DC–9 series airplane in which

the cargo door opened but did not

separate from its hinge. The open door

disturbed the airflow over the

empennage, which resulted in loss of

flight control and consequent loss of the

airplane. Although cargo doors have

opened occasionally without mishap

shortly after the airplane was in flight,

these two accidents served to highlight

the extreme potential dangers associated

with the opening of a cargo door while

the airplane is in flight.

As a result of these cargo door

opening accidents, the Air Transport

Association (ATA) of America formed a

task force, including representatives of

Federal Register / Vol. 65, No. 188 / Wednesday, September 27, 2000 / Proposed Rules 58205

the FAA, to review the design,

manufacture, maintenance, and

operation of airplanes fitted with

outward opening cargo doors, and to

make recommendations to prevent

inadvertent cargo door openings while

the airplane is in flight. A design

working group was tasked with

reviewing 14 Code of Federal

Regulations (CFR) part 25.783 [and its

accompanying Advisory Circular (AC)

25.783–1, dated December 10, 1986]

with the intent of clarifying its contents

and recommending revisions to enhance

future cargo door designs. This design

group also was tasked with providing

specific recommendations regarding

design criteria to be applied to existing

outward opening cargo doors to ensure

that inadvertent openings would not

occur in the current transport category

fleet of airplanes.

The ATA task force made its

recommendations in the ‘‘ATA Cargo

Door Task Force Final Report,’’ dated

May 15, 1991 (hereinafter referred to as

‘‘the ATA Final Report’’). On March 20,

1992, the FAA acknowledged the ATA’s

recommendations and issued an FAA

memorandum (hereinafter referred to as

‘‘the FAA Memorandum’’) providing

additional guidance for purposes of

assessing the continuing airworthiness

of existing designs of outward opening

doors. The FAA Memorandum was not

intended to upgrade the certification

basis of the various airplanes, but rather

to identify criteria to evaluate potential

unsafe conditions identified on inservice airplanes.

Utilizing the applicable requirements

of Civil Air Regulations (CAR) part 4b

and the design criteria provided by the

FAA Memorandum, the FAA has

reviewed the original type design of

major transport airplanes, including

McDonnell Douglas Model DC–8 series

airplanes equipped with outward

opening doors, for any design deficiency

or service difficulty. Based on that

review, the FAA identified unsafe

conditions and issued, among others,

the following AD’s:

• For certain McDonnell Douglas

Model DC–9 series airplanes: AD 89–

11–02, amendment 39–6216 (54 FR

21416, May 18, 1989);

• For all Boeing Model 747 series

airplanes: AD 90–09–06, amendment

39–6581 (55 FR 15217, April 23, 1990);

• For certain McDonnell Douglas

Model DC–8 series airplanes: AD 89–

17–01 R1, amendment 39–6521 (55 FR

8446, March 8, 1990);

• For certain Boeing Model 747–100

and –200 series airplanes: AD 96–01–51,

amendment 39–9492 (61 FR 1703,

January 23, 1996);

• For certain Boeing Model 727–100

and –200 series airplanes: AD 96–16–08,

amendment 39–9708 (61 FR 41733,

August 12, 1996); and

• For certain McDonnell Douglas

Model DC–8 series airplanes: AD 2000–

09–01 R1, amendment 39–11809 (65 FR

41869, June 7, 2000).

FAA/Industry Collaborative Effort

In late 1997, the FAA informed the

STC holders and operators of Model

DC–8 series airplanes that it was

embarking on a review of Model DC–8

series airplanes that have been

converted from a passenger- to a cargocarrying (‘‘freighter’’) configuration by

STC. The FAA proposed at a subsequent

industry sponsored meeting in early

1998, that DC–8 operators and STC

holders work together to identify and

address potential safety concerns. This

suggestion to the affected industry

resulted in the creation of the DC–8

Cargo Conversion Joint Task Force (JTF)

(hereinafter referred to as ‘‘the JTF’’).

The current composition of the JTF

includes holders of each of the six STC’s

that address the installation of a main

deck cargo door in Model DC–8 series

airplanes and operators and lessors of

those modified airplanes. At the JTF’s

request, the FAA participates in its

meetings to offer counsel and guidance

with respect to the FAA’s regulatory

processes. The JTF is a clearinghouse for

the gathering and sharing of information

among the parties affected by the FAA

review of STC cargo conversions of

Model DC–8 series airplanes. The JTF

also is a liaison between the FAA,

operators, and STC holders.

The JTF has been working with the

FAA to provide data relating to the

number of STC-modified Model DC–8

series airplanes and operators of those

airplanes, and identified which

airplanes are modified by each STC. It

also was instrumental in polling the

operators and providing maintenance

schedules and locations to the FAA,

which helped the FAA arrange visits to

operators of airplanes modified by each

of the STC’s. These visits allowed the

FAA to review both the available data

supporting each STC and modified

airplanes and to identify potential safety

concerns with each of the STC

modifications. Additionally, the JTF has

coordinated funding of the industry

review of the data supporting the STC’s

and ongoing efforts to resolve safety

issues identified by the FAA.

Identification of Unsafe Conditions

Using the certification basis of the

airplane (i.e., CAR part 4b), the FAA, in

collaboration with the JTF, conducted

an engineering design review, inspected

an airplane modified in accordance with

STC SA1802SO, and identified a

number of design features of this STC

that are unsafe, which are applicable to

STC SA421NW, as well. The FAA

considers the following four specific

design deficiencies to be unsafe:

1. Main Deck Cargo Door and

Associated Fuselage Structure

The FAA, in collaboration with

structural engineering representatives of

the JTF, has identified several areas of

the main deck cargo door and door jamb

structure of STC’s SA1802SO and

SA421NW that require modification to

meet type design requirements. These

areas include the addition of structural

elements to augment and, in some

places, to add the structural capability

necessary to safely support design loads.

When taken individually, these areas do

not necessarily represent an unsafe

condition. However, the critical load

condition for each of the elements is the

same, so that all of the elements could

fail at the same time. Therefore, the

FAA has determined that the potential

of concurrent failure of several

structural elements presents an unsafe

condition for the airplane, and that

these elements require modification to

ensure the safety of the airplane.

The modifications include:

• Reinforcement of the fuselage door

jamb elements across the main deck

cargo door sill;

• Reinforcement of the shear transfer

capability between the door jamb frames

and the fuselage skin and doubler;

• Reinforcement of the inner cap of

the frame at fuselage station (FS) 1700;

• Replacement of existing fasteners in

the door side end segments of the hinge

with increased strength bolts;

• Reinforcement of the existing shear

transfer capability of the frames below

the main deck cargo door, as well as in

the door itself; and

• Reinforcement of the frames that

support the two latches at both ends of

the main deck cargo door.

As part of its continuing work to

maintain the structural integrity of older

transport category airplanes, in the early

1980’s, the FAA concluded that the

incidence of fatigue cracking may

increase as these airplanes continue in

service. In light of this, and as a result

of increased utilization, longer

operational lives, and the levels of

safety expected of the currently

operated transport category airplanes,

the FAA has determined that a damage

tolerance assessment of the structural

modifications associated with STC

SA1802SO is necessary to ensure the

structural integrity for all airplanes in

the affected fleet. This damage tolerance

58206 Federal Register / Vol. 65, No. 188 / Wednesday, September 27, 2000 / Proposed Rules

assessment is to identify any principal

structural elements (PSE), including the

associated inspection threshold,

inspection method, and repetitive

inspection interval, to ensure continued

operational safety of the airplane. The

PSE information must be identified in

any method of compliance presented to

address the requirements of the

proposed AD.

2. Main Deck Cargo Door Hinge

In order to avoid catastrophic

structural failure of outward opening

cargo doors, a typical industry approach

has been to design them and their

attaching structure to be fail safe (i.e.,

designed so that if a single structural

element fails, other structural elements

are able to carry the redistributed load).

The hinge installed by STC’s SA1802SO

and SA421NW is no exception.

However, based on the results of the

FAA’s and JTF’s structural evaluation of

the hinge of the subject STC’s, the FAA

has determined that the existing

fasteners attaching the two hinge

elements to the cargo door at both the

forward and aft ends of the hinge are

inadequate to carry the design loads.

Therefore, these fasteners must be

replaced with fasteners of sufficient

strength.

Structural elements, such as the main

deck cargo door hinge, are subject to

severe in-service operating conditions

that could result in corrosion, binding,

or seizure of the hinge. These

conditions, in addition to the normal

operational loads, can lead to early and

unpredictable fatigue cracking. A

possible consequence of the undetected

failure of hinge elements is the opening

of the main deck cargo door while the

airplane is in flight. Service experience

indicates that the opening of a cargo

door while the airplane is in flight can

be extremely hazardous in a variety of

ways including possible loss of flight

control, severe structural damage, or

rapid decompression, any of which

could lead to loss of the airplane.

Therefore, a detailed visual inspection

to detect cracks of the exposed surfaces

of the main deck cargo door hinge (both

fuselage and door side hinge elements)

is also necessary to ensure that the

affected airplanes are not in immediate

risk of hinge failure.

3. Capability of the Unmodified Floor

Based on the results of the FAA’s and

JTF’s structural evaluation of the main

deck cargo floor, the FAA has

determined that the unmodified main

deck cargo floor is not capable of safely

supporting the main deck zone loading

(cargo weight) currently allowed by

STC’s SA1802SO and SA421NW. There

are several methods to address the

unsafe condition. The floor beams and

their attachment to the fuselage frames

and struts, which support the floor

beams on either side of the fuselage,

could be modified to support the

currently acceptable main deck zone

loading. It is also possible to limit the

main deck zone loading to a level that

the main deck cargo floor can be

supported safely without modification.

A further possibility is to modify the

main deck cargo floor beams to a

configuration compatible with the

desired level of zone loading.

In assessing the load carrying

capability of the main deck cargo floor

for STC’s SA1802SO and SA421NW, the

manner in which the load is applied to

the floor, as well as the magnitude of

that load, must be considered. For

example, it is possible to directly place

the cargo onto the floor and secure it to

the floor in a safe manner. However,

most operators utilize a cargo handling

system installed in the airplane that

allows the use of unit load devices

(ULD), such as pallets and containers.

Together, the cargo handling system and

ULD’s expedite loading and unloading

of the airplanes. Technical Standard

Order (TSO) TSO–C90c, dated April 3,

1992, identifies both the ultimate loads

that the ULD’s produced under the TSO

must support, and the number and

location of restraints necessary to carry

those loads. The TSO requires

identification of the type and size of the

ULD’s. Although this TSO is the most

common method of approval for ULD’s,

it is not the only means of approving

ULD’s. ULD designs also may be

approved as part of a type certificate or

STC. Therefore, the total cargo weight,

distribution of cargo weight in the

airplane, and restraint requirements for

ULD’s must be identified in any method

of compliance presented to address the

requirements of the proposed AD.

During evaluations of Model 727 and

DC–8 series airplanes converted to a

freighter configuration by STC, the FAA

found instances where the existing

venting capability of certain airplanes

had been compromised by installation

of the Class E compartment. In some

cases, the vent area was decreased or

restricted during modification. The FAA

also found that the available design data

for the main deck cargo floor for STC’s

SA1802SO and SA421NW do not

demonstrate the adequacy of the venting

system of the modified DC–8 airplanes.

The FAA is concerned about the venting

between the main cabin floor and the

baggage compartments below the main

deck cargo floor in the event of a rapid

decompression. If the vent area of the

original type design has been decreased

or restricted during modification, the

loads on the main deck cargo floor may

be increased to an unsafe level during

a rapid decompression event. The

increased loads on the main deck cargo

floor could lead to collapse of the floor

beams. Collapse of the main deck cargo

floor could restrict the motion of the

flight and engine control cables routed

through the floor beams or could cause

the failure of those cables, which could

result in reduced controllability of the

airplane or loss of control. Rapid

decompression of the airplane could

result from a sufficiently large failure in

the fuselage pressure boundary either

above or below the main deck cargo

floor, such as inadvertent opening of the

cargo door.

Therefore, the FAA has determined

that an inspection and evaluation of the

affected floor structure must be

accomplished to ensure that the venting

capability of the passenger configuration

has not been compromised by

installation of the Class E compartment.

If the current venting capability of the

affected floor is less than that of the

passenger configuration, it must be

modified to limit decompression loads

to a level that can be supported

successfully by the existing floor

structure.

4. 9g Crash Barrier

In order to ensure the safety of

occupants during emergency landing

conditions, the FAA first established in

1934 a set of inertia load factors used to

design the structure for restraining items

of mass in the fuselage. Because the

airplane landing speeds have increased

over the years as the fleet has

transitioned from propeller to jet design,

inertia load factors were changed as

specified in CAR part 4b.260.

Experience has shown that an airplane

designed to this regulation has a

reasonable probability of protecting its

occupants from serious injury in an

emergency landing. The DC–8 passenger

airplane was designed to these criteria

that specified an ultimate inertia load

requirement of 9g in the forward

direction. These criteria were applied to

the seats and structure restraining the

occupants, including the flight crew, as

well as other items of mass in the

fuselage.

When a Model DC–8 series airplane is

converted from a passenger to a cargocarrying (‘‘freighter’’) configuration, a 9g

crash barrier is required, since most

cargo containers and container-to-floor

attaching devices are not designed to

withstand emergency landing loads. In

fact, the FAA estimates that the

container-to-floor attaching devices will

only support approximately 1.5g’s to

Federal Register / Vol. 65, No. 188 / Wednesday, September 27, 2000 / Proposed Rules 58207

3g’s in the forward direction. Without a

9g crash barrier, it is probable that the

loads associated with an emergency

landing would cause the cargo to

become unrestrained and impact the

occupants of the airplane, which could

result in serious injury to the occupants.

The structural inadequacy of the 9g

crash barrier was evident to the FAA

during its review in January 1999 of a

McDonnell Douglas Model DC–8

modified in accordance with STC

SA1802SO. The observations revealed

that the design of the crash barrier floor

attachment and circumferential

supporting structure neither provide

adequate strength to withstand the 9g

forward inertia load generated by the

main deck cargo mass, nor provide a

load path to effectively transfer the

loads from the crash barrier to the

fuselage structure of the airplane.

Therefore, the FAA has determined

that installation of a 9g crash barrier that

complies with the applicable

requirements of CAR part 4b is

necessary to prevent serious injury to

occupants of the airplane.

Development of Engineering Data

The FAA is aware that the JTF is

currently sponsoring an effort to

develop engineering data to address the

identified unsafe conditions of this

NPRM. The FAA is anticipating that this

effort will result in an STC that

addresses the proposed requirements of

this NPRM, and that this STC will be

made available to all operators.

Explanation of Requirements of

Proposed Rule

Since an unsafe condition has been

identified that is likely to exist or

develop on other products of this same

type design, the proposed AD would

require the following eight actions:

1. Incorporation of inspections into

the operator’s FAA-approved

maintenance or inspection program that

ensures the continued operational safety

of the airplane. These inspections

should be based on a damage tolerance

assessment that identifies any PSE

associated with the STC modification

and should include associated

inspection thresholds, inspection

methods, and repetitive inspection

intervals.

2. Modification of the main deck

cargo door structure and fuselage

structure immediately surrounding the

main deck cargo door to comply with

the applicable requirements of CAR part

4b.

3. A detailed visual inspection to

detect cracks of the exposed surfaces of

the main deck cargo door hinge (both

fuselage and door side hinge elements);

and repair or replacement of the hinge

element with a new, like part, if

necessary.

4. Replacement of the existing

fasteners in the two door-side hinge

elements at the forward and aft ends of

the hinge with fasteners of acceptable

strength.

5. An inspection and evaluation of the

cargo handling system to determine if

the side restraints provide the support

required by the ULD; and modification

of the vertical side restraint to provide

the support appropriate to the ULD’s

compatible with the cargo handling

system, if necessary.

6. Modification of the main deck

cargo floor to safely carry the applicable

FAA-approved payload limits for above

and below the main deck cargo floor.

The modification must comply with the

applicable requirements of CAR part 4b

for the FAA-approved payload

distribution.

7. An inspection and evaluation of the

venting system of the main deck cargo

floor to determine if the system limits

decompression loads to a level that can

be carried by the floor structure without

failure; and modification of the venting

system, as necessary, to limit the

decompression loads to a level that can

be supported successfully by the

existing floor structure, if necessary.

8. Installation of a main deck cargo 9g

crash barrier that complies with the

applicable requirements of CAR part 4b.

The actions described above would be

required to be accomplished in

accordance with a method approved by

the FAA.

Differences Between 727 and DC–8

NPRM Format

The format and content of this NPRM

differs from the following rulemaking

actions that address similar concerns for

Boeing Model 727 series airplanes that

have been modified to freighters by

STC:

• AD 98–26–18, amendment 39–

10961 (64 FR 1994, January 12, 1999);

• AD 98–26–19, amendment 39–

10962 (64 FR 2016, January 12, 1999);

• AD 98–26–20, amendment 39–

10963 (64 FR 2038, January 12, 1999);

• AD 98–26–21, amendment 39–

10964 (64 FR 2061, January 12, 1999);

and

• NPRM Rules Dockets 97–NM–232–

AD, 97–NM–233–AD, 97–NM–234–AD,

and 97–NM–235–AD.

However, the FAA used the same

criteria (i.e., CAR part 4b) for evaluation

of the subject Model 727 series airplanes

and Model DC–8 series airplanes

affected by this NPRM. The differences

in the subject rulemaking actions are

accounted for by the variance in the

design philosophies embraced by

Douglas (now Boeing) and Boeing.

The original floor beams for the DC–

8 passenger airplanes have a deeper

cross section, which reduces internal

stresses for the same applied bending

moment, than those for Model 727

series airplanes. Additionally, DC–8

passenger airplanes utilize intermediate

‘‘struts’’ between the main deck cargo

floor beams and fuselage frames below

the floor to help support the floor

beams, which decreases the

unsupported span. A shorter

unsupported span helps reduce the

bending moment for a given applied

load. The amount of design data

available to the FAA for review of each

of the DC–8 STC’s (i.e., SA1063SO,

SA10377SO, SA1802SO, SA1832SO,

SA1862SO, and SA00309AT) was

greater than that available when the

FAA issued the subject Model 727

NPRM’s and AD’s. Additionally, the JTF

has assisted the FAA in engineering

review of this greater volume of data

and in the creation of additional data

necessary for substantiation of the

existing designs. Based on the data

available for review, the margins of

safety of the DC–8 floor beams indicate

a lower level of immediate concern than

those margins indicated for the 727 floor

beams when the 727 AD’s and NPRM’s

were proposed. Therefore, the FAA has

determined that the type of restrictions

and interim floor loading and side

vertical restraint that were applied to

the 727 are not required for the subject

DC–8 STC’s.

To address the safety concerns of

Boeing Model 727 series airplanes that

have been modified to freighters by

STC, the FAA issued AD’s 98–26–19,

98–26–20, 98–26–21, and 98–26–22 to

address the capability of the main deck

cargo floor and then issued NPRM Rules

Dockets 97–NM–232–AD, 97–NM–233–

AD, 97–NM–234–AD, and 97–NM–235–

AD to address the door indicating

system and related systems issues;

means to prevent pressurization to an

unsafe level if the door is not closed,

latched, and locked; door hinge; and 9g

crash barrier. Because there have been

events involving the cargo door opening

in flight on the modified DC–8 series

airplanes, the FAA has issued the

following AD’s to address the door

indication system and other related

systems issues for those airplanes:

• AD 2000–09–01 R1, amendment

39–11809 (65 FR 41869, July 7, 2000);

• AD 2000–09–02, amendment 39–

11710 (65 FR 25437, May 2, 2000);

• AD 2000–13–03 R1, amendment

39–11865 (65 FR 49735, August 15,

2000); and

58208 Federal Register / Vol. 65, No. 188 / Wednesday, September 27, 2000 / Proposed Rules

• AD 2000–15–11, amendment 39–

11843 (65 FR 47660, August 3, 2000).

This DC–8 NPRM, and NPRM Rules

Dockets 2000–NM–280–AD, 2000–NM–

281–AD, and 2000–NM–282–AD would

address the structures issues, including

the main deck cargo floor, as discussed

previously.

Cost Impact

There are approximately 32 Model

DC–8 series airplanes of the affected

design in the worldwide fleet. The FAA

estimates that 29 airplanes of U.S.

registry would be affected by this

proposed AD. The following table

shows the estimated cost impact for

airplanes affected by this AD. The

average labor rate is $60 per work hour.

The estimated maximum total cost for

all airplanes affected by this proposed

AD is $6,718,140, or $231,660 per

airplane.

Action Work hours

(estimated)

Parts cost

(estimated)

Total cost

(estimated)

Incorporation of inspections into maintenance or inspection program .................... 8 N/A $13,920, or $480 per airplane.

Modification of main deck cargo door structure and fuselage structure .................. 1,420 $6,500 $2,659,300, or $91,700

per airplane.

Inspection of exposed surfaces of main deck cargo door hinge ............................. 16 N/A $27,840, or $960 per airplane.

Replacement of the existing fasteners in the two door-side hinge elements .......... 60 100 $107,300, or $3,700 per

airplane

Inspection and evaluation of the cargo handling system ......................................... 16 N/A $27,840, or $960 per airplane.

Modification of main deck cargo floor ...................................................................... 40 $500 $84,100, or $2,900 per airplane.

Inspection and evaluation of the venting system ..................................................... 16 N/A $27,840, or $960 per airplane.

Installation of main deck cargo 9g crash barrier ...................................................... 1,500 40,000 $3,770,000, or $130,000

per airplane.

The cost impact figures discussed

above are based on assumptions that no

operator has yet accomplished any of

the proposed requirements of this AD

action, and that no operator would

accomplish those actions in the future if

this proposed AD were not adopted. The

cost impact figures discussed in AD

rulemaking actions represent only the

time necessary to perform the specific

actions actually required by the AD.

These figures typically do not include

incidental costs, such as the time

required to gain access and close up,

planning time, or time necessitated by

other administrative actions.

Regulatory Impact

The regulations proposed herein

would not have a substantial direct

effect on the States, on the relationship

between the national Government and

the States, or on the distribution of

power and responsibilities among the

various levels of government. Therefore,

it is determined that this proposal

would not have federalism implications

under Executive Order 13132.

For the reasons discussed above, I

certify that this proposed regulation (1)

is not a ‘‘significant regulatory action’’

under Executive Order 12866; (2) is not

a ‘‘significant rule’’ under the DOT

Regulatory Policies and Procedures (44

FR 11034, February 26, 1979); and (3) if

promulgated, will not have a significant

economic impact, positive or negative,

on a substantial number of small entities

under the criteria of the Regulatory

Flexibility Act. A copy of the draft

regulatory evaluation prepared for this

action is contained in the Rules Docket.

A copy of it may be obtained by

contacting the Rules Docket at the

location provided under the caption

ADDRESSES.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation

safety, Safety.

The Proposed Amendment

Accordingly, pursuant to the

authority delegated to me by the

Administrator, the Federal Aviation

Administration proposes to amend part

39 of the Federal Aviation Regulations

(14 CFR part 39) as follows:

PART 39—AIRWORTHINESS

DIRECTIVES

1. The authority citation for part 39

continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.

§ 39.13 [Amended]

2. Section 39.13 is amended by

adding the following new airworthiness

directive:

McDonnell Doublas: Docket 2000–NM–

283–AD.

Applicability: Model DC–8 series airplanes

that have been converted from a passengerto a cargo-carrying (‘‘freighter’’) configuration

in accordance with Supplemental Type

Certificate (STC) SA1802SO or SA421NW;

certificated in any category.

Note 1: This AD applies to each airplane

identified in the preceding applicability

provision, regardless of whether it has been

otherwise modified, altered, or repaired in

the area subject to the requirements of this

AD. For airplanes that have been modified,

altered, or repaired so that the performance

of the requirements of this AD is affected, the

owner/operator must request approval for an

alternative method of compliance in

accordance with paragraph (h) of this AD.

The request should include an assessment of

the effect of the modification, alteration, or

repair on the unsafe condition addressed by

this AD; and, if the unsafe condition has not

been eliminated, the request should include

specific proposed actions to address it.

Compliance: Required as indicated, unless

accomplished previously.

To prevent opening of the cargo door while

the airplane is in flight or collapse of the

main deck cargo floor, and consequent rapid

decompression of the airplane including

possible loss of flight control or severe

structural damage, accomplish the following:

Actions Addressing the Main Deck Cargo

Door and Associated Fuselage Structure

(a) Accomplish the actions specified in

paragraphs (a)(1) and (a)(2) of this AD in

accordance with a method approved by the

Manager, Los Angeles Aircraft Certification

Office (ACO), FAA.

(1) Within 1 year or 1,200 flight cycles after

the effective date of this AD, whichever

occurs first, incorporate inspections into the

operator’s FAA-approved maintenance or

inspection program that ensure the continued

operational safety of the airplane. These

inspections should be based on a damage

tolerance assessment that identifies any

principal structural element (PSE) associated

with the STC modification and should

include associated inspection thresholds,

inspection methods, and repetitive

inspection intervals.

(2) Within 3 years or 4,000 flight cycles

after the effective date of this AD, whichever

Federal Register / Vol. 65, No. 188 / Wednesday, September 27, 2000 / Proposed Rules 58209

occurs first, accomplish the actions specified

in paragraphs (a)(2)(i) and (a)(2)(ii) of this

AD.

(i) Modify the main deck cargo door

structure and fuselage structure immediately

surrounding the main deck cargo door to

comply with the applicable requirements of

Civil Air Regulations (CAR) part 4b.

(ii) Incorporate inspections into the

operator’s FAA-approved maintenance or

inspection program that ensure the continued

operational safety of the airplane. These

inspections should be based on a damage

tolerance assessment that identifies any PSE

associated with the STC modification

required by paragraph (a)(2)(i) of this AD and

should include associated inspection

thresholds, inspection methods, and

repetitive inspection intervals.

Actions Addressing the Main Deck Cargo

Floor

(b) Within 2 years or 2,000 flight cycles

after the effective date of this AD, whichever

occurs first, perform an inspection and

evaluation of the cargo handling system to

determine if the side restraints provide the

support required by the unit load device

(ULD), in accordance with a method

approved by the Manager, Los Angeles ACO.

If any vertical side restraint does not provide

the required support, within 2 years or 2,000

flight cycles after the effective date of this

AD, whichever occurs first, modify the

vertical side restraint to provide the support

appropriate to the ULD’s compatible with the

cargo handling system, in accordance with a

method approved by the Manager, Los

Angeles ACO.

(c) Within 3 years or 4,000 flight cycles

after the effective date of this AD, whichever

occurs first, modify the main deck cargo floor

to safely carry the applicable FAA-approved

payload limits for above and below the main

deck cargo floor. The modification and

payload distribution shall be accomplished

in accordance with a method approved by

the Manager, Los Angeles ACO. The

modification must comply with the

applicable requirements of CAR part 4b for

the FAA-approved payload distribution.

(d) Except for those airplanes that have

been modified in accordance with paragraph

(c) of this AD, within 1 year or 1,000 flight

cycles after the effective date of this AD,

whichever occurs first, perform an inspection

and evaluation of the venting system of the

main deck cargo floor to determine if the

system limits decompression loads to a level

that can be carried by the floor structure

without failure, in accordance with a method

approved by the Manager, Los Angeles ACO.

(e) If, based on the evaluation required by

paragraph (d) of this AD, the venting system

does not limit decompression loads to a level

that can be carried by the floor structure

without failure, within 2 years after the

effective date of this AD, modify the venting

system, as necessary, to limit the

decompression loads to a level that can be

supported successfully by the existing floor

structure, in accordance with a method

approved by the Manager, Los Angeles ACO.

Actions Addressing Main Deck Cargo Door

Hinge

(f) Accomplish the actions specified in

paragraphs (f)(1) and (f)(2) of this AD in

accordance with a method approved by the

Manager, Los Angeles ACO.

(1) Within 250 flight hours after the

effective date of this AD, perform a detailed

visual inspection to detect cracks of the

exposed surfaces of the main deck cargo door

hinge (both fuselage and door side hinge

elements). If any crack is detected, prior to

further flight, repair in accordance with a

method approved by the Manager, Los

Angeles ACO, or replace the cracked hinge

element with a new, like part.

Note 2: For the purposes of this AD, a

detailed visual inspection is defined as: ‘‘An

intensive visual examination of a specific

structural area, system, installation, or

assembly to detect damage, failure, or

irregularity. Available lighting is normally

supplemented with a direct source of good

lighting at intensity deemed appropriate by

the inspector. Inspection aids such as mirror,

magnifying lenses, etc., may be used. Surface

cleaning and elaborate access procedures

may be required.’’

(2) Within 2 years or 2,000 flight hours

after the effective date of this AD, whichever

occurs first, replace the existing fasteners in

the two door-side hinge elements at the

forward and aft ends of the hinge with

fasteners of acceptable strength.

Actions Addressing Main Deck Cargo 9g

Crash Barrier

(g) Within 3 years or 4,000 flight cycles

after the effective date of this AD, whichever

occurs first, install a main deck cargo 9g

crash barrier that complies with the

applicable requirements of CAR part 4b, in

accordance with a method approved by the

Manager, Los Angeles ACO.

Alternative Methods of Compliance

(h) An alternative method of compliance or

adjustment of the compliance time that

provides an acceptable level of safety may be

used if approved by the Manager, Los

Angeles ACO, FAA. Operators shall submit

their requests through an appropriate FAA

Principal Maintenance Inspector, who may

add comments and then send it to the

Manager, Los Angeles ACO.

Note 3: Information concerning the

existence of approved alternative methods of

compliance with this AD, if any, may be

obtained from the Los Angeles ACO.

Special Flight Permit

(i) Special flight permits may be issued in

accordance with sections 21.197 and 21.199

of the Federal Aviation Regulations (14 CFR

21.197 and 21.199) to operate the airplane to

a location where the requirements of this AD

can be accomplished.

Issued in Renton, Washington, on

September 21, 2000.

Donald L. Riggin,

Acting Manager, Transport Airplane

Directorate, Aircraft Certification Service.

[FR Doc. 00–24746 Filed 9–26–00; 8:45 am]

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