Airworthiness Directives; Boeing Model 747-300 and -400 Series Airplanes Equipped With BFGoodrich Stretched Upper Deck Evacuation Slides, Part Number 7A1323-( )

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94-NM-153-AD]

Airworthiness Directives; Boeing Model 747-300 and -400 Series

Airplanes Equipped With BFGoodrich Stretched Upper Deck Evacuation

Slides, Part Number 7A1323-( )

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness

directive (AD) that is applicable to Boeing Model 747-300 and -400

series airplanes equipped with certain stretched upper deck evacuation

slides manufactured by BFGoodrich. This proposal would require

modification of the slide's main restraint strap, regulator assembly,

and turbo fan flapper retaining roll pins. This proposal is prompted by

reports of loss of air pressure and non-inflation of the inflatable

tubes of the slide due to problems associated with the restraint strap,

regulator assembly, and turbo fan flapper retaining roll pins. The

actions specified by the proposed AD are intended to prevent loss of

air pressure or non-inflation of the inflatable tubes of the slide,

which could impede the successful evacuation of passengers from the

airplane during an emergency.

DATES: Comments must be received by January 26, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Transport Airplane Directorate, ANM-103,

Attention: Rules Docket No. 94-NM-153-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.

The service information referenced in the proposed rule may be

obtained from BFGoodrich Company, Aircraft Evacuation Systems, Dept.

7916, Phoenix , Arizona 85040. This information may be examined at the

FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton,

Washington; or at the FAA, Los Angeles Aircraft Certification Office,

Transport Airplane Directorate, 3229 East Spring Street, Long Beach,

California.

FOR FURTHER INFORMATION CONTACT: Andrew Gfrerer, Aerospace Engineer,

Systems & Equipment Branch, ANM-130L, Los Angeles Aircraft

Certification Office, 3229 East Spring Street, Long Beach, California

90806-2425; telephone (310) 988-5338; fax (310) 988-5210.

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.

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 94-NM-153-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-103, Attention: Rules

Docket No. 94-NM-153-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

The FAA has received reports of various problems involving

BFGoodrich stretched upper deck evacuation slides, part number (P/N)

7A1323-( ), installed on Boeing Model 747-300 and -400 series

airplanes:

There have been several incidents in which the main restraint strap

of the slide was ingested into one of the turbo fans. This resulted in

damage to the turbo fan and loss of air pressure in one tube of the

slide.

There have been two occurrences of the inflation system regulator

shutting down due to internal pressure differentials. These incidents

resulted in non-inflation of one inflatable tube of the slide.

There has been a report that, during deployment of the slide, the

turbo fan flapper retaining roll pin broke, allowing the flapper to

fall out. This resulted in the loss of air pressure in the inflation

tube. The cause of the broken pin was determined to be the particular

heat treatment used during manufacture of a certain lot of roll pins.

Loss of air pressure or non-inflation of the inflation tubes of an

evacuation slide, if not corrected, could impede the successful

evacuation of passengers from the airplane during an emergency.

The FAA has reviewed and approved BFGoodrich Service Bulletin

7A1323-25-266, Revision 1, dated September 30, 1994, which describes

procedures for the following modifications:

1. Relocating the slide's elastic cord ``bungee strap'' attachment

point and shortening the elastic cord. This will prevent the main

restraint strap of the slide from being ingested into the turbo fan.

2. Modifying and making other changes to the regulator assembly,

such as modifying the regulator cartridge engagement sleeve by the

addition of drilled holes to prevent the potential for pressure

differentials that could cause the regulator to shut down; installing a

revised burst disk to prevent galling when tightening the cartridge

assembly; changing the type of lubricant to reduce friction forces; and

installing a new regulator release pin with a baked-on lubricant to

provide a consistent release force.

3. Replacing the turbo fan flapper retaining roll pins. This will

prevent breakage of the pins, thereby preventing the possibility of the

flapper falling out.

4. Replacing the original bottle relief valve assembly (P/N 5A2644-

4) with a safety plug assembly (P/N 3A3259-3); and adding a charge

fitting on the reservoir safety plug assembly to allow for bottle

charging after the modifications described above have been

accomplished.

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 modifying the stretched upper deck evacuation

slide by relocating the elastic cord ``bungee strap'' attachment point

and shortening the elastic cord; modifying the regulator assembly; and

replacing the turbo fan flapper retaining roll pins. The actions would

be required to be accomplished in accordance with the service bulletin

described previously.

Operators should note that this proposed AD is applicable to the

manufacturer of the airplane model on which the evacuation slides are

installed, rather than to the manufacturer of the slide. The FAA's

general policy is that, when an unsafe condition results from the

installation of an appliance or other item that is installed in only

one particular make and model of aircraft, the AD is issued so that it

is applicable to the aircraft, rather than the item. The reason for

this is simple: Making the AD applicable to the airplane model on which

the item is installed ensures that operators of those airplanes will be

notified directly of the unsafe condition and the action required to

correct it. While it is assumed that an operator will know the models

of airplanes that it operates, there is a potential that the operator

will not know or be aware of specific items that are installed on its

airplanes. Therefore, calling out the airplane model as the subject of

the AD prevents ``unknowing non-compliance'' on the part of the

operator.

(The FAA recognizes that there are situations when an unsafe condition

exists in an item that is installed in many different aircraft. In

those cases, the FAA considers it impractical to issue AD's against

each aircraft; in fact, many times, the exact models and numbers of

aircraft on which the item is installed may not be known. Therefore, in

those situations, the AD is issued so that it is applicable to the

item; furthermore, those AD's usually indicate that the item is known

to be installed on, but not limited to, various aircraft models.)

There are approximately 900 BFGoodrich stretched upper deck

evacuation slides of the affected design installed on Boeing Model 747

series airplanes worldwide. The FAA estimates that 100 of these slides

are installed on airplanes of U.S. registry that would be affected by

this proposed AD. It would take approximately 4.5 work hours per slide

to accomplish the proposed actions, and that the average labor rate is

$60 per work hour. Required parts would cost approximately $1,402 per

slide assembly. Based on these figures, the total cost impact of the

proposed AD on U.S. operators is estimated to be $167,200, or $1,672

per slide.

The total cost impact figure discussed above is 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 AD were not adopted.

The regulations proposed herein would not have substantial direct

effects 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, in

accordance with Executive Order 12612, it is determined that this

proposal would not have sufficient federalism implications to warrant

the preparation of a Federalism Assessment.

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. App. 1354(a), 1421 and 1423; 49 U.S.C.

106(g); and 14 CFR 11.89.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding the following new

airworthiness directive:

Boeing: Docket 94-NM-153-AD.

Applicability: Model 747-300 and -400 series airplanes equipped

with BFGoodrich stretched upper deck evacuation slides, part number

(P/N) 7A1323-1, -2, -3, -4, -105, -106, -107, -108, -109, or -110;

certificated in any category.

Compliance: Required as indicated, unless accomplished

previously.

To prevent loss of air pressure or non-inflation of the

inflation tubes of an evacuation slide, which could impede the

evacuation of passengers from the airplane during an emergency,

accomplish the following:

(a) Within 36 months after the effective date of this AD, modify

the BFGoodrich stretched upper deck evacuation slide, P/N 7A1323-(

), in accordance with the Accomplishment Instructions of BFGoodrich

Service Bulletin 7A1323-25-266, Revision 1, dated September 30,

1994.

Note 1: Installation of the ``product improvements,'' specified

in paragraph 2.J. of the Accomplishment Instructions of the service

bulletin, is not required by this AD.

(b) 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 Aircraft Certification

Office (ACO), FAA, Transport Airplane Directorate. 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 2: Information concerning the existence of approved

alternative methods of compliance with this AD, if any, may be

obtained from the Los Angeles ACO.

(c) Special flight permits may be issued in accordance with

Secs. 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 November 23, 1994.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-29438 Filed 11-29-94; 8:45 am]

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