Airworthiness Directives; Boeing Model 737 Series Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94-NM-80-AD]

Airworthiness Directives; Boeing Model 737 Series Airplanes

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 certain Boeing Model 737 series

airplanes. This proposal would require modification of certain number 2

galley upper attachment support structure. This proposal is prompted by

results of engineering tests and analyses which revealed that certain

upper attachment support structure of the number 2 galley is unable to

support certain loads that may occur during emergency landing

conditions. If the galley support breaks, the galley may shift and

cause blockage of the forward service door. The actions specified by

the proposed AD are intended to prevent inability of passengers and

crew to exit the airplane through this door after an emergency landing.

DATES: Comments must be received by October 27, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 94-NM-80-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 Boeing Commercial Airplane Group, P.O. Box 3707, Seattle,

Washington 98124-2207. This information may be examined at the FAA,

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

Washington.

FOR FURTHER INFORMATION CONTACT: Thomas Rodriguez, Aerospace Engineer,

Airframe Branch, ANM-120S, Seattle Aircraft Certification Office, FAA,

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

Washington 98055-4056; telephone (206) 227-2779; fax (206) 227-1181.

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-80-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-80-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion -

The FAA has received results of engineering tests and subsequent

analyses, which revealed that certain number 2 galley upper attachment

structure will not support loads generated under emergency landing

conditions. Airplanes having rectangular airplane intercostal support

structure from Body Station (BS) 344 to BS 360 (inclusive) with number

2 galleys exceeding 1,170 pounds (including any attached equipment that

may impose loads on the galley), or airplanes having triangular

intercostal support structure from BS 344 to BS 360 (inclusive) with

number 2 galleys exceeding 1,050 pounds (including any attached

equipment which may impose loads on the galley) will not support the

load generated under emergency landing conditions as specified by the

Federal Aviation Regulations (FAR). If the galley support structure

breaks, the galley may shift and cause blockage of the forward service

door. This condition, if not corrected, could result in the inability

of passengers and crew to exit the airplane using the galley door after

an emergency landing. -

The FAA has reviewed and approved Boeing Service Bulletin 737-53-

1154, dated November 11, 1993, which describes procedures for adding

new shear ties to the BS 360 frame and changing the intercostals

between BS 344 and BS 360 (inclusive) on certain airplanes. The purpose

of this modification is to strengthen the airplane support structure

when the weight of galley number 2 exceeds limits described in the

service bulletin. Accomplishment of the actions described in this

service bulletin will ensure that the galley support structure can

withstand 9G forward load in the event of an emergency landing. -

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 modification of the airplane support

structure from BS 344 to BS 360 (inclusive) for airplanes where the

number 2 galley exceeds certain weight limits. The actions would be

required to be accomplished in accordance with the service bulletin

described previously. -

There are approximately 613 Model 737 series airplanes of the

affected design in the worldwide fleet. The FAA estimates that 139

airplanes of U.S. registry would be affected by this proposed AD, that

it would take approximately 64 work hours per airplane to accomplish

the proposed actions, and that the average labor rate is $55 per work

hour. Required parts would cost approximately $1,205 per airplane.

Based on these figures, the total cost impact of the proposed AD on

U.S. operators is estimated to be $656,775, or $4,725 per airplane. -

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-80-AD.

-Applicability: Model 737 series airplanes; as listed in Boeing

Service Bulletin 737-53-1154, dated November 11, 1993; equipped with

rectangular intercostal support structures from Body Station (BS)

344 to BS 360 (inclusive) and a number 2 galley weight exceeding

1,170 pounds (including any attached equipment that imposes loads on

the galley), or equipped with triangular intercostal support

structures from BS 344 to BS 360 (inclusive) and a number 2 galley

weight exceeding 1,050 pounds (including any attached equipment that

imposes loads on the galley); certificated in any category. -

Compliance: Required as indicated, unless accomplished

previously. -

To prevent inability of passengers and crew to exit the forward

service door during an emergency landing condition, accomplish the

following: -

(a) Within 18 months after the effective date of this AD, modify

the airplane support structure from BS 344 to BS 360 (inclusive), in

accordance with Boeing Service Bulletin 737-53-1154, dated November

11, 1993. -

(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, Seattle 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, Seattle ACO.

-Note: Information concerning the existence of approved

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

obtained from the Seattle ACO.

-(c) 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 August 26, 1994.

N.B. Martenson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-21581 Filed 8-31-94; 8:45 am]

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