Airworthiness Directives; Boeing Model 747 Series Airplanes Equipped With General Electric CF6-45 or CF6-50 Engines or Pratt & Whitney JT9D Series Engines

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94-NM-52-AD]

Airworthiness Directives; Boeing Model 747 Series Airplanes

Equipped With General Electric CF6-45 or CF6-50 Engines or Pratt &

Whitney JT9D Series Engines

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 Boeing Model 747 series

airplanes. This proposal would require installation of a seal on the

wing front spar at each engine strut. This proposal is prompted by a

report of a fire that occurred due to fuel leakage from the fuel line

coupling in the engine strut area along with the wing front spar while

the airplane was on the ground after engine shutdown. The actions

specified by the proposed AD are intended to ensure that fuel is

contained within the strut drainage area and channeled away from

ignition sources.

DATES: Comments must be received by August 3, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 94-NM-52-AD, 1601 Lind Avenue SW., Renton,

Washington 98055-4056. Comments may be inspected at this location

between 9 a.m. and 3 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:

G. Michael Collins, Aerospace Engineer, Propulsion Branch, ANM-140S,

FAA, Transport Airplane Directorate, Seattle Aircraft Certification

Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone

(206) 227-2689; 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 proposal 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-52-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-52-AD, 1601 Lind Avenue SW., Renton, Washington 98055-

4056.

Discussion

The FAA has received a report of a strut fire that occurred due to

fuel leakage from the fuel line (Wiggins) coupling in the engine strut

area of a Boeing Model 747 series airplane that was on the ground. Fuel

leaked from the fuel line coupling and flowed along the wing front

spar. After engine shutdown, fuel dripped from the wing onto the engine

exhaust section and ignited. The flame also ignited fuel that was

contained in the strut. This condition, if not corrected, could result

in a strut fire.

Although airflow when the airplane is in flight or airflow from the

engine running when the airplane is on the ground prevents fuel from

leaking onto hot engine surfaces, the FAA has determined that a

potential unsafe condition exists because a fire can occur after engine

shutdown.

The FAA has reviewed and approved Boeing Service Bulletin 747-28-

2160, Revision 1, dated December 16, 1993, that describes procedures

for installing a seal on the wing front spar at each engine strut.

Installation of this seal will contain fuel leaks within the strut

drainage area and channel any leakage away from ignition sources.

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 installation of a seal on the wing front spar

at each engine strut. The actions would be required to be accomplished

in accordance with the service bulletin described previously.

There are approximately 610 Boeing Model 747 series airplanes of

the affected design in the worldwide fleet. The FAA estimates that 183

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

it would take approximately 14 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 $57 per airplane. Based

on these figures, the total cost impact of the proposed AD on U.S.

operators is estimated to be $151,341, or $827 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 14

CFR part 39 of the Federal Aviation Regulations 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-52-AD.

Applicability: Model 747 series airplanes, equipped with General

Electric CF6-45 or CF6-50 engines, or Pratt & Whitney JT9D series

engines; as listed in Boeing Service Bulletin 747-28-2160, Revision

1, dated December 16, 1993; certificated in any category.

Compliance: Required as indicated, unless accomplished

previously.

To ensure that fuel is contained within the strut drainage area

and channeled away from ignition sources, accomplish the following:

(a) Within 12 months after the effective date of this AD,

install a seal on the wing front spar at each engine strut in

accordance with Boeing Service Bulletin 747-28-2160 dated July 23,

1992, or Revision 1, dated December 16, 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 June 3, 1994.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-14019 Filed 6-8-94; 8:45 am]

BILLING CODE 4910-13-M