[Federal Register Volume 66, Number 210 (Tuesday, October 30, 2001)]
[Proposed Rules]
[Pages 54727-54729]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-27189]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2001-NM-93-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 777-200 Series Airplanes 
Equipped With General Electric Engines

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 all Boeing Model 777-200 series 
airplanes equipped with General Electric engines. This proposal would 
require installation of a high-temperature silicone foam seal on the 
aft fairing of the strut. This action is necessary to prevent primary 
engine exhaust from entering the aft fairing of the strut, elevating 
the temperature in the aft fairing of the strut, and creating a 
potential source of ignition, which could lead to an uncontrolled fire 
in the aft fairing of the strut. Such a fire would expose the wing fuel 
tank to high-temperature gasses and flames and result in a potential 
ignition source for the fuel tank, and reduced structural integrity of 
the wing. This action is intended to address the identified unsafe 
condition.

DATES: Comments must be received by December 14, 2001.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2001-NM-93-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. Comments may be submitted via fax to (425) 227-1232. 
Comments may also be sent via the Internet using the following address: 
[email protected]. Comments sent via fax or the Internet must 
contain ``Docket No. 2001-NM-93-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.
    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: John Vann, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification 
Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone 
(425) 227-1024; fax (425) 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 action 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 2001-NM-93-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. 2001-NM-93-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

[[Page 54728]]

Discussion

    The FAA has received reports that, during routine inspections of 
the aft fairing of the strut, evidence of an elevated temperature in 
the interior cavity of the aft fairing has been found on several Boeing 
Model 777-200 series airplanes equipped with General Electric engines. 
The evidence includes charred seals, soot build-up, and discoloration. 
Investigation revealed that primary engine exhaust entering through a 
gap in the heat shield of the aft fairing of the strut elevates the 
temperature in the aft fairing. The aft fairing of the strut is a 
flammable leakage zone. An elevated temperature in this area would 
create a potential source of ignition, and an ignition source is not 
allowed to exist in a flammable leakage zone because there is no 
provision for detecting or extinguishing a fire in these zones. A 
potential source of ignition due to an elevated temperature in the aft 
fairing of the strut, if not corrected, could result in an uncontrolled 
fire in the aft fairing of the strut. Such a fire would expose the wing 
fuel tank to high-temperature gasses and flames and result in a 
potential ignition source for the fuel tank, and reduced structural 
integrity of the wing.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Alert Service Bulletin 
777-54A0015, dated January 18, 2001, which describes procedures for 
installation of a high-temperature silicone foam seal to fill the gap 
in the heat shield of the aft fairing of the strut on the left- and 
right-hand sides of the airplane. The procedures involve removing 
certain heat shield castings for the aft fairing of the strut, cleaning 
the area, bonding a foam seal to the upper surface of the heat shield 
cover plates, re-installing the heat shield castings, restoring the 
leveling compound and seal application, and doing a leak check of the 
aft fairing.

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 accomplishment of the actions specified in 
the service bulletin described previously, except as discussed below.

Difference Between Proposed AD and Service Bulletin

    The referenced service bulletin states that all actions for which 
the Boeing 777 Airplane Maintenance Manual (AMM) is specified as the 
appropriate source of service information for work instructions may 
instead be done according to an ``operator's equivalent procedure.'' 
However, the FAA finds that Chapter 54-55-01 of the AMM must be used to 
accomplish the leak check of the aft fairing of the strut, which is 
specified in the Work Instructions in the service bulletin. For this 
leak check, an ``operator's equivalent procedure'' may be used only if 
approved as an alternative method of compliance per paragraph (c) of 
this AD.

Interim Action

    This is considered to be interim action until final action is 
identified, at which time the FAA may consider further rulemaking.

Cost Impact

    There are approximately 97 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 18 airplanes of U.S. registry 
would be affected by this proposed AD, that it would take approximately 
15 work hours per airplane to accomplish the proposed actions, and that 
the average labor rate is $60 per work hour. Based on these figures, 
the cost impact of the proposed AD on U.S. operators is estimated to be 
$16,200, or $900 per airplane.
    The 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 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.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

Boeing: Docket 2001-NM-93-AD.
    Applicability: Model 777-200 series airplanes equipped with 
General Electric engines, certificated in any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
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 (c) 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 primary engine exhaust from entering the aft fairing 
of the strut, elevating the temperature in the aft fairing of the 
strut, and creating a potential source of ignition, which could lead 
to an uncontrolled fire in the aft fairing of the strut and exposure 
of the wing fuel tank to high-temperature gasses and flames, and 
result in a potential ignition source for the fuel tank and reduced 
structural integrity of the wing, accomplish the following:

[[Page 54729]]

Installation of Seal

    (a) Within 1,000 flight hours after the effective date of this 
AD, install a high-temperature silicone foam seal to fill the gap in 
the heat shield of the aft fairing of the strut on the left- and 
right-hand sides of the airplane. Do the installation according to 
Boeing Alert Service Bulletin 777-54A0015, dated January 18, 2001, 
except as provided by paragraph (b) of this AD. (Procedures for the 
installation include removing certain heat shield castings for the 
aft fairing of the strut, cleaning the area, bonding a foam seal to 
the upper surface of the heat shield cover plates, re-installing the 
heat shield castings, restoring the leveling compound and seal 
application, and doing a leak check of the aft fairing.)

``Operator's Equivalent Procedure''

    (b) Though Boeing Alert Service Bulletin 777-54A0015, dated 
January 18, 2001, specifies that an ``operator's equivalent 
procedure'' may be used for the leak check described in the service 
bulletin, that leak check must be done according to Chapter 54-55-01 
of the Boeing 777 Airplane Maintenance Manual, as specified in the 
service bulletin.

Alternative Methods of Compliance

    (c) 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. 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 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

Special Flight Permits

    (d) 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 October 23, 2001.
Ali Bahrami,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-27189 Filed 10-29-01; 8:45 am]
BILLING CODE 4910-13-P