[Federal Register Volume 67, Number 68 (Tuesday, April 9, 2002)]
[Rules and Regulations]
[Pages 16991-16994]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-8280]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2002-NM-30-AD; Amendment 39-12701; AD 2002-07-07]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 777-200 Series Airplanes 
Equipped With General Electric GE90 Series Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
is applicable to certain Boeing Model 777-200 series airplanes equipped 
with General Electric GE90 series engines. This action requires 
repetitive inspections of the diagonal brace and forward seals of the 
aft fairing of the strut to find discrepancies, and corrective actions, 
if necessary. This action is necessary to prevent primary engine 
exhaust from entering the aft fairing of the strut and elevating the 
temperature, which could lead to heat damage of the seals and diagonal 
brace. Such damage could result in cracking and fracture of the forward 
attachment point of the diagonal brace, loss of the diagonal brace load 
path, and consequent separation of the strut and engine from the 
airplane. This action is intended to address the identified unsafe 
condition.

DATES: Effective April 24, 2002.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of April 24, 2002.
    Comments for inclusion in the Rules Docket must be received on or 
before June 10, 2002.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2002-NM-

[[Page 16992]]

30-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: [email protected]. 
Comments sent via fax or the Internet must contain ``Docket No. 2002-
NM-30-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 this AD 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; or at 
the Office of the Federal Register, 800 North Capitol Street, NW., 
suite 700, Washington, DC.

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: 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 GE90 series engines. One operator reported significant 
heat damage to the forward end of the diagonal brace on the left strut 
of a General Electric GE90 powered airplane. The diagonal brace 
material is aluminum 7075-T73, with a specified conductivity range of 
38.0 through 42.5 percent International Annealed Copper Standard 
(IACS). The damaged brace assembly had a conductivity reading of 47 
percent IACS. Investigation revealed that the damage was caused by 
primary engine exhaust entering the aft fairing of the strut through a 
gap in the heat shield and elevating the temperature, resulting in heat 
damage to the primary fire seal, heat shield seal, and secondary fluid 
seal. The damaged seals allowed the exhaust to pass into the aft 
fairing cavity causing heat damage to the diagonal brace assembly. Such 
damage, if not found and fixed, could result in cracking and fracture 
of the forward attachment point of the diagonal brace, loss of the 
diagonal brace load path, and consequent separation of the strut and 
engine from the airplane.

Related Rulemaking

    In light of this AD, the FAA is considering withdrawing Notice of 
Proposed Rulemaking (NPRM) 2001-NM-93-AD (66 FR 54727, October 30, 
2001). That NPRM proposed to require installation of a high temperature 
silicone foam seal to fill the gap in the strut aft fairing fire seal 
and firewall.
    Since the issuance of that NPRM, the FAA has received new 
information that indicates that the unsafe condition would not be 
prevented by the installation of the high temperature silicone foam 
seal alone. Of primary importance is the integrity of the existing 
primary fire, heat shield, and secondary fluid seals to prevent heat 
damage to the diagonal brace. This AD is being issued to require the 
inspection and maintenance of those existing seals, in addition to the 
inspection and maintenance of the diagonal brace. The installation of 
the high temperature silicone foam seal recommended in Boeing Service 
Bulletin 777-54A0015, dated January 18, 2001 (referenced in the NPRM as 
the appropriate source of service information for accomplishment of the 
specified actions), is not currently being mandated, and the FAA is 
considering withdrawal of the NPRM.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Alert Service Bulletin 
777-54A0017, dated December 21, 2001, which describes the following 
procedures:
     Part 1 of the service bulletin specifies repetitive 
detailed inspections of the diagonal brace and forward seals of the aft 
fairing of the strut to find discrepancies, and corrective actions, if 
necessary. The discrepancies include heat damage to the diagonal brace 
and/or forward seals, and cracks and/or fracture of the diagonal brace. 
Part 1 also specifies either replacing the diagonal brace per Part 4 of 
the service bulletin if any crack or fracture is found, or contacting 
Boeing for rework instructions.
     If necessary, due to findings from the detailed inspection 
specified in Part 1 of the service bulletin, Part 2 of the service 
bulletin specifies a conductivity inspection to verify the conductivity 
of the diagonal brace material. If the diagonal brace is within the 
specified conductivity limits (38.0 through 42.5 percent IACS), the 
detailed inspection specified in Part 1 is repeated. If the diagonal 
brace is not within the specified conductivity limits (greater than 
42.5 percent and less than or equal to 44 percent IACS), Part 2 
specifies inspecting the strut to wing attachments and reworking if 
additional damage is found, and within 18 months, replacing the 
diagonal brace. If the conductivity limit is greater than 44 percent 
IACS, Part 2 specifies immediately replacing the diagonal brace. If the 
diagonal brace is within the specified limits, Part 2 specifies 
repeating the Part 1 inspection.
     Part 3 of the service bulletin specifies replacing any 
damaged seal (primary fire seal, heat shield seal, or secondary fluid 
seal, with a new seal), then repeating the Part 1 inspection. Part 3 
also specifies contacting Boeing for alternate repair instructions for 
the seals.
     Part 4 of the service bulletin specifies replacing any 
damaged diagonal brace with a new brace, then repeating the Part 1 
inspection.
    We also have reviewed and approved Boeing All Operator Message M-
7200-02-00173, dated January 30, 2002, which describes procedures for a 
temporary repair of the forward seals of the aft fairing of the strut.

Explanation of the Requirements of the Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other airplanes of the same type design, this AD 
requires accomplishment of the actions specified in the service 
information described previously, except as discussed below.

Differences Between This AD and the Alert Service Bulletin

    Part 2 of the referenced service bulletin specifies a compliance 
time of 18 months for replacement of the diagonal brace if the brace is 
not within the specified conductivity limits (greater than 42.5 percent 
and less than or equal to 44 percent IACS); however, this AD requires 
the replacement be done within 90 days after the initial conductivity 
inspection if the brace is not within the specified conductivity 
limits.
    In developing an appropriate compliance time for this AD, the FAA 
considered not only the manufacturer's recommendation, but the degree 
of urgency associated with addressing the subject unsafe condition, the 
average utilization of the affected fleet, and the time necessary to 
perform the modifications. In light of all of these factors, the FAA 
finds a compliance time of 90 days for completing the replacement to be 
warranted, in that it represents an appropriate interval of time 
allowable for affected airplanes to continue to operate without 
compromising safety.

[[Page 16993]]

    The service bulletin also specifies 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 54-54-03 of the AMM must be used to 
accomplish the inspection of the forward seals of the aft fairing of 
the strut for signs of heat damage, which is specified in the Work 
Instructions in the service bulletin. For this inspection, an 
``operator's equivalent procedure'' may be used only if approved as an 
alternative method of compliance per paragraph (c) of this AD.
    Although the service bulletin specifies that the manufacturer may 
be contacted for disposition of certain rework/repairs, this proposed 
AD would require all rework/repairs to be accomplished per a method 
approved by the FAA, or per data meeting the type certification basis 
of the airplane approved by a Boeing Company Designated Engineering 
Representative who has been authorized by the Manager, Seattle Aircraft 
Certification Office, to make such findings.

Interim Action

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

Determination of Rule's Effective Date

    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All 
communications received on or before the closing date for comments will 
be considered, and this rule may be amended in light of the comments 
received. Factual information that supports the commenter's ideas and 
suggestions is extremely helpful in evaluating the effectiveness of the 
AD action and determining whether additional rulemaking action would be 
needed.
    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 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 rule that might 
suggest a need to modify the 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 that 
summarizes each FAA-public contact concerned with the substance of this 
AD will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 2002-NM-30-AD.'' The postcard will be date stamped and 
returned to the commenter.

Regulatory Impact

    The regulations adopted herein will 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 final rule does not have federalism 
implications under Executive Order 13132.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in aircraft, and that it is not a ``significant regulatory 
action'' under Executive Order 12866. It has been determined further 
that this action involves an emergency regulation under DOT Regulatory 
Policies and Procedures (44 FR 11034, February 26, 1979). If it is 
determined that this emergency regulation otherwise would be 
significant under DOT Regulatory Policies and Procedures, a final 
regulatory evaluation will be prepared and placed in the Rules Docket. 
A copy of it, if filed, may be obtained from the Rules Docket at the 
location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends 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:

2002-07-07  Boeing: Amendment 39-12701. Docket 2002-NM-30-AD.

    Applicability: Model 777-200 series airplanes equipped with 
General Electric GE90 series engines, as listed in Boeing Alert 
Service Bulletin 777-54A0017, dated December 21, 2001, 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 heat damage of the diagonal brace and forward seals 
of the aft fairing of the strut, which could result in cracking and 
fracture of the forward attachment point of the diagonal brace, loss 
of the diagonal brace load path, and consequent separation of the 
strut and engine from the airplane; accomplish the following:

Repetitive Inspections

    (a) Within 500 flight hours after the effective date of this AD: 
Do a detailed inspection of the diagonal brace and forward seals of 
the aft fairing of the strut to find discrepancies (heat damage to 
the diagonal brace and/or forward seals, and cracks and/or fracture 
of the diagonal brace), per Part 1 of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 777-54A0017, dated 
December 21, 2001. If no discrepancies are found, repeat the 
inspection after that every 1,000 flight hours.

[[Page 16994]]

Corrective Actions

    (1) If any sign of heat damage to the diagonal brace is found: 
Before further flight, do the conductivity inspection of all areas 
of the forward clevis lugs and brace body of the diagonal brace, as 
specified in and per Part 2 of the Accomplishment Instructions of 
the service bulletin.
    (i) If the conductivity readings are all within the specified 
range of 38.0 through 42.5 percent International Annealed Copper 
Standard (IACS); then repeat the inspection required by paragraph 
(a) of this AD every 1,000 flight hours.
    (ii) If any conductivity readings are within the specified range 
of greater than 42.5 percent and less than or equal to 44 percent 
IACS, before further flight, do the inspection specified in and per 
Part 2 of the Accomplishment Instructions of the service bulletin. 
If additional damage is found, repair per a method approved by the 
Manager, Seattle Aircraft Certification Office (ACO), FAA, or per 
data meeting the type certification basis of the airplane approved 
by a Boeing Company Designated Engineering Representative (DER) who 
has been authorized by the Manager, Seattle ACO, to make such 
findings. For a repair method to be approved by the Manager, Seattle 
ACO, as required by this paragraph, the Manager's approval letter 
must specifically reference this AD. Within 90 days after doing the 
conductivity inspection, replace the diagonal brace with a new brace 
per Part 4 of the Accomplishment Instructions of the service 
bulletin. Then, repeat the inspection required by paragraph (a) of 
this AD every 1,000 flight hours.
    (iii) If any conductivity readings are greater than 44 percent 
IACS, before further flight, replace the diagonal brace per Part 4 
of the Accomplishment Instructions of the service bulletin. Then, 
repeat the inspection required by paragraph (a) of this AD every 
1,000 flight hours.
    (2) If any crack or fracture of the diagonal brace is found, 
before further flight, replace the diagonal brace with a new brace 
per Part 4 of the Accomplishment Instructions of the service 
bulletin; or rework the diagonal brace per a method approved by the 
Manager, Seattle ACO, or per data meeting the type certification 
basis of the airplane approved by a Boeing Company DER who has been 
authorized by the Manager, Seattle ACO, to make such findings. For a 
repair method to be approved by the Manager, Seattle ACO, as 
required by this paragraph, the Manager's approval letter must 
specifically reference this AD. Then, repeat the inspection required 
by paragraph (a) of this AD every 1,000 flight hours.
    (3) If any sign of heat damage to any seal is found, before 
further flight, replace the seal per Part 3 of the Accomplishment 
Instructions of the service bulletin, or do the actions required by 
paragraph (a)(3)(i) or (a)(3)(ii) of this AD, as applicable. Then, 
repeat the inspection required by paragraph (a) of this AD every 
1,000 flight hours.
    (i) If there is any damage to any seal but no leakage of the 
seal is found, do a detailed inspection of the seal every 50 flight 
hours until the replacement or temporary repair is done per Boeing 
All Operator Message (AOM) M-7200-02-00173, dated January 30, 2002. 
Do the repair within 500 flight hours after the initial inspection 
required by paragraph (a) of this AD, or do the replacement within 
1,000 flight hours after that initial inspection, as applicable. If 
the temporary repair is done, inspect the repaired seal every 500 
flight hours until the seal is replaced. Replacement of the seal 
must be done within 1,000 flight hours after the repair is done.
    (ii) If there is damage to any seal and leakage of the seal is 
found, before further flight, do the replacement or temporary repair 
of the seal per the AOM. If the temporary repair is done, inspect 
the repaired seal every 250 flight hours until the seal is replaced. 
Replacement of the seal must be done within 1,000 flight hours after 
the repair is done.

``Operator's Equivalent Procedure''

    (b) Though Boeing Alert Service Bulletin 777-54A0017, dated 
December 21, 2001, specifies that an ``operator's equivalent 
procedure'' may be used for the inspection of the forward seals of 
the aft fairing of the strut for signs of heat damage, that 
inspection must be done according to Chapter 54-54-03 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 ACO. 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 
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.

Incorporation by Reference

    (e) Except as provided by paragraphs (a)(1)(ii), (a)(2), and (b) 
of this AD, the actions shall be done in accordance with Boeing 
Alert Service Bulletin 777-54A0017, dated December 21, 2001; and 
Boeing All Operator Message M-7200-02-00173, dated January 30, 2002; 
as applicable. This incorporation by reference was approved by the 
Director of the Federal Register in accordance with 5 U.S.C. 552(a) 
and 1 CFR part 51. Copies may be obtained from Boeing Commercial 
Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. 
Copies may be inspected at the FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington; or at the Office of the 
Federal Register, 800 North Capitol Street, NW., suite 700, 
Washington, DC.

Effective Date

    (f) This amendment becomes effective on April 24, 2002.

    Issued in Renton, Washington, on March 29, 2002.
Ali Bahrami,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 02-8280 Filed 4-8-02; 8:45 am]
BILLING CODE 4910-13-P