Airworthiness Directives; General Electric Company GE90-85B Series Turbofan Engines

[Federal Register Volume 65, Number 47 (Thursday, March 9, 2000)]
[Rules and Regulations]
[Pages 12460-12462]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-5582]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NE-06-AD; Amendment 39-11619; AD 2000-05-10]
RIN 2120-AA64


Airworthiness Directives; General Electric Company GE90-85B 
Series Turbofan 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 General Electric Company GE90-85B series turbofan 
engines. This action requires removing from service aft mount 
whiffletrees prior to reaching a new cyclic life limit, and replacing 
with serviceable parts. This amendment is prompted by a reassessment of 
the low cycle fatigue capability of the engine mount system due to an 
increase in engine and propulsion system weight. The actions specified 
in this AD are intended to prevent aft mount

[[Page 12461]]

whiffletree failure, which if it occurred with other critical aft mount 
component failures, could possibly result in an engine mount system 
failure, and separation of the engine from the aircraft.

DATES: Effective April 7, 2000.
    Comments for inclusion in the Rules Docket must be received on or 
before May 8, 2000.

ADDRESSES: Submit comments to the Federal Aviation Administration 
(FAA), New England Region, Office of the Regional Counsel, Attention: 
Rules Docket No. 2000-NE-06-AD, 12 New England Executive Park, 
Burlington, MA 01803-5299. Comments may also be sent via the Internet 
using the following address: ``[email protected]''. Comments sent 
via the Internet must contain the docket number in the subject line.

FOR FURTHER INFORMATION CONTACT: John E. Golinski, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803-5299; telephone 781-
238-7135, fax 781-238-7199.

SUPPLEMENTARY INFORMATION: General Electric Company (GE), the 
manufacturer of GE90-85B series turbofan engines, has recently 
reassessed the low cycle fatigue (LCF) capability of the engine mount 
system due to an increase in engine and propulsion system weight. The 
analysis indicates a reduction in the LCF life for aft mount 
whiffletree, part number (P/N) 1692M12G02. Prior to completing the 
assessment for the engine weight and propulsion system weight increase, 
there was no life limit for the aft mount whiffletree, P/N 1692M12G02, 
in Chapter 5, Airworthiness Limitations Section, of the Engine Manual 
for GE90-85B engines because the calculated LCF life value was greater 
than the aircraft life. Chapter 5 has now been revised to include a new 
life limit for the aft mount whiffletree, P/N1692M12G02, of 18,000 
cycles-since-new (CSN). An aft mount whiffletree failure, which if it 
occurred with other critical aft mount component failures, could 
possibly result in an engine mount system failure, and separation of 
the engine from the aircraft.

New Components

    GE has developed improved aft mount whiffletrees that are eligible 
for installation on all GE90 engine models and do not have a life 
limit. The majority of GE90 engines in revenue service incorporate one 
of these improved wiffletrees.

No Domestic Engines

    The FAA estimates that there are only 3 engines in revenue service 
that contain the aft mount whiffletree, P/N 1692M12G02, and that none 
of these are installed on aircraft of US registry.

Required Actions

    Since an unsafe condition has been identified that is likely to 
exist or develop on other engines of the same type design, this AD is 
being issued to prevent aft mount whiffletree failure. This AD requires 
removing from service aft mount whiffletrees prior to accumulating 
18,000 CSN, and replacing with serviceable parts.

Immediate Adoption

    There are currently no domestic operators of this engine model with 
the affected component installed. Accordingly, a situation exists that 
allows the immediate adoption of this regulation. Notice and 
opportunity for prior public comment hereon are impracticable, and 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 should identify the Rules Docket number and be submitted 
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.
    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 notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 2000-NE-06-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 (EO) No. 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 is not a ``significant regulatory action'' 
under EO No. 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, 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:

2000-05-10  General Electric Company: Amendment 39-11619. Docket 
2000-NE-06-AD.
    Applicability: General Electric Company (GE) GE90-85B series 
turbofan engines, with aft mount whiffletrees, part number (P/N) 
1692M12G02, installed. These engines are installed on but not 
limited to Boeing 777 series airplanes.


[[Page 12462]]


    Note 1: This airworthiness directive (AD) applies to each engine 
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 engines 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 aft mount whiffletree failure, which if it occurred 
with other critical aft mount component failures, could possibly 
result in an engine mount system failure, and separation of the 
engine from the aircraft, accomplish the following:

New Life Limit

    (a) Remove from service aft mount whiffletrees, P/N 1692M12G02, 
before accumulating 18,000 cycles-since-new, and replace with 
serviceable parts.
    (b) Except for the provisions of paragraph (c) of this AD, no 
aft mount whiffletrees, P/N 1692M12G02, may remain in service beyond 
the new life limit stated in paragraph (a) of this AD.

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, Engine Certification Office (ECO). 
Operators shall submit their requests through an appropriate FAA 
Principal Maintenance Inspector, who may add comments and then send 
it to the Manager, ECO.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this airworthiness directive, 
if any, may be obtained from the ECO.

    (d) This amendment becomes effective on April 7, 2000.

    Issued in Burlington, Massachusetts, on March 1, 2000.
Diane S. Romanosky,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 00-5582 Filed 3-8-00; 8:45 am]
BILLING CODE 4910-13-U

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