Airworthiness Directives; General Electric Company GE90 Series Turbofan Engines

[Federal Register Volume 62, Number 113 (Thursday, June 12, 1997)]
[Rules and Regulations]
[Pages 32023-32025]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-14955]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-ANE-22-AD; Amendment 39-10046; AD 97-12-04]
RIN 2120-AA64


Airworthiness Directives; General Electric Company GE90 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 (GE) GE90 series turbofan 
engines. This action requires initial and repetitive borescope 
inspections of compressor discharge pressure (CDP) manifolds for 
cracks, and replacement, if necessary, with an improved design CDP 
manifold. In addition, this AD requires, as terminating action to the 
inspections, replacement with an improved design CDP manifold. This 
amendment is prompted by reports of CDP manifold cracking that has 
resulted in liberated material causing high pressure compressor (HPC) 
blade damage. The actions specified in this AD are intended to prevent 
inflight engine power loss or shutdown due to HPC blade damage caused 
by liberated material from the CDP manifold.

DATES: Effective June 27, 1997.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of June 27, 1997.
    Comments for inclusion in the Rules Docket must be received on or 
before August 11, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), New England Region, Office of the Assistant Chief 
Counsel, Attention: Rules Docket No. 97-ANE-22-AD, 12 New England 
Executive Park, Burlington, MA 01803-5299. Comments may also be sent 
via the Internet using the following address: ``9-ad-
[email protected]''. Comments sent via the Internet must contain 
the docket number in the subject line.
    The service information referenced in this AD may be obtained from 
General Electric Technical Services, Attention: Leader for 
distribution/microfilm, 10525 Chester Road, Cincinnati, OH 45215; 
telephone (513) 672-8400 Ext. 114, fax (513) 672-8422. This information 
may be examined at the FAA, New England Region, Office of the Assistant 
Chief Counsel, 12 New England Executive Park, Burlington, MA; or at the 
Office of the Federal Register, 800 North Capitol Street, NW., suite 
700, Washington, DC.

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 (617) 
238-7135, fax (617) 238-7199.

SUPPLEMENTARY INFORMATION: The Federal Aviation Administration (FAA) 
has received reports of cracked compressor discharge pressure (CDP) 
manifolds, Part Number (P/N) 1686M48G11, installed on General Electric 
Company (GE) GE90 series turbofan engines. In two reports, the cracked 
CDP manifold liberated material that resulted in high pressure 
compressor (HPC) blade damage beyond serviceable limits. The failure 
investigation has determined that the cause of the crack initiation and 
propagation is attributed to excessive stresses in the manifold. The 
cracks may initiate in a localized area around any one of the six outer 
diameter bolts that attach the CDP manifold to the combustor case. 
Multiple cracks that initiate can propagate in a direction that allow 
CDP manifold material to become liberated. This material can enter the 
HPC and result in hard body impact damage to the HPC blades. The FAA 
has determined that an earlier configuration CDP manifold, P/N 
1686M48G10, is also susceptible to cracking, which could result in 
liberated CDP manifold material. This condition, if not corrected, 
could result in inflight engine power loss or shutdown due to HPC blade 
damage caused by liberated material from the CDP manifold.
    The FAA has reviewed and approved the technical contents of GE 
Aircraft Engines GE90 Service Bulletin (SB) No. 72-263, dated February 
5, 1997, that describes procedures for initial and repetitive borescope 
inspections for cracks in the CDP manifold, P/Ns 1686M48G10, 
1686M48G11, and 1686M48G12. This AD, however, only requires inspection 
of CDP manifolds, P/Ns 1686M48G10 and 1686M48G11. The FAA has also 
reviewed and approved the technical contents of GE Aircraft Engines 
GE90 SB No. 72-126, Revision 1, dated April 29, 1997, that describes 
procedures for installation of improved design CDP manifolds.
    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 liberation of CDP manifold material. This AD 
requires initial and repetitive borescope inspections for cracks in CDP 
manifolds, P/Ns 1686M48G10 and 1686M48G11. The repetitive inspection 
intervals, or possible removal and replacement prior to further flight, 
are defined by the condition of the CDP manifold based on the borescope 
inspections. In addition, this AD requires, at the next shop visit 
after the effective date of this AD, installing the improved design CDP 
manifold, P/N 1686M48G12. Installation of the improved design CDP 
manifold constitutes terminating action to the inspection requirements 
of this AD. The actions are required to be accomplished in accordance 
with the SBs described previously.
    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

[[Page 32024]]

arguments as they may desire. Communications should 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.
    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 97-ANE-22-AD.'' The postcard will be date stamped and 
returned to the commenter.
    The regulations adopted herein will 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 final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    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 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:
97-12-04 General Electric Company: Amendment 39-10046. Docket 97-
ANE-22-AD.

    Applicability: General Electric Company (GE) Models GE90-76B, -
77B, -85B, -90B, and -92B turbofan engines, with compressor 
discharge pressure (CDP) manifolds, Part Numbers (P/Ns) 1686M48G10 
or 1686M48G11, installed. These engines are installed on but not 
limited to Boeing 777 series aircraft.

    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 (e) 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 inflight engine power loss or shutdown due to 
liberated CDP manifold material, accomplish the following:
    (a) Perform borescope inspections of the CDP manifold for cracks 
in accordance with the Accomplishment Instructions of GE90 Service 
Bulletin (SB) No. 72-263, dated February 5, 1997, as follows:
    (1) For engines with greater than 500 total engine cycles (TEC) 
on the effective date of this AD, inspect within 25 cycles in 
service (CIS) after the effective date of this AD.
    (2) For engines with 500 or less TEC on the effective date of 
this AD, inspect within 125 CIS after the effective date of this AD, 
or prior to accumulating 500 TEC, whichever occurs first.
    (b) Based on inspections accomplished in paragraph (a) of this 
AD, accomplish the following:
    (1) Prior to further flight, remove those manifolds found with 
liberated pieces or with cracks that meet or exceed the length or 
orientation criteria in paragraph C(3)(c) or D(3)(c) of the 
Accomplishment Instructions of GE90 SB No. 72-263, dated February 5, 
1997, and replace with CDP manifolds, P/N 1686M48G12, in accordance 
with GE90 SB No. 72-126, Revision 1, dated April 29, 1997.
    (2) For manifolds found with axial cracks less than or equal to 
0.5 inches, thereafter, perform borescope inspections of CDP 
manifolds daily, remove, if necessary, and replace in accordance 
with paragraph (b)(1) of this AD.
    (3) For manifolds with no visible cracks, accomplish the 
following:
    (i) Perform borescope inspections of CDP manifolds at intervals 
not to exceed 125 CIS since last inspection, remove, if necessary, 
and replace in accordance with paragraph (b)(1) of this AD.
    (ii) If manifolds are found with axial cracks less than or equal 
to 0.5 inches, thereafter, perform borescope inspections of CDP 
manifolds daily, remove, if necessary, and replace in accordance 
with paragraph (b)(1) of this AD.
    (c) At the next shop visit after the effective date of this AD, 
install an improved CDP manifold, P/N 1686M48G12, in accordance with 
GE90 SB No. 72-126, Revision 1, dated April 29, 1997. Installation 
of this CDP manifold constitutes terminating action to the 
inspection requirements of this AD.
    (d) For the purpose of this AD, a shop visit is defined as an 
engine removal for engine maintenance that cannot be performed while 
installed on the aircraft and that entails separation of pairs of 
mating engine flanges.
    (e) 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. 
Operators shall submit their request through an appropriate FAA 
Principal Maintenance Inspector, who may add comments and then send 
it to the Manager, Engine Certification Office.

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

    (f) 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 aircraft to a location where 
the inspection requirements of this AD can be accomplished.
    (g) The actions required by this AD shall be done in accordance 
with the following GE90 SBs:

[[Page 32025]]



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         Document No.            Revision     Pages          Date       
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72-263.......................  Original....  1-18     Feb. 5, 1997.     
  Total pages: 18.                                                      
72-126.......................  1...........   1-8     Apr. 29, 1997.    
  Total pages: 8.                                                       
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    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 General Electric Technical 
Services, Attention: Leader for distribution/microfilm, 10525 
Chester Road, Cincinnati, OH 45215; telephone (513) 672-8400 Ext. 
114, fax (513) 672-8422. Copies may be inspected at the FAA, New 
England Region, Office of the Assistant Chief Counsel, 12 New 
England Executive Park, Burlington, MA; or at the Office of the 
Federal Register, 800 North Capitol Street, NW., suite 700, 
Washington, DC.
    (h) This amendment becomes effective on June 27, 1997.

    Issued in Burlington, Mass., on May 30, 1997.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 97-14955 Filed 6-11-97; 8:45 am]
BILLING CODE 4910-13-U

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