[Federal Register Volume 65, Number 4 (Thursday, January 6, 2000)]
[Rules and Regulations]
[Pages 692-695]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-134]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NE-62-AD; Amendment 39-11496; AD 99-27-15]
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 certain General Electric Company GE90 series turbofan 
engines. This action requires visually inspecting Ps3 and P3B sense 
lines and full authority digital engine control (FADEC) Ps3 and P3B 
sensing ports and fittings, cleaning Ps3 and P3B fittings and sensing 
ports, purging the Ps3 and P3B systems of moisture, and, if necessary, 
blending of high metal, nicks, burrs, or scratches on Ps3 and P3B 
fitting threads. This amendment is prompted by seven reports of loss of 
thrust control due to corruption of the signals to the FADEC caused by 
water freezing in the Ps3 sensing system. The actions specified in this 
AD are intended to prevent loss of thrust control due to corruption of 
the Ps3 and P3B signals to the FADEC which if it occurs in a critical 
phase of flight, could result in loss of aircraft control.

DATES: Effective January 11, 2000.

    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of January 11, 2000.

    Comments for inclusion in the Rules Docket must be received on or 
before March 6, 2000.

ADDRESSES: Submit comments to the Federal Aviation Administration 
(FAA), New England Region, Office of the Regional Counsel, Attention: 
Rules Docket No. 99-NE-62-AD, 12 New England Executive Park, 
Burlington, MA

[[Page 693]]

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.

    The service information referenced in this AD may be obtained from 
General Electric Company via Lockheed Martin Technology Services, 10525 
Chester Road, Suite C, Cincinnati, OH 45215; telephone 513-672-8400, 
fax 513-672-8422. This information may be examined at the FAA, New 
England Region, Office of the Regional 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 781-
238-7135, fax 781-238-7199.

SUPPLEMENTARY INFORMATION: The Federal Aviation Administration (FAA) 
has received seven reports of loss of thrust control (LOTC) on General 
Electric Company (GE) Model GE90 turbofan engines installed on Boeing 
777 series aircraft. Five LOTC events occurred in-flight and two 
occurred on the ground. The five in-flight LOTC events were temporary 
in that the engine recovered and continued to operate normally for the 
remainder of the flight.

Investigation

    The investigation revealed that water can accumulate in the Ps3 and 
P3B pressure sensing system, which can freeze in the full authority 
digital engine control (FADEC) sensing ports or pressure line. Frozen 
water can result in a restriction or a blocked signal to the FADEC. 
This blocked signal can cause a corruption of the FADEC signal and 
result in abnormal engine start characteristics on the ground or lack 
of engine response to commanded thrust levels in flight. Although there 
have been no LOTC events attributed to icing of the P3B sensing system 
in the field, inspections have identified moisture in this system, 
which could freeze and corrupt the P3B signal to the FADEC as well. 
This condition, if not corrected, could result in LOTC due to blockage 
of the FADEC sense lines, which if it occurs in a critical phase of 
flight, could result in loss of aircraft control.

Simultaneous LOTC Events

    The FAA is especially concerned about the possibility of 
simultaneous LOTC events on both engines installed on the Boeing 777 
series aircraft due to common mode threats, such as certain atmospheric 
conditions that may result in ice in the Ps3 or P3B pressure sensing 
system and causing corrupted signals to the FADEC in both engines.

Interim Action

    Both Ps3 and P3B pressure systems incorporate weep holes that 
allows drainage of water in the lines that may accumulate from 
condensation or ingested water; however, the field events and the 
investigation have determined that these design features may not always 
be effective in eliminating water from these systems. GE is assessing 
design changes that will prevent water from freezing in these systems 
and causing corruption of the signals to the FADEC. The requirements of 
this AD may change based on the ongoing investigation of the root cause 
and field inspection results, and future rulemaking may be necessary.

Service Information

    The FAA has reviewed and approved the technical contents of GE 
Alert Service Bulletin (ASB) GE90 73-A0060, dated December 23, 1999, 
that describes procedures for visually inspecting Ps3 and P3B sense 
lines and FADEC sensing ports and fittings, cleaning Ps3 and P3B 
fittings and sensor ports, purging the Ps3 and P3B systems of moisture, 
and, if necessary, blending of high metal, nicks, burrs, or scratches 
on Ps3 and P3B fitting threads.

Difference between ASB and AD

    This AD contains provisions for initial actions, and the ASB 
assumes that all operators have completed the initial actions based on 
field reports. If, however, operators have already accomplished the 
required initial actions, they need not repeat those actions, but may 
proceed directly to accomplishing the repetitive actions.

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 
airworthiness directive (AD) is being issued to prevent engine LOTC 
events. This AD requires:

     Visual inspections for high metal, nicks, burrs, or 
scratches on Ps3 and P3B fitting threads, and, if necessary, blending.

     Visual inspections for moisture, debris, or ice in Ps3 and 
P3B FADEC fittings, ports, and open sense lines.

     Cleaning of Ps3 and P3B FADEC fittings and sensing ports.

     Purging of any moisture from the Ps3 and P3B sense system.

     Engine idle leak check run following the maintenance 
activity to confirm no Ps3 or P3B sense system faults are present.

Compliance Times

    One of the GE90 series engines installed on the Boeing 777 series 
airplane must have the initial inspection, cleaning, moisture purging, 
and, if necessary, blending of high metal, nicks, burrs, or scratches 
on Ps3 and P3B fitting threads, within 10 cycles-in-service (CIS) after 
the effective date of this AD. The other engine installed on the 
airplane must have the initial inspection, cleaning, moisture purging, 
and, if necessary, blending of high metal, nicks, burrs, or scratches, 
on Ps3 and P3B fitting threads, within 20 CIS after the effective date 
of this AD. Based on concerns over concurrent engine maintenance, 
engines installed on the same Boeing 777 series airplane must not have 
the inspection, cleaning, moisture purging and, if necessary, blending 
of high metal, nicks, burrs, or scratches on Ps3 and P3B fitting 
threads performed concurrently.

Credit for Previous Inspections, Cleaning, and Moisture Purging

    Engines that have been inspected, cleaned, and moisture purged in 
accordance with GE90 All Reps Wire, JSB99-11-24-1, Revision 1, dated 
November 25, 1999, may count those inspections, cleaning, and moisture 
purging as accomplished and must be inspected, cleaned, moisture 
purged, and, if necessary, have high metal, nicks, burrs, or scratches 
on Ps3 and P3B fitting threads blended, within 30 CIS since those last 
actions. Engines that have accumulated 30 CIS or greater since previous 
inspection, cleaning, and moisture purging on the effective date of the 
AD must repeat the required procedures within 5 CIS after the effective 
date of this AD. Engines that have accumulated less than 30 CIS since 
previous inspection, cleaning, and moisture purging on the effective 
date of this AD must repeat the required procedures within 30 CIS since 
last inspection, or within 5 CIS after the effective date of this AD, 
whichever occurs later.

Repetitive Actions

    Thereafter, operators must inspect, clean, moisture purge, and, if 
necessary, blend high metal, nicks, burrs, or scratches on Ps3 and P3B 
fitting threads at intervals not to exceed 30 CIS since last 
inspection.

[[Page 694]]

Immediate Adoption

    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 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 99-NE-62-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) 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 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:

99-27-15  General Electric Company: Amendment 39-11496. Docket 99-
NE-62-AD.

    Applicability: General Electric Company (GE) Models GE90-76B, -
77B, -85B, -90B, and -92B turbofan engines, installed on but not 
limited to Boeing 777 series airplanes.

    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 (f) 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 loss of thrust control due to corruption of the Ps3 
and P3B signals to the full authority digital engine control 
(FADEC), which if it occurs in a critical phase of flight, could 
result in loss of aircraft control, accomplish the following:

Initial Inspection, Cleaning, Moisture Purging, and Blending

    (a) Perform the following initial actions in accordance with the 
Accomplishment Instructions, Section (3) of GE Alert Service 
Bulletin (ASB) No. 73-A0060, dated December 23, 1999:
    (1) Inspect, clean, moisture purge, and if necessary, blend any 
high metal, nicks, or burrs on fitting threads, on one engine 
installed on Boeing 777 series aircraft, within 10 cycles-in-service 
(CIS) after the effective date of this AD.
    (2) Inspect, clean, moisture purge, and if necessary, blend any 
high metal, nicks, or burrs on fitting threads, on the other engine 
installed on the Boeing 777 series aircraft, within 20 CIS after the 
effective date of this AD.

Credit for Previous Inspections, Cleaning, and Moisture Purging

    (b) Engines that have been inspected, cleaned, and moisture 
purged in accordance with GE90 All Reps Wire, JSB99-11-24-1, 
Revision 1, dated November 25, 1999, may count those inspections, 
cleaning, and moisture purging as accomplished and must be 
inspected, cleaned, moisture purged, and if necessary, have any high 
metal, nicks, or burrs on fitting threads blended, in accordance 
with the Accomplishment Instructions, Section (3) of GE ASB No. 73-
A0060, dated December 23, 1999, and the following schedule:
    (1) Engines that have accumulated 30 CIS or greater since 
previous inspection, cleaning, and moisture purging on the effective 
date of the AD must repeat the required procedures within 5 CIS 
after the effective date of this AD.
    (2) Engines that have accumulated less than 30 CIS since 
previous inspection, cleaning, and moisture purging on the effective 
date of this AD must repeat the required procedures within 30 CIS 
since last inspection, or within 5 CIS after the effective date of 
this AD, whichever occurs later.

New and Replacement Engines

    (c) For new and replacement engines, perform the initial 
inspection, cleaning, and moisture purging, and if necessary, blend 
any high metal, nicks, or burrs on fitting threads, prior to 
accumulating 30 CIS since entering service in accordance with the 
Accomplishment Instructions, Section (3) of GE ASB No. 73-A0060, 
dated December 23, 1999.

Repetitive Inspections

    (d) Thereafter, inspect, clean, and moisture purge, and if 
necessary, blend any high metal, nicks, or burrs on fitting threads 
each engine within 30 CIS since last inspection, in accordance with 
the Accomplishment Instructions, Section (3) of GE ASB No. 73-A0060, 
dated December 23, 1999.

Idle Leak Check

    (e) After accomplishing the required actions of this AD, and 
prior to entry into

[[Page 695]]

service, perform an idle leak check to confirm no Ps3 or P3B sense 
system faults in accordance with the Accomplishment Instructions, 
Section (3), paragraph (14), of GE ASB No. 73-A0060, dated December 
23, 1999.

No Simultaneous Actions

    (f) Do not perform the actions required by this AD concurrently 
on both engines installed on a Boeing 777 series aircraft.

Alternative Methods of Compliance

    (g) 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.

Ferry Flights

    (h) 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 requirements of this AD can be accomplished.

Incorporation by Reference

    (i) The actions required by this AD shall be done in accordance 
with GE ASB No. 73-A0060, dated December 23, 1999. 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 Company via 
Lockheed Martin Technology Services, 10525 Chester Road, Suite C, 
Cincinnati, OH 45215; telephone 513-672-8400, fax 513-672-8422. 
Copies may be inspected at the FAA, New England Region, Office of 
the Regional 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.
    (j) This amendment becomes effective on January 11, 2000.

    Issued in Burlington, Massachusetts, on December 29, 1999.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 00-134 Filed 1-5-00; 8:45 am]
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