[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
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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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