AD #: 2006-06-51
The FAA is sending an
emergency airworthiness directive (AD), 2006-06-51, to all owners
and operators of certain General Electric Company Aircraft Engines
(GEAE) CT7-8A turboshaft engines installed on Sikorsky S92
helicopters.
Background
This emergency AD results from two failures of the No. 3 bearing
in GEAE CT7-8A engines. Bearing contamination by Aluminum Oxide
caused the first failure. The Aluminum Oxide contamination is a
hard-particle contamination, left in the air cavity of the front
frame core after cleaning, that entered the bearing and caused
damage and metal loss at the roller ball and race interface. The
loss of metal caused a warning light for an electrical chip
detector to illuminate in the cockpit. The pilot reduced power to
the engine. Inspection found the bearing unserviceable. The engine
accumulated 458 flight hours-since-new before the failure. Improper
use of a bearing support tool at production assembly caused the
second failure. Damage from improper use of a bearing support tool
caused bearing metal loss at the roller ball and race interface.
The loss of metal caused a warning light for an electrical chip
detector to illuminate in the cockpit and signaled an impending oil
bypass. The pilot performed an in-flight shutdown of the engine.
The engine accumulated 686 hours since-new. This condition, if not
corrected, could result in failures of the No. 3 bearings and
possible dual in-flight shutdowns of the engines.
Interim Action
These actions are interim actions and we might take additional
rulemaking actions in the future.
FAA’s Determination and Requirements of the Rule
We have identified an
unsafe condition that is likely to exist or develop on certain
other GEAE CT7-8A turboshaft engines of this same type design. This
AD requires inspecting the electrical chip detector for debris
within 25 hours time-in-service after receipt of this emergency AD,
and repetitive inspections at intervals of 25 hours time-since-last
inspection.
Authority for this Rulemaking
Title 49 of the United States Code specifies the FAA’s
authority to issue rules on aviation safety. Subtitle I, Section
106, describes the authority of the FAA Administrator. Subtitle
VII, Aviation Programs, describes in more detail the scope of the
Agency’s authority.
We are issuing this rulemaking under the authority described in
Subtitle VII, Part A, Subpart III, Section 44701, “General
requirements.” Under that section, Congress charges the FAA
with promoting safe flight of civil aircraft in air commerce by
prescribing regulations for practices, methods, and procedures the
Administrator finds necessary for safety in air commerce. This
regulation is within the scope of that authority because it
addresses an unsafe condition that is likely to exist or develop on
products identified in this rulemaking action.
Determination of Rule’s Effective Date
We are issuing this AD
under 49 U.S.C. Section 44701 according to the authority delegated
to me by the Administrator, and it is effective immediately on
receipt. 2006-06-51 General Electric Company Aircraft Engines:
Directorate Identifier. 2006-NE-12-AD
Effective Date
(a) Emergency AD 2006-06-51, issued on March 16, 2006, is
effective on receipt.
Affected ADs
(b) None.
Applicability
(c) This AD applies to General Electric Company Aircraft Engines
(GEAE) CT7-8A serial numbers (SNs) 947201 through 947204, 947209
through 947235, 947238 through 9472268, 947273 through 947281, and
947283 though 947285. These engines are installed on, but not
limited to, Sikorsky S92 helicopters.
Unsafe Condition
(d) This AD results from
two failures of the No. 3 bearing in GEAE CT7-8A engines. We are
issuing this AD to prevent failures of the No. 3 bearings and
possible dual in-flight shutdowns of the engines.
Compliance
(e) You are responsible for having the actions required by this
AD performed within the compliance times specified unless the
actions have already been done.
Initial Inspection of the Electrical Chip Detector
(f) Within 25 hours
time-in-service after receipt of this AD, do the following:
(1) Remove the electrical
chip detector assembly.
(2) If the chip detector assembly contains any bearing material,
replace the engine.
(3) Stagger the inspection intervals so the chip detectors on both
engines on the same helicopter are not inspected at the same
time.
Repetitive Inspection of the Electrical Chip Detector
(g) Thereafter, within 25 hours time-since-last inspection,
perform the inspection specified in paragraph (f)(1) through (f)(3)
of this AD.
Alternative Methods of Compliance
(h) The Manager, Engine Certification Office, has the authority
to approve alternative methods of compliance for this AD if
requested using the procedures found in 14 CFR 39.19.
Related Information
(i) None.
Contact Information
(j) For further information, contact: Mark Boyer, Aerospace
Engineer, Engine Certification Office, FAA, Engine and Propeller
Directorate, 12 New England Executive Park, Burlington, MA 01803,
telephone (781) 238-7755; fax (781) 238-7199.
Issued in Burlington, Massachusetts on March 17, 2006.