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.

FMI: www.faa.gov/aircraft/safety/alerts/