AD/Ecureuil/134 Starter-generator Damping Assembly (Cth)
AIRWORTHINESS DIRECTIVE
For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.001(1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.
Eurocopter AS 350 (Ecureuil) Series Helicopters
| AD/ECUREUIL/134 | Starter-generator Damping Assembly | 3/2009 |
Applicability: | EUROCOPTER (formerly EUROCOPTER FRANCE, AEROSPATIALE) AS 350 B, BA, BB, B1, B2, B3 and EC 130 B4 helicopters, all serial numbers if equipped with Aircraft Parts Corporation (APC) 150SG and 200SGL-type starter-generators. |
Requirement: | 1. Inspect the APC starter-generator shaft/damper assembly and ensure that its alignment and tightening torque comply with the approved configuration, in accordance with paragraph 2.B. of the relevant ASB. 2. Do not install a starter-generator of the type affected by this AD on a helicopter, unless its shaft/damper assembly compliance with the approved configuration has been verified in accordance with paragraph 2.B. of the relevant ASB. 3. Send the results of the inspection, whatever they are, to EUROCOPTER. Ref. Publications: EUROCOPTER AS350 Alert Service Bulletin No. 80.00.07 Rev. 0 dated EUROCOPTER EC130 Alert Service Bulletin No. 80A003 Rev. 0 dated The use of later approved revisions of these documents is acceptable for compliance with the requirements of this AD. Note: EASA AD 2009-0004 dated 12 January 2009 refers. |
Compliance: | For Requirement 1 - Within 110 flight hours or 3 months, whichever occurs first after the effective date of this AD, unless previously accomplished. For Requirement 2 - From the effective date of this AD. For Requirement 3 - Within 30 days after the accomplishment of the ASB. |
| This Airworthiness Directive becomes effective on 12 March 2009. | |
Background: | EUROCOPTER has received reports of engine flame-outs in operation. In all cases of engine flame-out there was a failure of the 41-tooth pinion in the engine accessory gear box. |
| All the concerned helicopters were equipped with starter-generators manufactured by the APC company (currently UNISON). In each case, it was found that the torque damping system of the starter-generator was inoperative. Further investigations have been conducted to assess the efficiency of the 150SG and 200SGL-type generator damping systems, which have revealed that the failure of the torque damping system was due to an incorrect adjustment. If the damping system is incorrectly adjusted, torque oscillations may not be limited and can induce bending stress on the 41-tooth pinion of the accessory gear box, contributing to the pinion failure. Such pinion failure causes the fuel pump to stop which results in an engine flame-out. Pending additional investigations, this AD requires an inspection of the alignment and torque of the APC starter-generator damping assembly and, in case of discrepancies, the accomplishment of corrective actions. |
James Coyne
Delegate of the Civil Aviation Safety Authority
27 January 2009
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