AD/AS 355/61 Amdt 1 Starter Generators (Cth)

AIRWORTHINESS DIRECTIVE

On the effective date specified below, and for the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/AS 355/61 and issues the following 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 355 (Twin Ecureuil) Series Helicopters

AD/AS 355/61 Amdt 1 Starter Generators 12/2006

Applicability:

AS 355N helicopters fitted with starter generators, all part numbers except helicopters modified jointly, in compliance with:

-      TURBOMECA Service Bulletin (SB) No. 319 78 0073 (engine exhaust pipe with restraining cables) which corresponds to embodiment of modification TU 106; and

-      Eurocopter SB No. 80.00.12 (Modification to starter generator, PN 524- 061) which corresponds to the embodiment of MOD 073159.

Requirement:

1.    For helicopters before embodiment of modification TU 106 and before embodiment of MOD 073159:

a. Perform a vibration level check in compliance with paragraph 2.B.1 of Eurocopter AS355 Alert Service Bulletin (ASB) No. 01.00.45 R1 or later approved revisions.

b. Perform vibration level checks of the starter generator in compliance with paragraph 2.B.1 of ASB 01.00.45 R1 or later approved revisions.

c. Check tightening torque of the attachment clamp, in compliance with paragraph 2.B.2 of ASB 01.00.45 R1 or later approved revisions.

d. Perform periodic vibration level checks of the starter generator, in compliance with paragraph 2.B.1 of ASB 01.00.45 R1 or later approved revisions.

2.    Helicopters after embodiment of TU 106 and before embodiment of MOD 073159:

a. Perform a vibration level check in compliance with paragraph 2.B.1 of Eurocopter AS355 Alert Service Bulletin (ASB) No. 01.00.45 R1 or later approved revisions.

b. Perform vibration level checks of the starter generator in compliance with paragraph 2.B.1 of ASB 01.00.45 R1 or later approved revisions and

c. Check tightening torque of the attachment clamp, in compliance with paragraph 2.B.2 of ASB 01.00.45 R1 or later approved revisions,

d. Perform periodic vibration level checks of the starter generator, in compliance with paragraph 2.B.1 of ASB 01.00.45 R1 or later approved revisions.

If at least one restraining cable has failed, Modification TU 106 is no longer considered valid, consequently:

e. Perform vibration level checks of the starter generator in compliance with paragraph 2.B.1 of ASB 01.00.45 R1 or later approved revisions.

f. Check tightening torque of the attachment clamp, in compliance with paragraph 2.B.2 of ASB 01.00.45 R1 or later approved revisions.

g. Perform periodic vibration level checks of the starter generator, in compliance with paragraph 2.B.1 of ASB 01.00.45 R1 or later approved revisions.

3.    Helicopters before embodiment of TU 106 and after embodiment of MOD 073159:

a. Perform vibration level checks of the starter generator in compliance with paragraph 2.B.1 of ASB 01.00.45 R1 or later approved revisions and

b. Check tightening torque of the attachment clamp, in compliance with paragraph 2.B.2 of ASB 01.00.45 R1 or later approved revisions,

c. Perform periodic vibration level checks of the starter generator, in compliance with paragraph 2.B.1 of ASB 01.00.45 R1 or later approved revisions.

Note:  EASA AD 2006-0254 refers.

Compliance:

For Requirement 1.a.                  -   Before next flight following installation of starter generator.

For Requirement 1.b. and 1.c.     -   After 10 to 15 hours Time In Service (TIS).

For Requirement 1.d.                  -   After 25 to 35 hours TIS.

   -   After 45 to 55 hours TIS.

   -   After 70 to 80 hours TIS.

   -   Then, at 110 hour TIS intervals.

For Requirement 2.a.                  -   Before next flight following installation of starter generator.

For Requirement 2.b. and 2.c.     -   After 10 to 50 hours TIS.

For Requirement 2.d.                  -   At 220 hour TIS intervals.

For Requirement 2.e. and 2.f.     -   Within 10 hours TIS following cable failure.

For Requirement 2.g.                  -   After 25 to 35 hours TIS.

   -   After 45 to 55 hours TIS.

   -   After 70 to 80 hours TIS.

   -   Then, at 110 hour TIS intervals.

For Requirement 3.a. and 3.b.     -   After 10 to 15 hours TIS.

For Requirement 3.c.                  -   At 220 hour TIS intervals.

This Amendment becomes effective on 23 November 2006.

Background:

The DGAC advised that in some cases starter generator wear/vibration has resulted in cracks which, if not corrected, may lead to failure of the engine exhaust pipe attachment lugs.  This in turn may result in loss of part of the exhaust pipe ejector in flight.

This Directive requires repetitive inspection and vibration checks to detect early failure of the starter generators.

Amendment 1 is issued following a case of failure of a restraining cable and acknowledges new procedures suited to the various cases of embodiment of MOD TU 106 and MOD 073159.

James Coyne
Delegate of the Civil Aviation Safety Authority

12 October 2006