1AD/DAUPHIN/58 Amdt 1 - Main Gearbox Torque Tightening

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AIRWORTHINESS DIRECTIVE

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For the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/DAUPHIN/58 and issues the following AD under subregulation 39.1 (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.

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Eurocopter SA 360 and SA 365 (Dauphin) Series Helicopters

AD/DAUPHIN/58

Amdt 1

Main Gearbox Torque Tightening 9/2003

Applicability: AS 365 helicopters versions N, N1, N2 and N3 fitted with Main GearBox (MGB) P/N 365 A 32.6000.00/02, or 365 A 32.6001.00/01; and modified to MOD 0763B79 (new O-ring seals) but not modified per MOD 0763B76 (new reinforced attachment studs);

and

SA 365 helicopters versions C, C1, C2 and C3 fitted with Main Gearbox P/N 365 A 32.4000.02/03/05, and modified to MOD 0763B79 (new O-ring seals) but not modified per MOD 0763B76 (new reinforced attachment studs).

Requirement: Carry out re-torque of the MGB in accordance with the Accomplishment Instructions of Eurocopter Alert Service Bulletin (ASB) No. 05.00.42 or 05.23 as applicable.

Note: DGAC AD 2002-283-048(A) R1 and DGAC AD 2002-285-055(A) R1 refer.

Compliance: 1. Unless previously accomplished for MGB’s that have logged less than 500 flight hours since last overhaul, no later than 550 hours Time in Service (TIS).

2. Unless previously accomplished for MGB that have logged more than 500 flight hours since last overhaul, within 50 hours TIS from when this Directive becomes effective.

3. Repeat at intervals of not more than 550 flight hours. This Amendment becomes effective on 4 September 2003.

Background: This Amendment reflects changes in the reference documentation.

Loosening of the main gearbox studs is a problem with the MGB, but oil leakage showed that the MGB studs were failing and gave sufficient warning for the problem to be addressed. MOD 0763B79 was introduced to improve the sealing of the MGB. Operators that chose to incorporate MOD 0763B79 without including MOD 0763B76, which improved the stud installation, have found that stud failure is no longer indicated by oil leakage. Failure to not address loosening of the studs could lead to MGB failure. This Directive addresses this problem by introducing a repetitive inspection of the stud torque.