AD/Ecureuil/118 Amdt 1 Upper and Lower Fins of Stabilisers (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/ECUREUIL/118 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 350 (Ecureuil) Series Helicopters

AD/ECUREUIL/118 Amdt 1 Upper and Lower Fins of Stabilisers 9/2008

Applicability:

Model AS 350 B, B1, B2, BA, BB and D helicopters, equipped with upper and lower stabiliser fins pre-MOD 073288.

Model AS350 B3 helicopters, equipped with upper and lower stabiliser fins pre-MOD 073288, or,

upper and lower stabiliser fins post-MOD 073288, with the upper fin pre-MOD 073148.

Requirement:

For Model AS 350 B, B1, B2, BA, BB and D helicopters.

1.    Replace the upper fin and lower fin attachment screws in accordance with paragraph 2.B. of Eurocopter AS 350 Alert Service Bulletin (ASB) No. 55.00.12.

As of 30 June 2006 it is prohibited to install screws part number 22201BC060016L or part number 22201BV060016L on upper and lower fins.

For Model AS 350 B3 helicopters.

Helicopters equipped with upper and lower fins pre-MOD 073288, with the upper fin pre-MOD 073148:

2.    Replace the upper and lower fin attachment screws in accordance with paragraph 2.B.2. of ASB No. 55.00.13.

2.a. Check the tightening torque of the upper fin attachment screws and check there is no cracking and no loose rivet in the upper fin reinforcement splice, in accordance with paragraph 2.B.3. of ASB No. 55.00.13.

(i)    If a crack is detected in the reinforcing splice, replace the fin, scrap the two attachment screws and replace them before installing a new fin, in accordance with paragraph 2.B.3.a.1. of ASB No. 55.00.13.

(ii)   If the tightening torque of one or both of the attachment screws is less than 80% of the minimum torque value and/or if there is a loose rivet, check that there is no cracking in the upper fin spar, in accordance with paragraph 2.B.3.a.2. of ASB 55.00.13,

-      If there is a crack in the spar, replace the upper fin, scrap the two attachment screws and replace them before installing a new fin in accordance with paragraph 2.B.3.a.2. of the ASB,

-      If there is a loose rivet, replace the loose rivet(s), scrap the two attachment screws and replace them in accordance with paragraph 2.B.3.a.2. of the ASB,

-      If there is no cracking and no loose rivet, scrap the two attachment screws and replace them in accordance with paragraph 2.B.3.a.2. of the ASB,

(iii)   If the tightening torque of the two attachment screws is equal to or more than 80% of the minimum torque value and if there is no cracking and no loose rivet, scrap the two attachment screws and replace them in accordance with paragraph 2.B.3.a.3. of the ASB.

Helicopters equipped with upper and lower fins pre-MOD 073288, with the upper fin post-MOD 073148.

3.    Replace the upper and lower fin attachment screws in accordance with paragraph 2.B.2. of the ASB.

Helicopters equipped with upper and lower fins post-MOD 073288 with the upper fin pre-MOD 073148.

4.    Check the tightening torque of the upper fin attachment screws and check that there is no crack and no loose rivet in the upper fin reinforcement splice, in accordance with paragraph 2.B.3. of ASB No. 55.00.13.

a.     If a crack is detected in the reinforcement splice, replace the fin, scrap the two attachment screws and replace them before installing a new fin, in accordance with paragraph 2.B.3.a.1,

b.    If the tightening torque of one or both of the attachment screws is less than 80% of the minimum torque value and/or there is a loose rivet, check there is no crack in the upper fin spar, in accordance with paragraph 2.B.3.a.2,

-      If a crack is detected in the spar, replace the upper fin, scrap the two attachment screws and replace them before installing a new fin, in accordance with paragraph 2.B.3.a.2,

-      If there is a loose rivet, replace the loose rivet(s), scrap the two attachment screws and replace them in accordance with paragraph 2.B.3.a.2,

-      If there is no cracking and no loose rivet, scrap the two attachment screws and replace them in accordance with paragraph 2.B.3.a.2,

c.     If the tightening torque of the two attachment screws is equal to or more than 80% of the minimum torque value, and if there is no cracking and no loose rivet, scrap the two attachment screws and replace them in accordance with paragraph 2.B.3.a.3.

Note 1:  EASA AD 2006-0060-E refers.

Note 2:  Accomplishment of AD/ECUREUIL/131 constitutes terminating action to the requirements of this Directive.

Compliance:

1.    At the next “T” inspection after 15 March 2006 or before 30 June 2006, whichever occurs first.

2.    Within 110 flight hours after 15 March 2006.

2.a. At intervals not to exceed 110 flight hours.

3.    At the next 500 hour inspection after 15 March 2006 or before 31 March 2006, whichever occurs first.

4.    Within 110 flight hours after 15 March 2006, and thereafter at intervals not to exceed 110 flight hours.

The compliance times remain unchanged by this issue of the Directive.

This Amendment becomes effective on 28 August 2008.

Background:

The European Aviation Safety Agency received two reports of cracks in the spar of the upper fin on AS 355 N helicopters.  Undetected crack growth could lead to failure of the spar and consequent loss of the fin.

For the AS 350 B3 helicopters, compliance with this Directive cancels the requirements of DGAC AD F-2005-010 (AD/ECUREUIL/107), planned to be replaced, in the very short term by an EASA AD, without modification to its technical content.

Amendment 1 is issued to introduce AD/ECUREUIL/131, which provides mandatory terminating action to the requirements of this Directive.

David Villiers
Delegate of the Civil Aviation Safety Authority

17 July 2008