AD/Dauphin/72 Amdt 1 Hydraulic Power Hydraulic Pipes Clamps (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/DAUPHIN/72 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 SA 360 and SA 365 (Dauphin) Series Helicopters

AD/DAUPHIN/72 Amdt 1 Hydraulic Power - Hydraulic Pipes Clamps 4/2006

Applicability:

Eurocopter Model SA 365 N and N1, AS 365 N2 and N3 helicopters, not modified per Mod 0729B67.

Requirement:

AS 365 N2 and N3 model helicopters delivered after 01 January 1998:

1.    Replace attachment clamps in accordance with paragraph 2.B.4. of Eurocopter Alert Service Bulletin (ASB) No. 29.00.08 dated 15 November 2005 or later revisions approved by the French DGAC (installation of compliant attachment clamps).

2.    Do not install clamps with silicone protection on hydraulic pipes.

AS 365 N2 and N3 model helicopters, delivered prior to 01 January 1998; and SA 365 N and N1 model helicopters:

3.    Inspect the attachment clamps of the left hand (LH) hydraulic power system and carry out corrective action, if required, in accordance with paragraph 2.B.5 (Checking the attachment clamps of the LH hydraulic power system ) of ASB No. 29.00.08 or later revisions approved by the French DGAC.

4.    Do not install clamps with silicone protection on hydraulic pipes.

Note:  DGAC AD UF-2006-042 as approved by EASA under reference number 2006-0042-E dated 10 February 2006 refers.  AD UF-2006-042 supersedes DGAC AD
F-2004-115, which now stands cancelled.

Compliance:

1.    Unless previously installed, within 50 flying hours or 1 month after the effective date of this Directive, whichever occurs first.

2.    From the effective date of this Directive.

3.    Unless previously installed, within 660 flying hours or 26 months after the effective date of this Directive, whichever occurs first.

4.    From the effective date of this Directive.

This Amendment becomes effective on 13 April 2006.

Background:

Following an incident on the hydraulic power system of an EC 155 B1 helicopter in flight, which led to illumination of the "HYD" warning light, with no further consequence, a leak was found in the pressure pipe of the LH hydraulic pump.

Analysis conducted by Eurocopter has revealed damage to the silicone protection of an attachment clamp due to contact with hydraulic fluid.  The damage caused the clamp to chafe against the pipe, which led to wear and subsequent perforation of the pipe.

Consequently, to prevent any wear of the hydraulic pipes, original issue of this AD imposed a mandatory periodic check of the condition of the attachment clamps and pipes pending installation of attachment clamps fitted with an acrylonitrile butadiene or polychloroprene protection which retains the mechanical characteristics in a hydraulic environment.

Current amendment requires installation of ASB No. 29.00.08 compliant clamps and extends the AD applicability to model SA 365 N and N1 helicopters and refers to the latest DGAC AD and related service literature on the subject.

The original issue of this AD became effective on 30 September 2004.

Jayaprakashan Ambali
Delegate of the Civil Aviation Safety Authority

21 February 2006