AD/DHC-1/25 Amdt 2 Wing Flaps (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/DHC-1/25 Amdt 1 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.

De Havilland DHC-1 (Chipmunk) Series Aeroplanes

AD/DHC-1/25 Amdt 2 Wing Flaps 10/2007

Applicability:

English-built DHC-1 Chipmunk aircraft, all marks.

Requirement:

Action in accordance with De Havilland Support Ltd TNS CT(C1) No. 166 Issue 5.

Compliance:

At the next annual maintenance check after 30 August 2007, unless the satisfactory condition of the flap brackets and associated structure is already known beyond reasonable doubt.  Repeat the inspection at intervals not to exceed 300 flight hours or 6 years, whichever occurs first.

This Amendment becomes effective on 27 September 2007.

Background:

Cracking has been reported in both of the subject flap components.  It has been attributed to fatigue induced by repeated use of the footstep on the flap.  The Inner Hinge Bracket inspections were unchanged from the previous issue of this Directive.  However, the inspection of the reinforcing channel is a new requirement.

Amendment 2 is issued in response to the latest issue of the Requirement document, which completely revises the inspection of the inboard wing-mounted and flap-mounted flap hinge brackets and associated flap structure, and introduces a compliance time of flight hours and calendar time.

David Villiers
Delegate of the Civil Aviation Safety Authority

23 July 2007