AD/DHC-1/25 Amdt 3 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 2 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 3 Wing Flaps 13/2011

Applicability:

All English production (C1) all models and Portuguese production (T Mk 20) aircraft.

Requirement:

Action in accordance with De Havilland Support TNS CT(C1) No. 166, Issue 5, dated 1 June 2007.

Compliance:

At the next annual maintenance check after the effective date of this AD, unless the satisfactory condition of the flap brackets and associated structure is already known.  Repeat the inspection at intervals not to exceed 300 flight hours or six years, whichever occurs first.

This Amendment becomes effective on 22 June 2011.

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 are unchanged from the previous issues of this Directive.  However, the inspection of the Reinforcing Channel was a new requirement introduced in the previous amendment (Amdt 2) of this Directive.

This amendment adds the Portuguese manufactured (T Mk 20) to the applicability of the AD.  A review has indicated that the inspection is applicable to the Portuguese manufactured model.

Amendment 2, effective 27 September 2007, was issued in response to a revision of the requirement document and introduced a compliance of flight hours and calendar time.

Glen Steemson
Delegate of the Civil Aviation Safety Authority

17 June 2011