AD/DHC-1/28 Amdt 10 Undercarriage Mounting Casting (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-1/28 Amdt 9 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-1/28 Amdt 10 Undercarriage Mounting Casting 13/2011

Applicability:

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

Requirement:

Inspect in accordance with British Aerospace Technical News Sheet CT (C1) No. 165 Issue 7, dated 1 June 2010 or later revision approved by the UK CAA.

Wings modified in accordance with De Havilland Mod H.310 may not need further inspection per this AD.  Consult the requirement document and contact the TC holder for further information if there is any doubt about your aircrafts status in relation to this modification and the need for continuing inspections.

Note 1:  UK CAA AD 2807 refers.

Compliance:

At the inspection intervals and limits specified in the Requirement document.

Prior compliance with this Directive at Amendment 8 constitutes compliance with this amendment.

This Amendment becomes effective on 23 June 2011.

Background:

Numerous cases of cracking have been documented in the main undercarriage leg mounting casting in each wing.  Inspection of wings returned for overhaul and repair revealed cracking of the undercarriage mounting casting.  These cracks are the result of stress corrosion which is related primarily to elapsed calendar time rather than flight hours.

This amendment adds the Portuguese manufactured DHC-1 (T Mk 20) to the applicability of this AD.  A review has indicated that this inspection is applicable to the Portuguese manufactured T Mk 20 model.

There is no change to the requirements or compliance from the previous amendment.

Recent amendment history:

Amendment 4 relaxed inspection intervals, and introduced suggested examination techniques.

Amendment 5, effective 23 May 1996, reflected a variation to re-inspection intervals.

Amendment 6, effective on 7 October 1999, amended the mounting casting top and bottom flange inspection limits.

Amendment 7, effective 2 December 1999, corrected administrative problems which occurred during processing of Amendment 6.

Amendment 8 was issued in response to the latest issue of the Requirement document which reflects the need to defuel the aircraft prior to the inspection.

Amendment 9, effective 10 January 2011, was issued to update the requirement document to Issue 7.

The original issue of this Airworthiness Directive became effective on 1 April 1979.

Glen Steemson
Delegate of the Civil Aviation Safety Authority

17 June 2011