Ad/Ac-Cla/6 Amdt 1 - Wing Struts Carry-Through Tube (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/AC-CLA/6 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.

Aircraft Parts and Development (CALL AIR) A-9 Series Aeroplanes

AD/AC-CLA/6 Amdt 1 Wing Struts Carry-Through Tube 10/2008

Applicability:

All models A-9, A-9A and A-9B with wing struts carry through tube running through hopper.

Requirement:

To prevent failure of the main carry-through tube perform the following:

1.    Remove the hopper top and inspect for a fibreglass wrapped carry-through tube.  The main carry through tube if located in the hopper is located 625 mm aft of the hopper forward bulkhead and 150 mm below hopper surface.  Visually inspect fibreglass wrapping for cracks.

2.    If wrapping is cracked, remove wrapping and inspect main carry-through tube for corrosion.

3.    Remove all corrosion on tube; if corrosion exceeds depth of 0.25 mm in one location or 2 per cent of the tube cross-sectional area, the main carry-through must be replaced.  Nominal cross-sectional area of 262.5 sq. mm.  Finish the tube with two coats of zinc chromate primer after corrosion removal.  Rewrap the exposed tube with a fibreglass laminate using a minimum of 3 layers of
MIL-C-9084 glass cloth or equivalent and chemical resistant resin such as Reichbold 33-402.

Note: 1:  Local equivalents may be substituted for glass cloth and resin.

Note 2:  FAA AD 78-20-06 refers.

Compliance:

At intervals of three years after 12 December 1978.

This Amendment becomes effective on 25 September 2008.

Background:

This AD has been amended to remove reference to “major inspection” which is no longer required by legislation.  Reference to FAA AD 78-20-06 also included.

The AD was originally raised in 1979 following reports of severe corrosion of the wing strut carry-through tube being found in a number of overseas aeroplanes, causing a fatal accident due failure of the wing strut carry-through tube.

David Villiers
Delegate of the Civil Aviation Safety Authority

7 August 2008