AD/Cessna 400/103 Amdt 3 Wing Spars Delamination and Corrosion (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/CESSNA 400/103 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.

Cessna 400 Series Aeroplanes

AD/CESSNA 400/103 Amdt 3 Wing Spars Delamination
and Corrosion 26/2010

Applicability:

All models 404 and 441.

Requirement:

1.    Gain access to the rear spar from CWS 34.25 to CWS 82.3 Port and Starboard and inspect the full area of the laminated spar web for delamination and/or corrosion, between the specified stations using an NDI method acceptable to the Authority.

Note:  Qantas NDT Technique U-53 using a Fokker Bond tester and Cessna SID Inspections 57-10-07 and 57-10-08 are acceptable methods.

2.    Repair any detected corrosion in accordance with a scheme approved pursuant to CAR 35.  Where an aircraft has been repaired as a result of inspection in accordance with this issue, or previous issues, of this Directive, inspect in accordance with the requirements of the approved repair scheme.

Compliance:

a.    Unless already accomplished, within forty five days after 03 August 1994; thereafter at intervals not exceeding one year; or

b.    As specified in the approved repair scheme.

Spar web replacement and internal corrosion protection in accordance with a scheme approved pursuant to CAR 35 terminates the repeat inspection requirement.

The date for compliance with the initial issue of this Directive was within 30 days after 8 June 1994, for amendment 1 the effective date was 3 August 1994.

This Amendment becomes effective on 10 January 2011.

Background:

An Australian operator found substantial delamination and corrosion necessitating replacement of the rear spar web in a number of aircraft.  Due to similar construction techniques, and as a precautionary measure, a one time visual inspection was also required on the front and centre spar webs.

Amendment 1 was raised following advice from the manufacturer, and an Australian major maintenance organisation, as well as the results of inspections in accordance with the initial issue of the Directive, which demonstrated the total unreliability of a tap test in one case, and extensive spar cap corrosion in another.

Amendment 2 was raised following the extensive inspections undertaken as a result of Amendment 1.  These have shown that the problem is confined to the rear spar web.

Amendment 3 is raised to accept the inspection methods contained in the related Cessna Supplemental Inspections 57-10-07 and 57-10-08 for the Cessna 441 and Cessna 404 models respectively.

David Villiers
Delegate of the Civil Aviation Safety Authority

22 December 2010