AD/Cessna 337/22 Amdt 3 Wing Front and Rear Spars Inspection (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 337/22 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 337 Series Aeroplanes

AD/CESSNA 337/22 Amdt 3 Wing Front and Rear
Spars - Inspection 10/2005

Applicability:

Models 337, 337A, 337B, T337B, 337C, T337C, 337D and T337D with the following serial numbers 337-0001 through 337-1193; and

Models 337E, T337E, 337F, T337F, 337G, 337H and T337H with the following serial numbers 33701194 through 33701852; and

Models T337G and P337H with the following serial numbers P3370001 through P3370313.

Requirement:

Inspect the front and rear spars for cracking in accordance with Cessna SL ME78-2 Supplement No. 1 except that in connection with the front spar inspection the eddy current test sensitivity shall be established so that a 10% full scale meter deflection is obtained from a slot .030" + .003" deep, .060" + .003" long and .010" maximum width, machined in the wall of a 3/16" diameter hole in an aluminium alloy test block.

Note 1:  FAA AD 78-09-05 also refers.

Note 2:  A suitable test block is Nortec Part No. TB-12.

Note 3:  Scoring of bolt holes can cause spurious eddy current indications of cracking and may be the cause of future fatigue crack initiations.  Great care must therefore be taken when removing the subject bolts.

Compliance:

Inspect both the front and rear spars in accordance with the times specified for the rear spar in “Action Required” Section of Cessna SL ME78-2 Supplement No. 1 except that for aircraft incorporating Robertson Aircraft Corporation Modification to United States STC 1627 WE a reduction of 1000 hours in the inspection threshold and 100 hours in inspection intervals shall apply.  This exception is subject to change should fatigue substantiating data on the Robertson conversion be supplied to the Authority.

This Amendment becomes effective on 29 September 2005.

Background:

Amendment 2 was issued to clarify the eddy current test block specifications.

This amendment is issued to clearly define which serial numbered aircraft are affected by this AD.

David Villiers
Delegate of the Civil Aviation Safety Authority

8 August 2005