COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Piper PA-31 Series Aeroplanes
AD/PA-31/118
Amdt 1
Applicability: All PA-31 Series.
Aileron Spar 1/93
Requirement: 1. (a). Remove the LH and RH ailerons from the aircraft, and remove the inboard and outboard hinge brackets and the control horn brackets. Strip and clean the areas around the bracket attachments including the spar flanges, and inspect the visible surfaces of the front spar element (doubler) for cracks, using an approved dye penetrant inspection procedure. Particular attention should be paid to the hinge bracket attachment and the horn bracket attachment areas; or,
- (b). Inspect the aileron in accordance with an alternative scheme approved by the Authority.
2. If any cracking or damage is identified, dismantle sufficient of the aileron structure to remove the spar doubler and gain good access to the main spar element, and the aft rib forward flange, in the vicinity of the identified defect. Inspect all surfaces in the area using an approved dye penetrant inspection procedure.
Note 1: Colour contrast dye penetrant used in accordance with Appendix II to CAO
108.10 is an approved procedure.
Note 2: Cracking in these areas may be exacerbated by degradation of the control system stiffness eg due to pivot bearing wear, and by aileron deflection during ground handling and pre-flight inspection.
Compliance: Inspect before 5000 hours aileron time in service, or within 5000 hours aileron time in service after repair in accordance with a design approved by the Authority, or within 500 hours aileron time in service since last inspected in accordance with the previous issue of this AD, or before the issue of the next Maintenance Release after
7 January 1993, whichever is the latest. Repeat thereafter at intervals not exceeding 500 hours aileron time in service.
Background: Numerous reports have been received of fatigue cracking in the aileron spar, spar doubler, and rib flanges, which appear to be caused by high out of plane stresses. Cracking in these areas will degrade the strength of the hinge attachment and may have an adverse affect on the aileron flutter characteristics.
Amendment 1 is raised to alleviate the requirement to repetitively dismantle structure which shows no sign of defect. As a result of service experience, visual inspection requirements have been upgraded to a recognised dye penetrant inspection procedure, at shorter intervals, and additional areas have been included.