COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Aerostar (Piper/Ted Smith) 600 and 700 Series Aeroplanes
AD/TSA-600/37 Lower Wing Skin and Spar Caps 7/87 DM
Applicability: All models.
Requirement: 1. Visually inspect the lower wing skin and accessible areas of the 35% and 55% lower spar caps for cracks in the area surrounding the MLG cutout from WS 54 to WS 58.
2. Gain access as necessary and inspect the 35% and 55% lower spar caps in the immediate vicinity of any skin crack, paying particular attention to possible scoring of the lower surface of the spar cap resulting from fretting action with wing skin cracks.
Note 1. For aircraft which have external wing skin doublers installed, access to the lower wing skin can be gained from within the MLG well. Spar cap access is also available from within the MLG well. The area concerned should be thoroughly cleaned prior to inspection.
Note 2. Particular attention should be paid to skin cracks emanating from the aft outboard corner radius of the MLG cutout, which could propagate rearwards and outboard towards the engine nacelle.
Note 3. Service experience has shown that skin cracks may propagate underneath external wing skin doubler installations around the MLG cutout.
Note 4. Repair of skin cracks may be deferred provided they do not exceed 70 millimetres in length and are stop drilled. The removal of external wing skin doublers may be required to ascertain skin crack lengths. Any spar cap crack or score must be repaired before further flight.
Compliance: For Para 1. Prior to the issue of the next Maintenance Release after 6 May 1987, and thereafter at each issue of a new Maintenance Release.
For Para 2. When wing skin cracks exceeding 70 millimetres in length are found when inspected in accordance with paragraph 1.
Background: Reports have been received concerning cracking of the 55% lower spar cap and wing skin in the region surrounding the outboard rear corner of the MLG cutout.