COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES British Aerospace BAe 125 Series Aeroplanes AD/HS 125/138 Wing Leading Edge Corrosion 9/93 Applicability: Model 125 Series 800 and 1000 aircraft pre-Mod. 253538A or B (Improved Corrosion Protection). Requirement: Action in accordance with British Aerospace Mandatory Service Bulletin 57-77. Note: UK CAA AD 016-05-93 refers. Compliance: Within 2 years of the date of aircraft manufacture or prior to 31 May 1994, whichever occurs later. Background: Reports have been received of exfoliation corrosion of the wing leading edge section at the interface with the TKS panels. This is due to the ingress of moisture through gaps in the sealant that have developed during service.