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-31/57 Elevator Balance Weights - Inspection 9/77 Applicability: All model PA-31 and PA-31-300 with wing luggage lockers per nayak STC. SA 986 SW. Requirement: 1. Inspect the elevator balance weights fitted in the nose channel of the elevator for security of attachment ("Rivnut" pull-up) and check elevator unbalance (96.4 inch lbs. tail heavy maximum); or 2. FAA AD 77-12-02 amdt. 39-2915. Compliance: Within 25 hours time in service after 19 August 1977.