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-600/21 Engine Nacelle Drain Tubes - Modification 6/79 Applicability: All models with Airframe Sequence Numbers below 0660. Document: 1. Piper Aerostar SB No. SB600-80, Part II; or 2. FAA AD 79-08-05, Amendment 39-3449. Compliance: Within 100 hours time in service after 30 June 1979. Background: In the event of a wing tank fuel leak there is a possibility that fuel will enter and accumulate in the lower nacelle compartment aft of the firewall to be ignited during engine startup.