COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Cessna 400 Series Aeroplanes AD/CESSNA 400/33 Firewall Screws - Inspection and Replacement 6/72 Applicability: All model 401, 401A and 401B with S/Nos. 401-0226 to 401-0322, 401A-0001 to 401A-0179 and 401B-0001 to 401B- 0216. All model 402, 402A and 402B with S/Nos. 402-0226 to 402-0322, 402A-0001 to 402A-0143 and 402B-0001 to 402B- 0220. Document: Cessna SL ME72-11. Compliance: Within 100 hours time in service after 31 July 1972.