COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES British Aerospace (Hawker Siddeley) HS 748 Series Aeroplanes AD/HS 748/4 Door Sill and Secondary Lock Mechanism Micro Switches 13/94 Applicability: All HS 748 aircraft. Requirement: Inspect all door sill and secondary lock mechanism micro switches in accordance with the Accomplishment Instructions of British Aerospace Aircraft Group, Manchester Division HS 748 Service Bulletin 52/106 dated November 1982. Note: CAA(UK) AD 001-01-83 refers. Compliance: At intervals not to exceed 1000 hours time in service, effective 8 December 1994. Background: This Directive introduces a periodic inspection to confirm the integrity of the door sill and secondary lock mechanism micro switches of the crew/freight, passenger and baggage doors, including large freight doors where applicable.