COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Boeing 747 Series Aeroplanes
AD/B747/140 Fuselage - Lap Joint Upper Nose Section BS 400 to 520
Applicability: Boeing 747 line number 001 to 628 inclusive.
5/95
Requirement: Do a close visual and high frequency eddy current inspection of the fuselage between BS 400 and BS 520 at the stringer 6L and 6R lap splice in accordance with Boeing Service Bulletin 747-53A2303 Revision 1.
Note 1: FAA AD 90-21-17 refers.
Note 2: Modification per Boeing SB 747-53A2303 is mandatory under the 747 Ageing Fleet Modification Programme (AD/B747/79) at 23000 flights.
Compliance: 1. Initially inspect before the accumulation of 13000 flights, unless accomplished within the last 5000 flights. Aircraft which have exceeded 12 000 flights as of 27 April 1995 shall be initially inspected as follows:
- Aircraft that have accumulated more than16000 flights, inspect within 100 flights after 27 April 1995.
b. Aircraft that have accumulated between 12000 and 16000 flights, inspect within 1000 flights after 27 April 1995.
c. The inspection threshold for aircraft which have been modified to the stretched upper deck configuration may be measured from the time of the modification.
d. Aircraft which have been modified in accordance with Boeing SB 747- 53A2303, initial issue or Revision 1, need not be initially inspected until 10000 flights after the modification.
2. Re-inspect at intervals not exceeding 5000 flights.
Note: For the purposes of this AD a flight shall be taken as a ground-air- ground cycle where the cabin pressure differential has equalled or exceeded 1.5 psi.
Background: One operator reported finding numerous cracks in the stringer 6 lap joint which originated in the fastener countersinks. The inspection programme will control the situation.