COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Boeing 747 Series Aeroplanes
AD/B747/53
Amdt 3
Longitudinal Skin Lap Joint and Body Frame Corrosion and Cracking
6/95
Applicability: B747 aircraft line numbers 1 to 200.
Requirement: 1. Conduct an external visual inspection of the lower fuselage lap joints for corrosion in accordance with Boeing Service Bulletin (SB) 747-53A2267, dated 28 March 1986.
2. Inspect, using high frequency eddy current, the upper fastener row of lap joints which have been modified in accordance with Boeing SB 747-53A2267. Inspect in accordance with Boeing SB 747-53A2267, Revision 3, Fig 7.
Note: FAA ADs 94-17-01 and 86-09-07 refer.
Compliance: 1. Inspect in accordance with Requirement 1 before 12 000 hours time in service or before 100 hours time in service after 30 October 1986, whichever is the later.
Re-inspect at intervals not to exceed 4000 hours time in service or 15 months, whichever is the sooner. Inspect until modified in accordance with Boeing SB747- 53A2267, dated March 28 1986.
Compliance 1. is unchanged by this Amendment.
2. Initially inspect in accordance with Requirement 2 at the thresholds below:
- For aircraft modified in accordance with SB 747-53A2267 Revision 2 or Revision 3 “Full modification”; before 10 000 flights after modification.
b. For aircraft modified in accordance with SB 747-53A2267 original issue or Revision 1 “Full modification”; before 7000 flights after modification.
c. For aircraft modified in accordance with SB 747-53A2267 Revision 2 or Revision 3 “Optional modification”; before 7000 flights after modification.
Re-inspect at intervals not to exceed 3000 flights.
Background: Corrosion and fatigue cracking of fuselage skin lap joints has been reported on many B747 aircraft. The initial issue of this AD required visual inspections for corrosion and cracking. Amendment 1 allowed an optional terminating modification.
Amendment 2 referenced FAA AD 86-09-07.
Amendment 3 requires inspection after modification, which is no longer considered to be terminating. The inspection requirement is dependent on the SB revision at the time of installation. The above modification is now mandatory before 20 years of service: AD/B747/49 refers.