COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Boeing 747 Series Aeroplanes
AD/B747/128
Amdt 1
Lower Lobe Lap Joints at Wing to Body Fairing 6/95
Applicability: Boeing Model 747 aircraft, Line Numbers 201 to 814 inclusive.
Requirement: 1. Conduct a visual inspection to determine all countersunk fastener locations in the upper rows of the following nominated lap splice areas;
a) B747-100, -200, -300, -400 and 747SR. Inspect from Body Station (BS) 741 - BS1000 at Stringers (S-) 34L, 34R, 39L, 39R, 44L and 44R and from BS1480 - BS1741 at S-34L, 34R, 40L and 40R.
b) B747SP from BS520 - BS1000 at S-34L, 34R, 39L, 39R, 44L and 44R and from BS1480 - BS1901 at S-34L, 34R, 40L, 40R and 46L.
2. For unmodified aircraft, conduct a High Frequency Eddy Current (HFEC) inspection for cracks around all countersunk fastener heads in the upper row of the nominated lap splice areas. Inspect in accordance with Boeing Alert Service Bulletin (ASB) 747-53A2312, Revision 2, Accomplishment Instructions Part I.A.
3. Modify the aircraft, in accordance with Boeing ASB 747-53A2312 Revision 2, Accomplishment Instructions Part II, by replacing the countersunk fasteners with protruding head fasteners.
4. For modified aircraft, at all locations where countersunk fasteners have been replaced, do a HFEC inspection in accordance with Boeing ASB747-53A2312, Revision 2, Accomplishment Instructions Part III.
Note: FAA AD 94-15-06 refers.
Compliance: 1. For unmodified aircraft, inspect in accordance with the full extent of the new Requirement 1 before 11 000 flights or before 1000 flights after 25 May 1995, whichever occurs later, unless previously inspected.
2. Initially inspect in accordance with the full extent of the new Requirement 2 before further flight after inspection in accordance with Requirement 1, unless previously inspected within the last 3000 flights before 25 May 1995.
Re-inspect at intervals not to exceed 4000 flights until modified in accordance with Requirement 3.
3. Modify the aircraft in accordance with Requirement 3 before 20 000 flights.
4. Initially inspect each modified area in accordance with Requirement 4 before 10,000 flights after the date of modification.
Re-inspect at intervals not to exceed 4000 flights.
COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Background: This Directive has been prompted by reports of cracking in the stringer 34 lap joint near the interface with the wing-to-body fairing. This condition, if not corrected, could result in an in-flight depressurisation of the aircraft. This Amendment reduces the number of aircraft to be inspected and widens the inspection area to include all lap splice upper rows under the wing to body fairing.