COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Boeing 747 Series Aeroplanes
AD/B747/48
Amdt 2
Nacelle Strut Midspar Fitting Lugs 13/93 DM
Applicability: All Model 747 series aircraft.
Requirement: Action in accordance with the technical requirements of FAA AD 93-17-07 Amdt 39- 8678.
Note: Boeing ASB 747-54A2152 refers.
Compliance: As specified in the Requirement Document with a revised effective date of 13 October 1993 for Australian registered aircraft.
Background: Fatigue cracking had been reported in the lug bores. The cracking was thought to have initiated at corrosion pits. Terminating action for repeated inspections consisted of removal of the existing press-fit bushings from the midspar fitting, inspection of the lugs, removal of any corrosion, and installation of roller-swaged, shrink-fit bushings.
Amendment 1 was issued to align this Directive with the issue of a FAA AD which reduced certain inspection intervals, removed the optional terminating action for repetitive inspections of the lugs, and added aircraft to the applicability of the AD. This action was in response to a report of fatigue cracking which occurred well below the inspection threshold, and additionally, numerous reports of migration of the press- fit and roller-swaged, shrink-fitted bushings.
Amendment 2 is issued in response to the issue of a new FAA AD which is prompted by the results of flight tests, conducted to determine strut-to-wing interface loads, and by additional reports of cracked lugs.