1AD/B747/143 - Fuselage Section 41 Skin Stringer Joints

COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY

SCHEDULE OF AIRWORTHINESS DIRECTIVES

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Boeing 747 Series Aeroplanes

AD/B747/143 Fuselage Section 41 Skin Stringer Joints 5/95

Applicability: Boeing 747 aircraft line numbers 001 to 430 inclusive.

Requirement: 1. Inspect the Section 41 upper fuselage skin at the skin to stringer fastener rows in the areas between Body Stations (BS) 220 and BS 520 left and right hand sides, between stringers S-6 and S-14, excluding the lap joints.

Inspect, using close visual and eddy current methods in accordance with Boeing Service Bulletin (SB) 747-53A2321, Revision 5.

2. Inspect using high frequency Eddy Current, and, if required modify, any external repair doublers that overlap the skin-stringer fastener locations.

Inspect and modify in accordance with Boeing SB 747-53A2321, Revision 5, Fig 3.

Note 1: FAA AD 90-26-10 refers.

Compliance: 1. Inspect in accordance with Requirement 1 before 12 000 flights, or before 1000 flights after 27 April 1995, whichever occurs later.

Re-inspect at intervals not to exceed 2000 flights.

2. Inspect doublers in accordance with Requirement 2 before 10 000 flights after doubler installation, or before 1000 flights after 27 April 1995, whichever occurs later.

Re-inspect at intervals not to exceed 1500 flights.

Modify doublers before 15 000 flights, or within 1000 flights after 27 April 1995, whichever is the later.

Note 2: For the purposes of this AD a flight shall be where the cabin pressure differential equals or exceeds 2.0 psi.

Background: A number of operators have reported skin cracks at skin-stringer fastener locations. Some cracks were up to 0.5" long. Skin cracks that reach critical length can cause an in flight de-pressurization.