1AD/B747/144 - Engine Thrust Control - Idler Cable Pulley Support Bracket

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/B747/144 Engine Thrust Control - Idler Cable Pulley Support Bracket

5/95

Applicability: B747 Line numbers 202 to 886 inclusive equipped with GE CF6-45/50 engines.

Requirement: 1. Visually inspect number 1 strut engine thrust control cable idler pulley support bracket for cracking in accordance with Boeing SB 747-76A2083. Brackets with a single crack less than 2.0 inches long may remain in service provided the interim repair is installed in accordance with Boeing SB 747-76A2083 Revision 1.

2. Replace the aluminium alloy idler pulley support bracket with one made of Inconel 625 in accordance with Boeing SB 747-76A2083 Revision 2.

Note: FAA AD 93-17-06 refers.

Compliance: 1. a. Inspect in accordance with Requirement 1 before 9000 hours time in service or within 600 hours time in service from 27 April 1995, whichever is the later.

Re-inspect at intervals not to exceed 600 hours time in service.

b. Inspect brackets with the interim repair installed in accordance with Requirement 1 at intervals not to exceed 100 hours time in service.

2. a. Replace interim repaired brackets in accordance with Requirement 2 within 750 hours time in service from repair installation.

2. b. Replace brackets in accordance with Requirement 2 before 10 November 1995.

Note: Replacement with brackets manufactured from Inconel 625 cancels the inspection requirements of this AD.

Background: Five operators have reported cracks in the thrust control cable idler pulley support brackets. Failure of the brackets could result in loss of control of engine thrust.