AD/B747/316 - Prevention of Mineral Deposits on Fire Shutoff Switches (Cth)

AIRWORTHINESS DIRECTIVE For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.

Boeing 747 Series Aeroplanes

AD/B747/316 Prevention of Mineral Deposits on Fire Shutoff Switches

13/2004

Applicability: Model 747SP, 747-200B, -200C, -200F, -300, -400, -400D and -400F series aeroplanes listed in Boeing Alert Service Bulletin (ASB) 747-26A2274, Revision 1, dated 9 January 2003.

Requirement: 1. Perform a functional test of the auxiliary power unit (APU) and engine fire shutoff switches, in accordance with ASB 747-26A2274 Revision 1.

2. If any fire shutoff switch fails during any functional test required by Requirements 1 or 5.a., replace the switch with a new or serviceable switch, in accordance with the ASB 747-26A2274 Revision 1.

3. Replace all APU and engine fire shutoff switches that have not been previously replaced per Requirement 2 with new or serviceable switches, in accordance with ASB 747-26A2274 Revision 1.

4. If Lucas flight deck humidifier part number part number (P/N) M01AA0101, M01AB0101, M01AB0102 or M01AB0103 is optionally deactivated, replace all APU and engine fire shutoff switches with new or serviceable switches in accordance with ASB 747-26A2274 Revision 1.