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.
5. If Lucas humidifier, P/N M01AA0101, M01AB0101, M01AB0102 or M01AB0103 is reactivated after the effective date of this Directive carry out the following:
- Action in accordance with Requirement 1.
b. Action in accordance with Requirement 3.
Actions accomplished before the effective date of this Directive per Boeing Alert Service Bulletin 747-26A2274, dated 29 August 2002, are considered acceptable for compliance with the corresponding action specified in this Directive.
Note: FAA AD 2004-20-16 Amdt 39-13821 refers.
Boeing 747 Series Aeroplanes
AD/B747/316 (continued)
Compliance: For Requirement 1 - At the later of the compliance times specified below and thereafter at intervals not to exceed 18 months unless Lucas humidifiers P/N M01AA0101, M01AB0101, M01AB0102 or M01AB0103 is optionally deactivated:
- Within 18 months after the original issue of a Certificate of Airworthiness, or
b. Within 90 days after the effective date of this Directive.
For Requirement 2 - Before further flight and thereafter at intervals not to exceed 36 months unless Lucas humidifier P/N M01AA0101, M01AB0101, M01AB0102 or M01AB0103 is optionally deactivated.
For Requirement 3 - Within 36 months after the effective date of this Directive and thereafter at intervals not to exceed 36 months unless Lucas humidifier P/N M01AA0101, M01AB0101, M01AB0102 or M01AB0103 is optionally deactivated.
For Requirement 4 - Before further flight immediately after the deactivation.
For Requirement 5.a. - Within 18 months after reactivating the humidifier and thereafter at intervals not to exceed 18 months.
For Requirement 5.b. - Within 36 months after reactivating the humidifier and thereafter at intervals not to exceed 36 months.
This Airworthiness Directive becomes effective on 23 December 2004.
Background: Boeing advised that during routine maintenance checks some engine fire control circuits were found to be faulty due to switch internal continuity failures. The humidified air being provided by the LUCAS Humidifier was identified as the source of mineral build up on APU and engine fire control switch contacts leading to failure of the switches to discharge fire suppressant in the affected area. This could result in an uncontrolled fire that could spread to the strut, wing, or aft body of the aeroplane.
This action is intended to address the identified unsafe condition by preventing the possibility of mineral build-up on the APU and engine fire shutoff switches.
James Coyne
Delegate of the Civil Aviation Safety Authority 11 November 2004
The above AD is notified in the Commonwealth of Australia Gazette on 1 December 2004.
Overview
The Airworthiness Directive (AD) issued by the Civil Aviation Safety Authority (CASA) in 2004, titled AD/B747/316, pertains to the Boeing 747 series aeroplanes, specifically addressing the issue of mineral deposits on fire shutoff switches, as identified in Boeing Alert Service Bulletin (ASB) 747-26A2274 Revision 1. This AD was enacted to mitigate the risk of fire in the auxiliary power unit (APU) and engine compartments due to faulty fire control circuits caused by mineral build-up from the LUCAS humidifier. The policy objective of this directive is to ensure the airworthiness and safety of the specified Boeing 747 aeroplanes by mandating specific maintenance actions to prevent such unsafe conditions. Compliance with this directive is mandatory, with specified intervals for functional tests and switch replacements, and applies to aeroplanes listed in the ASB and subsequent to the effective date of the directive.
Scope and Application
The Airworthiness Directive (AD) issued by the Civil Aviation Safety Authority (CASA) pertains specifically to the Boeing 747 series aeroplanes, including models 747SP, 747-200B, -200C, -200F, -300, -400, -400D, and -400F, as referenced in Boeing Alert Service Bulletin 747-26A2274, Revision 1 dated 9 January 2003. This legislation is issued under subregulation 39.1 (1) of the Civil Aviation Safety Regulations 1998 (CASR 1998) and is effective from 23 December 2004. The AD mandates specific actions to be taken to address the unsafe condition identified, which is the potential for mineral deposits on fire shutoff switches, leading to switch failures that could result in uncontrolled fires. These actions include conducting functional tests of the auxiliary power unit (APU) and engine fire shutoff switches, replacing failed switches, and replacing all switches that have not been previously replaced. Additionally, if certain Lucas humidifier parts are deactivated or reactivated, further specific actions must be taken. The AD applies to all relevant aircraft operators within the Commonwealth of Australia and is enforced by CASA, with compliance intervals specified for different actions.
Key Provisions
The Airworthiness Directive (AD) B747/316 issued by the Civil Aviation Safety Authority (CASA) under the Civil Aviation Safety Regulations (CASR) 1998 aims to mitigate the risk of fire due to the build-up of mineral deposits on fire shutoff switches of Boeing 747 series aeroplanes. The directive applies specifically to models 747SP, 747-200B, -200C, -200F, -300, -400, -400D and -400F listed in Boeing Alert Service Bulletin (ASB) 747-26A2274, Revision 1. The AD mandates that certain actions be taken to prevent this unsafe condition, as outlined in the requirements section. These include performing functional tests on the auxiliary power unit (APU) and engine fire shutoff switches, replacing any failed switches, and replacing all APU and engine fire shutoff switches that have not already been replaced in accordance with the bulletin (sections 1-5). Compliance with these requirements must be achieved within specified timeframes, with the AD becoming effective on 23 December 2004.
The obligations imposed by this AD on the operators and owners of the affected Boeing 747 series aeroplanes are clear and detailed. Operators must ensure that functional tests of the fire shutoff switches are conducted in line with ASB 747-26A2274 Revision 1. This includes testing the switches within 18 months after the original issue of a Certificate of Airworthiness, or within 90 days after the effective date of this AD. If any switches fail these tests, they must be replaced with new or serviceable switches. Additionally, all APU and engine fire shutoff switches that have not been replaced under previous requirements must be replaced within 36 months of the AD’s effective date. Operators must also replace all APU and engine fire shutoff switches if the Lucas humidifier, which has been identified as a source of the mineral build-up, is deactivated. If the humidifier is reactivated after the AD’s effective date, operators must then conduct the tests and replacements as specified within the timeframes provided in the directive.
Failure to comply with the requirements set out in AD B747/316 can result in significant consequences. While the AD does not explicitly state penalties for non-compliance, it is important to note that non-compliance with CASA directives can lead to enforcement actions under the Civil Aviation Act 1988 and the Civil Aviation Regulations 1988. These can include fines and, in severe cases, grounding of the aircraft until compliance is achieved. Operators are expected to adhere to the directive to maintain the airworthiness of their aircraft and ensure the safety of passengers and crew.