{"id":"F2005L00240","name":"AD/B767/207 - APU and Engine Fire Shutoff Switches","slug":"ad-b767-207-apu-and-engine-fire-shutoff-switches","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":33810,"registerId":"commonwealth-F2005L00240-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Boeing 767 Series Aeroplanes","sectionType":"division","heading":"Boeing 767 Series Aeroplanes","content":"### Boeing 767 Series Aeroplanes\n\n| AD/B767/207 | APU and Engine Fire Shutoff Switches | 3/2005 |\n| ----------- | ------------------------------------ | ------ |\n\n| Applicability: | Model 767-300 series aeroplanes; as listed in Boeing Alert Service Bulletin (ASB) 767-26A0127 dated 17 July 2003. |\n| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement: | 1. Carry out a functional test of the Auxiliary Power Unit (APU) and engine fire shutoff switches, in accordance with ASB 767-26A0127. |\n| | 2. If any APU or engine fire shutoff switch fails during any functional test required by Requirement 1 or 5.a. replace the switch with a new or serviceable switch, in accordance with ASB 767-26A0127. |\n| | 3. Replace all APU and engine fire shutoff switches, that have not been previously replaced in accordance with Requirement 2, with new or serviceable switches in accordance with ASB 767-26A0127. |\n| | Note 1: The Requirement 1 repetitive functional tests and the Requirement 2 and 3 repetitive switch replacements may be optionally terminated if the Lucas (also known as TRW Systemes Aeronautiques) humidifier, part number (P/N) M01AA0101, M01AB0101, M01AB0102 or M01AB0103 are deactivated. |\n| | 4. For any aeroplane on which Lucas humidifier, P/N M01AA0101, M01AB0101, M01AB0102 or M01AB0103 is deactivated - Replace all APU and engine fire shutoff switches with new or serviceable switches in accordance with ASB 767-26A0127. |\n| | 5. For any aeroplane on which Lucas humidifier, P/N M01AA0101, M01AB0101, M01AB0102 or M01AB0103 is reactivated after the effective date of this Directive accomplish the following: |\n| | a. Carry out the Requirement 1 functional tests. |\n| | b. Replace all APU and engine fire shutoff switches that have not been previously replaced in accordance with Requirement 2. |\n| | Note 2: FAA AD 2005-01-13 Amdt 39-13938 refers. |\n\n| Compliance: | For Requirement 1 - Initially, within 18 months since the date of issue of the original Certificate of Airworthiness or the original Export Certificate of Airworthiness or within 90 days after the effective date of this Directive, whichever occurs later and thereafter at intervals not to exceed 18 months unless Lucas (also known as TRW Systemes Aeronautiques) humidifier, P/N M01AA0101, M01AB0101, M01AB0102 or M01AB0103 is optionally deactivated. |\n| ----------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| | For Requirement 2 - Before further flight after the functional check and thereafter at intervals not to exceed 36 months unless Lucas (also known as TRW Systemes Aeronautiques) humidifier, P/N M01AA0101, M01AB0101, M01AB0102 or M01AB0103 is optionally deactivated. |\n| | For Requirement 3 - Within 18 months after the effective date of this Directive and thereafter at intervals not to exceed 36 months unless Lucas (also known as TRW Systemes Aeronautiques) humidifier, P/N M01AA0101, M01AB0101, M01AB0102 or M01AB0103 is optionally deactivated. |\n| | For Requirement 4 - Before further flight following the optional deactivation specified in Note 1. |\n| | For Requirement 5.a. - Within 18 months after reactivating the humidifier and thereafter at intervals not to exceed 18 months. |\n| | For Requirement 5.b. - Within 36 months after reactivating the humidifier and thereafter at intervals not to exceed 36 months. |\n| | This Airworthiness Directive becomes effective on 17 March 2005. |\n| 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 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. |\n| | This Directive requires repetitive functional tests and repetitive replacements of the APU and engine fire shutoff switches. The Directive also provides an optional terminating action for the repetitive functional tests and replacements. |\n\n| | 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. |\n| --- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n\n![](image.001.png) \nJames Coyne \nDelegate of the Civil Aviation Safety Authority\n\n4 February 2005","sortOrder":0},{"sectionNumber":"AD/B767/207","sectionType":"part","heading":"AD/B767/207","content":"## AD/B767/207","sortOrder":1},{"sectionNumber":"APU and Engine Fire Shutoff Switches","sectionType":"part","heading":"APU and Engine Fire Shutoff Switches","content":"## APU and Engine Fire Shutoff Switches","sortOrder":2},{"sectionNumber":"3/2005","sectionType":"part","heading":"3/2005","content":"## 3/2005","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":6,"scope_assessment":{"changed":false,"description":"The Directive remains focused on the original safety issue identified in the Background: mineral build-up from specified Lucas humidifiers causing APU and engine fire shutoff switch failures. The measures (functional testing, replacement of failed or aged switches, and an optional terminating action of humidifier deactivation) stay within that narrowly defined technical scope. The Directive does not expand into unrelated aircraft systems or broader regulatory areas; it prescribes targeted inspections, parts replacement, and an optional equipment deactivation directly related to the identified failure mode."},"complexity_factors":["Five substantive Requirements with interdependent actions (Requirements 1–5).","Optional terminating action (Note 1) that changes whether repetitive actions apply, creating conditional workflow.","Separate and differing compliance intervals for testing vs replacement (18 months for tests, 36 months for replacements in many cases), and special intervals after humidifier reactivation.","Multiple humidifier part numbers (M01AA0101, M01AB0101, M01AB0102, M01AB0103) that must be tracked per airframe.","\"Before further flight\" mandatory replacement after a failed test (immediate operational consequence).","Cross-reference to external Boeing ASB for procedural detail and to FAA AD 2005-01-13, requiring operators to consult multiple documents.","Applicability limited to aircraft listed in an external ASB rather than by a simple model designation, requiring record checks.","Repetitive replacement requirement (Requirement 3) plus an initial replacement mandate (Requirement 2) introduces overlapping obligations.","Notes that change the effect of other requirements (Note 1 and Note 2), increasing conditional reading complexity."],"plain_english_summary":"This directive affects Boeing 767-300s listed in Boeing ASB 767-26A0127 and requires functional testing and replacement of APU and engine fire‑shutoff switches after mineral deposits from specified Lucas humidifiers caused contact failures that could block fire suppression. Operators must test, replace failed or older switches on set intervals; deactivating the listed humidifier is an optional terminating action (reactivation mandates retesting).\n\nIt matters to operators, maintainers and parts suppliers because it raises maintenance costs, spare‑parts demand and tracking burdens, while deactivation trades recurring maintenance for lost humidification."},"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This AD appears tightly focused on its original safety purpose. The scope covers exactly what the Background describes: addressing mineral buildup on fire shutoff switches caused by a specific humidifier system. The various requirements (testing, replacement, deactivation options) are all mechanisms to achieve that single safety outcome. There is no evidence of scope creep into unrelated aircraft systems or operational matters."},"complexity_factors":["Multiple interdependent requirements (Requirements 1-5) with cross-references between them (e.g., Requirement 2 references Requirement 1 and 5.a, Requirement 3 references Requirement 2)","Conditional logic based on equipment status: different rules apply depending on whether the Lucas humidifier is active, deactivated, or reactivated","Multiple compliance timelines running in parallel: 18-month intervals for testing, 36-month intervals for replacement, with different start dates (Certificate of Airworthiness date vs Directive effective date vs deactivation/reactivation events)","Repetitive action structure: requirements are ongoing ('thereafter at intervals') rather than one-time, creating ongoing compliance obligations","Technical part number specificity: four specific part numbers for the humidifier must be tracked to determine applicability","Optional terminating action (Note 1) creates a branch in the compliance path that affects multiple other requirements","Reference to external technical document (Boeing Alert Service Bulletin 767-26A0127) for all procedural details — the AD itself doesn't contain the actual instructions"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's aviation regulator (CASA) to fix a dangerous defect in Boeing 767-300 aircraft.\n\n**What the problem is:**\nA humidifier system made by Lucas (also called TRW) was pumping moisture into the cabin air. Over time, minerals from this humidified air built up on the internal contacts of the **APU (Auxiliary Power Unit) and engine fire shutoff switches** — the buttons pilots press to extinguish fires. This mineral buildup could stop the switches from working when needed, meaning fire suppressant wouldn't release during an engine or APU fire. The result: an uncontrolled fire that could spread to the wing or fuselage.\n\n**What airlines must do:**\n- **Test the switches** every 18 months to check they still work\n- **Replace faulty switches immediately** if they fail testing, then replace them again every 36 months\n- **Replace ALL switches** every 36 months even if they haven't failed (until they've all been swapped out once)\n- **Optional escape route:** Airlines can permanently disable the Lucas humidifier system. If they do this, they must replace all switches once, then they're done — no more repetitive testing or replacements needed\n- **If they reactivate the humidifier later:** The testing and replacement schedule starts all over again\n\n**Who this affects:**\nOperators of Boeing 767-300 series aircraft that have the specific Lucas/TRW humidifier models listed (part numbers M01AA0101, M01AB0101, M01AB0102, or M01AB0103).\n\n**Why it matters:**\nThis is a life-safety issue. Fire shutoff switches are critical emergency equipment. The directive forces airlines to either maintain expensive repetitive maintenance or permanently remove the source of the problem (the humidifier)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b767-207-apu-and-engine-fire-shutoff-switches","history":"/api/acts/ad-b767-207-apu-and-engine-fire-shutoff-switches/history","analysis":"/api/acts/ad-b767-207-apu-and-engine-fire-shutoff-switches/analysis","conflicts":"/api/acts/ad-b767-207-apu-and-engine-fire-shutoff-switches/conflicts","importantCases":"/api/acts/ad-b767-207-apu-and-engine-fire-shutoff-switches/important-cases","documents":"/api/acts/ad-b767-207-apu-and-engine-fire-shutoff-switches/documents"}}