{"id":"F2008L00180","name":"AD/B747/367 - Lower Cargo Compartment Fire Extinguishing System - Time Delay Relays","slug":"ad-b747-367-lower-cargo-compartment-fire-extinguishing-system-time-delay-relays","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":72368,"registerId":"commonwealth-F2008L00180-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Boeing 747 Series Aeroplanes","sectionType":"division","heading":"Boeing 747 Series Aeroplanes","content":"### Boeing 747 Series Aeroplanes\n\n| AD/B747/367 | Lower Cargo Compartment FireExtinguishing System - Time Delay Relays | 2/2008 |\n| ----------- | -------------------------------------------------------------------- | ------ |\n\n| Applicability: | Model 747-400, 747-400D and 747-400F series aeroplanes as identified in Boeing Special Attention Service Bulletin (SASB) 747-26-2281, dated 24 July 2006.                                                                                                                                                                                                   |\n| -------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. Carry out general visual inspection, in accordance with SASB 747-26-2281 of part number (P/N) TDH6103-1204, -1804 and -6003 time delay relay, as applicable, in the main equipment centre to determine if the relay was manufactured during a certain date range                                                                                         |\n|                | 2. If, as a result of the Requirement 1 inspection, a relay manufactured during the date range specified in the SASB is found, replace the relay with a relay that was not manufactured during the specified date range, or with a relay that has been tested by the supplier and found to be unaffected by thermal expansion, in accordance with the SASB. |\n|                | 3. Time delay relay, P/N TDH6103-1204, -1804 or -6003, may not be installed on any aeroplane as a replacement spare, if the relay has a date code between 0000 and 0343 and does not have an additional date code with the letter \"T.''                                                                                                                     |\n|                | Later revisions of the above SASB, approved by the United States Federal Aviation Administration (FAA) as an Alternate Method of Compliance (AMOC) to FAA AD 2007-23-08, are considered acceptable for compliance with the equivalent Requirements of this Directive.                                                                                       |\n|                | Note: FAA AD 2007-23-08 Amdt 12524 refers.                                                                                                                                                                                                                                                                                                                  |\n| Compliance:    | For Requirement 1 - Within 24 months after the effective date of this Directive.                                                                                                                                                                                                                                                                            |\n|                | For Requirement 2 - Within 30 days after finding a relay manufactured during the date range specified in the ASAB.                                                                                                                                                                                                                                          |\n|                | For Requirement 3 - As of the effective date of this Directive                                                                                                                                                                                                                                                                                              |\n|                | This Airworthiness Directive becomes effective on 14 February 2008.                                                                                                                                                                                                                                                                                         |\n\n| Background: | The FAA has advised of a report indicating that failure of a time delay relay in the electrical load management system (ELMS) panel of a Boeing Model 777 led to testing of other time delay relays at Boeing and at the supplier. Similar relays are also used in the cargo fire suppression system controlling when the secondary fire bottles discharge.                                                                 |\n| ----------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n|             | This Directive is issued to ensure there is sufficient fire suppressant to control a cargo fire if the aeroplane is more than the relay delay time from a suitable airport, which could result in an uncontrollable fire in the cargo compartment. The Directive requires an inspection to determine the date code of the time delay relay for the cargo fire suppression system and, if necessary, replacing of the relay. |\n\n![](image.001.png)  \nCharles Lenarcic  \nDelegate of the Civil Aviation Safety Authority\n\n10 December 2007","sortOrder":0},{"sectionNumber":"AD/B747/367","sectionType":"part","heading":"AD/B747/367","content":"## AD/B747/367","sortOrder":1},{"sectionNumber":"Lower Cargo Compartment FireExtinguishin","sectionType":"part","heading":"Lower Cargo Compartment FireExtinguishing System - Time Delay Relays","content":"## Lower Cargo Compartment Fire  \nExtinguishing System - Time Delay Relays","sortOrder":2},{"sectionNumber":"2/2008","sectionType":"part","heading":"2/2008","content":"## 2/2008","sortOrder":3}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a standard, targeted airworthiness directive addressing a specific safety-critical component failure. The scope remains tightly focused on the identified relay defect in the cargo fire suppression system of specific Boeing 747-400 variants. There is no evidence of scope creep; the directive maintains its original purpose of ensuring cargo fire suppression system reliability."},"complexity_factors":["Short, single-purpose directive with only 3 requirements","Limited applicability (specific Boeing 747-400 variants only)","References external technical document (Boeing Service Bulletin 747-26-2281) for detailed procedures","Simple conditional logic (if manufactured during date range X, then replace)","Only 4 defined elements: specific part numbers (P/N TDH6103-1204, -1804, -6003), date code range (0000-0343), and the \"T\" suffix marking","No nested exceptions or complex cross-referencing within the directive itself","Single compliance pathway with clear deadlines"],"plain_english_summary":"CASA requires operators of Boeing 747-400/-400D/-400F to inspect and, if necessary, replace specific time-delay relays in the cargo fire suppression system because certain date-coded relays can fail and prevent secondary extinguisher discharge. Inspections, prompt replacement of affected relays, and an immediate ban on installing those spare relays are mandated to prevent uncontrolled cargo fires."},"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"This Directive implements targeted inspection, replacement and spare-prohibition measures for specified relays to address relay delay risk, consistent with FAA AD 2007-23-08. It does not broaden the population of affected aircraft or parts beyond the models, part numbers and date-code ranges identified in the Boeing service bulletin."},"complexity_factors":["Narrow technical scope: applies only to specific Boeing 747-400 series models and three relay part numbers","Procedure delegation: requires compliance with Boeing SASB 747-26-2281 for inspection and replacement steps","Date-code identification: requires correctly reading/managing manufacturing date ranges and an additional 'T' code exception","Logistics impact: immediate prohibition on installing certain date-coded spares affects spare-parts management","Compliance timing: staggered deadlines (24 months for inspection; 30 days to replace found relays) create operational scheduling needs","Acceptance of alternative methods: later SASB revisions are acceptable if FAA-approved, creating reliance on external regulator approvals","Supplier-testing option: replacement can be avoided if supplier testing demonstrates a relay is unaffected, adding a supplier-dependency step"],"plain_english_summary":"This Directive requires operators of Boeing 747-400, -400D and -400F series aeroplanes to inspect specific time-delay relays in the lower cargo fire-extinguishing system (per Boeing SASB 747-26-2281). Relays with certain date codes must be replaced or proven unaffected, and some date-coded spares are prohibited. Inspections are due within 24 months and replacements within 30 days. Operators pay for inspections/replacements and must follow the Boeing service bulletin or FAA‑approved revisions to ensure enough fire suppressant is available if a relay delay occurs."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b747-367-lower-cargo-compartment-fire-extinguishing-system-time-delay-relays","history":"/api/acts/ad-b747-367-lower-cargo-compartment-fire-extinguishing-system-time-delay-relays/history","analysis":"/api/acts/ad-b747-367-lower-cargo-compartment-fire-extinguishing-system-time-delay-relays/analysis","conflicts":"/api/acts/ad-b747-367-lower-cargo-compartment-fire-extinguishing-system-time-delay-relays/conflicts","importantCases":"/api/acts/ad-b747-367-lower-cargo-compartment-fire-extinguishing-system-time-delay-relays/important-cases","documents":"/api/acts/ad-b747-367-lower-cargo-compartment-fire-extinguishing-system-time-delay-relays/documents"}}