{"id":"F2012L01608","name":"AD/B737/228 Amdt 1 - Honeywell Start Converter Unit","slug":"ad-b737-228-amdt-1-honeywell-start-converter-unit","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":89583,"registerId":"commonwealth-F2012L01608-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Boeing 737 Series Aeroplanes","sectionType":"division","heading":"Boeing 737 Series Aeroplanes","content":"### Boeing 737 Series Aeroplanes\n\n| AD/B737/228 Amdt 1 | Honeywell Start Converter Unit | 14/2012 |\n| ------------------ | ------------------------------ | ------- |\n\n```html\n

Applicability:

Model 737-600, -700, -700C, -800, and -900 series aeroplanes, equipped with start converter units (SCU) having Honeywell part number (P/N) 1151858- 241, Series 1 through 9 inclusive, or P/N 1152426-245, Series 1 through 6 inclusive.

Requirement:

Replace the SCU of the auxiliary power unit (APU) located in the electrical and electronics (E/E) compartment in accordance with a method approved by the Manager, Seattle Aircraft Certification Office, Federal Aviation Administration (FAA) of the United States.

Boeing 737-600/700/800/900 Maintenance Manual, Chapter 49-41-61, dated 5 June 1998; and Aircraft Maintenance Manual, Chapter 49-41-61, dated 10 October 2003, are approved methods of compliance with this Requirement. Replace the applicable SCU listed in the \"Existing Honeywell P/N\" column below, with the corresponding SCU listed in the \"Replacement Honeywell P/N\" column below, as follows.

Existing Honeywell P/N

1151858-241, of any series 1 through 9 inclusive



1152426-245, of any series 1 through 6 inclusive

Replacement Honeywell P/N

1151858-241, series 10 or
1151858-241, series 11 or
1151858-241, series 12

1152426-245, series 7 or
1152426-245, series 8 or
1152466-250, series 1 or
1152466-250, series 2 or
1152466-250, series 3 or
1152466-250, series 4

Note: FAA AD 2004-10-10 Amdt 39-13640 refers.

Compliance:

Remains unchanged as within 36 months after 5 August 2004.

This Amendment becomes effective on 27 July 2012.

\n```\n\n| Background: | This amendment updates the list of approved APU SCU that may be fitted to these aircraft in accordance with United States Federal Aviation Authority approved Alternate Method Of Compliance 130S-04-314.The original effective date and compliance time remains unchanged.The original issue of this Airworthiness Directive became effective on 5 August 2004.The original Directive required replacement of the APU SCU, located in the E/E compartment, with a new or modified SCU. This action is necessary to prevent overheating of the electrical connector of the SCU, which could create an ignition source and possible fire in the E/E compartment and cause damage to certain electrical wire bundles on the E2-2 shelf. Such damage could result in loss of power from the APU generator, failure of electrically powered aeroplane systems, and consequent reduction in the ability of the flight crew to control the aeroplane in certain adverse operating conditions. |\n| ----------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n\n![](image.001.png)\n\n \nPeter Nikolic \nDelegate of the Civil Aviation Safety Authority\n\n24 July 2012","sortOrder":0},{"sectionNumber":"AD/B737/228 Amdt 1","sectionType":"part","heading":"AD/B737/228 Amdt 1","content":"## AD/B737/228 Amdt 1","sortOrder":1},{"sectionNumber":"Honeywell Start Converter Unit","sectionType":"part","heading":"Honeywell Start Converter Unit","content":"## Honeywell Start Converter Unit","sortOrder":2},{"sectionNumber":"14/2012","sectionType":"part","heading":"14/2012","content":"## 14/2012","sortOrder":3}],"analysis":{"summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"The amendment does not alter the scope of the original directive; it adds new acceptable replacement start converter unit part numbers on top of those already listed."},"complexity_factors":["Amendment only updates the list of approved replacement part numbers","No change to compliance deadline, applicability or required action","Relies on FAA-approved alternate method of compliance"],"plain_english_summary":"This amendment to AD/B737/228 expands approved replacement part numbers for the Honeywell start converter unit (SCU) on certain Boeing 737-600/700/700C/800/900 series aircraft, letting operators fit later-series SCU models as FAA-approved alternate compliance. It does not change the original replacement deadline (36 months after 5 Aug 2004) and simply provides additional acceptable part-number options for Australian operators and maintainers. Effective 27 July 2012."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"The amendment updates the list of approved replacement Honeywell SCU series that may be fitted (adds newer series P/Ns and alternates) while leaving the original compliance deadline and overall replacement requirement unchanged. Functionally this widens/clarifies permissible replacement parts rather than imposing additional timing obligations (see Background and Requirement)."},"complexity_factors":["Specificity of parts: multiple Honeywell part numbers and series ranges are listed for existing and permissible replacement SCUs (table of Existing and Replacement Honeywell P/Ns).","Cross‑jurisdictional approval: compliance may follow methods approved by the Manager, Seattle Aircraft Certification Office, FAA, or specified Boeing Maintenance Manual chapters (Requirement: 'in accordance with a method approved by the Manager, Seattle Aircraft Certification Office, Federal Aviation Administration (FAA)'; AMM chapters cited).","Limited applicability: applies only to Model 737-600, -700, -700C, -800, and -900 with SCUs having the listed P/Ns (Applicability).","Implementation burden: physical replacement required in the E/E compartment (Requirement: 'Replace the SCU of the auxiliary power unit (APU) located in the electrical and electronics (E/E) compartment'), which involves maintenance scheduling, parts procurement and possible downtime.","Inventory and procurement impact: operators must obtain the specified replacement series (Replacement Honeywell P/N column), affecting spare‑parts stock and supply chains.","Compliance timing: unchanged fixed deadline (Compliance: 'Remains unchanged as within 36 months after 5 August 2004'), creating a hard window for fleet compliance.","Safety rationale documented: replacement linked to a defined failure mode—connector overheating causing ignition risk, wiring damage and loss of APU electrical power (Background).","Regulatory amendment narrowness: this is an update to approved parts rather than a new operating restriction, limiting the scope of operational change but altering permissible equipment."],"plain_english_summary":"This amendment requires operators of Boeing 737-600/700/700C/800/900 aeroplanes fitted with certain Honeywell auxiliary power unit (APU) start converter units (SCUs) to replace those SCUs with specified newer Honeywell series part numbers using an FAA‑approved method. The update changes which SCU series are acceptable (per FAA Alternate Method of Compliance 130S-04-314) while keeping the original 36‑month compliance window; the stated purpose is to prevent connector overheating that could lead to fire, wiring damage and loss of APU electrical power."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This amendment maintains the original scope of the 2004 directive. It does not expand applicability to new aircraft models or introduce new safety requirements. The change is purely administrative — adding alternative replacement part numbers approved by the FAA — while preserving the original compliance deadline and safety objective."},"complexity_factors":["Technical aviation terminology throughout (APU, SCU, P/N, E/E compartment)","Multiple nested part number series requiring cross-referencing (e.g., Series 1-9 must become Series 10-12)","Reference to external FAA documentation (AD 2004-10-10 and Alternate Method of Compliance 130S-04-314)","Amendment structure requires understanding of original 2004 directive to fully comprehend compliance timeline","Specific technical manual references (Boeing Maintenance Manual Chapter 49-41-61) as approved compliance methods"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). It requires airlines and aircraft operators to replace a specific faulty electrical component on certain Boeing 737 aircraft.\n\n**What it does:**\n- **Targets:** Boeing 737-600, -700, -700C, -800, and -900 series planes\n- **The problem:** The auxiliary power unit (APU) \"start converter unit\" (SCU) — a device that helps start the small engine that provides power when the main engines are off — has a defective electrical connector that can overheat\n- **The risk:** Overheating could cause a fire in the electrical compartment, damage wiring, and potentially lead to loss of power to critical aircraft systems\n\n**What operators must do:**\n- Replace the old Honeywell SCU part with a newer, approved version\n- Old parts: P/N 1151858-241 (Series 1-9) or P/N 1152426-245 (Series 1-6)\n- New parts: Higher series numbers of the same part numbers, or alternative part P/N 1152466-250 (Series 1-4)\n- **Deadline:** Within 36 months of 5 August 2004 (so by August 2007)\n\n**Why this amendment matters:**\nThis is **Amendment 1** from July 2012. It expands the list of approved replacement parts to include additional options approved by the US FAA, giving operators more flexibility in sourcing compliant components without changing the original safety deadline."},"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"}},"importantCases":[],"_links":{"self":"/api/acts/ad-b737-228-amdt-1-honeywell-start-converter-unit","history":"/api/acts/ad-b737-228-amdt-1-honeywell-start-converter-unit/history","analysis":"/api/acts/ad-b737-228-amdt-1-honeywell-start-converter-unit/analysis","conflicts":"/api/acts/ad-b737-228-amdt-1-honeywell-start-converter-unit/conflicts","importantCases":"/api/acts/ad-b737-228-amdt-1-honeywell-start-converter-unit/important-cases","documents":"/api/acts/ad-b737-228-amdt-1-honeywell-start-converter-unit/documents"}}