{"id":"F2006L00382","name":"AD/APU/20 - Hamilton Sundstrand Compressor Impeller Assemblies","slug":"ad-apu-20-hamilton-sundstrand-compressor-impeller-assemblies","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":117011,"registerId":"commonwealth-F2006L00382-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Auxiliary Power Units","sectionType":"division","heading":"Auxiliary Power Units","content":"### Auxiliary Power Units\n\n| AD/APU/20 | Hamilton Sundstrand CompressorImpeller Assemblies | 3/2006 |\n| --------- | ------------------------------------------------- | ------ |\n\n| Applicability: | Hamilton Sundstrand Power Systems (formerly Sundstrand Power Systems) auxiliary power units (APUs) models T-62T-46C2, T-62T-46C2A, T-62T-46C3, T-62T-46C7, and T-62T- 46C7A, with compressor impeller assembly, part number (P/N) 4502020 or 4502020A installed.Note 1: These APUs are installed on, but not limited to, BAE Systems AVRO 146, Fokker 50, Saab 2000, and Saab 340 aeroplanes. |\n| -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Remove compressor impeller assemblies from service.Note 2: FAA AD 2005-23-11 Amdt 39-14369 refers.                                                                                                                                                                                                                                                                                            |\n| Compliance:    | For APUs with compressor impeller assemblies that have 12,000 or more cycles-since-new (CSN) accumulated on the effective date of this AD; before accumulating 500 additional cycles.For APUs with compressor impeller assemblies that have fewer than 12,000 CSN on the effective date of this AD; before accumulating 12,500 CSN.                                                           |\n|                | This Airworthiness Directive becomes effective on 16 March 2006.                                                                                                                                                                                                                                                                                                                              |\n| Background:    | This AD results from two reports of uncontained failures of compressor impeller assemblies. The issuing of this AD is to prevent an uncontained APU failure and damage to the aeroplane.                                                                                                                                                                                                      |\n\n![](image.001.png)  \nJames Coyne  \nDelegate of the Civil Aviation Safety Authority\n\n1 February 2006","sortOrder":0},{"sectionNumber":"AD/APU/20","sectionType":"part","heading":"AD/APU/20","content":"## AD/APU/20","sortOrder":1},{"sectionNumber":"Hamilton Sundstrand Compressor Impeller ","sectionType":"part","heading":"Hamilton Sundstrand Compressor Impeller Assemblies","content":"## Hamilton Sundstrand Compressor  \nImpeller Assemblies","sortOrder":2},{"sectionNumber":"3/2006","sectionType":"part","heading":"3/2006","content":"## 3/2006","sortOrder":3}],"analysis":{"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"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard, narrow Airworthiness Directive targeting a specific safety defect in specific aircraft components. The scope remains tightly focused on the original safety issue (compressor impeller failures) and has not expanded beyond this technical remedy."},"complexity_factors":["Single, specific technical requirement with clear part numbers and aircraft models","Straightforward two-tier compliance deadline based on cycle count","No defined terms section, no cross-references to other legislation beyond a single FAA reference note","Limited conditional logic — only two scenarios based on existing cycle count","Short document (approximately 200 words of substantive content)","Single purpose: removal of specific component, no exceptions or exemptions stated"],"plain_english_summary":"This AD requires operators and maintenance organisations to remove specific Hamilton Sundstrand APU compressor impeller assemblies (P/N 4502020 or 4502020A) from BAE Avro 146, Fokker 50, Saab 2000 and Saab 340 aircraft before they reach specified flight-cycle limits. \n\nPrompt action—removal within 500 cycles for high-time parts or before 12,500 cycles for lower-time parts—mitigates reported uncontained failures that could cause catastrophic airframe or personnel damage."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive's scope aligns with its stated purpose in the Background: it targets specified APU models and the two impeller part numbers to prevent uncontained APU failure and aircraft damage. It neither expands applicability beyond the identified parts/models nor adds requirements other than the cycle-based removal deadlines and associated recordkeeping (Requirement/Compliance; Background)."},"complexity_factors":["Narrow applicability tied to specific APU models and two precise impeller part numbers (P/N 4502020, 4502020A).","Two alternative cycle-based compliance thresholds (>=12,000 CSN: remove before +500 cycles; <12,000 CSN: remove before reaching 12,500 CSN).","Recordkeeping and fleet tracking burden to monitor cycles‑since‑new (CSN) for each impeller.","Short compliance window from the effective date (effective 16 March 2006) increases scheduling pressure for operators.","Cross-reference to FAA AD 2005-23-11 creates reliance on external certification/action history.","Safety-critical context (uncontained failure reports) raises operational risk and potential for urgent part replacement logistics."],"plain_english_summary":"This directive requires operators of Hamilton Sundstrand APUs (models T‑62T‑46C2, ‑46C2A, ‑46C3, ‑46C7, ‑46C7A) with compressor impeller P/N 4502020 or 4502020A to remove those impellers from service by specified cycles (see Requirement/Compliance). It follows two reports of uncontained impeller failures and aims to prevent APU uncontained failure and aircraft damage. Operators bear the cost and must track cycles and schedule replacements; the regulator set an effective date of 16 March 2006 and concrete removal deadlines."}},"importantCases":[],"_links":{"self":"/api/acts/ad-apu-20-hamilton-sundstrand-compressor-impeller-assemblies","history":"/api/acts/ad-apu-20-hamilton-sundstrand-compressor-impeller-assemblies/history","analysis":"/api/acts/ad-apu-20-hamilton-sundstrand-compressor-impeller-assemblies/analysis","conflicts":"/api/acts/ad-apu-20-hamilton-sundstrand-compressor-impeller-assemblies/conflicts","importantCases":"/api/acts/ad-apu-20-hamilton-sundstrand-compressor-impeller-assemblies/important-cases","documents":"/api/acts/ad-apu-20-hamilton-sundstrand-compressor-impeller-assemblies/documents"}}