{"id":"F2007L01061","name":"AD/APU/19 Amdt 1 - Micorturbo - Overspeed Protection Channel","slug":"ad-apu-19-amdt-1-micorturbo-overspeed-protection-channel","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":65021,"registerId":"commonwealth-F2007L01061-current","compilationNumber":null,"startDate":"2026-04-02","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/19 Amdt 1 | Micorturbo - Overspeed Protection Channel | 5/2007 |\n| ---------------- | ----------------------------------------- | ------ |\n\n| Applicability: | Auxiliary Power Unit (APU) SAPHIR 20 model 095. These APUs are installed on Eurocopter AS332 and EC225 helicopters.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |\n| -------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Unless already accomplished, replace the existing ECU and the Drain Valve by an ECU and Drain Valve, modified in accordance with the instructions of MICROTURBO Alert Service Bulletin (ASB) 095-49A11, Edition 2, dated7 October 2005 or later NAA approved revisions.Note 1: The modified ECU includes the new EGT limit setting.Note 2: Edition 2 of the ASB 095-49A11 dated 7 October 2005 contains revised torque values.Note 3: DGAC AD F-2005-146 EASA reference No 2005-6137 dated 9 August 2005 refers.                                                                                                                                                                                                                                                                                                                                                                 |\n| Compliance:    | Within 60 days, after the effective date of this AD.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |\n|                | This Amendment becomes effective on 10 May 2007.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |\n| Background:    | With the existing configuration, a certain failure could cause over-speed of the gas generator rotor resulting in uncontained burst of the turbine, liberating high-energy fragments. The occurrence that the high-energy fragments would be uncontained is considered a potentially dangerous situation which requires imperative corrective action. The purpose of the modification is to limit gas generator speed during acceleration towards over-speed by installation of a modified Electronic Control Unit (ECU) and Drain Valve. In addition, the modification also renders the EGT control function compliant with the certificated specifications. In operation, if EGT exceeds the certificated limit value, turbine blade shedding could occur.The current amendment of the AD makes reference to the service document ASB 095-49A11 at the latest revision status. |\n\n|     | The original issue of this AD became effective on 27 October 2005. |\n| --- | ------------------------------------------------------------------ |\n\n![](image.001.png)  \nCharles Lenarcic  \nDelegate of the Civil Aviation Safety Authority\n\n27 March 2007","sortOrder":0},{"sectionNumber":"AD/APU/19 Amdt 1","sectionType":"part","heading":"AD/APU/19 Amdt 1","content":"## AD/APU/19 Amdt 1","sortOrder":1},{"sectionNumber":"Micorturbo - Overspeed Protection Channe","sectionType":"part","heading":"Micorturbo - Overspeed Protection Channel","content":"## Micorturbo - Overspeed Protection Channel","sortOrder":2},{"sectionNumber":"5/2007","sectionType":"part","heading":"5/2007","content":"## 5/2007","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"The amendment updates the AD to require compliance with MICROTURBO ASB 095-49A11 at its latest NAA-approved revision and records revised torque values and the ECU’s new EGT limit setting. The original AD (effective 27 October 2005) is superseded by this amendment effective 10 May 2007 (Requirement; Background)."},"complexity_factors":["Narrow technical applicability: specific APU model (SAPHIR 20 model 095) and helicopter types (Eurocopter AS332, EC225) (Applicability)","Mandatory hardware replacement (ECU and drain valve) rather than optional inspection (Requirement)","Short compliance window (60 days) creating scheduling and downtime pressure (Compliance)","Dependence on an external service document and its NAA-approved revision status (ASB 095-49A11) for exact modification steps and torque values (Requirement; Background)","Safety-critical stakes (risk of gas-generator overspeed, uncontained turbine burst, and EGT blade shedding) driving imperative corrective action (Background)","References to foreign authority and earlier ADs increase cross-jurisdictional coordination (Requirement; Background)"],"plain_english_summary":"This airworthiness directive requires operators of MICROTURBO SAPHIR 20 model 095 APUs fitted to Eurocopter AS332 and EC225 helicopters to replace the ECU and drain valve with modified units per MICROTURBO Alert Service Bulletin ASB 095-49A11 (Edition 2 or later) to add overspeed protection and correct the EGT limit setting (Applicability; Requirement). Operators and maintenance organisations must complete the work within 60 days; they bear the cost and downtime while CASA enforces the AD and relies on the ASB’s NAA-approved revisions (Compliance)."},"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":3,"scope_assessment":{"changed":false,"description":"This amendment maintains the original safety purpose of preventing APU overspeed failures. It simply updates the reference to the latest revision of the service bulletin (Edition 2) and confirms the effective date. The scope remains tightly focused on the specific mechanical modification required for the SAPHIR 20 APU."},"complexity_factors":["Single, specific technical requirement with clear reference to an external service bulletin (ASB 095-49A11)","Limited applicability — only one APU model (SAPHIR 20 model 095) on two helicopter types","Straightforward compliance deadline (60 days from effective date)","Minimal defined terms — only standard aviation abbreviations (ECU, EGT, APU, ASB) used without formal definitions section","No nested exceptions or conditional logic — applies universally to affected aircraft unless already modified","Short document length with single operational requirement","Cross-reference to one foreign aviation directive (DGAC AD F-2005-146) for background context only"],"plain_english_summary":"This AD requires operators of Eurocopter AS332 and EC225 helicopters with SAPHIR 20 model 095 APUs to replace the ECU and drain valve with modified units to prevent gas-generator overspeed, uncontained turbine bursts, and EGT-related blade failures. \n\nCompliance must follow Microturbo Alert Service Bulletin 095-49A11 (Edition 2 or later) and be completed within 60 days of 10 May 2007."}},"importantCases":[],"_links":{"self":"/api/acts/ad-apu-19-amdt-1-micorturbo-overspeed-protection-channel","history":"/api/acts/ad-apu-19-amdt-1-micorturbo-overspeed-protection-channel/history","analysis":"/api/acts/ad-apu-19-amdt-1-micorturbo-overspeed-protection-channel/analysis","conflicts":"/api/acts/ad-apu-19-amdt-1-micorturbo-overspeed-protection-channel/conflicts","importantCases":"/api/acts/ad-apu-19-amdt-1-micorturbo-overspeed-protection-channel/important-cases","documents":"/api/acts/ad-apu-19-amdt-1-micorturbo-overspeed-protection-channel/documents"}}