{"id":"F2006B01907","name":"AD/A320/17 Amdt 2 - Auxiliary Power Unit","slug":"ad-a320-17-amdt-2-auxiliary-power-unit","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41129,"registerId":"commonwealth-F2006B01907-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/A320/17 Amdt 2 - Auxiliary Power Unit","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nAirbus Industrie A319, A320 and A321 Series Aeroplanes\n\nAD/A320/17\n\nAmdt 2\n\n  \nAuxiliary Power Unit 9/93\n\nApplicability: Model A320 series 100 and 200 aircraft equipped with Garrett Auxiliary Power Unit GTCP 36-300 (A) P/N 3800278-2 but excluding APU’s with serial numbers P-453,\n\nP-454, R-477 and subsequent and APU’s modified in accordance with Garrett Service Bulletin GTCP36-49-6525 any revision.\n\nRequirement: Action in accordance with Garrett Service Bulletin GTCP36-49-6549. Compliance: By 2 April 1995.\n\nBackground: This directive introduces a secondary containment shield as the result of a turbine rotor separation that occurred during a Garrett APU development bench test.\n\nAmendment 1 adopted the FAA closing requirement promulgated in AD 92-27-14 while this amendment revises applicability by excluding certain serial numbered items and items incorporating SB GTCP36-49-6525 as nominated in the FAA AD.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":true,"description":"The original directive applied broadly to all affected APU models. Amendment 2 narrowed the scope by excluding specific serial numbers and units already modified under a different service bulletin, reducing the number of aircraft requiring compliance. This reflects a refinement based on manufacturer data showing certain units were already safe or had alternative fixes."},"complexity_factors":["Single technical requirement with clear cross-reference to manufacturer service bulletin","Precise applicability criteria using part numbers and serial number ranges","Two layers of exclusions (serial numbers and prior modifications)","Brief amendment history referencing external FAA documentation","No defined terms section or extensive conditional logic"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety fix ordered by Australia's aviation regulator (CASA) for specific aircraft.\n\n**What it does:**\nOrders owners and operators of certain Airbus A320 family aircraft to install a protective shield around a specific type of auxiliary power unit (APU) — a small engine at the back of the plane that provides power when the main engines are off.\n\n**Why it matters:**\nDuring testing, a turbine rotor in this APU model broke apart. Without the shield, flying debris could damage the aircraft or injure people. The shield acts as a \"containment\" barrier to catch fragments if the rotor fails again.\n\n**Who it affects:**\n- **Aircraft:** Airbus A319, A320, and A321 planes with specific serial numbers\n- **Specifically:** A320-100 and A320-200 models with Garrett GTCP 36-300(A) APUs, part number 3800278-2\n- **Exemptions:** APUs with serial numbers P-453, P-454, R-477 and later, plus any already modified under Service Bulletin GTCP36-49-6525\n\n**What must be done:**\nFollow the instructions in Garrett Service Bulletin GTCP36-49-6549 to install the shield. This had to be completed by **2 April 1995**.\n\n**The amendments explained:**\n- **Original (1993):** Required the shield after the test failure\n- **Amendment 1:** Aligned with a US FAA directive\n- **Amendment 2 (this version):** Narrows which APUs need the fix by excluding certain serial numbers and already-modified units"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"Amendment 1 narrows the AD's scope by excluding APUs with serial numbers P-453, P-454, R-477 and subsequent, and APUs already modified in accordance with Garrett Service Bulletin GTCP36-49-6525. This revises the applicability compared to the earlier version of the directive. (Applicability, Amendment 1)"},"complexity_factors":["Technical specificity: exact aircraft models, APU model and part number (Applicability, Requirement)","Serial-number and modification-status exclusions that require record checks (Applicability)","Reference to an external service bulletin (GTCP36-49-6549) for the required technical work (Requirement)","Fixed statutory compliance deadline (Compliance)","Safety-engineering context driven by a bench-test failure (Background)","Operational and logistical constraints (parts supply, maintenance slots) implicit but not detailed in the text (Requirement, Compliance)"],"plain_english_summary":"Operators of Airbus A320-100/200 aircraft with Garrett APU GTCP36-300 (P/N 3800278-2) must complete the work in Garrett Service Bulletin GTCP36-49-6549 by 2 April 1995, except for specified serial-numbered or previously modified units. The measure—mandated by CASA—adds a secondary containment shield after a turbine rotor separation was seen in a Garrett bench test. Operators (or their MROs) bear parts, labour and downtime costs and must verify serials/modification status to determine applicability."}},"importantCases":[],"_links":{"self":"/api/acts/ad-a320-17-amdt-2-auxiliary-power-unit","history":"/api/acts/ad-a320-17-amdt-2-auxiliary-power-unit/history","analysis":"/api/acts/ad-a320-17-amdt-2-auxiliary-power-unit/analysis","conflicts":"/api/acts/ad-a320-17-amdt-2-auxiliary-power-unit/conflicts","importantCases":"/api/acts/ad-a320-17-amdt-2-auxiliary-power-unit/important-cases","documents":"/api/acts/ad-a320-17-amdt-2-auxiliary-power-unit/documents"}}