{"id":"F2006B02437","name":"AD/APU/3 - Incorporation of Back-Up Plate to Improve Turbine Wheel Containment","slug":"ad-apu-3-incorporation-of-back-up-plate-to-improve-turbine-wheel-containment","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41693,"registerId":"commonwealth-F2006B02437-current","compilationNumber":null,"startDate":"2026-04-01","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/APU/3 - Incorporation of Back-Up Plate to Improve Turbine Wheel Containment","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-generator: Aspose.Words for .NET 22.10.0\n---\n\n?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 107 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Auxiliary Power Units\n\n \n\n# AD/APU/3 Incorporation of Back-Up Plate to Improve\n\nTurbine Wheel Containment\n\nApplicability: Garrett Model No. GTCP36-4A, -6, -16, -16A, -28. Document:  Garrett SB No. GTCP36-49-5323R2.\n\nCompliance: Prior to July 1st 1984.\n\n# 1/83\n\n \n\nBackground:  An uncontained turbine disc failure and a near uncontained turbine disc failure have occurred locally over the past two years. This Directive is issued to preclude further uncontained failed discs.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":2807},"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This directive maintains a narrow, targeted scope focused specifically on containment failures in the identified Garrett APU models. It addresses the exact safety issue described in the background without expanding to broader regulatory requirements."},"complexity_factors":["Single, unambiguous compliance requirement with fixed deadline","No conditional provisions, exceptions, or defined terms","Brief document with only essential fields (applicability, document reference, compliance date)","Technical implementation details delegated to referenced service bulletin rather than included in text"],"plain_english_summary":"**What this does:** This Airworthiness Directive requires aircraft operators to install a protective 'back-up plate' on specific models of Garrett auxiliary power units (APUs) — essentially small jet engines used to power aircraft systems on the ground.\n\n**Who it affects:** Owners and operators of aircraft using Garrett GTCP36-4A, -6, -16, -16A, or -28 model APUs.\n\n**What must be done:** Install the back-up plate in accordance with Garrett Service Bulletin GTCP36-49-5323R2 before 1 July 1984.\n\n**Why it matters:** Following several incidents where turbine discs (spinning metal parts inside the engine) broke apart and nearly escaped their housings, this safety fix ensures that if a disc fails, the metal fragments are contained within the engine casing rather than flying out and potentially damaging the aircraft or injuring people."}},"importantCases":[],"_links":{"self":"/api/acts/ad-apu-3-incorporation-of-back-up-plate-to-improve-turbine-wheel-containment","history":"/api/acts/ad-apu-3-incorporation-of-back-up-plate-to-improve-turbine-wheel-containment/history","analysis":"/api/acts/ad-apu-3-incorporation-of-back-up-plate-to-improve-turbine-wheel-containment/analysis","conflicts":"/api/acts/ad-apu-3-incorporation-of-back-up-plate-to-improve-turbine-wheel-containment/conflicts","importantCases":"/api/acts/ad-apu-3-incorporation-of-back-up-plate-to-improve-turbine-wheel-containment/important-cases","documents":"/api/acts/ad-apu-3-incorporation-of-back-up-plate-to-improve-turbine-wheel-containment/documents"}}