{"id":"F2006B02428","name":"AD/APU/10 - GTCP 85 Series APU Axial Containment","slug":"ad-apu-10-gtcp-85-series-apu-axial-containment","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41682,"registerId":"commonwealth-F2006B02428-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/APU/10 - GTCP 85 Series APU Axial Containment","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 107 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nAuxiliary Power Units\n\nAD/APU/10 GTCP 85 Series APU Axial Containment 8/95\n\nApplicability: AlliedSignal Aerospace GTCP85 Series Auxiliary Power Units (APU's) incorporating a one piece cast turbine rotor, except those APU's installed on Boeing 737 and British Aerospace BAC 1-11 series aircraft.\n\nRequirement: Install an exhaust centrebody in accordance with AlliedSignal Aerospace Alert Service Bulletin GTCP85-49-A6831 or AlliedSignal Aerospace Service Bulletin GTCP85-49-6919 as applicable.\n\nNote: FAA AD 95-07-03 also refers.\n\nCompliance: (a) Flight operable APU's are to be modified no later than 30 June 1997.\n\n(b) APU's that are ground operable only are to be modified no later than 30 June 1998.\n\nBackground: There have been at least two uncontained failures where turbine wheel fragments have exited the APU exhaust axially and damaged the aircraft.\n\nB737 and BAC 1-11 aircraft are exempt from this requirement because the APU exhaust configuration on these aircraft is such that aircraft damage is highly improbable in the event of an uncontained turbine wheel failure which liberates fragments axially.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive focuses on preventing axial egress of turbine fragments from specified GTCP85 APUs and exempts certain aircraft types; the text sets modification requirements and two compliance deadlines. There is no indication in the instrument that the covered population or required corrective action was broadened beyond that stated purpose (Applicability; Requirement; Compliance)."},"complexity_factors":["Narrow technical applicability: only GTCP85 series APUs with a one‑piece cast turbine rotor (Applicability).","Explicit exemptions for Boeing 737 and BAC 1‑11 installations, which alters who must comply (Applicability; Background).","Different compliance deadlines for flight‑operable versus ground‑only units, creating staged implementation (Compliance (a)/(b)).","Mandated method relies on external AlliedSignal service bulletins to specify the modification procedure (Requirement).","Cross‑reference to an FAA airworthiness directive, indicating alignment with overseas regulator action (Note).","Implementation requires aircraft downtime and technical installation work, imposing operational and cost burdens on operators (Requirement; Compliance)."],"plain_english_summary":"Requires operators of AlliedSignal GTCP85 Series APUs with a one‑piece cast turbine rotor (excluding installations on Boeing 737 and BAC 1‑11) to install an exhaust centrebody following AlliedSignal service bulletins, to reduce the risk of turbine fragments exiting axially. Flight‑capable APUs must be modified by 30 June 1997 and ground‑only units by 30 June 1998 (Requirement; Compliance). Operators fund and schedule the modification work and the regulator enforces the deadlines."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific mechanical failure mode in a specific APU model series. The scope remains tightly focused on the original safety issue (axial containment of turbine fragments) with no evidence of scope creep or expansion beyond the initial safety concern."},"complexity_factors":["Single, specific technical requirement (install exhaust centrebody)","Only 2 defined applicability criteria (APU model type + exclusion list)","Simple binary compliance structure (flight operable vs ground operable)","No nested exceptions or conditional logic beyond the B737/BAC 1-11 exemption","Short document (approximately 200 words)","Single cross-reference to FAA AD 95-07-03 for additional context","Clear, unambiguous deadlines with no alternative compliance methods"],"plain_english_summary":"This AD requires owners/operators of aircraft equipped with AlliedSignal GTCP85 series APUs with a one-piece cast turbine rotor to install an exhaust centrebody to contain turbine fragments. Boeing 737 and BAC 1‑11 aircraft are excluded. The mandate (compliance by 30 June 1997 for in‑flight APUs, 30 June 1998 for ground‑only APUs) addresses incidents of disintegrating turbine wheels that could eject high‑speed debris and cause catastrophic damage or injury."}},"importantCases":[],"_links":{"self":"/api/acts/ad-apu-10-gtcp-85-series-apu-axial-containment","history":"/api/acts/ad-apu-10-gtcp-85-series-apu-axial-containment/history","analysis":"/api/acts/ad-apu-10-gtcp-85-series-apu-axial-containment/analysis","conflicts":"/api/acts/ad-apu-10-gtcp-85-series-apu-axial-containment/conflicts","importantCases":"/api/acts/ad-apu-10-gtcp-85-series-apu-axial-containment/important-cases","documents":"/api/acts/ad-apu-10-gtcp-85-series-apu-axial-containment/documents"}}