{"id":"F2006B02432","name":"AD/APU/14 - TSCP700 First Stage LPC Disc","slug":"ad-apu-14-tscp700-first-stage-lpc-disc","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41688,"registerId":"commonwealth-F2006B02432-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/APU/14 - TSCP700 First Stage LPC Disc","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\nAD/APU/14 TSCP700 First Stage LPC Disc 3/98\n\nApplicability: AlliedSignal Inc. TSCP700 series auxiliary power units (APUs) incorporating stage one low pressure compressor (LPC1) disc, P/No 3606429-1.\n\n \n\nRequirement: Remove from service affected TSCP700 LPC1 discs in accordance with AlliedSignal Service Bulletin TSCP700-49-7266.\n\n \n\nNote: FAA AD 97-19-18 also refers\n\n \n\nCompliance: As specified in the requirement document, with a revised effective date of 26 February 1998.\n\n \n\nThis airworthiness directive becomes effective 26 February 1998.\n\n \n\nBackground: The manufacturer has advised there has been LPC1 disc rim separation events.\n\nSubsequent investigation has resulted in a reduction in the LPC1 life limit.\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":{"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 aircraft component. It has not expanded beyond its original purpose of grounding at-risk compressor discs."},"complexity_factors":["Single, specific mechanical part targeted (one part number)","Single compliance action required (remove from service per specified service bulletin)","No defined terms section — uses standard aviation terminology","No nested exceptions or conditional logic","Short document (approximately 150 words of substantive content)","Cross-reference to only one external document (FAA AD) and one manufacturer service bulletin","Clear, unambiguous applicability criteria"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA).\n\n**What it does:**\n- Orders the removal from service of a specific aircraft engine part: the **first stage low pressure compressor disc** (part number 3606429-1) used in **TSCP700 series auxiliary power units (APUs)**.\n- APUs are small engines that provide power to aircraft when the main engines aren't running (for example, when parked at the gate).\n\n**Who it affects:**\n- Airlines and aircraft operators using AlliedSignal (now Honeywell) TSCP700 APUs with the affected disc.\n- Maintenance engineers responsible for inspecting and replacing these parts.\n\n**Why it matters:**\n- The manufacturer discovered that these discs can suffer **rim separation** — meaning the outer edge of the disc can break off during operation. This is a serious safety risk that could damage the aircraft or injure people.\n- Because of this failure risk, the **safe operating life of these discs has been reduced**, meaning they must be replaced sooner than originally planned.\n\n**What must happen:**\n- Operators must follow the manufacturer's service bulletin (TSCP700-49-7266) to identify and remove affected discs.\n- The deadline for compliance is tied to the service bulletin's requirements, with this directive taking effect on **26 February 1998**.\n\nThis directive mirrors a US Federal Aviation Administration (FAA) safety order (AD 97-19-18), showing this is an international safety concern."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":true,"description":"The directive shortens the allowable life of LPC1 discs following rim-separation events and requires earlier removal than prior limits, reflecting a change in service life scope (Background; Requirement)."},"complexity_factors":["Narrow applicability: single APU model and single part number (Applicability)","Prescriptive required action: remove affected parts per a single service bulletin (Requirement)","Clear compliance date established by regulator (Compliance)","Safety rationale based on specific failure mode and reduced life limit (Background)","Dependence on manufacturer service bulletin for technical steps","Potential operational cost and parts-availability impacts for operators"],"plain_english_summary":"This airworthiness directive requires operators of AlliedSignal TSCP700 APUs with stage‑one low pressure compressor disc P/No 3606429-1 to remove affected LPC1 discs and follow AlliedSignal Service Bulletin TSCP700-49-7266 (Requirement; Applicability). CASA set an effective compliance date of 26 February 1998 and enforces the removal (Compliance). Operators bear the cost of inspection, removal and replacement; the action follows reported LPC1 rim separations and a manufacturer-imposed reduction in LPC1 life limit (Background)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-apu-14-tscp700-first-stage-lpc-disc","history":"/api/acts/ad-apu-14-tscp700-first-stage-lpc-disc/history","analysis":"/api/acts/ad-apu-14-tscp700-first-stage-lpc-disc/analysis","conflicts":"/api/acts/ad-apu-14-tscp700-first-stage-lpc-disc/conflicts","importantCases":"/api/acts/ad-apu-14-tscp700-first-stage-lpc-disc/important-cases","documents":"/api/acts/ad-apu-14-tscp700-first-stage-lpc-disc/documents"}}