{"id":"F2006B06305","name":"AD/PORSCHE/2 - Engine - Output Shaft Bearing","slug":"ad-porsche-2-engine-output-shaft-bearing","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":47413,"registerId":"commonwealth-F2006B06305-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PORSCHE/2 - Engine - Output Shaft Bearing","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nPorsche Piston Engines\n\nAD/PORSCHE/2 Engine \\- Output Shaft Bearing 4/89 DM\n\nApplicability: Porsche 930/67 (Skyship 600) and 930/01 (Skyship 500).\n\nRequirement: Replace bell housing, complete with output shaft, bearing, bearing housing, sealing ring and retaining nut in accordance with,\n\nFor Skyship 500, Airship Industries SB 500-72-A297\n\nand For Skyship 600, Airship Industries SB 600-72-A297\n\nNote 1: CAA(UK) Airworthiness Directive 057-12-88 refers.\n\nNote 2: Compliance with this Directive: for 930/01 engines is Mod 25 (embodiment of kit No 5-877) and, for 930/67 MK 1 engines - Mod 24 and 930/67 MK2 engines Mod 4.\n\nCompliance: Unless already accomplished;\n\nFor installed engines within 75 operating hours, For uninstalled engines prior to installation,\n\nAfter 17 February 1989.\n\nBackground: This Directive is issued following further investigation by the manufacturer after the issue of Inspection Service Bulletin 500-72-297 on 24-10-88, revealed the cause of bearing failure. All known failures were on bearings having a heat stabilised polyamide bearing cage with a limiting speed of 3200 rpm.. This has resulted in the necessity to replace the bearing with an improved item with a higher limiting speed.","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 defect in specific engine models. It has not expanded beyond its original purpose of mandating bearing replacement to prevent failures."},"complexity_factors":["Single, specific mechanical component addressed (output shaft bearing)","Only two engine models affected with clear applicability statement","Straightforward compliance timeline (75 hours or prior to installation)","Minimal cross-referencing (only two manufacturer service bulletins and one UK reference)","No nested exceptions or conditional logic — compliance is mandatory with clear deadlines","Short document (approximately 200 words) with simple structure"],"plain_english_summary":"This AD requires owners/operators of aircraft with Porsche 930/67 (Skyship 600) and 930/01 (Skyship 500) engines to replace the output‑shaft bearing because the original heat‑stabilised polyamide bearing cages can fail above 3,200 RPM and have failed in service.\n\nInstalled engines must have the bearing assembly replaced within 75 operating hours after 17 Feb 1989, and uninstalled engines before installation, using the manufacturer’s service bulletins to fit a higher‑speed rated bearing to prevent catastrophic engine failure."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"Changes scope from an earlier inspection advisory to a mandatory replacement requirement. The Background notes a prior Inspection Service Bulletin (500-72-297) and that further investigation revealed the root cause; the AD now requires replacement of the specified assembly within 75 operating hours or before installation, rather than only inspection (Background; Requirement; Compliance)."},"complexity_factors":["Narrow applicability — only two engine models specified (930/67 and 930/01)","Technical specificity — exact components to be replaced (bell housing, output shaft, bearing, housing, sealing ring, retaining nut)","Fixed compliance window — 75 operating hours for installed engines or prior to installation","Cross‑references to manufacturer Service Bulletins (Airship Industries SB 500-72-A297 / SB 600-72-A297) and a UK AD","Notes on prior modifications for different submodels (Mod 25, Mod 24, Mod 4) which affect conformity","Low administrative discretion — mandatory replacement rather than optional inspection"],"plain_english_summary":"Mandates replacement of the bell housing assembly (including output shaft, bearing, bearing housing, sealing ring and retaining nut) on Porsche 930/67 (Skyship 600) and 930/01 (Skyship 500) piston engines. Affects owners/operators and maintenance organisations, who must carry out the replacement within 75 operating hours for installed engines or before installation. The directive follows a manufacturer investigation that linked bearing failures to heat‑stabilised polyamide bearing cages limited to 3,200 rpm and requires a higher‑speed bearing (Requirement; Compliance; Background)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-porsche-2-engine-output-shaft-bearing","history":"/api/acts/ad-porsche-2-engine-output-shaft-bearing/history","analysis":"/api/acts/ad-porsche-2-engine-output-shaft-bearing/analysis","conflicts":"/api/acts/ad-porsche-2-engine-output-shaft-bearing/conflicts","importantCases":"/api/acts/ad-porsche-2-engine-output-shaft-bearing/important-cases","documents":"/api/acts/ad-porsche-2-engine-output-shaft-bearing/documents"}}