{"id":"F2006B09268","name":"AD/DHE/18 Amdt 5 - Tapered Crankshaft Inspection","slug":"ad-dhe-18-amdt-5-tapered-crankshaft-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":53288,"registerId":"commonwealth-F2006B09268-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DHE/18 Amdt 5 - Tapered Crankshaft Inspection","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)  \nDe Havilland Piston Engines\n\nAD/DHE/18\n\nAmdt 5\n\n  \nTapered Crankshaft Inspection 7/98\n\nApplicability: Gipsy Major series engines fitted with a tapered crankshaft Requirement: 1. Insitu ultrasonic inspection:\n\nIn accordance with a procedure approved by the Authority, carry out an ultrasonic inspection of the crankshaft in the area forward of the thrust bearing flange.\n\n    2. Crankshaft inspection \\- Pre Mod G2495 crankshafts:\n\n    (a) In accordance with a procedure approved by the Authority, carry out an ultrasonic inspection of the crankshaft in the area forward of the thrust bearing flange , and\n\n    (b) carry out a magnetic particle inspection of the entire crankshaft utilising the wet continuous technique applied in a manner that both longitudinal and circumferential cracking will be detected, CAO 108.8 Appendix 1 refers.\n\n    3. Crankshaft inspection \\- Post Mod G2495 crankshafts:\n\n    (a) Remove the Mod G2495 thrust bearing location nut sleeve, and\n\n    (b) carry out a magnetic particle inspection of the entire crankshaft utilising the wet continuous technique applied in a manner that both longitudinal and circumferential cracking will be detected, CAO 108.8 Appendix 1 refers.\n\nCompliance: Effective 18 June 1998:\n\n    Insitu ultrasonic inspection: Unless previously carried out;\n\n    (a) within 25 hours time in service or at the next maintenance release inspection, whichever occurs first, and then\n\n    (b) at 45 to 50 hours time in service following an inspection in accordance with Compliance requirement 1 (a).\n\nNote 1: In service experience since the issue of AD/DHE/18 Amdt. 4 indicates the airworthiness of Gipsy Major tapered crankshafts in service can be reasonably established with two ultrasonic inspections. Therefore, engines in service which have already had two ultrasonic inspections of the tapered crankshaft, adequately satisfy Requirement 1 of this directive. No further insitu ultrasonic inspections are required.\n\n    2. Crankshaft inspection - Pre Mod G2495 crankshafts: Prior to installation of the crankshaft in an engine.\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n3 Crankshaft inspection \\- Post Mod G2495 crankshafts. Prior to installation of the crankshaft in an engine.\n\nThis amendment becomes effective on 18 June 1998.\n\nBackground: This directive was originally issued to require a visual and a magnetic particle inspection (MPI) of the tapered crankshaft in the area forward of the thrust bearing flange. Amendment 4 replaced the visual inspection with repetitive insitu ultrasonic inspections. In service experience since the issue of Amdt. 4 has indicated the airworthiness of tapered crankshafts in service can be satisfactorily determined by two consecutive, insitu, ultrasonic inspections. In response, this amendment limits the insitu ultrasonic inspection requirement to two consecutive inspections.\n\nIn addition to the amended ultrasonic inspection compliance requirement, this amendment also includes a requirement to carry out an ultrasonic inspection of pre Mod G2495 crankshafts before installing that crankshaft in an engine. A Pre Mod G2495 crankshaft, recently inspected insitu by the ultrasonic inspection technique, was reported to be cracked in the area of the thrust bearing location nut threads. On removal of the crankshaft from the engine, and despite knowledge of the crack location, the crack could not be confirmed by MPI. An independent ultrasonic inspection confirmed the presence of a 6mm long by 3mm deep crack.\n\nAmendment 4 of this Airworthiness Directive became effective on 22 July 1993. Amendment 3 of this Airworthiness Directive became effective on 30 May 1993. The original issue of this Airworthiness Directive became effective in August 1963.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":true,"description":"Scope was narrowed and clarified compared with earlier versions: the amendment limits the in‑service ultrasonic regime to two consecutive insitu ultrasonic inspections as sufficient to establish airworthiness (Note 1; Background), and it adds mandatory ultrasonic inspection (and MPI where specified) prior to installation of pre‑Mod G2495 crankshafts after a reported case where MPI failed to reveal a crack that ultrasonic detected (Requirement 2; Background)."},"complexity_factors":["Multiple inspection methods required: in‑situ ultrasonic inspection and wet continuous magnetic particle inspection (MPI) with both longitudinal and circumferential detection (Requirement 1; Requirement 2(b); Requirement 3(b); CAO 108.8 Appendix 1).","Different obligations for pre‑Mod G2495 versus post‑Mod G2495 crankshafts (Requirement 2 vs Requirement 3), including removal of the thrust bearing location nut sleeve for post‑Mod shafts (Requirement 3(a)).","Procedures must be approved by the Civil Aviation Safety Authority, creating administrative/approval burden for maintainers (Requirement 1; Requirement 2(a)).","Timing and repetition rules: immediate first inspection deadlines (25 hours or next maintenance release) and a 45–50 hour follow‑up interval, plus a hard limit of two consecutive in‑situ ultrasonic inspections for in‑service airworthiness confirmation (Compliance; Note 1).","Installation prohibition unless required inspections completed: pre‑ and post‑Mod G2495 crankshafts must be inspected prior to installation (Compliance items 2 and 3).","Reference to a specific MPI technique ('wet continuous') increases technical specificity and potential equipment/training costs (Requirement 2(b); Requirement 3(b); CAO 108.8 Appendix 1).","Historical amendments and staged changes (original AD, Amendments 3–5) mean operators must track amendment history to confirm which inspection regime applies (Background)."],"plain_english_summary":"This amendment requires inspections of Gipsy Major piston-engine tapered crankshafts using in‑situ ultrasonic testing and magnetic particle inspection (MPI). It narrows the repetitive ultrasonic checks to two consecutive in‑service ultrasonic inspections and adds mandatory ultrasonic/MPI checks before installing certain crankshafts (pre‑ and post‑Mod G2495). The rule affects owners, maintainers and overhaul facilities who must follow Authority‑approved procedures and specific timing for inspections."},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"The legislation remains tightly focused on its original purpose: ensuring the airworthiness of tapered crankshafts in Gipsy Major engines. While Amendment 5 refines the inspection requirements based on operational experience, it does not expand beyond the original safety mandate for this specific engine component."},"complexity_factors":["Multiple inspection pathways depending on crankshaft modification status (Pre Mod G2495 vs Post Mod G2495 vs standard insitu)","Nested compliance timelines with conditional triggers ('whichever occurs first', 'following an inspection in accordance with...')","Cross-reference to CAO 108.8 Appendix 1 for technical inspection methodology","Amendment history creates layered context (original 1963 directive, Amendment 4 in 1993, now Amendment 5 in 1998)","Specific technical terminology requiring aviation engineering knowledge ('thrust bearing flange', 'wet continuous technique', 'time in service')"],"plain_english_summary":"This safety directive targets De Havilland Gipsy Major engines with tapered crankshafts (common in Tiger Moth–type biplanes), requiring ultrasonic testing of a known failure-prone area and magnetic particle inspection when crankshafts are removed. It affects owners, operators, and maintenance engineers.\n\nIt matters because crankshaft failure can be catastrophic; the update clears engines that already had two ultrasonic inspections from further testing and adds mandatory ultrasonic checks for older crankshafts before installation."},"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhe-18-amdt-5-tapered-crankshaft-inspection","history":"/api/acts/ad-dhe-18-amdt-5-tapered-crankshaft-inspection/history","analysis":"/api/acts/ad-dhe-18-amdt-5-tapered-crankshaft-inspection/analysis","conflicts":"/api/acts/ad-dhe-18-amdt-5-tapered-crankshaft-inspection/conflicts","importantCases":"/api/acts/ad-dhe-18-amdt-5-tapered-crankshaft-inspection/important-cases","documents":"/api/acts/ad-dhe-18-amdt-5-tapered-crankshaft-inspection/documents"}}