{"id":"F2006B09269","name":"AD/DHE/19 - Crankshaft - Inspection and Modification","slug":"ad-dhe-19-crankshaft-inspection-and-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":53291,"registerId":"commonwealth-F2006B09269-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DHE/19 - Crankshaft - Inspection and Modification","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 - 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  De Havilland Piston Engines\n\n \n\nAD/DHE/19 Crankshaft - Inspection and Modification 4/66\n\nApplicability: Gipsy Queen 30 series engines modified to Mod. 2036 or Mod. 2162.\n\n \n\nDocument: Bristol Siddeley TNS GQ 30 No. 70 dated 16 Nov. 1965 and Gipsy Mod. No. 2925.\n\n \n\nCompliance: Inspect within 100 hours time in service after 15 April 1966 and thereafter at intervals not exceeding 400 hours time in service until Mod. 2925 is incorporated. Modify before installation in an aircraft following next overhaul completed after 15 April 1966.\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\n \n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue airworthiness directive focused specifically on crankshaft safety in Gipsy Queen 30 engines. It has not expanded beyond its original technical safety purpose. The document appears complete as issued."},"complexity_factors":["Single, specific technical subject matter (one engine type, one component)","Only two applicable modification states triggering the directive","Clear, unambiguous compliance timeline with specific hour-based triggers","No nested exceptions or conditional logic - straightforward 'inspect until modified' structure","Minimal cross-referencing (only two technical documents cited)","Extremely short length (under 200 words of substantive content)"],"plain_english_summary":"This is an **Airworthiness Directive** (a mandatory safety order) issued by Australia's Civil Aviation Safety Authority for specific aircraft engines.\n\n**What it does:**\n- Requires owners and operators of **Gipsy Queen 30 series engines** (specifically those modified by Mod. 2036 or Mod. 2162) to inspect the crankshaft for defects.\n- Mandates a specific modification (Mod. 2925) to be performed before the engine can be installed in an aircraft after its next overhaul.\n\n**Who it affects:**\n- Owners and operators of aircraft using these specific De Havilland piston engines.\n- Aircraft maintenance engineers and overhaul facilities working on these engines.\n\n**Why it matters:**\nCrankshaft failures can cause catastrophic engine failure in flight. This directive ensures potential defects are caught early through regular inspections and permanently fixed through mandatory modification, preventing accidents and saving lives.\n\n**Key requirements:**\n- **First inspection:** Within 100 hours of flight time after 15 April 1966\n- **Ongoing inspections:** Every 400 hours of flight time until the modification is done\n- **Mandatory modification:** Must be completed before the engine goes back into service after its next overhaul"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The text sets out a specific, time-limited inspection regime and a one-off modification requirement for engines modified to Mod. 2036 or Mod. 2162, terminating the recurring inspection requirement once Mod. 2925 is incorporated. The instrument itself does not indicate any later expansion or narrowing of that applicability; there is no textual indication that the scope has changed from the instrument as written."},"complexity_factors":["Narrow applicability limited to Gipsy Queen 30 series engines with specific prior modifications (Mod. 2036 or Mod. 2162), which simplifies scope but requires accurate identification of affected units.","Time-based compliance schedule tied to a historical anchor date (\"after 15 April 1966\") and to flight hours, requiring reliable time-in-service tracking and scheduling.","Conditional termination of recurring inspections (inspections continue only \"until Mod. 2925 is incorporated\"), requiring record evidence that Mod. 2925 has been fitted.","A one-time modification required before re-installation after the next overhaul, introducing logistical coordination between overhaul timing and modification work.","Dependence on external technical documents (Bristol Siddeley TNS GQ 30 No. 70 and Gipsy Mod. No. 2925) for procedural detail, which raises administrative steps to obtain and apply those documents."],"plain_english_summary":"What this instrument does (mechanics)\n\n- It imposes mandatory inspection and modification requirements on a specific group of aircraft engines: Gipsy Queen 30 series engines that have been modified to Mod. 2036 or Mod. 2162. (Applicability)\n- It requires an initial inspection \"within 100 hours time in service after 15 April 1966\" and repeat inspections \"at intervals not exceeding 400 hours time in service\" until Mod. 2925 has been incorporated. (Compliance)\n- It requires that Mod. 2925 be incorporated by modifying the crankshaft \"before installation in an aircraft following next overhaul completed after 15 April 1966.\" (Compliance)\n- It refers users to two source documents for the inspection/modification procedure: Bristol Siddeley TNS GQ 30 No. 70 dated 16 Nov. 1965 and Gipsy Mod. No. 2925. (Document)\n\nWho is affected\n\n- Owners and operators of Gipsy Queen 30 series engines that have Mod. 2036 or Mod. 2162 applied. (Applicability)\n- Maintenance organisations and mechanics who carry out inspections and the Mod. 2925 modification, and the certificating authority that enforces the directive. (Implicit from the compliance and document references)\n\nWho decides and who pays\n\n- The directive is issued under the Commonwealth Civil Aviation framework (Civil Aviation Safety Authority / Schedule of Airworthiness Directives). The regulator determines the mandatory requirements. (header/context)\n- The text places the practical compliance burden on engine owners/operators and the maintenance organisations that perform the inspections and modification. The directive itself does not specify who pays; compliance actions (inspections, modification, aircraft downtime for overhaul/installation) would be undertaken by or at the direction of the owner/operator. (Compliance)\n\nWhat behaviour changes\n\n- Affected engines must be inspected on a specified time-in-service schedule until Mod. 2925 is fitted. (Inspect within 100 hours after 15 Apr 1966; thereafter intervals not exceeding 400 hours.)\n- After the next overhaul completed after 15 April 1966, affected crankshafts must be modified (Mod. 2925) before the engine is installed back into an aircraft. (Modify before installation following next overhaul completed after 15 Apr 1966.)\n\nStated rationale and practical trade-offs (source-grounded)\n\n- The instrument itself contains no explicit textual statement of its policy rationale beyond its title (\"Crankshaft - Inspection and Modification\") and the operative compliance requirements. The title and the operative steps indicate the directive is imposing recurring inspections and a one-off modification on a defined engine population. (Title; Compliance)\n\n- Practical costs and trade-offs that follow mechanically from the text:\n  - Recurrent inspection costs and aircraft downtime until Mod. 2925 is incorporated, because inspections are required every up to 400 flight hours until the modification is fitted. (Compliance)\n  - A one-off modification must be completed before re-installation after the next overhaul; that will impose labour, parts, and scheduling costs at that overhaul. (Compliance)\n  - Until the modification is done, operators must plan for repeat inspections, which substitutes maintenance/inspection time for potential flying time and may affect operational scheduling. (Compliance)\n  - Maintenance providers must be able to follow the procedures in the referenced documents (Bristol Siddeley TNS GQ 30 No. 70 and Gipsy Mod. No. 2925). Accessing and applying those documents is a precondition of compliance. (Document)\n\nImplementation risk, compliance burden, and discretion\n\n- Implementation requires: accurate time-in-service tracking, scheduling of inspections at the specified intervals, and a capability to carry out the Mod. 2925 modification at overhaul before re-installation. These are concrete operational tasks the operator/maintainer must perform. (Compliance; Document)\n- The directive is prescriptive in its timetable and scope; the text leaves little operational discretion about inspection frequency or the requirement to incorporate Mod. 2925 before reinstallation after the identified overhaul. (Compliance)\n\nNotes on benefits and costs concentration (source-grounded)\n\n- The compliance burdens (inspections and the modification) are concentrated on owners/operators of the specified modified engines and on the maintenance organisations they use. The text does not describe any compensating funding or exemptions. (Applicability; Compliance)\n\nSource citations (operative text)\n\n- Applicability: \"Gipsy Queen 30 series engines modified to Mod. 2036 or Mod. 2162.\"\n- Document: \"Bristol Siddeley TNS GQ 30 No. 70 dated 16 Nov. 1965 and Gipsy Mod. No. 2925.\"\n- Compliance: \"Inspect within 100 hours time in service after 15 April 1966 and thereafter at intervals not exceeding 400 hours time in service until Mod. 2925 is incorporated. Modify before installation in an aircraft following next overhaul completed after 15 April 1966.\""}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhe-19-crankshaft-inspection-and-modification","history":"/api/acts/ad-dhe-19-crankshaft-inspection-and-modification/history","analysis":"/api/acts/ad-dhe-19-crankshaft-inspection-and-modification/analysis","conflicts":"/api/acts/ad-dhe-19-crankshaft-inspection-and-modification/conflicts","importantCases":"/api/acts/ad-dhe-19-crankshaft-inspection-and-modification/important-cases","documents":"/api/acts/ad-dhe-19-crankshaft-inspection-and-modification/documents"}}