{"id":"F2006B09159","name":"AD/DHC-6/71 - Fuselage Station FS 239 Frame","slug":"ad-dhc-6-71-fuselage-station-fs-239-frame","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":52866,"registerId":"commonwealth-F2006B09159-current","compilationNumber":null,"startDate":"2026-04-02","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DHC-6/71 - Fuselage Station FS 239 Frame","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nDHC-6 (Twin Otter) Series Aeroplanes\n\nAD/DHC-6/71 Fuselage Station FS 239 Frame 11/95\n\nApplicability: All DHC-6 aircraft.\n\nRequirement: Inspect the fuselage frames for cracks by visual methods in accordance with the Accomplishment Instructions described in de Havilland Service Bulletin 6/521.\n\nNote: Transport Canada AD CF-95-12 refers.\n\nCompliance: Within 1200 hours time in service after 12 October 1995 or before 12 October 1996, whichever occurs first.\n\n    (a) If crack(s) are found which are within the tolerances specified in paragraph 5, Accomplishment Instructions of SB 6/521, perform repetitive inspections in accordance with de Havilland Inspection Requirement Manual, PSM 1-6-7 Temporary Revision 77, or as detailed in PSM 1-6-7 normal revision No.8, when issued.\n\n    (b) If crack(s) are found which exceed the tolerances specified in paragraph 5, Accomplishment Instructions of SB 6/521, repair or replace the subject part area before further flight.\n\nBackground: There have been two reported instances of cracking on the skin flange of the machined fuselage frame at fuselage station FS 239.","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":2160},"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive maintains a narrow, targeted scope focused exclusively on the inspection and remediation of cracking at Fuselage Station 239 on DHC-6 aircraft. There is no evidence of scope expansion beyond this specific airworthiness safety issue."},"complexity_factors":["Reliance on external technical documents not reproduced in the directive (de Havilland Service Bulletin 6/521 and Inspection Requirement Manual PSM 1-6-7)","Binary conditional compliance paths requiring technical interpretation (cracks 'within tolerances' versus 'exceed tolerances')","Cross-reference to foreign aviation safety regulation (Transport Canada AD CF-95-12)","Technical aviation terminology requiring specialized knowledge (fuselage station, skin flange, time in service)"],"plain_english_summary":"If you own or operate a DHC-6 Twin Otter, you must inspect the fuselage frame at Fuselage Station 239 using the procedures in de Havilland Service Bulletin 6/521 within 1,200 flight hours or by October 1996, whichever comes first.  \n\nSmall cracks within tolerance require repeated inspections per the maintenance manual; cracks beyond tolerance mean grounding and repair before further flight. This follows discovery of cracks on two aircraft and addresses a potential structural safety risk."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-6-71-fuselage-station-fs-239-frame","history":"/api/acts/ad-dhc-6-71-fuselage-station-fs-239-frame/history","analysis":"/api/acts/ad-dhc-6-71-fuselage-station-fs-239-frame/analysis","conflicts":"/api/acts/ad-dhc-6-71-fuselage-station-fs-239-frame/conflicts","importantCases":"/api/acts/ad-dhc-6-71-fuselage-station-fs-239-frame/important-cases","documents":"/api/acts/ad-dhc-6-71-fuselage-station-fs-239-frame/documents"}}