{"id":"F2006B09142","name":"AD/DHC-6/54 Amdt 2 - Side Folding Cabin Utility Seats - Inspection and Modification","slug":"ad-dhc-6-54-amdt-2-side-folding-cabin-utility-seats-inspection-and-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115703,"registerId":"commonwealth-F2006B09142-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DHC-6/54 Amdt 2 - Side Folding Cabin Utility Seats - Inspection and Modification","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-6/54\n\nAmdt 2\n\n  \n\nSide Folding Cabin Utility Seats \\- Inspection and Modification\n\n  \n5/85\n\nApplicability: All model DHC-6 Aircraft fitted with side folding cabin utility seats. Document: De Havilland of Canada S.B. No. 6/447 Rev. A.\n\nNote: Transport Canada AD CF-83-25 R1 refers.\n\nCompliance: 1. Unless already accomplished, inspect within 10 hours time in service after 27 March 1984 in accordance with requirements detailed in the requirement document.\n\n    2. Repeat inspections in accordance with requirements detailed in the requirement document at intervals not exceeding 50 hours time in service until modification No. 6/1828 is incorporated on all side folding utility seats.\n\n    3. After incorporation of modification No. 6/1828 inspect in accordance with the De Havilland Inspection Requirement Manual Revision 6, chapter 25, Item 5.\n\nBackground: Service experience has shown that the front legs of the cabin utility seats can be become disengaged from the keyhole slots in the floor, creating a hazard to the occupants.\n\nThis directive is amended to reflect Revision 1 of the Canadian AD which requires compliance with the DHC6 Inspection Requirement Manual after modification.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is Amendment 2 to an existing Airworthiness Directive. The amendment simply updates the post-modification inspection requirements to align with a revised Canadian directive. The scope remains tightly focused on the original safety issue (seat leg disengagement) and has not expanded beyond the DHC-6 side-folding utility seats."},"complexity_factors":["Single, specific aircraft type and component targeted","Only 3 compliance requirements with clear timeframes","One defined reference document (De Havilland Service Bulletin 6/447 Rev. A)","Simple conditional logic: 'unless already accomplished' and 'until modification incorporated'","No nested exceptions or cross-references to other legislation","Background explanation provided in plain language"],"plain_english_summary":"This CASA Airworthiness Directive requires owners/operators of De Havilland DHC‑6 Twin Otter aircraft fitted with side‑folding cabin utility seats to inspect seat front legs for disengagement from floor mountings within 10 flight hours and at regular intervals until a permanent modification (kit 6/1828) is installed. It prevents in‑flight seat leg separation that could cause serious injury, and shifts to the manufacturer’s inspection schedule once the kit is fitted."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"The amendment alters the post‑modification inspection requirement: after modification No. 6/1828 is incorporated, inspections must be carried out in accordance with the De Havilland Inspection Requirement Manual Revision 6, chapter 25, Item 5. Previously the directive required inspections until the modification was fitted; the amendment adds a defined, manual‑based inspection regime after modification and expressly aligns the directive with Transport Canada AD Revision 1 (see Compliance 2–3; Background)."},"complexity_factors":["References and dependence on multiple external documents (De Havilland Service Bulletin No. 6/447 Rev. A; modification No. 6/1828; De Havilland Inspection Requirement Manual Rev. 6, ch.25, Item 5; Transport Canada AD CF-83-25 R1) — requires operators to obtain and follow external material (Applicability; Document; Compliance; Background).","Time‑based compliance windows and repeating intervals (initial inspection within 10 hours TIS; repeat inspections at ≤50‑hour intervals until modification) create ongoing operational scheduling and recordkeeping burdens (Compliance 1–2).","Staged obligation: different inspection regime before and after incorporation of the designated modification (Compliance 2–3) — operators must track modification status to apply the correct standard.","Specificity of a single identified modification (No. 6/1828) concentrates compliance around parts availability and maintenance capacity.","Scope language (“all model DHC‑6 Aircraft fitted with side folding cabin utility seats”) requires operators to determine applicability across individual airframes, which can create interpretation tasks.","Enforcement by CASA and alignment with a Canadian AD introduce inter‑jurisdictional alignment and possible variation in how documentation and manuals are applied in practice."],"plain_english_summary":"This CASA airworthiness directive requires operators of DHC‑6 (Twin Otter) aircraft fitted with side‑folding cabin utility seats to inspect those seats promptly and to fit modification No. 6/1828. It requires an initial inspection within 10 hours time‑in‑service after 27 March 1984, repeated at intervals not exceeding 50 hours until the modification is installed, and thereafter inspections under the De Havilland Inspection Requirement Manual. It responds to reports that front seat legs can disengage from floor keyhole slots, creating an occupant hazard."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-6-54-amdt-2-side-folding-cabin-utility-seats-inspection-and-modification","history":"/api/acts/ad-dhc-6-54-amdt-2-side-folding-cabin-utility-seats-inspection-and-modification/history","analysis":"/api/acts/ad-dhc-6-54-amdt-2-side-folding-cabin-utility-seats-inspection-and-modification/analysis","conflicts":"/api/acts/ad-dhc-6-54-amdt-2-side-folding-cabin-utility-seats-inspection-and-modification/conflicts","importantCases":"/api/acts/ad-dhc-6-54-amdt-2-side-folding-cabin-utility-seats-inspection-and-modification/important-cases","documents":"/api/acts/ad-dhc-6-54-amdt-2-side-folding-cabin-utility-seats-inspection-and-modification/documents"}}