{"id":"F2006B08551","name":"AD/CHA/24 Amdt 1 - Seat Frames","slug":"ad-cha-24-amdt-1-seat-frames","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":51347,"registerId":"commonwealth-F2006B08551-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CHA/24 Amdt 1 - Seat Frames","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)  \nAmerican Champion (Aeronca, Bellanca) Series Aeroplanes\n\nAD/CHA/24\n\nAmdt 1\n\n  \nSeat Frames 13/89\n\nApplicability: All models fitted with folding seat back frames.\n\nRequirement: 1 (a) Install a placard in a prominent position facing the door opening reading,\n\n“PULLING OR PUSHING ON SEAT BACK DURING ENTRY OR EXIT IS PROHIBITED”.\n\n    (b) Install a placard in full view of the pilot reading\n\n“OPERATION IN ACROBATIC CATEGORY PROHIBITED UNLESS INSPECTION IN ACCORDANCE WITH AD/CHA/24 REQUIREMENT 3 HAS BEEN CARRIED OUT”.\n\n    (c) Lettering for the placards shall be of no less than 3.5mm height. Letters of the word PROHIBITED are to be at least 40% larger than the other lettering.\n\n    2. Visually inspect the seat back hinges for evidence of cracks, elongation of hinge bolt holes or deformation, using 10x magnification. Ensure that present or replacement hinge bolts are hex headed AN3-7A and secured with an AN365- 1032 elastic stopnut.\n\n    3. Carry out a magnetic particle or dye penetrant inspection of the left and right sides of the lower seat frame side tube to side brace junction, seat back side tube to hinge tube and brace tube areas, and the hinges and backstraps, for evidence of cracking.\n\nNote 1: FAA AD 89-18-06 refers.\n\nNote 2: American Champion Aircraft Service Letter 401 refers.\n\nNote 3: Replacement in accordance with SL 401 or Approved Modification of the seat frame is considered terminating action for this Directive.\n\nCompliance: 1 (a)(b)(c) Within 10 hours time in service after 26 April 1989.\n\n    2. At each inspection for issue of a Maintenance Release after 26 April 1989, for operation in the Normal and Utility Categories, until replaced in accordance with American Champion Aircraft SL 401 or modified in accordance with an Approved Scheme.\n\n    3. Within 10 hours time in service after 26 April 1989 and thereafter at intervals not exceeding 50 hours time in service, if operated in acrobatic category, until replaced in accordance with American Champion Aircraft SL 401 or modified in accordance with a scheme approved by the Authority.\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\nBackground: A number of in flight failures of folding seat backs have been reported overseas. An Australian registered aircraft inspected as a precaution due to overseas incidents was found to have cracking of front seat frames in similar areas. Amendment 1 notes manufacturers Service Letter 401 which enables replacement with an exchange seat frame provided by the manufacturer, if desired.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"This amendment is a focused technical update to an existing airworthiness directive. It clarifies and records the manufacturer’s Service Letter 401 as an accepted terminating action (exchange seat frame), prescribes placarding and specific inspection requirements, and confirms the inspection intervals for different operational categories. It does not materially expand the classes of aircraft affected (still limited to models with folding seat back frames) nor broaden the subject matter beyond seat frame integrity and related warnings; therefore the scope has not significantly changed from the Directive’s original safety-focused purpose."},"complexity_factors":["Short, single-aircraft-family directive (limited scope)","Three easy-to-read substantive requirements (placards, visual inspection, NDT inspection)","Two operational-condition branches: Normal/Utility (Inspection at each Maintenance Release) vs Acrobatic (initial + 50‑hour recurring NDT)","Technical specificity (hardware callouts AN3-7A and AN365-1032; 10× magnification; NDT methods) increases implementation detail but not legislative complexity","Cross-references to external documents (FAA AD 89-18-06; American Champion Service Letter 401) and to \"Approved Scheme\" introduce reliance on external approvals","Termination option depends on compliance with SL 401 or an Authority‑approved modification, which creates a single dependency rather than multiple nested exceptions"],"plain_english_summary":"**What this instrument does (mechanically)**\n\n- Applies to all American Champion (Aeronca, Bellanca) series aeroplanes that have folding seat back frames.\n- Requires three visible placards to be fitted: one facing the door telling people not to push or pull on the seat back during entry/exit, and one in full view of the pilot saying that acrobatic operation is prohibited unless a specific inspection has been done. Letter size and relative sizing are specified (minimum 3.5 mm letters; the word \"PROHIBITED\" must have letters at least 40% larger) (Requirement 1(a)(b)(c)).\n- Requires visual inspection of seat back hinges for cracks, elongated hinge bolt holes or deformation using 10× magnification, and that hinge bolts (if present or replaced) be hex-headed AN3-7A secured with an AN365-1032 elastic stopnut (Requirement 2).\n- Requires a non-destructive test (magnetic particle or dye-penetrant) of specific joints and hinge areas of the lower seat frame and associated tubes and hinges to check for cracking (Requirement 3).\n- Identifies the manufacturer’s Service Letter 401 (SL 401) as a document that provides replacement options, and states that replacing the seat frame in accordance with SL 401 or an Authority-approved modification is a terminating action for the Directive (Notes and Requirement 3 termination language).\n\n**Who must act and who bears the costs**\n\n- Aircraft owners/operators of affected American Champion models are responsible for compliance. They must fit the placards, perform the inspections, and, where necessary, arrange repairs or replacement.\n- Maintenance organisations or approved repair stations will normally perform the inspections and any non-destructive testing; they (and operators) will bear labour, parts and down-time costs. If operators choose replacement through the manufacturer under SL 401, the manufacturer supplies exchange frames (costs depend on the manufacturer’s terms).\n\n**When the work must be done (timing rules)**\n\n- Placards (Requirement 1(a)(b)(c)): within 10 hours time in service after 26 April 1989 (Compliance 1).\n- Visual hinge inspection (Requirement 2): at each inspection for issue of a Maintenance Release after 26 April 1989 for Normal and Utility category operation, until the seat frame is replaced per SL 401 or modified under an approved scheme (Compliance 2).\n- NDT inspections (Requirement 3): initially within 10 hours time in service after 26 April 1989 and thereafter at intervals not exceeding 50 hours time in service if the aeroplane is operated in the Acrobatic category, until replaced per SL 401 or modified per an approved scheme (Compliance 3).\n\n**Why the rule exists (stated rationale) and the practical implications**\n\n- The directive follows overseas reports of in‑flight failures of folding seat backs and one Australian precautionary inspection that found cracking in similar areas. The safety mechanism is to reduce the risk of seat back failure in flight by warning placards, regular inspections (visual and NDT), and by offering replacement/modification as terminating action (Background; Notes).\n\nPractical implications and trade-offs to consider:\n- Operators who fly in the Acrobatic category face a recurring inspection interval (50 flight hours) and therefore higher recurring maintenance costs and more frequent down-time (Requirement 3; Compliance 3).\n- Operators who remain in Normal or Utility categories still must inspect hinges at every Maintenance Release until the seat frame is replaced per SL 401 or via an approved modification (Requirement 2; Compliance 2). This creates an ongoing compliance obligation until terminating action is taken.\n- The manufacturer benefits from providing exchange frames under SL 401 (Note 3). Owners can choose replacement to stop recurring inspections, but that shifts cost from recurring inspections to a one‑off replacement cost.\n- The directive prescribes specific hardware standards (AN3-7A bolts and AN365-1032 elastic stopnuts) and inspection methods (10× magnification visual inspection and magnetic particle or dye penetrant NDT). That limits operator discretion about how to demonstrate compliance (Requirement 2 and 3).\n- Implementation and enforcement depend on maintenance providers and the Civil Aviation Safety Authority to approve modification schemes; delays or differing interpretations of \"Approved Scheme\" could create practical uncertainty (Notes and termination language).\n\n**Behavioural changes required**\n\n- Fit specified placards promptly.\n- Increase inspection frequency for seat frames and hinges, with NDT for aircraft used acrobatically.\n- Replace or modify seat frames per SL 401 or an approved modification to stop recurring inspections.\n\n(References: Requirement paragraphs 1–3; Compliance paragraphs; Notes referencing FAA AD 89-18-06 and American Champion SL 401.)"},"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"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is Amendment 1 to an existing directive (AD/CHA/24). The amendment adds a manufacturer's service letter as an approved replacement option (terminating action) but does not expand beyond the original scope of addressing seat frame failures in American Champion aircraft. The core requirements remain unchanged from the original 1989 directive."},"complexity_factors":["Short, single-purpose directive focused on one specific mechanical issue","Only 3 main requirements with clear, numbered sub-paragraphs","Minimal defined terms (relies on standard aviation terminology like 'AN3-7A' bolts and 'AN365-1032' nuts)","Simple conditional logic: different inspection intervals depending on whether aircraft operates in Normal/Utility vs Acrobatic categories","Clear compliance dates and terminating action (replacement per Service Letter 401)","Cross-references limited to one FAA directive and one manufacturer service letter in notes"],"plain_english_summary":"This CASA Airworthiness Directive requires owners and operators of affected American Champion (including older Aeronca/Bellanca) aeroplanes with folding seat back frames to fit warning placards (including a prominent “PROHIBITED” aerobatics warning), carry out magnified visual inspections and bolt checks, and perform specialised crack detection (magnetic particle or dye penetrant) on critical frame joints. It targets operators and maintenance personnel to prevent in‑flight seat‑back failures that could cause injury or loss of control."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cha-24-amdt-1-seat-frames","history":"/api/acts/ad-cha-24-amdt-1-seat-frames/history","analysis":"/api/acts/ad-cha-24-amdt-1-seat-frames/analysis","conflicts":"/api/acts/ad-cha-24-amdt-1-seat-frames/conflicts","importantCases":"/api/acts/ad-cha-24-amdt-1-seat-frames/important-cases","documents":"/api/acts/ad-cha-24-amdt-1-seat-frames/documents"}}