{"id":"F2006B04951","name":"AD/CESSNA 170/16 Amdt 1 - Rear Spar","slug":"ad-cessna-170-16-amdt-1-rear-spar","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44818,"registerId":"commonwealth-F2006B04951-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CESSNA 170/16 Amdt 1 - Rear Spar","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)  \nCessna 170, 172, F172, FR172 and 175 Series Aeroplanes\n\nAD/CESSNA 170/16\n\nAmdt 1\n\n  \nRear Spar 11/67\n\nApplicability: All models prior to models M and F172M.\n\nRequirement: 1. Visually inspect the main plane rear spar web at the root attachment area and the upper flange of the rear channel, at the outer end of the attachment fitting, for fatigue cracks.\n\n    2. These cracks originate in the radius which is located beneath the attachment fittings.\n\n    3. This inspection shall be carried out using a magnifying glass of at least 4X magnification or alternatively, a device such as the “Syte Ade” may be employed.\n\n    4. Since the trailing edge root end rib fits closely to the spar, it may be difficult to detect possible cracks, therefore, where doubt exists, the trailing edge root end rib shall be removed for more detailed inspection.\n\nNote: The affected area is illustrated in Rex Aviation Technical Memorandum No. 12 dated 10 May 1960.\n\nCompliance: At intervals not exceeding 100 hours time in service.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard Airworthiness Directive maintaining its original purpose: mandating specific safety inspections for particular aircraft types. The amendment (Amdt 1) appears to be a routine update to an existing directive without expansion beyond the original safety intent."},"complexity_factors":["Very short document (approximately 150 words)","Only 4 defined procedural requirements","Single applicability criterion (model years)","No cross-references to other legislation or regulations beyond the enabling authority","Simple conditional logic (only one alternative method permitted — Syte Ade device)","Single compliance interval (100 hours) with no exceptions or alternative schedules"],"plain_english_summary":"This mandatory CASA Airworthiness Directive requires owners and operators of certain pre‑“M” Cessna 170/172/F172/FR172/175 series aircraft to perform recurring inspections of the wing rear spar at the wing‑fuselage attachment to detect fatigue cracking. \n\nIt matters because undetected cracks can cause wing structural failure. Inspections are required at 100‑hour intervals using at least 4× magnification (and removing an obstructing rib if necessary); compliance is legally mandatory for affected operators and maintenance organisations."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The provided text does not show an expanded or narrowed scope compared with an earlier version; it sets inspection requirements for specified pre‑M models and a 100‑hour recurrence. The amendment label (Amdt 1) is present but no comparative language or removed/added provisions are included here, so no scope change can be ascertained from this instrument alone."},"complexity_factors":["Technical inspection standard (visual with ≥4× magnification or approved device) requires operator judgement about adequacy (Req 3).","Potential need to remove trailing‑edge root end rib for detailed inspection adds mechanical work, downtime and cost where doubt exists (Req 4).","Short recurring compliance interval (≤100 hours TIS) creates ongoing scheduling and cost obligations (Compliance).","Applicability limited to models prior to M and F172M requires precise model/serial verification to determine coverage (Applicability).","Reliance on external illustration in Rex Aviation Technical Memorandum No. 12 may require access to that document to interpret the affected area (Note)."],"plain_english_summary":"This Airworthiness Directive requires owners/operators of Cessna 170, 172, F172, FR172 and 175 series (all models prior to M and F172M) to inspect the main plane rear spar web and the rear channel upper flange at the root attachment for fatigue cracks. Inspections must be done at intervals not exceeding 100 hours TIS, using at least 4× magnification or an equivalent device; the trailing‑edge root end rib must be removed where cracks may be concealed (Reqs 1–4; Compliance). Owners/operators pay for inspections and any rib removal."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cessna-170-16-amdt-1-rear-spar","history":"/api/acts/ad-cessna-170-16-amdt-1-rear-spar/history","analysis":"/api/acts/ad-cessna-170-16-amdt-1-rear-spar/analysis","conflicts":"/api/acts/ad-cessna-170-16-amdt-1-rear-spar/conflicts","importantCases":"/api/acts/ad-cessna-170-16-amdt-1-rear-spar/important-cases","documents":"/api/acts/ad-cessna-170-16-amdt-1-rear-spar/documents"}}