{"id":"F2006B04987","name":"AD/CESSNA 170/59 Amdt 1 - Horizontal Stabiliser Front Spar","slug":"ad-cessna-170-59-amdt-1-horizontal-stabiliser-front-spar","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44884,"registerId":"commonwealth-F2006B04987-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CESSNA 170/59 Amdt 1 - Horizontal Stabiliser Front 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)  \n\nAIRWORTHINESS DIRECTIVE\n\n![](image.001.png)\n\n![](image.001.png)  \nFor the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/CESSNA 170/59 and issues the following AD under subregulation 39.1 (1) of CAR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\nCessna 170, 172, F172, FR172 & 175 Series Aeroplanes\n\nAD/CESSNA 170/59\n\nAmdt 1\n\n  \nHorizontal Stabiliser Front Spar 3/2001\n\nApplicability: All Model 172 and 175 series aircraft, all Reims Model F172 and FR172 series aircraft; except Models 172R & 172S, and subsequent.\n\nRequirement: Visually inspect the horizontal stabiliser front spar for cracking in accordance with Cessna Service Bulletin SEB94-8.\n\nCompliance: At intervals not to exceed 100 hours time in service.\n\nThis amendment becomes effective on 22 March 2001.\n\nBackground: A number of instances of cracking of the horizontal stabiliser front spar have been reported. In July 1984 the Authority issued AAC 153-2 highlighting the problem. The most likely cause was incorrect ground handling; pushing down on the stabiliser to lift the nose wheel. However cracks continue to be reported and in one instance the spar was reported to have been completely severed. Reports have also been received of cracking of modified and reinforced spars, Cessna P/N 0532001-98.\n\nThe intent of this Directive is not applicable to later Model 172 aircraft, and is amended accordingly.\n\nThe original issue of this Airworthiness Directive became effective on 17 August 1995.\n\n![](image.002.png)  \n\nDavid Alan Villiers\n\nDelegate of the Civil Aviation Safety Authority 24 January 2001\n\n![](image.001.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 21 February 2001.\n\n  \nPage 1 of 1","sortOrder":0}],"analysis":{"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"The amendment narrows the AD's applicability: it excludes later Model 172 variants (Models 172R & 172S and subsequent) and revokes the prior AD to reissue the requirement with that narrower scope."},"complexity_factors":["Technical inspection of a primary structural component (horizontal stabiliser front spar) (Requirement, Background)","Recurring compliance interval (every 100 hours) requires operator tracking and maintenance scheduling (Compliance)","Reliance on external Cessna Service Bulletin SEB94-8 for inspection procedure (Requirement)","Amendment excludes specific later variants (172R & 172S and subsequent) and revokes the earlier AD, creating administrative linkage between directives (Applicability, Background)","Reports include cracking of modified/reinforced spars (Cessna P/N 0532001-98), introducing part-specific assessment considerations (Background)"],"plain_english_summary":"Requires a visual inspection of the horizontal stabiliser front spar on specified Cessna 172 and 175 series and Reims F172/FR172 aircraft (excluding 172R, 172S and later variants) every 100 flight hours, performed in accordance with Cessna Service Bulletin SEB94-8. It affects owners/operators of those aircraft, who must do or arrange the inspections. \n\nCASA cites repeated reports of spar cracking—linked to incorrect ground handling and including one severed spar—as the reason for revoking and reissuing the earlier AD with narrowed applicability."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":true,"description":"The original 1995 directive applied broadly to Cessna 170, 172, F172, FR172 and 175 series. This amendment narrows the scope by explicitly excluding Models 172R and 172S (and subsequent models), limiting the directive to older aircraft where the unsafe condition actually exists. This represents a refinement rather than expansion — the scope contracted to better match the actual safety risk."},"complexity_factors":["Single, clearly defined applicability section with one explicit exception","Single requirement referencing an external technical document (Cessna Service Bulletin SEB94-8)","Simple compliance condition: fixed 100-hour recurring interval","No nested definitions, cross-references to other legislation, or conditional logic","Background narrative is descriptive rather than creating legal conditions","Total length: approximately 1 page with minimal structural sections"],"plain_english_summary":"This CASA Airworthiness Directive requires owners/operators of older Cessna 172/175 and Reims F172/FR172 aircraft to perform a visual inspection of the horizontal stabiliser front spar every 100 flight hours, following Cessna Service Bulletin SEB94‑8. It responds to discovered cracks — including at least one complete failure likely linked to improper tail handling — and clarifies that newer 172R/172S models are excluded."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cessna-170-59-amdt-1-horizontal-stabiliser-front-spar","history":"/api/acts/ad-cessna-170-59-amdt-1-horizontal-stabiliser-front-spar/history","analysis":"/api/acts/ad-cessna-170-59-amdt-1-horizontal-stabiliser-front-spar/analysis","conflicts":"/api/acts/ad-cessna-170-59-amdt-1-horizontal-stabiliser-front-spar/conflicts","importantCases":"/api/acts/ad-cessna-170-59-amdt-1-horizontal-stabiliser-front-spar/important-cases","documents":"/api/acts/ad-cessna-170-59-amdt-1-horizontal-stabiliser-front-spar/documents"}}