{"id":"F2006B07369","name":"AD/TBM 700/21 - Horizontal Stabiliser Top Skin","slug":"ad-tbm-700-21-horizontal-stabiliser-top-skin","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":49506,"registerId":"commonwealth-F2006B07369-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# AIRWORTHINESS DIRECTIVE\n\n![](image.002.png)\n\n![](image.002.png)  \nFor the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (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.","sortOrder":0},{"sectionNumber":"AD/TBM 700/21 Horizontal Stabiliser Top ","sectionType":"part","heading":"AD/TBM 700/21 Horizontal Stabiliser Top Skin 11/2000","content":"# AD/TBM 700/21 Horizontal Stabiliser Top Skin 11/2000\n\nApplicability: All TBM 700 aircraft, except for aircraft which have Modification No. Mod. 70-117- 55 installed.\n\nRequirement: Visually inspect for cracks in the top skin of the horizontal stabiliser at the junction of the root rib and central spar, and take action in accordance with Socata Service Bulletin 70-081-55.\n\nNote: DGAC AD 2000-306(A) refers.\n\nCompliance: Aircraft with less than 900 total hours at the effective date of this Directive: Upon reaching 900 hours total time in service.\n\nAircraft with more than 900 total hours at the effective date of this Directive: At the next inspection for maintenance release issue after 2 November 2000.\n\nThis Airworthiness Directive becomes effective on 2 November 2000.\n\nBackground: The manufacturer received reports of fatigue cracks in the top skin of the horizontal stabiliser. Such cracking could lead to a decrease in structural strength of the stabiliser. This Directive requires an inspection and installation of reinforcement plates.\n\n![Signature of David Alan Villiers Delegate of the Civil Aviation Safety Authority](image.003.png)  \n\nDavid Alan Villiers\n\nDelegate of the Civil Aviation Safety Authority 13 September 2000\n\n![](image.002.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 4 October 2000.","sortOrder":1}],"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"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"N/A - This is a discrete safety directive addressing a specific airworthiness issue. No evidence of scope creep from original purpose."},"complexity_factors":["Single, clearly defined applicability (one aircraft type with one exception)","Straightforward two-tier compliance schedule based on flight hours","Single inspection requirement referencing external technical document (Service Bulletin)","No nested conditions, defined terms section, or cross-references to other legislation","Total length: approximately 250 words"],"plain_english_summary":"This CASA Airworthiness Directive orders owners/operators of TBM 700 aircraft (unless fitted with factory Mod. 70‑117‑55) to inspect the horizontal stabiliser top skin at the root rib/central spar for fatigue cracking and, if found, repair per the manufacturer's service bulletin (reinforcement plates). It targets aircraft based on flight hours/scheduled checks to catch cracks early and prevent potential tail-structure failure."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The AD stays within the original, stated purpose: address fatigue cracks in the horizontal stabiliser top skin by requiring inspection and reinforcement. It does not expand the regulated subject beyond that safety-focused remediation, add unrelated regulatory burdens, or broaden applicability beyond TBM 700 aircraft (excepting the specified modification)."},"complexity_factors":["Short, single-topic directive (inspection and reinforcement) — limited number of operative requirements","Single aircraft type (TBM 700) with one explicit exception (Mod. 70-117-55) — simple applicability","One external normative reference: Socata Service Bulletin 70-081-55 (adds detail but is external to the AD)","One cross-reference note to DGAC AD 2000-306(A)","Simple compliance branching based on total time-in-service (two branches: <900 hours and >900 hours)","Action specified is a visual inspection and corrective action per the service bulletin — limited technical permutations","Clear effective date and compliance triggers — minimal nested conditions or multi-stage timelines"],"plain_english_summary":"**What this directive does (mechanics)\n\n- Applies to: all TBM 700 aircraft except those that already have Modification No. Mod. 70-117-55 installed. (Applicability)\n\n- Requires: a visual inspection for cracks in the top skin of the horizontal stabiliser at the junction of the root rib and central spar, and then taking whatever corrective action the manufacturer’s Socata Service Bulletin 70-081-55 specifies (Requirement).\n\n- Timing (Compliance):\n  - If the aircraft had less than 900 total hours on the effective date of the Directive: inspect when the aircraft reaches 900 total hours.\n  - If the aircraft had more than 900 total hours on the effective date: inspect at the next maintenance release inspection after 2 November 2000. (Compliance)\n\n- Effectiveness date: 2 November 2000. (Compliance)\n\n- Rationale: the manufacturer reported fatigue cracking in the top skin of the horizontal stabiliser that could reduce structural strength; the AD requires inspection and installation of reinforcement plates per the service bulletin to address that condition (Background).\n\n\nWho this affects and who pays\n\n- Aircraft operators and owners of TBM 700s (except those with Mod. 70-117-55) must perform the inspection and any remedial work described in the Socata Service Bulletin 70-081-55. (Applicability; Requirement)\n- The operator/owner bears the direct costs: labour time for inspection, parts (reinforcement plates or other parts required by the service bulletin), and aircraft downtime while the work is performed. (Requirement)\n- The Civil Aviation Safety Authority (CASA) delegate issued the AD and sets the mandatory requirement; the work must follow the manufacturer’s instructions referenced in the AD. (Intro/Requirement)\n\n\nHow it changes behaviour and decision-making\n\n- Operators must plan for a one-off or recurring maintenance action: perform a targeted visual inspection at the specified times and install reinforcement plates as required by the service bulletin. (Requirement; Compliance)\n- Operators with Mod. 70-117-55 already installed are exempt from this AD, so installation of that modification is a compliance-avoidance option (if available and appropriate). (Applicability)\n\n\nPractical implementation and compliance risks\n\n- Detection limits: the AD specifies a visual inspection. Visual checks can miss subsurface or very fine fatigue cracks, so detection depends on inspection quality and access to the inspection area. (Requirement)\n- Reliance on the manufacturer’s service bulletin: the AD requires actions in accordance with Socata Service Bulletin 70-081-55. The bulletin defines exact repair steps and parts; operators must obtain and follow that document. (Requirement)\n- Operational costs: owners/operators will incur parts costs (reinforcement plates), labour, and aircraft out-of-service time; those are concentrated costs on TBM 700 operators. (Requirement)\n- Compliance scheduling: the AD phases inspection timing by total time in service; operators must track total hours to meet the specified deadlines. (Compliance)\n- Regulatory clarity and discretion: the AD imposes a clear mandatory inspection/remedy; discretionary judgment by CASA is limited once the AD prescribes the actions, but some judgement remains with maintenance personnel when following the service bulletin. (Intro/Requirement)\n\n\nTrade-offs, incentives and likely responses\n\n- Concentrated cost vs diffuse benefit: the direct costs fall on TBM 700 owners/operators, while the safety benefit—reduced risk of structural failure—is spread to passengers and the public. (Background; Requirement)\n- Incentive to adopt the exemption modification: operators may choose to install Mod. 70-117-55 (if available and feasible) to avoid repeated inspections tied to this AD. (Applicability)\n- Opportunity costs: time spent on inspections/repairs displaces other maintenance or flight time.\n\n\nCross-references\n\n- The AD directs compliance with Socata Service Bulletin 70-081-55 (Requirement) and refers to French DGAC AD 2000-306(A) (Note).\n\n\nBottom line (plain): If you own or operate a TBM 700 that does not already have Mod. 70-117-55, you must have the horizontal stabiliser top skin visually inspected for cracks at the times stated and carry out the corrective work described in Socata Service Bulletin 70-081-55. The owner/operator pays for and schedules the inspection and any reinforcement plate installation; CASA issued the directive and requires compliance. (Applicability; Requirement; Compliance; Background)\n"}},"importantCases":[],"_links":{"self":"/api/acts/ad-tbm-700-21-horizontal-stabiliser-top-skin","history":"/api/acts/ad-tbm-700-21-horizontal-stabiliser-top-skin/history","analysis":"/api/acts/ad-tbm-700-21-horizontal-stabiliser-top-skin/analysis","conflicts":"/api/acts/ad-tbm-700-21-horizontal-stabiliser-top-skin/conflicts","importantCases":"/api/acts/ad-tbm-700-21-horizontal-stabiliser-top-skin/important-cases","documents":"/api/acts/ad-tbm-700-21-horizontal-stabiliser-top-skin/documents"}}