{"id":"F2006B04920","name":"AD/CESSNA 150/21 - Wing Strut Attachment Strap","slug":"ad-cessna-150-21-wing-strut-attachment-strap","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44764,"registerId":"commonwealth-F2006B04920-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CESSNA 150/21 - Wing Strut Attachment Strap","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-generator: Aspose.Words for .NET 22.10.0\n---\n\n?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Cessna 150, F150, 152 & F152 Series Aeroplanes\n\n \n\nAD/CESSNA 150/21 Wing Strut Attachment Strap 10/73\n\nApplicability: Model 150 with S/Nos. 15074635 to 15074799 and Model A150 with S/Nos.\n\nA1500415 to A1500427.\n\n \n\nRequirement: Action in accordance with Cessna SL SE 73-20. Compliance:  Within 100 hours time in service after 24 September 1973.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The instrument, as presented, applies to a defined set of serial-numbered aircraft and mandates compliance with Cessna Service Letter SE 73-20 within a fixed time-in-service window. The text does not indicate any alteration of scope from an earlier or original intent; it sets a single, specific requirement and compliance deadline without referencing amendments or broadened applicability."},"complexity_factors":["Narrow applicability by specific serial-number ranges (requires checking aircraft records to determine applicability).","Dependence on an external technical document (Cessna SL SE 73-20) for the substantive technical work — that document must be obtained and interpreted by maintenance personnel.","Compliance deadline measured in hours time in service tied to a historical calendar date (100 hours TIS after 24 September 1973), which requires scheduling relative to each aircraft's utilisation.","Technical nature of the required work (wing strut attachment strap) requires certified maintenance capability and possible parts or tooling, creating practical execution complexity."],"plain_english_summary":"This directive mandates owners/operators of specific Cessna 150 (S/N 15074635–15074799) and A150 (S/N A1500415–A1500427) to have the wing strut attachment strap inspected/modified in accordance with Cessna Service Letter SE 73‑20 within 100 hours TIS after 24 Sep 1973. It makes the service letter’s technical steps compulsory, imposing direct maintenance costs and scheduling obligations on operators and the maintenance organisations who carry out and certify the work."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive from 1973 addressing a specific manufacturing defect in a limited production run of Cessna aircraft. The scope remains precisely limited to the identified serial numbers and the specified structural component. No evidence of scope creep or expansion beyond original intent."},"complexity_factors":["Extremely short document (under 150 words)","Only 2 defined applicability criteria (specific serial number ranges)","Single, unambiguous requirement referencing an external technical document","No nested conditions, exceptions, or cross-references to other legislation","Clear, fixed compliance deadline (100 hours time in service after specified date)","No interpretive ambiguity — applies only to explicitly listed aircraft"],"plain_english_summary":"**What this is:** This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). Think of it as a \"recall notice\" for aircraft, but legally binding.\n\n**What it does:** It requires owners and operators of specific Cessna 150 series aeroplanes to inspect or fix a problem with the **wing strut attachment strap** — a critical component that helps hold the wing to the fuselage. If this strap fails, the wing could detach in flight.\n\n**Who it affects:** Only specific serial numbers:\n- **Cessna Model 150:** Serial numbers 15074635 through 15074799\n- **Cessna Model A150:** Serial numbers A1500415 through A1500427\n\n**What must be done:** Operators must follow the instructions in **Cessna Service Letter SE 73-20** (a technical bulletin from the manufacturer).\n\n**When:** Within 100 hours of flying time after **24 September 1973**.\n\n**Why it matters:** This addresses a structural defect that could cause catastrophic wing failure. Compliance is mandatory — flying without completing this action would violate civil aviation safety regulations."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cessna-150-21-wing-strut-attachment-strap","history":"/api/acts/ad-cessna-150-21-wing-strut-attachment-strap/history","analysis":"/api/acts/ad-cessna-150-21-wing-strut-attachment-strap/analysis","conflicts":"/api/acts/ad-cessna-150-21-wing-strut-attachment-strap/conflicts","importantCases":"/api/acts/ad-cessna-150-21-wing-strut-attachment-strap/important-cases","documents":"/api/acts/ad-cessna-150-21-wing-strut-attachment-strap/documents"}}