{"id":"F2006B04924","name":"AD/CESSNA 150/26 - Wing Flap Actuator Ball Nut Assemblies","slug":"ad-cessna-150-26-wing-flap-actuator-ball-nut-assemblies","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44769,"registerId":"commonwealth-F2006B04924-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CESSNA 150/26 - Wing Flap Actuator Ball Nut Assemblies","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 150, F150, 152 & F152 Series Aeroplanes\n\nAD/CESSNA 150/26 Wing Flap Actuator Ball Nut Assemblies 3/77\n\nApplicability: Models 150 and A150 with S/Nos. as detailed in Cessna SL SE76-25. Requirement: 1. Inspect P/N C301002-0101 wing flap actuator for date stamp code as detailed in\n\nCessna SL SE 76-25.\n\n    2. If the date stamp code on the actuator is OH, HH, WH or ZH, install a placard near the flap control which reads:\n\n“FLAP EXTENSION PROHIBITED”.\n\nNote: This placard may be removed when the paragraph 3 requirement is satisfied.\n\n    3. Replace affected wing flap actuator ball nut assemblies in accordance with Cessna SL SE 76-25.\n\nCompliance: For Paragraphs 1 and 2 \\- Before further flight after 28 January 1977.\n\nFor Paragraph 3 \\- Within 100 hours time in service after 28 January 1977.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive focused on a specific mechanical defect in specific aircraft models. It has not expanded beyond its original purpose of addressing the wing flap actuator ball nut assembly issue identified in 1977."},"complexity_factors":["Very short document (under 200 words)","Only 3 operative requirements with clear sequential logic","Single defined reference (Cessna SL SE76-25 for serial numbers and replacement procedures)","Simple conditional structure: IF date stamp matches specific codes, THEN install placard AND replace part","No nested exceptions or cross-references to other legislation","Clear compliance deadlines with specific dates and flight hour limits"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for specific aircraft.\n\n**What it does:**\nOrders owners and operators of certain **Cessna 150 series aeroplanes** (including models 150, A150, 152 and F152) to inspect and potentially replace a specific part — the **wing flap actuator ball nut assembly** (part number C301002-0101).\n\n**Why it matters:**\nThe date stamp codes \"OH\", \"HH\", \"WH\", or \"ZH\" indicate potentially faulty components that could fail during flight. If these codes are found, operators must:\n- **Immediately** install a warning placard saying \"FLAP EXTENSION PROHIBITED\" (meaning pilots cannot use the wing flaps)\n- **Within 100 flight hours**, replace the faulty assembly entirely\n\n**Who it affects:**\nAnyone who owns or operates the affected Cessna models with specific serial numbers listed in Cessna Service Letter SE76-25.\n\n**The bottom line:**\nThis is a **flight safety measure**. The wing flaps are crucial for landing and takeoff. A failed actuator could mean losing control of the flaps — potentially causing a crash. The directive forces immediate action to prevent accidents while allowing a reasonable timeframe for permanent repairs."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The text defines applicability and prescribes inspection, placarding, and replacement actions with specific compliance deadlines. There is no indication within this instrument that its scope was altered from an earlier or original version; the directive sets the affected models/serial numbers (as detailed in Cessna SL SE 76-25) and the required measures without amendment language. (Applicability; Requirement; Compliance)"},"complexity_factors":["Specific, short list of discrete actions (inspect, placard, replace) reduces procedural complexity","Reference to an external manufacturer document (Cessna SL SE 76-25) for technical detail increases dependency on another source","Applicability tied to serial numbers in the service letter requires cross-referencing documents to determine who is affected","Time-limited compliance windows (before next flight; within 100 hours TIS) create operational scheduling considerations","Conditional step (placard may be removed after replacement) introduces a dependency between requirements"],"plain_english_summary":"This airworthiness directive requires owners/operators of certain Cessna 150/A150s to inspect wing flap actuator P/N C301002-0101 for specified date-stamp codes and, if present, install a “FLAP EXTENSION PROHIBITED” placard until the actuator’s ball nut assemblies are replaced per Cessna Service Letter SE 76-25. Compliance is mandatory within set time limits, costs fall to operators, and the regulator prescribes the outcome while the manufacturer provides the technical procedures."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cessna-150-26-wing-flap-actuator-ball-nut-assemblies","history":"/api/acts/ad-cessna-150-26-wing-flap-actuator-ball-nut-assemblies/history","analysis":"/api/acts/ad-cessna-150-26-wing-flap-actuator-ball-nut-assemblies/analysis","conflicts":"/api/acts/ad-cessna-150-26-wing-flap-actuator-ball-nut-assemblies/conflicts","importantCases":"/api/acts/ad-cessna-150-26-wing-flap-actuator-ball-nut-assemblies/important-cases","documents":"/api/acts/ad-cessna-150-26-wing-flap-actuator-ball-nut-assemblies/documents"}}