{"id":"F2006B04965","name":"AD/CESSNA 170/33 Amdt 1 - Flap Actuator","slug":"ad-cessna-170-33-amdt-1-flap-actuator","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44843,"registerId":"commonwealth-F2006B04965-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CESSNA 170/33 Amdt 1 - Flap Actuator","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 170/33\n\nAmdt 1\n\n  \nFlap Actuator 10/82\n\nApplicability: Model 172RG with S/Nos. 172RG0001 to 172RG0005, 172RG0007 to 172RG0012, 172RG0014, 172RG0016 and 172RG0019.\n\nRequirement: Modify the flap actuator assembly P/N C301002-0108 by installing a new mechanical stop nut in accordance with Cessna Service Information Letter SE79-57, or install a replacement flap actuator assembly, P/N C301002-0110.\n\nNote: Although Cessna SIL SE79-59 does not include the model 172RG, the actuator modification for this model is the same as that provided for the model 152.\n\nFAA AD 80-01-06, Amendment 39-3649 refers.\n\nCompliance: If not already accomplished, within 100 hours time in service after 31 October 1982.\n\nBackground: This amendment includes the option to replace the actuator with a new type which provides shorter travel. Overtravel may lead to an asymmetric flap condition.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":true,"description":"The amendment expands the mechanical remedies available compared with the base instruction by adding an explicit option to replace the actuator with part number C301002-0110 which provides shorter travel, in addition to modifying the existing actuator with a mechanical stop nut per Cessna SIL SE79-57 (Requirement; Background). Applicability remains limited to specific 172RG serial numbers and compliance retains a fixed 100-hour time window (Applicability; Compliance)."},"complexity_factors":["Narrow applicability (specific serial numbers) reduces scope complexity (Applicability).","Single, concrete technical remedy options: install stop nut per Cessna SIL SE79-57 or replace with specified P/N (Requirement).","Short, specific compliance timeframe (100 hours TIS after 31 Oct 1982) simplifies scheduling and enforcement (Compliance).","Dependence on manufacturer service information and correct part numbers introduces modest operational complexity and a small risk of following the wrong SIL (Requirement; Note).","Technical installation requires certified maintenance personnel and parts availability, creating routine logistical complexity for operators and maintainers (Requirement)."],"plain_english_summary":"This AD requires Cessna 172RG owners/operators to either fit a new mechanical stop nut per Cessna SIL SE79‑57 or install a shorter‑travel replacement flap actuator (P/N C301002‑0110) to prevent flap overtravel and asymmetric flap conditions. It affects listed 172RG serials, imposes compliance within 100 flight hours, and creates direct costs for owners/operators while directing work to maintenance providers and parts suppliers."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is an amendment to an existing Airworthiness Directive that adds an alternative compliance method (replacement option) without expanding the affected aircraft population or the safety issue being addressed. The scope remains tightly focused on the specific flap actuator defect in the identified Cessna 172RG serial numbers."},"complexity_factors":["Very short document (under 200 words)","Only 3 defined elements: specific aircraft model, serial number range, and part numbers","Single requirement with two alternative compliance paths (modify OR replace)","No nested exceptions or conditional logic beyond the serial number applicability","Clear, fixed compliance deadline","Minimal cross-referencing (one FAA AD reference and one Cessna service letter)"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) that requires specific repairs or modifications to aircraft.\n\n**What it does:**\nOrders owners and operators of specific Cessna 172RG aircraft to fix a potentially dangerous flaw in the flap actuator (the mechanical device that moves the wing flaps up and down).\n\n**The problem:**\nThe original flap actuator can \"overtravel\" — meaning the flaps can move too far, potentially causing **asymmetric flaps** (where one wing's flaps extend more than the other). This creates a serious flight safety risk, as uneven flaps can make the aircraft difficult or impossible to control.\n\n**Who must comply:**\nOwners of Cessna 172RG aircraft with specific serial numbers: 172RG0001 through 172RG0005, 172RG0007 through 172RG0012, 172RG0014, 172RG0016, and 172RG0019.\n\n**What must be done:**\nChoose one of two options:\n- **Modify** the existing flap actuator by installing a new mechanical stop nut (following Cessna Service Information Letter SE79-57), OR\n- **Replace** the entire flap actuator with a new part (P/N C301002-0110) that has shorter travel built in\n\n**Deadline:**\nIf not already done, the fix must be completed within **100 hours of flight time** after 31 October 1982.\n\n**Why it matters:**\nThis directive prevents a known mechanical failure that could cause loss of aircraft control. The amendment adds flexibility by allowing owners to either modify their existing part or install a redesigned replacement."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cessna-170-33-amdt-1-flap-actuator","history":"/api/acts/ad-cessna-170-33-amdt-1-flap-actuator/history","analysis":"/api/acts/ad-cessna-170-33-amdt-1-flap-actuator/analysis","conflicts":"/api/acts/ad-cessna-170-33-amdt-1-flap-actuator/conflicts","importantCases":"/api/acts/ad-cessna-170-33-amdt-1-flap-actuator/important-cases","documents":"/api/acts/ad-cessna-170-33-amdt-1-flap-actuator/documents"}}