{"id":"F2006B04907","name":"AD/CESSNA 120/7 - Met-Co-Aire Tricycle Landing Gear","slug":"ad-cessna-120-7-met-co-aire-tricycle-landing-gear","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44751,"registerId":"commonwealth-F2006B04907-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# ![](image.001.png)  \nAIRWORTHINESS DIRECTIVE\n\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 CASR 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\n![](image.001.png)\n\nCessna 120 and 140 Series Aeroplanes","sortOrder":0},{"sectionNumber":"AD/CESSNA 120/7 Met-Co-Aire Tricycle Lan","sectionType":"part","heading":"AD/CESSNA 120/7 Met-Co-Aire Tricycle Landing Gear 5/2003","content":"# AD/CESSNA 120/7 Met-Co-Aire Tricycle Landing Gear 5/2003\n\nApplicability: Model 120, 140, and 140A aircraft, on which a Met-Co-Aire Tricycle Landing Gear (STC SA4-916) has been installed.\n\nRequirement: 1. Tighten and torque the four AN 4 bolts (two on each side) which extend through the Cessna main gear wedges and the part number RD-1001C-11 Met-Co-Aire support plate to 50-70 inch pounds. Care should be taken to insure that the AN 365 stop nuts have not bottomed on the bolt threads before adequately tightening the wedge in place as specified above; use metal washers under the nut or bolt heads as necessary.\n\n    2. Conduct a detail visual inspection for cracks in the corners of the slots in the support plate, part number RD-1001C-11, and the attach plate. If cracks are evident, before further flight, replace cracked part with Met-Co-Aire part number RD-1001C-6 or FAA approved equivalent part. When a new part is installed, the repetitive inspection requirement for this paragraph may be discontinued.\n    3. Inspect the attachment of the top flanges of the bulkheads in the landing gear attachment box and check that all rivets which secure the box to the floor structure are properly installed. Rectify any rivet which is improperly installed. Refer to Met-Co-Aire installation instructions, dated 29 August 1959, revised 1 January 1961.\n\nIf installed, remove the adaptor plates, Cessna part number 0441147, which may have been used to extend the main gears forward.\n\nNote: FAA AD 61-25-01 Amdt 376 and Met-Co-Aire Service Directive SD-1003 refer.\n\nCompliance: For Requirements 1 and 2: Within 20 hours time in service after 15 May 2003, and thereafter at intervals not to exceed 100 hours time in service; except for Requirement 2, when a new part is installed.\n\nFor Requirement 3: Unless already accomplished, within 20 hours time in service after 15 May 2003.\n\nThis Airworthiness Directive becomes effective on 15 May 2003.","sortOrder":1}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This Airworthiness Directive maintains its original narrow scope: addressing a specific unsafe condition in a specific aftermarket modification (Met-Co-Aire tricycle landing gear) on specific Cessna models. The requirements remain tightly focused on the identified safety issues without expansion into unrelated systems or broader aircraft modifications."},"complexity_factors":["Multiple specific part numbers referenced (RD-1001C-11, RD-1001C-6, 0441147) requiring cross-referencing to aircraft records","Conditional logic: Requirement 2 has an exception allowing discontinuation of repetitive inspections upon part replacement","Technical aviation terminology requiring specialised knowledge (torque values, 'time in service', 'bottomed on threads', 'detail visual inspection')","Cross-references to external documents (FAA AD 61-25-01, Met-Co-Aire Service Directive SD-1003, installation instructions dated 1959/1961)","Specific compliance timelines with exceptions (20 hours initial, 100 hours repetitive, with discontinuation clause)"],"plain_english_summary":"This CASA safety order requires owners/operators of Cessna 120/140/140A aircraft fitted with the Met‑Co‑Aire tricycle landing gear (STC SA4‑916) to perform urgent maintenance to prevent landing‑gear failure: torque four main‑gear bolts to 50–70 in‑lb and ensure nuts aren’t bottomed out, visually inspect a support plate for slot‑corner cracks (replace before flight if cracked), and verify rivets securing the gear box to the floor.\n\nBolt torque and crack checks are due within 20 flight hours after 15 May 2003 and repeat every 100 hours unless the improved part is fitted; rivet inspection is one‑time within 20 hours."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD is narrowly targeted to correct an identified unsafe condition on a specific modification (Met‑Co‑Aire Tricycle Landing Gear STC SA4‑916) for Cessna 120/140/140A aircraft. The actions (torque, inspect, replace, remove adaptor plates) are directly related to that safety objective. There is no indication the AD has grown beyond that original technical safety purpose or added unrelated regulatory obligations."},"complexity_factors":["Short document with three discrete requirements (Req. 1–3)","Clear applicability limited to Model 120/140/140A aircraft with Met‑Co‑Aire STC SA4‑916","Single numeric torque specification (50–70 in‑lb) and simple visual inspection criteria","Repetitive inspection interval: initial 20 hours then every 100 hours (conditional cessation if new part installed)","Cross‑references to external documents (FAA AD 61‑25‑01, Met‑Co‑Aire Service Directive SD‑1003, Met‑Co‑Aire installation instructions)","One conditional removal requirement (adaptor plates part 0441147)","Legal basis cited: CASR subregulation 39.1(1)"],"plain_english_summary":"**What this instrument does (mechanical summary)**\n\n- Requires specific maintenance and inspections for Cessna 120, 140 and 140A aeroplanes that have had a Met‑Co‑Aire Tricycle Landing Gear fitted under STC SA4‑916.\n- Three mandatory actions (Requirement 1–3):\n  - Tighten and torque four AN‑4 bolts that pass through the Cessna main gear wedges and the Met‑Co‑Aire support plate (part RD‑1001C‑11) to 50–70 inch‑pounds. Take care that the AN‑365 stop nuts are not bottomed on the bolt threads; use metal washers if needed. (Req. 1)\n  - Carry out a detailed visual inspection for cracks at the corners of the slots in the RD‑1001C‑11 support plate and in the attach plate. If cracks are found, replace the cracked part before further flight with Met‑Co‑Aire part RD‑1001C‑6 or an FAA‑approved equivalent. If a new part is installed, the repetitive inspection requirement for this paragraph may be discontinued. (Req. 2)\n  - Inspect the attachment of the top flanges of the bulkheads in the landing‑gear attachment box and confirm all rivets securing the box to the floor are properly installed. Fix any improperly installed rivets. Follow the Met‑Co‑Aire installation instructions (29 Aug 1959; revised 1 Jan 1961). (Req. 3)\n- If adaptor plates (Cessna part 0441147) that extend the main gears forward are fitted, they must be removed.\n- Compliance timing: Requirements 1 and 2 must be done within 20 hours time in service after 15 May 2003 and then at intervals not exceeding 100 hours time in service (except the repetitive inspection in Req. 2 can cease once a new part is installed). Requirement 3 must be done within 20 hours time in service after 15 May 2003.\n\n**Who is affected**\n\n- Owners/operators of Cessna Model 120, 140 and 140A aircraft that have the Met‑Co‑Aire Tricycle Landing Gear installed under STC SA4‑916.\n- Licensed maintenance organisations or engineers who perform the required torqueing, inspections and any part replacements.\n\n**Why the directive matters (official purpose and practical effects)**\n\n- Official purpose (as stated): correct an unsafe condition associated with the Met‑Co‑Aire tricycle landing gear installation — specifically potential cracking in the support/attach plates and insecure attachment that could affect landing gear integrity.\n\n- Practical effects and mechanics of those effects:\n  - Who pays: the aircraft owner/operator bears the direct costs — labour for the torqueing and inspections, possible replacement parts (RD‑1001C‑6 or FAA equivalent), and any grounding time while work is done.\n  - Who decides and performs the work: CASA (by delegate) mandates the action; licensed maintenance personnel perform the work according to the AD and referenced Met‑Co‑Aire instructions.\n  - Behaviour changes required: more frequent inspections (initial within 20 hours, then every 100 hours for Req. 1 & 2) until a new part is installed; tightening to a specified torque and possible removal of adaptor plates.\n  - Compliance burden: routine but time‑sensitive mechanical work and repetitive inspections while older parts remain in service; owners who fly frequently will reach the 100‑hour repeat interval sooner, increasing maintenance frequency.\n  - Implementation risk and precision: torqueing to 50–70 in‑lb and ensuring stop nuts have not bottomed requires appropriate tools and competence; improper installation or missing washers could leave the unsafe condition uncorrected.\n  - Trade‑offs and opportunity cost: short‑term downtime and maintenance expense for operators versus mitigating risk of landing‑gear failure. Replacement with a new part removes the need for repetitive inspection (reducing ongoing cost once replacement is done).\n\n**Referenced materials and cross‑checks**\n\n- The AD refers to FAA AD 61‑25‑01 Amdt 376 and Met‑Co‑Aire Service Directive SD‑1003, and relies on the Met‑Co‑Aire installation instructions (29 Aug 1959; rev. 1 Jan 1961) for some details.\n\n**Where the wording matters**\n\n- The torque band (50–70 in‑lb) and the warning about AN‑365 stop nuts are operationally important — if the nut bottoms on the thread before the wedge is clamped, the required clamping force will not be achieved, so the AD requires washers as needed.\n- The exception that allows stopping repetitive inspections once a new part is installed materially reduces ongoing cost for owners who replace parts.\n\n(Requirements and compliance timing cited from Requirement paragraphs 1–3 and the Compliance section of the AD.)"},"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"}},"importantCases":[],"_links":{"self":"/api/acts/ad-cessna-120-7-met-co-aire-tricycle-landing-gear","history":"/api/acts/ad-cessna-120-7-met-co-aire-tricycle-landing-gear/history","analysis":"/api/acts/ad-cessna-120-7-met-co-aire-tricycle-landing-gear/analysis","conflicts":"/api/acts/ad-cessna-120-7-met-co-aire-tricycle-landing-gear/conflicts","importantCases":"/api/acts/ad-cessna-120-7-met-co-aire-tricycle-landing-gear/important-cases","documents":"/api/acts/ad-cessna-120-7-met-co-aire-tricycle-landing-gear/documents"}}