{"id":"F2005L02418","name":"AD/CESSNA 337/22 Amdt 3 - Wing Front and Rear Spars - Inspection","slug":"ad-cessna-337-22-amdt-3-wing-front-and-rear-spars-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":36947,"registerId":"commonwealth-F2005L02418-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Cessna 337 Series Aeroplanes","sectionType":"division","heading":"Cessna 337 Series Aeroplanes","content":"### Cessna 337 Series Aeroplanes\n\n| AD/CESSNA 337/22 Amdt 3 | Wing Front and RearSpars - Inspection | 10/2005 |\n| ----------------------- | ------------------------------------- | ------- |\n\n| Applicability: | Models 337, 337A, 337B, T337B, 337C, T337C, 337D and T337D with the following serial numbers 337-0001 through 337-1193; andModels 337E, T337E, 337F, T337F, 337G, 337H and T337H with the following serial numbers 33701194 through 33701852; andModels T337G and P337H with the following serial numbers P3370001 through P3370313.                                                                                                                                                                                                                                                                                                                                                                                                               |\n| -------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Inspect the front and rear spars for cracking in accordance with Cessna SL ME78-2 Supplement No. 1 except that in connection with the front spar inspection the eddy current test sensitivity shall be established so that a 10% full scale meter deflection is obtained from a slot .030\" + .003\" deep, .060\" + .003\" long and .010\" maximum width, machined in the wall of a 3/16\" diameter hole in an aluminium alloy test block.Note 1: FAA AD 78-09-05 also refers.Note 2: A suitable test block is Nortec Part No. TB-12.Note 3: Scoring of bolt holes can cause spurious eddy current indications of cracking and may be the cause of future fatigue crack initiations. Great care must therefore be taken when removing the subject bolts. |\n| Compliance:    | Inspect both the front and rear spars in accordance with the times specified for the rear spar in “Action Required” Section of Cessna SL ME78-2 Supplement No. 1 except that for aircraft incorporating Robertson Aircraft Corporation Modification to United States STC 1627 WE a reduction of 1000 hours in the inspection threshold and 100 hours in inspection intervals shall apply. This exception is subject to change should fatigue substantiating data on the Robertson conversion be supplied to the Authority.                                                                                                                                                                                                                         |\n|                | This Amendment becomes effective on 29 September 2005.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |\n\n| Background: | Amendment 2 was issued to clarify the eddy current test block specifications.This amendment is issued to clearly define which serial numbered aircraft are affected by this AD. |\n| ----------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n8 August 2005","sortOrder":0},{"sectionNumber":"AD/CESSNA 337/22 Amdt 3","sectionType":"part","heading":"AD/CESSNA 337/22 Amdt 3","content":"## AD/CESSNA 337/22 Amdt 3","sortOrder":1},{"sectionNumber":"Wing Front and RearSpars - Inspection","sectionType":"part","heading":"Wing Front and RearSpars - Inspection","content":"## Wing Front and Rear  \nSpars - Inspection","sortOrder":2},{"sectionNumber":"10/2005","sectionType":"part","heading":"10/2005","content":"## 10/2005","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"This amendment explicitly defines which serial‑numbered aircraft are affected, clarifying the population subject to the inspections. Earlier amendments focused on test‑block specifications; the current text narrows/clarifies applicability by model and serial number (Background)."},"complexity_factors":["Applicability defined by multiple model types and specific serial‑number ranges, increasing administrative effort to identify affected aircraft (Applicability).","Technical eddy‑current test specification requiring a 10% full‑scale meter deflection from a precisely machined slot and use of a suitable test block (Requirement).","Reference to an external service letter (Cessna SL ME78‑2 Supplement No.1) for detailed procedures and an FAA AD, creating dependency on external documents (Requirement; Note 1).","Exception for aircraft incorporating Robertson Aircraft Corporation STC 1627 WE that reduces inspection threshold by 1,000 hours and intervals by 100 hours, adding a conditional compliance track and potential for future change pending submitted data (Compliance).","Operational caution about bolt‑hole scoring causing false eddy‑current indications and potential for inducing fatigue cracks, raising skill and procedural risks during inspection and maintenance (Requirement Note 3).","Specified test block part number (Nortec TB‑12) and effective date impose procurement and scheduling actions on operators (Requirement; Note 2; Compliance).","Background change history: prior amendment clarified test block specs; this amendment clarifies serial‑number applicability, meaning scope and compliance population were adjusted (Background)."],"plain_english_summary":"Instructs owners/operators of specified Cessna 337-series aeroplanes (listed by model and serial number) to inspect wing front and rear spars for cracking using the Cessna SL ME78‑2 Supplement No.1 eddy‑current procedure, with prescribed test‑block and sensitivity settings. Owners bear inspection and repair costs; the Civil Aviation Safety Authority sets timing and allows a 1,000‑hour/100‑hour reduction for aircraft fitted with the Robertson STC. The requirement targets early detection of fatigue cracks to protect structural integrity."},"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"},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This Amendment 3 remains tightly focused on its original purpose: ensuring structural integrity of Cessna 337 wing spars through inspection requirements. The amendment merely clarifies which specific serial numbers are affected (resolving ambiguity from previous versions) and refines technical testing specifications. No expansion of scope beyond the original safety intent."},"complexity_factors":["Multiple nested applicability conditions combining model variants (337, 337A, T337B, etc.) with non-contiguous serial number ranges","Technical cross-reference to external document (Cessna SL ME78-2 Supplement No. 1) without reproducing its contents","Precise engineering specifications for eddy current testing including dimensional tolerances (.030\" + .003\" deep, etc.)","Conditional compliance exception for Robertson Aircraft Corporation STC 1627 WE modification with modified thresholds","Provisional language suggesting future amendment possible ('subject to change should fatigue substantiating data... be supplied')","Reference to third-party test block manufacturer (Nortec Part No. TB-12) creating external dependency"],"plain_english_summary":"This AD mandates eddy‑current inspection of the front and rear wing spars on specified Cessna 337 Skymasters (1960s–mid‑1970s serials, including T and P variants) to detect fatigue cracks. It sets required test sensitivity and procedures and is legally enforceable for affected owners/operators. It matters because undetected spar cracks can cause structural failure. Certain aircraft with a Robertson modification must be inspected sooner and more frequently."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cessna-337-22-amdt-3-wing-front-and-rear-spars-inspection","history":"/api/acts/ad-cessna-337-22-amdt-3-wing-front-and-rear-spars-inspection/history","analysis":"/api/acts/ad-cessna-337-22-amdt-3-wing-front-and-rear-spars-inspection/analysis","conflicts":"/api/acts/ad-cessna-337-22-amdt-3-wing-front-and-rear-spars-inspection/conflicts","importantCases":"/api/acts/ad-cessna-337-22-amdt-3-wing-front-and-rear-spars-inspection/important-cases","documents":"/api/acts/ad-cessna-337-22-amdt-3-wing-front-and-rear-spars-inspection/documents"}}