{"id":"F2006B09991","name":"AD/FU24/44 - Part 1. Wing Spar Modification, and Part 2. Wing Spar Inspection","slug":"ad-fu24-44-part-1-wing-spar-modification-and-part-2-wing-spar-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":55329,"registerId":"commonwealth-F2006B09991-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/FU24/44 - Part 1. Wing Spar Modification, and Part 2. Wing Spar Inspection","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)  \nAirparts (NZ) Ltd. FU 24 Series Aeroplanes\n\nAD/FU24/44 Part 1. Wing Spar Modification, and\n\nPart 2. Wing Spar Inspection\n\n  \n3/72\n\nApplicability: All models in the agricultural category, and all models previously used in agricultural operations, except aircraft incorporating spar steel doublers in accordance with Air Parts SB No. AP.55 Part B.\n\nRequirement: For Aircraft in the Agricultural Category PART 1 - Modification\n\nModify the centre-wing main spar lower cap in accordance with Air Parts Service Bulletin No. AP.59.\n\nPART 2 \\- Inspection\n\n    Carry out a visual inspection for cracking of the centre-wing main spar lower cap over the area which is accessible after removing the main beam slot fairing, leading edge fuel tanks, access panels etc. Special attention shall be paid to areas adjacent to fastener holes and changes in section.\n\n    2. (a) Carry out a visual inspection for cracking of the centre-wing main spar lower cap over the area which is accessible after removing the main beam slot fairing, leading edge fuel tanks, access panels etc.\n\n(b) Inspect the edges of the spar cap members by inserting a borescope wherever possible between the edge of the spar doubler and the fuselage structure. It is essential that at least one side of the original spar cap be inspected along the whole length covered by the doubler. The borescope inspection is based upon the capability of finding a major crack or a failure of one of the five original spar cap members.\n\nNote: As an alternative to the borescope inspection the Authority may consider any alternative scheme using a radiographic inspection technique based upon the detection of a complete failure of any one of the five original spar cap members.\n\n    3. Carry out a visual and dye penetrant inspection for cracking of the outer and centre-wing main spar lower attachment fittings after removing the lower attachment bolts.\n\nFor Aircraft not now in the Agricultural Category but which have previously been engaged in Agricultural Operations.\n\nThe Authority shall be consulted to establish the inspection and modification requirements.\n\nCompliance: For Part 1 \\- Within 1000 hours time in service after 31 March 1972.\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\nNote: To obtain the maximum fatigue life benefit the modification should be incorporated at the earliest possible opportunity.\n\nFor Part 2, Para. 1 \\- For aircraft not modified in accordance with Part 1 and with more than 5000 hours total time in service \\- within 200 hours time in service after 31 March 1972 and therefore at intervals not exceeding 200 hours time in service.\n\nFor Part 2, Paras. 2(a) and 2(b):\n\n    (1) For aircraft modified in accordance with Part 1 at not more than 500 hours time in service - within 200 hours time in service after reaching the additional time “T” and thereafter at intervals not exceeding 200 hours total time in service where:\n\nT \\= 20,000 \\- 19,000 x n hours additional time in service; and 5,000\n\nn \\= aircraft total hours time in service as at incorporation of modification in accordance with Part 1.\n\n    (2) For aircraft modified in accordance with Part 1 at more than 5000 hours time in service - within 100 hours time in service from date of modification and thereafter at intervals not exceeding 200 hours time in service.\n\nFor Part 2, Para. 3 \\- Within 100 hours time in service after 31 March 1972 for aircraft with more than 8000 hours time in service and thereafter at intervals not exceeding 100 hours time in service.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":6,"scope_assessment":{"changed":false,"description":"The directive's scope is explicit in the text: it targets all FU 24 models in the agricultural category and those previously used in agricultural operations, excluding aircraft already fitted with spar steel doublers per SB AP.55 Part B. It does not purport to broaden applicability beyond those groups; for aircraft previously used in agriculture the Authority must be consulted to set specific requirements (Applicability; Part 2)."},"complexity_factors":["Multiple conditional compliance timelines depending on aircraft total hours, modification status, and historical use (Part 2 timing rules and initial deadlines referencing 31 March 1972).","Mathematical formula for an additional-time threshold (T) tied to aircraft hours at modification, requiring calculation (Part 2 paras. 2(a)/(b)).","Technical inspection methods with alternatives and equipment needs (visual, borescope, dye‑penetrant, optional radiographic technique) creating operational and equipment burdens (Part 2 paras. 1–2).","Reference to external Air Parts Service Bulletins (AP.59 and AP.55 Part B) for the required modification and an exception, requiring access to and compliance with those documents (Applicability; Part 1).","Exception and consultation paths: aircraft not currently agricultural but previously used must consult the Authority to set requirements, introducing administrative discretion and case-by-case decisions.","Access and disassembly requirements (removal of fairings, fuel tanks, access panels, lower attachment bolts) impose labour and downtime costs and technical skill demands (Part 2).","Historic compliance dates and staged intervals create record‑keeping and retrospective-compliance complexity for operators with long-in-service aircraft."],"plain_english_summary":"Requires FU 24 series agricultural aeroplanes to have the centre‑wing main spar lower cap modified (per Air Parts SB AP.59) and to undergo recurring inspections—visual, borescope (or radiographic alternative), and dye‑penetrant—of the spar and its lower attachment fittings. Applies to aircraft currently used for agricultural work and those previously so used, except machines already fitted with spar steel doublers (SB AP.55 Part B). The rule sets fixed deadlines and repeat intervals to detect and address spar cracking before failure."},"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":6,"scope_assessment":{"changed":false,"description":"This appears to be the original scope of the Airworthiness Directive. The document addresses a specific safety issue (wing spar fatigue in agricultural operations) with a targeted two-part remedy. There is no evidence of scope creep; the agricultural use exemption and former-agricultural aircraft provisions appear to be original design features rather than later additions."},"complexity_factors":["Multiple conditional compliance paths based on aircraft history (agricultural vs former-agricultural vs non-agricultural)","Mathematical formula for calculating inspection intervals (T = 20,000 - 19,000 × n/5,000) with defined variable","Nested exceptions: exemption for aircraft with SB AP.55 Part B doublers, alternative inspection methods subject to Authority approval","Cross-references to external documents (Service Bulletins AP.59 and AP.55 Part B) not reproduced in the text","Four distinct compliance timelines depending on modification status and flight hours (100 hours, 200 hours, 1000 hours, and formula-derived intervals)","Technical aviation terminology requiring specialised knowledge (spar cap, borescope, dye penetrant, time in service)","Dual structure with Part 1 (modification) and Part 2 (inspection) having interdependent compliance requirements"],"plain_english_summary":"This Airworthiness Directive for Airparts (NZ) FU 24 agricultural aircraft tackles fatigue cracking in the centre wing spar that can lead to catastrophic wing failure. It applies to all FU 24s, including retired agricultural machines, except those already modified per the specified bulletin.\n\nOwners must either install a permanent steel doubler reinforcement or carry out repeated targeted inspections (visual, borescope/X‑ray and dye‑penetrant checks) on the spar and fittings to detect cracks and prevent accidents."}},"importantCases":[],"_links":{"self":"/api/acts/ad-fu24-44-part-1-wing-spar-modification-and-part-2-wing-spar-inspection","history":"/api/acts/ad-fu24-44-part-1-wing-spar-modification-and-part-2-wing-spar-inspection/history","analysis":"/api/acts/ad-fu24-44-part-1-wing-spar-modification-and-part-2-wing-spar-inspection/analysis","conflicts":"/api/acts/ad-fu24-44-part-1-wing-spar-modification-and-part-2-wing-spar-inspection/conflicts","importantCases":"/api/acts/ad-fu24-44-part-1-wing-spar-modification-and-part-2-wing-spar-inspection/important-cases","documents":"/api/acts/ad-fu24-44-part-1-wing-spar-modification-and-part-2-wing-spar-inspection/documents"}}