{"id":"F2006L01058","name":"AD/FU24/53 Amdt 2 - Flap Control Torque Tube - Inspection","slug":"ad-fu24-53-amdt-2-flap-control-torque-tube-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":58360,"registerId":"commonwealth-F2006L01058-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Airparts (NZ) Ltd. FU 24 Series Aeroplan","sectionType":"division","heading":"Airparts (NZ) Ltd. FU 24 Series Aeroplanes","content":"### Airparts (NZ) Ltd. FU 24 Series Aeroplanes\n\n| AD/FU24/53 Amdt 2 | Flap Control Torque Tube - Inspection | 5/2006 |\n| ----------------- | ------------------------------------- | ------ |\n\n| Applicability: | All models. |\n| -------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement: | 1. For FU 24 models engaged only in agricultural operations, inspect the Flap Control Torque Tube in accordance with NZ Aerospace SB No. ASB/FU/033, issued on 30 May 1977.2. For FU 24 models engaged only in operations other than agricultural, inspect the Flap Control Torque Tube in accordance with NZ Aerospace SB No. ASB/FU/033.3. For FU 24 models engaged in mixed usage operations (i.e. a combination of agricultural and non-agricultural operations), inspect the Flap Control Torque Tube in accordance with NZ Aerospace SB No. ASB/FU/033.Accomplishment of Department of Aviation (now CASA) approved SuperAir Engineering Order S46 Issue 1, approved 17 April 1980 is terminating action for all of the requirements of this AD.Note 1: SuperAir Engineering Order S46 Issue 1 modifies the torque tube outer attachment lugs, by welding re-inforcement strips to the existing lug material, providing greater cross sectional area and stiffness and eliminating susceptibility to fatigue cracking.Note 2: Other CAR 35 approved modifications may be considered acceptable for the purposes of terminating the inspection requirements of this AD, however, the only modification that has demonstrated in service reliability is the approved SuperAir Engineering Order S46. Other approved modifications may be considered as terminating modifications after consultation with CASA and only after demonstrating sufficient in service reliability.Note 3: New Zealand AD DCA/FU24/164 refers. |\n| Compliance: | 1. Every 100 flight hours.2. Every 220 flight hours.3. Every 100 flight hours. |\n\n| | This Amendment becomes effective on 11 May 2006. |\n| ----------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Background: | This amendment introduces a terminating action (modification) for the inspection requirements of the AD. The modification involves strengthening the flap torque tube outer attachment lugs, thus eliminating their susceptibility to fatigue cracking. The effectiveness of this modification in preventing cracking has been proven over 25 years, with no reports of cracking in any aircraft that has the modification per DoA (now CASA) approved SuperAir Engineering Order # S46 Issue 1.Amendment 1, effective 20 March 2003, was issued to make a distinction between aircraft engaged in agricultural operations and aircraft engaged in non-agricultural operations. It has been shown that fatigue in the flap control torque tube is a function of the number of flight cycles (i.e. flap deployments). Aircraft engaged in agricultural operations are generally subjected to an order of magnitude more cycles than non-agricultural operations, causing accelerated fatigue of the flap control torque tube. This amendment allows aircraft engaged predominantly in non-agricultural operations to inspect the torque tube at 220 hourly intervals rather than 100 hourly intervals as specified in the original issue of this AD. The inspection procedure remained unchanged from the previous issue of this AD.The original issue of this AD became effective on 01 August, 1977. |\n\n![](image.001.png) \nDavid Villiers \nDelegate of the Civil Aviation Safety Authority\n\n29 March 2006","sortOrder":0},{"sectionNumber":"AD/FU24/53 Amdt 2","sectionType":"part","heading":"AD/FU24/53 Amdt 2","content":"## AD/FU24/53 Amdt 2","sortOrder":1},{"sectionNumber":"Flap Control Torque Tube - Inspection","sectionType":"part","heading":"Flap Control Torque Tube - Inspection","content":"## Flap Control Torque Tube - Inspection","sortOrder":2},{"sectionNumber":"5/2006","sectionType":"part","heading":"5/2006","content":"## 5/2006","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"Compared with the original AD, the scope changed: Amendment 1 introduced differentiated inspection intervals by operation type (agricultural vs non‑agricultural), and Amendment 2 authorises a CASA‑approved terminating modification (SuperAir S46) that eliminates recurring inspections. The instrument therefore expands compliance options (inspect periodically or modify once) and shifts costs from ongoing inspections to a one‑off modification for those who choose it; other modifications remain possible only after CASA approval and in‑service proof."},"complexity_factors":["Multiple operator categories (agricultural / non‑agricultural / mixed) with different inspection intervals (Requirement; Compliance).","Terminating action via an approved structural modification (SuperAir Engineering Order S46) that removes recurring inspections (Requirement; Note 1).","Alternative CAR 35 approved modifications may be accepted only after CASA consultation and demonstrated in‑service reliability, adding an approval and evidence burden (Note 2).","Dependence on external technical documents and directives (NZ Aerospace SB ASB/FU/033; SuperAir S46; NZ AD DCA/FU24/164) increases compliance tracking and document control obligations.","Fatigue is driven by flap cycles but inspections are mandated on flight‑hour intervals, creating measurement and estimation complexity for operators (Background; Compliance).","Regulatory discretion by CASA to accept terminating or alternative modifications introduces case‑by‑case decision processes (Requirement; Note 2).","Amendment history and differing effective dates (original AD 1977; Amendment 1 2003; Amendment 2 effective 11 May 2006) require operators to track which version applies."],"plain_english_summary":"This AD requires regular inspections of the flap control torque tube on all Airparts (NZ) FU 24 series aeroplanes, with inspection intervals set according to the aircraft’s operational use (agricultural, non‑agricultural or mixed). It also permits a CASA‑approved modification (SuperAir Engineering Order S46) as a terminating action that removes the recurring inspection requirement. Operators must either perform periodic inspections or install the approved modification; CASA decides which alternative modifications, if any, will be accepted."},"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This amendment stays within the original scope of addressing fatigue cracking in the FU 24 flap control torque tube. Amendment 2 adds a terminating modification option and refines inspection intervals based on operational use, but these are natural evolutions of the same safety issue rather than scope creep. The original 1977 AD addressed the cracking problem; this version simply makes compliance more practical while maintaining safety."},"complexity_factors":["Short, single-purpose document (1 specific mechanical component on 1 aircraft type)","Only 3 defined operational categories with clear inspection intervals","Simple conditional logic (agricultural vs non-agricultural vs mixed)","One terminating action with clear reference (SuperAir Engineering Order S46)","Minimal cross-referencing (only to NZ Aerospace Service Bulletin ASB/FU/033 and one other AD)","Plain language background section explaining the engineering rationale","No nested exceptions or complex definitional sections"],"plain_english_summary":"This AD requires owners/operators of Airparts (NZ) FU 24 (Fletcher) aeroplanes to inspect the flap control torque tube for fatigue cracks at specified intervals (shorter for agricultural use) because cracks at the wing attachment can cause flap failure and loss of control. Amendment 2 adds a terminating modification (SuperAir S46 weld-on reinforcement) that, once installed, removes the need for repetitive inspections."}},"importantCases":[],"_links":{"self":"/api/acts/ad-fu24-53-amdt-2-flap-control-torque-tube-inspection","history":"/api/acts/ad-fu24-53-amdt-2-flap-control-torque-tube-inspection/history","analysis":"/api/acts/ad-fu24-53-amdt-2-flap-control-torque-tube-inspection/analysis","conflicts":"/api/acts/ad-fu24-53-amdt-2-flap-control-torque-tube-inspection/conflicts","importantCases":"/api/acts/ad-fu24-53-amdt-2-flap-control-torque-tube-inspection/important-cases","documents":"/api/acts/ad-fu24-53-amdt-2-flap-control-torque-tube-inspection/documents"}}