{"id":"F2006B10881","name":"AD/JETSTREAM/14 Amdt 4 - Flap Torque Tube Universal Joints","slug":"ad-jetstream-14-amdt-4-flap-torque-tube-universal-joints","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56404,"registerId":"commonwealth-F2006B10881-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/JETSTREAM/14 Amdt 4 - Flap Torque Tube Universal Joints","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)  \nBritish Aerospace BAe 3100 (Jetstream) Series Aeroplanes\n\nAD/JETSTREAM/14\n\nAmdt 4\n\n  \nFlap Torque Tube Universal Joints 13/94\n\nApplicability: All HP137 Mk1, Jetstream Series 200, 3100 and 3200 aircraft, except those which have the improved flap torque shaft assemblies introduced by Jetstream Service Bulletin 27-JA920340.\n\nNote: The improved flap torque shaft assemblies were factory fitted beginning with constructor’s number 957.\n\nRequirement: In accordance with British Aerospace Jetstream Alert Service Bulletin 27-A-JA 900544 Revision 3, or 4:\n\n    Identify whether Type F or Type M universal joints are fitted to the LH and to the RH flap torque shaft assemblies.\n\n    2. Inspect Type F universal joints for cracks, visually, and using eddy currents.\n\n    3. Replace Type F universal joints with Type M universal joints.\n\nCompliance: 1. Identify joint type before 15000 landings, or before exceeding 100 landings after 30 June 1990, whichever occurs later.\n\n    2. If a type F joint has been in service more than 15000 landings when identified, inspect before further flight after identification, and thereafter at intervals not exceeding 400 landings.\n\n    3. Replace not later than 15000 landings, or before exceeding 400 landings after 30 June 1990, whichever occurs later.\n\nThe provisions of the previous amendments are unchanged, this Amendment is effective from 8 December 1994.\n\nBackground: Two types of universal joints were fitted to the flap torque shaft assemblies. One, known as Type F, has a much shorter fatigue life than the other, known as Type M. This Directive first requires an inspection to determine which type is fitted to the aircraft. No further action is required for Type M joints, but Type F joints must be replaced before 15000 landings. For Type F joints that have already exceeded 15000 landings, safety is maintained by inspection for a short period to allow scheduling for the replacement.\n\nAmendment 4 exempts aircraft which have the later, improved flap torque shaft assemblies. The wording of this Directive has also been revised, without changing the intent.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"Amendment 4 narrows applicability by exempting aircraft fitted with the later improved flap torque shaft assemblies (factory fitted from constructor’s number 957 or introduced by Service Bulletin 27-JA920340). The AD’s wording was revised but the stated safety intent remains the same."},"complexity_factors":["Applicability scope with a specific exemption for aircraft fitted with improved flap torque shaft assemblies (constructor’s number 957 or per SB 27-JA920340)","Initial identification requirement to determine joint type on both left and right flap torque shafts","Two-tiered actions depending on joint type: no action for Type M, inspect and replace for Type F","Prescribed inspection methods for Type F (visual plus eddy-current testing)","Conditional compliance timelines tied to landing counts (15000 landings trigger, 100-landings-after-date threshold, 400-landing inspection intervals)","Replacement mandated to Type M per a specific manufacturer service bulletin (27-A-JA900544 Revision 3 or 4)","Reference to specific service bulletin revisions creates dependency on external technical documents"],"plain_english_summary":"**What this does:** Operators of British Aerospace Jetstream HP137 Mk1 and Series 200/3100/3200 aircraft (except those fitted with the improved flap torque shaft assembly) must identify whether Type F or Type M universal joints are fitted to each flap torque shaft and, if Type F is present, inspect it (visual and eddy‑current) and replace it with a Type M in accordance with the cited British Aerospace service bulletin.\n\n**Why it matters:** Type F joints have a shorter fatigue life; the AD sets inspection frequencies and replacement deadlines to manage that risk while exempting aircraft already fitted with the improved assembly."},"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":3,"scope_assessment":{"changed":false,"description":"This is Amendment 4 to an existing Airworthiness Directive. The amendment narrows the scope slightly by exempting aircraft with improved factory-fitted assemblies, but this is a refinement rather than scope creep. The core purpose — mandating inspection and replacement of Type F universal joints — remains unchanged from the original directive."},"complexity_factors":["Multiple conditional deadlines based on landing counts and calendar dates (whichever occurs later)","Nested applicability (all aircraft except those with specific factory modification)","Cross-reference to external technical documents (British Aerospace Service Bulletins)","Different compliance paths depending on joint type and service history","Technical aviation terminology requiring domain knowledge (eddy current testing, constructor's numbers, flap torque assemblies)"],"plain_english_summary":"This safety directive affects HP137 Mk1 and Jetstream 200/3100/3200 aircraft (except those built from constructor number 957 onward) and requires operators to identify whether the flap torque-tube universal joints are the wear-prone Type F. Any Type F found must be inspected for cracks (including eddy-current checks) and replaced with Type M within specified landing-count/deadline limits.\n\nIt matters because Type F joints can crack and cause flap failure during landing, so replacing them prevents loss-of-control risks."}},"importantCases":[],"_links":{"self":"/api/acts/ad-jetstream-14-amdt-4-flap-torque-tube-universal-joints","history":"/api/acts/ad-jetstream-14-amdt-4-flap-torque-tube-universal-joints/history","analysis":"/api/acts/ad-jetstream-14-amdt-4-flap-torque-tube-universal-joints/analysis","conflicts":"/api/acts/ad-jetstream-14-amdt-4-flap-torque-tube-universal-joints/conflicts","importantCases":"/api/acts/ad-jetstream-14-amdt-4-flap-torque-tube-universal-joints/important-cases","documents":"/api/acts/ad-jetstream-14-amdt-4-flap-torque-tube-universal-joints/documents"}}