{"id":"F2006L00142","name":"AD/F50/92 Amdt 2 - Engine Mounting Frame Welds","slug":"ad-f50-92-amdt-2-engine-mounting-frame-welds","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":58028,"registerId":"commonwealth-F2006L00142-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Fokker F50 (F27 Mk 50) Series Aeroplanes","sectionType":"division","heading":"Fokker F50 (F27 Mk 50) Series Aeroplanes","content":"### Fokker F50 (F27 Mk 50) Series Aeroplanes\n\n| AD/F50/92 Amdt 2 | Engine Mounting Frame Welds | 2/2006 |\n| ---------------- | --------------------------- | ------ |\n\n| Applicability: | Model F27 Mk.050, 0502, and 0604 aircraft, all serial numbers.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |\n| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Action in accordance with the requirements of Netherlands CAA AD NL-2005-015.Note 1: AD NL-2005-015 may be obtained by contacting CASA e-mail address airworthiness.directives@casa.com.au.Note 2: Fokker Service Bulletins F50-71-048 and F50-71-049; and Fokker Component Service Bulletins F8200-035-71-10 and F8200-035-71-11; or laterCAA-NL approved revisions, refer.                                                                                                                                                                                                                                                                                        |\n| Compliance:    | For the inspection requirement: Within 2 calendar months after 1 September 2005.The compliance time remains unchanged by this issue of the Directive.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |\n|                | This Amendment becomes effective on 16 February 2006.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |\n| Background:    | Welding defects were discovered during recent scheduled X-ray inspections of F50 engine mounting frames. Investigation revealed that during manufacture of the frames, when tubes were welded to the end fittings, movement of the electric arc resulted in some welds running beside the borderline for a part of the tube circumference. The defective welding process appears to have occurred at some of the welds in an unknown number of engine mounting frames. This condition, if not corrected, could lead to failure of an affected engine mounting frame.Amendment 1 changed the Requirement paragraphs specified in Paragraph e. of the original issue. |\n\n|     | Amendment 2 is issued in response to a new CAA-NL AD. Previous ADNL-2005-07 was issued to require a one-time inspection for improper welds, while the new AD further specifies the criteria and compliance times for the follow-up NDT inspection, and repair or replacement of engine mount frames, as necessary. |\n| --- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n21 December 2005","sortOrder":0},{"sectionNumber":"AD/F50/92 Amdt 2","sectionType":"part","heading":"AD/F50/92 Amdt 2","content":"## AD/F50/92 Amdt 2","sortOrder":1},{"sectionNumber":"Engine Mounting Frame Welds","sectionType":"part","heading":"Engine Mounting Frame Welds","content":"## Engine Mounting Frame Welds","sortOrder":2},{"sectionNumber":"2/2006","sectionType":"part","heading":"2/2006","content":"## 2/2006","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"Yes. The AD originally required a one‑time inspection (previous AD NL‑2005‑07). Amendment 2 expands and clarifies scope by adopting the newer CAA‑NL AD NL‑2005‑015: it adds specific criteria and compliance times for when follow‑up non‑destructive testing (NDT) is required and mandates repair or replacement of engine mounting frames if defects are confirmed. In other words, the measure moved from a single inspection event to a rule that can require additional testing and corrective action, increasing the potential for follow‑on work, cost and aircraft downtime."},"complexity_factors":["Short document with a single clear safety focus (engine mounting frame welds).","Cross‑references to external documents: Netherlands CAA AD NL‑2005‑015 and four Fokker service/component bulletins (requires obtaining and applying those documents).","One primary compliance window (inspection within 2 calendar months after 1 September 2005) plus subsequent conditional steps (follow‑up NDT and repair/replacement if criteria met).","Two amendments referenced (Amendment 1 and Amendment 2) with Amdt 2 responding to a newer CAA‑NL AD rather than introducing multiple new domestic exceptions.","Limited number of defined applicability items (three model variants, all serial numbers)."],"plain_english_summary":"**What this directive does**\n\n- This airworthiness directive (AD) requires owners/operators of Fokker F50 (F27 Mk 50) series aeroplanes to carry out inspections and, if necessary, non‑destructive testing (NDT) and repair or replacement of engine mounting frames because welding defects were found during prior X‑ray inspections. (See Background and Requirement.)\n\n**Who it affects**\n\n- Owners and operators of Fokker F27 Mk.050, 0502 and 0604 aircraft (all serial numbers).\n- Maintenance organisations and engineers who perform inspections, NDT and repairs to aircraft structure.\n- The regulator (Civil Aviation Safety Authority, CASA) enforces compliance and references the Netherlands Civil Aviation Authority (CAA‑NL) AD and Fokker service/component bulletins for the technical work.\n\n**How it works mechanically**\n\n- The AD does not set out new inspection steps itself; instead it mandates compliance with the Netherlands CAA AD NL‑2005‑015 and the referenced Fokker Service Bulletins (F50‑71‑048, F50‑71‑049 and component SBs F8200‑035‑71‑10 and F8200‑035‑71‑11) or later CAA‑NL‑approved revisions. (Requirement)\n- A one‑time inspection was required to be done within 2 calendar months after 1 September 2005. This Amendment (Amdt 2) becomes effective 16 February 2006 and follows a newer CAA‑NL AD that: (a) specifies the criteria for when follow‑up NDT is required; (b) sets compliance times for that NDT; and (c) requires repair or replacement of engine mount frames if defects are confirmed. (Compliance, Background)\n\n**Why it matters (stated purpose and practical implications)**\n\n- Stated purpose: during manufacture some welds on engine mounting frames were offset so that part of the tube circumference was not properly welded. Left uncorrected, this could lead to failure of an engine mounting frame. (Background)\n- Practical effect: operators must invest time and money to inspect the engine mount frames, perform NDT when indicated, and repair or replace affected frames. That work can cause aircraft downtime and maintenance cost.\n\n**Who pays, who decides, and what behaviour changes**\n\n- Who pays: aircraft owners/operators pay for inspections, NDT, repairs or replacements and for any associated aircraft downtime. Maintenance providers charge for labour and testing; if replacement frames are needed, parts cost and supply constraints may add expense.\n- Who decides: CASA enforces the AD and directs operators to comply with CAA‑NL AD NL‑2005‑015 and the specified Fokker service/component bulletins. The technical decisions about how to inspect, test and repair are made by certificated maintenance organisations following those documents and any approved revisions. If an operator chooses earlier/later approved revisions, those must be CAA‑NL approved.\n- Behaviour changes: operators must schedule the mandated inspections within the specified compliance window, perform follow‑up NDT where the CAA‑NL criteria require it, and repair or replace frames that do not meet the criteria.\n\n**Costs, incentives, trade‑offs and implementation risks**\n\n- Direct costs: inspection (including NDT), repairs, parts and aircraft out‑of‑service time. If frames require replacement, costs and lead times for parts could be significant.\n- Incentives: operators have a clear safety and regulatory incentive to comply; delaying increases regulatory and safety risk. There is also an incentive for maintenance providers to follow the chosen service bulletins and approved procedures to avoid repeated inspections.\n- Trade‑offs: the measure trades operator cost and downtime for reduced risk of structural failure. The directive delegates technical detail to the CAA‑NL AD and service bulletins, so CASA is relying on foreign technical material rather than restating methods locally.\n- Implementation risk and compliance burden: the AD is procedural — success depends on availability of NDT resources and spare parts, the clarity of CAA‑NL criteria, and timely approval of any revised service bulletins. Cross‑reference to external documents creates an administrative burden to obtain and apply the correct, approved revisions.\n\n**Where to find the technical steps**\n\n- The AD requires following Netherlands CAA AD NL‑2005‑015 and the listed Fokker service/component bulletins (or later CAA‑NL approved revisions). CASA can provide AD NL‑2005‑015 on request (contact airworthiness.directives@casa.com.au). (Requirement, Note 1/Note 2)\n\n(References: Requirement; Compliance; Background.)"},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":true,"description":"The original directive (AD/F50/92) appears to have been a one-time inspection requirement. Amendment 1 modified specific paragraphs. Amendment 2 significantly expands the scope by incorporating a new Dutch directive that adds ongoing non-destructive testing (NDT) inspection criteria, plus repair and replacement requirements — moving from a single check to a comprehensive airworthiness management program for these engine mounts."},"complexity_factors":["Heavy reliance on external documents: the actual technical requirements are contained in a Dutch CAA directive (NL-2005-015) and four Fokker Service Bulletins, not in the text itself","Multiple amendment layers: references to Amendment 1 changes and original issue requirements without reproducing them","Nested applicability: applies to specific model variants (Mk.050, 0502, 0604) but 'all serial numbers' within those","Dual compliance timeline structure: original inspection deadline plus unchanged compliance time for this amendment","Cross-border regulatory dependency: Australian directive simply 'adopts' foreign (Dutch) safety requirements"],"plain_english_summary":"This Airworthiness Directive compels owners/operators of Fokker F50 turboprops to inspect engine mounting frames for defective welds within two months after 1 September 2005 and to carry out non‑destructive testing, repairs or replacements per the referenced Dutch directive (NL‑2005‑015) and Fokker Service Bulletins. It responds to a welding defect that could allow an engine mount to fail and an engine to separate in flight. Amendment 2 updates the directive to align with the Dutch authority’s detailed follow‑up criteria."},"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-f50-92-amdt-2-engine-mounting-frame-welds","history":"/api/acts/ad-f50-92-amdt-2-engine-mounting-frame-welds/history","analysis":"/api/acts/ad-f50-92-amdt-2-engine-mounting-frame-welds/analysis","conflicts":"/api/acts/ad-f50-92-amdt-2-engine-mounting-frame-welds/conflicts","importantCases":"/api/acts/ad-f50-92-amdt-2-engine-mounting-frame-welds/important-cases","documents":"/api/acts/ad-f50-92-amdt-2-engine-mounting-frame-welds/documents"}}