{"id":"F2006B09739","name":"AD/F27/81 - Engine Mount Tubes - Inspection","slug":"ad-f27-81-engine-mount-tubes-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115937,"registerId":"commonwealth-F2006B09739-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F27/81 - Engine Mount Tubes - Inspection","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-generator: Aspose.Words for .NET 22.10.0\n---\n\n?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Fokker F27 Series Aeroplanes\n\n \n\nAD/F27/81 Engine Mount Tubes - Inspection 12/73\n\nApplicability: All model F27 on which engine mount P/N 27.1-8101-000-403 with S/Nos. 590 to 725 have been installed.\n\n \n\nRequirement: 1. Inspect referenced engine mount tubes in accordance with Fokker F27 SB F27/71- 25 for cracks using the radiographic technique as detailed; or\n\n \n\n2. Inspect the engine mount tubes detailed in Fokker F27 SB F27/71-25, for cracks using an alternative non destructive technique approved by the Secretary.\n\n \n\nCompliance: Within 500 hours time in service after 31 December 1973 and there-after at intervals not exceeding 1 year.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-bound safety directive issued in 1973 (as indicated by '12/73' in the reference). It addresses a specific technical defect in a specific aircraft part. There is no indication of scope creep; it remains tightly focused on its original purpose of preventing engine mount failures through mandatory inspection."},"complexity_factors":["Very short document (approximately 150 words of substantive content)","Only 2 defined technical references (part number and service bulletin number)","Simple binary compliance options (radiographic OR approved alternative)","Straightforward timing requirement (500 hours + annual)","No nested exceptions or conditional logic","Single applicability criterion (specific part/serial number range)","No cross-references to other legislation or regulations beyond the enabling Civil Aviation Regulations 1998"],"plain_english_summary":"**What this is:** This is an Airworthiness Directive (AD) — essentially a mandatory safety notice issued by Australia's Civil Aviation Safety Authority (CASA) for aircraft.\n\n**What it does:** It requires owners and operators of specific Fokker F27 aircraft to inspect certain engine mount tubes for cracks. These tubes are structural components that hold the engines to the aircraft wing.\n\n**Who it affects:** \n- **Aircraft:** All Fokker F27 models fitted with a specific engine mount part (part number 27.1-8101-000-403) with serial numbers 590 through 725.\n- **People:** Aircraft operators, maintenance engineers, and owners of these specific planes.\n\n**What must be done:**\n- **Option 1:** Inspect the engine mount tubes using X-ray techniques (radiographic inspection) following the manufacturer's service bulletin (Fokker F27 SB F27/71-25).\n- **Option 2:** Use an alternative crack-detection method, but only if pre-approved by the Secretary (the government official responsible for aviation safety at the time).\n\n**When it must be done:**\n- First inspection: Within 500 flight hours after 31 December 1973.\n- Repeat inspections: At least once every year thereafter.\n\n**Why it matters:** Cracked engine mount tubes could cause an engine to detach from the wing during flight — a catastrophic failure. This directive was issued to prevent accidents by catching fatigue cracks before they become dangerous."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The supplied text defines a specific, limited scope (engine mount P/N 27.1-8101-000-403, S/N 590–725 on F27 aircraft) and prescribes inspection methods and intervals. The instrument itself does not include information comparing this scope to any earlier or different intent, so there is no basis in the supplied text to conclude that the scope has changed from an original intent."},"complexity_factors":["Narrow technical scope limited to a specific part number and serial number range (Applicability)","Reference to an external technical document (Fokker Service Bulletin F27/71-25) for the inspection procedure (Requirement, clause 1)","Two-path compliance option: mandated radiographic technique or alternative NDT subject to Secretary approval (Requirement, clause 1 & 2)","Recurring compliance timing with an initial deadline tied to service hours and a subsequent annual interval (Compliance)","Regulatory discretion in approving alternative techniques (Requirement, clause 2)"],"plain_english_summary":"This instrument mandates inspections for cracks of specific engine mount tubes (Fokker F27, P/N 27.1-8101-000-403, S/N 590–725) using the radiographic technique in Fokker Service Bulletin F27/71-25, with the first check within 500 hours’ time‑in‑service after 31 Dec 1973 and then at least annually. Operators of affected aircraft must arrange and pay for inspections and any follow‑up; an alternative NDT method is only permitted if approved by the Secretary."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f27-81-engine-mount-tubes-inspection","history":"/api/acts/ad-f27-81-engine-mount-tubes-inspection/history","analysis":"/api/acts/ad-f27-81-engine-mount-tubes-inspection/analysis","conflicts":"/api/acts/ad-f27-81-engine-mount-tubes-inspection/conflicts","importantCases":"/api/acts/ad-f27-81-engine-mount-tubes-inspection/important-cases","documents":"/api/acts/ad-f27-81-engine-mount-tubes-inspection/documents"}}