{"id":"F2006B02265","name":"AD/AL 250/53 Amdt 1 - Compressor Mount Assembly","slug":"ad-al-250-53-amdt-1-compressor-mount-assembly","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41495,"registerId":"commonwealth-F2006B02265-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/AL 250/53 Amdt 1 - Compressor Mount Assembly","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nAllison Turbine Engines \\- 250 Series\n\nAD/AL 250/53\n\nAmdt 1\n\n  \nCompressor Mount Assembly 2/86\n\nApplicability: Model 250-C28 and -C30 series engines which incorporate compressor mount assemblies P/N 6896021, 6898966 or 6898611 with serial numbers as listed in the Requirement Document.\n\nRequirement: 1. Inspect compressor mount assemblies P/N 6896021, 6898966 and 6898611 in accordance with Allison CEB-A-72-2080/3081 dated 15 September 1982.\n\n2. Replace compressor mount assemblies P/N 6896021, 6898966 and 6898611 with mount P/N 23007217 in accordance with Allison CEB-72-2085/3085 Rev. 1 dated 30 April 1985.\n\nNote: FAA AD 85-25-08 Amendment 39-5189 refers.\n\nCompliance: Part 1. In accordance with the Requirement Document.\n\nPart 2. At the next compressor assembly overhaul or repair after 28 February 1986 but not later than 30 November 1986.\n\nBackground: This Directive is amended to include the FAA AD 85-25-08 mandatory introduction of the improved compressor mount assy.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is an amendment (Amdt 1) to an existing directive, but it remains tightly focused on its original purpose: addressing compressor mount assembly safety in specific Allison engine models. The amendment simply incorporates the corresponding FAA directive to ensure the Australian requirement aligns with the US safety standard. The scope has not expanded beyond the specific mechanical issue and engine models originally targeted."},"complexity_factors":["Short, single-purpose directive with only 2 operative requirements","Minimal defined terms (only specific part numbers and model numbers)","Simple conditional logic (inspection + replacement with clear deadlines)","Single cross-reference to FAA AD 85-25-08 for background context","No nested exceptions or complex procedural pathways","Clear, fixed compliance dates rather than calculated or conditional timelines"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for aircraft engines.\n\n**What it does:**\nThis directive requires owners and operators of specific Allison 250-C28 and 250-C30 turbine engines to inspect and replace certain compressor mount assemblies (critical parts that hold the compressor in place). The original parts (with part numbers 6896021, 6898966, or 6898611) must be replaced with an improved design (part number 23007217).\n\n**Who it affects:**\n- Operators of aircraft using Allison 250-C28 or 250-C30 series engines\n- Specifically those engines with the listed compressor mount assemblies\n- Maintenance organisations servicing these engines\n\n**What must happen:**\n1. **Inspection:** Check the compressor mount assemblies following Allison's technical bulletin CEB-A-72-2080/3081 (dated September 1982)\n2. **Replacement:** Swap out the old mount assemblies for the improved part (P/N 23007217) following Allison's bulletin CEB-72-2085/3085 Rev. 1 (dated April 1985)\n\n**When:**\n- The inspection follows the timeline in the Requirement Document\n- The replacement must happen at the next compressor overhaul or repair after 28 February 1986, but absolutely no later than 30 November 1986\n\n**Why it matters:**\nCompressor mount assemblies are structural components. If they fail, the compressor could break loose, causing catastrophic engine failure and potentially a crash. This directive mandates a safety upgrade based on US Federal Aviation Administration (FAA) findings (FAA AD 85-25-08), ensuring Australian-registered aircraft meet the same safety standard."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":true,"description":"The amendment makes the improved compressor mount assembly mandatory by adding the FAA AD 85‑25‑08 requirement. It expands the directive to require replacement of listed mount P/Ns with P/N 23007217 and sets specific compliance timing (inspection per Allison CEB‑A‑72‑2080/3081 and replacement per Allison CEB‑72‑2085/3085 Rev.1, at next overhaul after 28 Feb 1986 but not later than 30 Nov 1986)."},"complexity_factors":["Narrow applicability: specific engine models (250‑C28, 250‑C30) and three part numbers","Serial‑number‑limited scope referenced in an external Requirement Document","Two sequential actions: mandated inspection (per specified service bulletin) then mandatory replacement with a particular P/N","Fixed compliance window (next overhaul after 28 Feb 1986 but by 30 Nov 1986) creates scheduling constraints for operators","Reliance on external manufacturer documents (Allison CEBs) and cross‑referenced FAA AD for procedural detail","Operational and financial burden on aircraft owners/operators to procure replacement mounts and perform work"],"plain_english_summary":"This airworthiness directive requires operators of Allison 250‑C28 and 250‑C30 engines fitted with compressor mounts P/N 6896021, 6898966 or 6898611 (serial numbers in the Requirement Document) to inspect those mounts per Allison CEB‑A‑72‑2080/3081 and to replace them with mount P/N 23007217 per Allison CEB‑72‑2085/3085 Rev.1. It implements FAA AD 85‑25‑08; operators must schedule the inspection and the mandated replacement at the next compressor overhaul after 28 Feb 1986, and no later than 30 Nov 1986, bearing the inspection and replacement costs and following the prescribed service documents."}},"importantCases":[],"_links":{"self":"/api/acts/ad-al-250-53-amdt-1-compressor-mount-assembly","history":"/api/acts/ad-al-250-53-amdt-1-compressor-mount-assembly/history","analysis":"/api/acts/ad-al-250-53-amdt-1-compressor-mount-assembly/analysis","conflicts":"/api/acts/ad-al-250-53-amdt-1-compressor-mount-assembly/conflicts","importantCases":"/api/acts/ad-al-250-53-amdt-1-compressor-mount-assembly/important-cases","documents":"/api/acts/ad-al-250-53-amdt-1-compressor-mount-assembly/documents"}}