{"id":"F2006B05514","name":"AD/PA-23/87 - Engine Air Filter","slug":"ad-pa-23-87-engine-air-filter","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":46373,"registerId":"commonwealth-F2006B05514-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PA-23/87 - Engine Air Filter","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)  \nPiper PA-23 (Apache and Aztec) Series Aeroplanes\n\nAD/PA-23/87 Engine Air Filter 9/99\n\nApplicability: PA-23-235 aircraft serial numbers 27-505 through 27-622, and PA-23-250 aircraft serial numbers 27-01 through 27-2504;\n\nfitted with a Facet engine air inlet filter part number (P/N) 638873 manufactured in the period January 1997 to September 1998.\n\nNote 1: Filters of concern can be identified by accessing the filter and locating the brand name and part number. Filters of concern are branded “FACET 638873” in 0.250”(1/4”) high white characters with no date code.\n\nRequirement: To prevent pieces of a damaged air filter from being ingested in the engine, inspect applicable air filters in accordance with Piper Service Bulletin Number (No.) 1022 and/or Purolator Service Bulletin No. 090298.01.\n\nNote 2: Civil Aviation Regulation (CAR) 42ZC (4) (d) permits the holder of a pilot licence, other than a student pilot, that is valid for the aircraft, to change the air filter. Therefore, should applicable air filters be removed from service prior to the effective date of this directive, the directive will no longer be applicable.\n\nNote 3: FAA Airworthiness Directive 99-05-09 refers.\n\nCompliance: Installed filters: At next inspection of the engine air inlet filter element or within 25 hours time in service from the effective date of this directive, whichever occurs first, and thereafter at intervals not to exceed 25 hours time in service.\n\nSpare filters: Prior to installation in a engine.\n\nThis Airworthiness Directive becomes effective on 9 September 1999.\n\nBackground: This directive has been issued to address reports of cracking and break up of certain air filter elements. The defects resulted from evidence of manufacturing errors in filters produced during the period January 1997 though September 1998. The directive requires applicable filters to be inspected for evidence of deterioration.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive's scope aligns with its stated purpose: it targets a specific batch of Facet filters on listed Piper PA‑23 serial numbers and prescribes inspections and removal. It does not expand obligations beyond those aircraft, filters and service‑bulletin procedures identified in the instrument."},"complexity_factors":["Narrow applicability tied to specific aircraft models and serial number ranges (PA‑23‑235 s/n 27‑505 to 27‑622; PA‑23‑250 s/n 27‑01 to 27‑2504).","Component identification requires visual check of brand and part number marking: 'FACET 638873' with no date code.","Limited manufacturing date window specified (January 1997 to September 1998) for affected filters.","Mandated inspection schedule: at next inspection or within 25 hours, then every 25 hours thereafter (for installed filters).","Spare filters must be inspected prior to installation.","Compliance tied to external documents: Piper Service Bulletin No. 1022 and/or Purolator Service Bulletin No. 090298.01.","Regulatory interaction with CAR 42ZC(4)(d) permitting a licensed non‑student pilot to change the filter (affects who may act before the effective date).","Cross‑reference to FAA Airworthiness Directive 99‑05‑09 and an explicit effective date (9 September 1999)."],"plain_english_summary":"This airworthiness directive requires owners/operators of specified Piper PA‑23‑235 and PA‑23‑250 aeroplanes fitted with Facet engine air filter P/N 638873 (manufactured Jan 1997–Sep 1998 and marked “FACET 638873” with no date code) to inspect installed filters at the next filter inspection or within 25 hours and then every 25 hours, and to inspect spare filters before installation, using the referenced Piper or Purolator service bulletins. It aims to prevent engine ingestion of broken filter pieces; operators (or a licensed non‑student pilot under CAR 42ZC(4)(d)) bear the inspection and replacement cost."},"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":2,"scope_assessment":{"changed":false,"description":"This Airworthiness Directive maintains its original narrow scope. It addresses a specific manufacturing defect in a specific component (Facet air filter P/N 638873) for specific Piper aircraft models produced during a defined period. There is no evidence of scope creep; the directive remains tightly focused on the original safety issue of filter cracking due to manufacturing errors."},"complexity_factors":["Single, specific mechanical defect addressed with clear inspection intervals","Limited applicability: only two aircraft models with specific serial number ranges and one specific filter part number from a defined 21-month manufacturing period","Straightforward compliance timeline: 'whichever occurs first' logic with fixed 25-hour recurring intervals","Only two cross-references (to FAA directive and Civil Aviation Regulation 42ZC)","No nested definitions or interpretation sections","Clear identification criteria in Note 1 (brand name, part number, character height, absence of date code)"],"plain_english_summary":"This safety notice concerns Piper PA-23-235/250 aircraft fitted with Facet air filter P/N 638873 (manufactured Jan 1997–Sep 1998). Certain filters may crack and shed debris that can be ingested by the engine, risking in‑flight engine failure.\n\nAffected filters must be inspected at the next scheduled check or within 25 hours from 9 Sept 1999 (whichever is sooner) and every 25 hours thereafter; spares must be inspected before installation. Identify risky units by the white \"FACET 638873\" stamp (~6 mm) with no date code. Licensed pilots may change the filter under Australian rules."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pa-23-87-engine-air-filter","history":"/api/acts/ad-pa-23-87-engine-air-filter/history","analysis":"/api/acts/ad-pa-23-87-engine-air-filter/analysis","conflicts":"/api/acts/ad-pa-23-87-engine-air-filter/conflicts","importantCases":"/api/acts/ad-pa-23-87-engine-air-filter/important-cases","documents":"/api/acts/ad-pa-23-87-engine-air-filter/documents"}}