{"id":"F2006B09579","name":"AD/ENST 28/23 - RAJAY Turbocharger and Fuel Nozzle Vent Line - Modification","slug":"ad-enst-28-23-rajay-turbocharger-and-fuel-nozzle-vent-line-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":54274,"registerId":"commonwealth-F2006B09579-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/ENST 28/23 - RAJAY Turbocharger and Fuel Nozzle Vent Line - Modification","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)  Enstrom F-28 Series Helicopters\n\n \n\n# AD/ENST 28/23  RAJAY Turbocharger and Fuel Nozzle Vent Line - Modification\n\nApplicability: Model F-28C and 280C.\n\n \n\nRequirement: Part 1: For turbocharger S/Nos. less than 70484:\n\n# 12/79\n\n \n\n(a)     Remove the turbocharger from the helicopter in accordance with the Enstrom Maintenance Manual.\n\n \n\n(b)     Using a 5/32 Allen wrench, remove the six countersunk cap screws that secure the compressor housing to the bearing housing assembly. If necessary, gently tap the compressor\n\n \n\n(c)      Reinstall the compressor housing by placing the turbocharger on the compressor housing using a new gasket, Rajay P/N TC6-44. Secure with six cap screws and tighten evenly and alternately to 90 + 10 inch- pounds.\n\n \n\n(d)     Reinstall the turbocharger in the helicopter in accordance with the Enstrom Maintenance Manual.\n\n![RAJAY Turbocharger and Fuel Nozzle Vent Line - Modification](image.002.jpeg)  \n\n\n \n\nPart 2: for turbocharger S/Nos. 70484 and higher:\n\n \n\n(a)     Remove the induction system air inlet filter in accordance with the Enstrom Maintenance Manual.\n\n \n\n(b)     Remove the AN815-6D union which attaches the fuel nozzle air vent installation to the induction system air inlet filter container. Save the AN924- 6D nut which was holding the union in place, for reinstallation, in accordance with step D.\n\n \n\n(c)     Install an AN832-6D union, in place of the AN815-6D union, so that the AN924-6D nut is outside of the filter container.\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n(d)     Attach the fuel nozzle air vent line to the AN832-6D union.\n\n \n\n(e)     Replace the air filter in accordance with the Enstrom Maintenance Manual.\n\n \n\nNote: FAA AD 79-02-01 AMDT. 39-3390 refers.\n\n \n\nCompliance: Within 100 hours time in service after 29 February 1980.\n\n \n\nBackground:  This Directive is issued in order to prevent damage to the turbo charger and possible engine power loss.\n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive remains narrowly focused on a specific airworthiness concern: preventing turbocharger damage and possible engine power loss by requiring a gasket/assembly change for older turbochargers and a vent‑union modification for newer ones. It does not expand beyond that technical safety objective or introduce new regulatory powers or broad obligations outside the targeted mechanical modifications."},"complexity_factors":["Two straightforward branches based on one serial number threshold (S/No. <70484 and ≥70484)","Specific, limited set of required parts (Rajay P/N TC6‑44; AN815‑6D, AN832‑6D unions; AN924‑6D nut)","Single torque specification (90 ± 10 inch‑pounds) and simple assembly steps","Short compliance window and single compliance condition (100 hours TIS after 29 Feb 1980)","Requires reference to an external document (Enstrom Maintenance Manual) for removal/reinstallation procedure","Cross‑reference to one FAA AD (79‑02‑01) but no extensive cross‑referencing elsewhere"],"plain_english_summary":"**What this directive requires (mechanics first)\n\n- Affects: Enstrom F-28C and 280C helicopters that use RAJAY turbochargers.\n\n- Two different fixes depending on turbocharger serial number (S/No.):\n  - Part 1 — Turbochargers with S/No. less than 70484: remove the turbocharger, separate the compressor housing from the bearing housing, fit a new RAJAY gasket (P/N TC6-44), reassemble with six cap screws tightened evenly to 90 ± 10 inch‑pounds, and reinstall the turbocharger following the Enstrom Maintenance Manual.\n  - Part 2 — Turbochargers with S/No. 70484 and higher: remove the induction system air inlet filter, remove the existing AN815‑6D union that links the fuel nozzle air‑vent to the filter container (save the AN924‑6D nut), install an AN832‑6D union so the AN924‑6D nut sits outside the filter container, attach the fuel nozzle air vent line to the new union, and replace the air filter per the Enstrom Maintenance Manual.\n\n- Compliance time: complete the applicable work within 100 hours time in service after 29 February 1980.\n\n- Stated purpose: issued to prevent damage to the turbocharger and possible engine power loss (the directive also references the related FAA AD 79‑02‑01).\n\nWho this affects and who pays\n\n- Who must act: aircraft owners/operators and their authorised maintenance organisations that operate Enstrom F‑28C or 280C helicopters with the relevant turbochargers.\n- Who pays: direct costs fall on the owner/operator — parts (gasket Rajay P/N TC6‑44, or an AN832‑6D union) and labour to remove, reassemble and reinstall turbocharger components or to modify the vent union and replace the filter. There may be indirect costs from downtime while the helicopter is out of service.\n\nHow it changes behaviour and decision‑making\n\n- Operators must inspect the turbocharger serial number and follow the correct branch of work.\n- Maintenance organisations must follow the Enstrom Maintenance Manual and the torque/specifications in the directive.\n- Where parts are required, operators must source the specified parts and ensure competent installation to comply with the directive.\n\nTrade‑offs, implementation risks and compliance burden (testing the stated purpose)\n\n- Benefits asserted: the required actions are intended to reduce the risk of turbocharger damage and engine power loss by changing gasket/assembly practice for older units and altering how the fuel‑nozzle vent connects to the filter container for newer units.\n- Costs and trade‑offs: the directive imposes concentrated costs on individual owners/operators (parts, labour, downtime). There is no ongoing regulatory fee, but there is one‑off maintenance expense and possible grounding time.\n- Implementation risks: incorrect gasket choice, improper torqueing or poor reassembly could leave the hazard uncorrected; using incorrect union types or failing to locate the nut outside the filter container could defeat the modification. Compliance relies on availability of specified parts and competent maintenance personnel.\n- Opportunity cost: time and resources spent complying are diverted from other maintenance or operations.\n- Market effects: minor and targeted — small demand for specified parts and services for affected helicopters; no broad competition or ownership effects indicated.\n- Discretion and enforcement: the directive sets mandatory mechanical steps and a compliance window; enforcement and verification are through aviation safety/maintenance oversight and logbook records.\n\nNotes and cross‑references\n\n- The directive is technical and component‑specific: it lists RAJAY and AN part numbers and a torque specification. It explicitly requires following the Enstrom Maintenance Manual for removal/reinstallation steps.\n- It refers to FAA AD 79‑02‑01 as related background. The directive’s text sets out both the mechanical steps and the compliance deadline.\n\n(Plain‑English summary based on the directive text: Part 1 steps a–d for S/No. <70484; Part 2 steps a–e for S/No. ≥70484; compliance paragraph; background paragraph.)"},"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 a discrete, targeted safety directive addressing a specific mechanical defect in specific helicopter models. It has not expanded beyond its original purpose of preventing turbocharger damage and engine power loss."},"complexity_factors":["Two distinct compliance paths based on turbocharger serial number threshold (70484)","Specific part numbers and torque specifications (90 + 10 inch-pounds) requiring technical precision","Cross-reference to FAA AD 79-02-01 AMDT. 39-3390 for additional context","Mechanical procedure steps referencing external manual (Enstrom Maintenance Manual)","Time-based compliance deadline (100 hours time in service after fixed date)"],"plain_english_summary":"This Airworthiness Directive requires owners/operators of Enstrom F‑28C and 280C helicopters equipped with RAJAY turbochargers to make compulsory turbocharger modifications to prevent engine power loss. Depending on turbocharger serial number, the fix is either reinstalling the compressor housing with a new gasket and specific torque or replacing the fuel‑nozzle vent fitting so the vent exits outside the air‑filter container.\n\nThe work must be completed within 100 flight hours after February 29, 1980 to reduce risk of turbo damage and potential crashes."}},"importantCases":[],"_links":{"self":"/api/acts/ad-enst-28-23-rajay-turbocharger-and-fuel-nozzle-vent-line-modification","history":"/api/acts/ad-enst-28-23-rajay-turbocharger-and-fuel-nozzle-vent-line-modification/history","analysis":"/api/acts/ad-enst-28-23-rajay-turbocharger-and-fuel-nozzle-vent-line-modification/analysis","conflicts":"/api/acts/ad-enst-28-23-rajay-turbocharger-and-fuel-nozzle-vent-line-modification/conflicts","importantCases":"/api/acts/ad-enst-28-23-rajay-turbocharger-and-fuel-nozzle-vent-line-modification/important-cases","documents":"/api/acts/ad-enst-28-23-rajay-turbocharger-and-fuel-nozzle-vent-line-modification/documents"}}