{"id":"F2006B08853","name":"AD/DH 104/1 - Fire Protection Modifications - Engine Nacelles","slug":"ad-dh-104-1-fire-protection-modifications-engine-nacelles","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":52052,"registerId":"commonwealth-F2006B08853-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DH 104/1 - Fire Protection Modifications - Engine Nacelles","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)  \nDH 104 (Dove) Series Aeroplanes\n\nAD/DH 104/1 Fire Protection Modifications \\- Engine Nacelles 8/71\n\nApplicability: All models in transport category.\n\nRequirement: 1. Modify the existing nacelle fire detection system as follows:\n\n    1.1 Replace the existing pyrotechnic cord type detector with a minimum of eight (8) unit detectors in approved locations in each engine bay or, alternatively, with an approved continuous type detector. All fire detectors shall be of an approved type.\n\n    1.2 Detector Circuits:\n\n    (a) Provide separate independent detector circuits for each nacelle.\n\n    (b) Install a test switch adjacent to the warning lights for each nacelle and arrange the detector circuit so that the test switch checks the circuit protection, the indicator lamps and the continuity of the detector wiring.\n\n    1.3 Indicators:\n\nIn addition to the existing warning lights for each nacelle install in the cockpit an audible fire-warning device common to both detector circuits.\n\n    2. Oil System:\n\nRework the following flexible oil lines to ensure that they are rendered fully fireproof:\n\n    (a) Hoses from oil tank to engine-driven oil pump.\n\n    (b) Hose from oil tank to propeller feathering pump.\n\n    3. Electric Cables:\n\n    3.1 Ensure that wiring forward of the firewall is PVC insulated glass braided cable to Specification AN-J-C-48a or other cable approved as fire-resistant class 11 for the following circuits:\n\n    (a) Fire detectors.\n\n    (b) Propeller feathering.\n\n    (c) Those sections of the starter motor circuit in which a fault could adversely affect propeller feathering.\n\n    3.2 Protect cable with glass outer-braiding from abrasion by wrapping with PVC tape, shrouding with PVC tubing, or by other approved means.\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n    3.3 Ensure that cable and cable runs forward of the firewall are installed in the cooler parts of the engine nacelle. Cable runs shall also be arranged so that they are not exposed to mechanical damage during normal engine operation or during ground maintenance.\n\n    4. Firewall Sealing:\n\n    4.1 Install a steel slide forward of the present bakelite slides on the engine control rods.\n\n    4.2 Install a fire-proofing tube over the slow running cut-out control cable where it enters the engine bay.\n\n    4.3 Install a steel cover over the end of the fuel filter that protrudes into the engine bay.\n\n    4.4 Install steel covers over all light alloy electrical connectors; or\n\n    5. Part 100, Appendix “A” Notice No. 4/21 Issue 2; or\n\n    6. De Havilland Drawing DHZ-101A; or 7. ANO 105.1.14.13.5.2.\n\nCompliance: Before 1 September 1971.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a vintage Airworthiness Directive from 1971 (indicated by '8/71' in the reference). It remains focused on its original narrow purpose: mandating specific fire safety modifications for a particular aircraft type (DH 104 Dove). The scope has not expanded beyond this specific technical safety requirement."},"complexity_factors":["Single technical subject matter (fire protection modifications) with clear numbered requirements","7 specific technical alternatives provided for firewall sealing (paragraphs 4.1 through 7)","Cross-references to external technical standards: Part 100 Appendix A, De Havilland Drawing DHZ-101A, and ANO 105.1.14.13.5.2","Precise technical specifications (e.g., 'PVC insulated glass braided cable to Specification AN-J-C-48a', 'minimum of eight (8) unit detectors')","No defined terms section or interpretation provisions","Single compliance deadline (Before 1 September 1971)","Approximately 400 words total length"],"plain_english_summary":"This AD mandates upgraded engine‑nacelle fire protection for De Havilland DH 104 Dove aircraft used in Australian transport operations. Operators must fit modern continuous/independent detection and audible cockpit warnings, fire‑resistant oil lines and wiring, and improved firewall sealing to stop fires spreading from the engines.\n\nIt matters because older detectors and oil/wiring configurations can allow undetected engine fires; the upgrades reduce that catastrophic risk."},"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"},"flash_summary":{"complexity_score":6,"scope_assessment":{"changed":false,"description":"The directive does not change which aircraft are regulated: it applies to all DH 104 models in the transport category and imposes retrofit requirements. It mandates specific safety modifications rather than expanding regulatory applicability or introducing new operational restrictions."},"complexity_factors":["Multi‑system scope: changes span detection, oil system, electrical wiring, and firewall structure (requires coordinated engineering and maintenance).","Technical specificity: prescribes minimum detector counts/options, routing and insulation standards, and specific installations (requires detailed technical work).","External references: relies on approved types, Specification AN‑J‑C‑48a, De Havilland drawing DHZ‑101A and other notices—interpretation needs access to and alignment with those documents.","Alternative compliance paths: permits either unit detectors or continuous detector types and offers several acceptable drawings/notices, increasing choice but requiring conformity checks.","Operational/testing requirements: adds circuitry separation and test switches to verify protection, indicator lamps and wiring continuity—introduces functional testing and inspection burdens.","Compliance deadline: a fixed date imposes scheduling pressure on operators and maintenance providers to source parts and perform work before the cutoff.","Implementation risk: routing wiring to 'cooler parts' and protecting against mechanical damage may require structural or layout changes with attendant certification or approval.","Maintenance and parts costs: owners/operators bear direct costs for approved materials, installation labour and any necessary approvals or rework."],"plain_english_summary":"This airworthiness directive requires operators of De Havilland DH 104 (Dove) transport‑category aeroplanes to upgrade engine‑nacelle fire protection: install approved unit or continuous detectors with separate circuits and cockpit warnings, make oil hoses fireproof, fit fire‑resistant wiring forward of the firewall, and improve firewall sealing. Operators and maintenance organisations pay for and carry out the work using approved parts and procedures; the directive sets a mandatory compliance deadline and references external standards and drawings."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dh-104-1-fire-protection-modifications-engine-nacelles","history":"/api/acts/ad-dh-104-1-fire-protection-modifications-engine-nacelles/history","analysis":"/api/acts/ad-dh-104-1-fire-protection-modifications-engine-nacelles/analysis","conflicts":"/api/acts/ad-dh-104-1-fire-protection-modifications-engine-nacelles/conflicts","importantCases":"/api/acts/ad-dh-104-1-fire-protection-modifications-engine-nacelles/important-cases","documents":"/api/acts/ad-dh-104-1-fire-protection-modifications-engine-nacelles/documents"}}