{"id":"F2006B11431","name":"AD/OXY/3 Amdt 1 - Puritan-Bennett Oxygen Regulator Diaphragm - Replacement","slug":"ad-oxy-3-amdt-1-puritan-bennett-oxygen-regulator-diaphragm-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":57359,"registerId":"commonwealth-F2006B11431-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/OXY/3 Amdt 1 - Puritan-Bennett Oxygen Regulator Diaphragm - Replacement","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 107 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nOxygen Systems\n\nAD/OXY/3\n\nAmdt 1\n\n  \n\nPuritan-Bennett Oxygen Regulator NK Diaphragm - Replacement\n\nApplicability: Puritan-Bennett Aero Systems Company oxygen masks as follows : P/N 174039 S/N 0001-0012, P/N 174010-01 and 174010-03 S/N 00100-00144, 00146, 00147,\n\n00149-00259, 00261-00273, 00275-00292, 00294-00390 and P/N ZMR 100 series\n\nS/N 6603-7234.\n\nRequirement: 1\\. Remove diaphragm assembly P/N F334-1001-1 and install diaphragm assembly P/N F334-1001-1 modified to include diaphragm and plate assembly P/N F334- 1003-1 Revision E.\n\n    2. After modification per para. 1, permanently mark letter \"M\" at the end of or beneath the mask serial number. This serial number is located under the face cushion on the left-hand side of the hardshell on the 174039 and ZMR 100 series masks, and on the back surface of the head harness on the 174010-01 and 174010- 03 masks.\n\n    3. The modified diaphragm replacement (para. 1) shall be accomplished by returning the mask to Puritan-Bennett Aero Systems Company, 111 Penn Street, El Segundo, California 90245, USA. However this replacement in ZMR 100 series masks listed below may be accomplished in the field in accordance with the following Puritan-Bennett Aero Systems ATA Component Maintenance Manuals:\n\n35-10-25 for the ZMR 160 mask. 35-10-27 for the ZMR 129 mask. 35-10-28 for the ZMR 129-1 mask. 35-10-29 for the ZMR 118 mask.\n\nNote 1. Puritan-Bennett Aero Systems Company Service Bulletin No. 1 pertains to this subject.\n\nNote 2. FAA AD 81-08-04 Amendment 39-4092 refers.\n\nCompliance: Within 100 hours time in service after 30 June 1981.\n\nNote: Oxygen masks which have previously been reworked in accordance with AD/OXY/3 are deemed to comply with this Directive AD/OXY/3A.\n\nBackground: The regulators in approximately half of the mask assemblies listed contain oversize diaphragms. Under certain conditions, an oversize diaphragm can cause a regulator inlet valve either to leak or to develop positive pressure within the face cone.\n\nAlthough the regulator may work properly in normal usage, it can develop one of the above conditions without warning. There is no reliable field test method for determining when or whether the mask will develop a problem. This Directive is revised in issue to conform with revisions to FAA AD 81-02-03 which include additional S/Nos. of masks and a method of field compliance.","sortOrder":0}],"analysis":{"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"Scope was expanded from the earlier directive: the instrument was revised to include additional mask serial numbers and to allow a method of field compliance for certain ZMR 100 series masks. This is stated in the Background noting conformity with revisions to FAA AD 81‑02‑03 and reflected in Requirement para. 3 (Background; Requirement para. 3)."},"complexity_factors":["Narrow, technical applicability limited to specific part numbers and serial‑number ranges (Applicability).","Mandatory hardware swap to a defined replacement part and revision (Requirement para. 1).","Permanent marking requirement on each modified mask (Requirement para. 2) increases record/traceability work.","Default requirement to return masks to the manufacturer for modification, with limited field‑service exceptions for certain ZMR 100 series models (Requirement para. 3) creates logistical and cost implications for operators.","Field‑service allowed only by reference to specific ATA Component Maintenance Manuals for listed ZMR masks (Requirement para. 3), imposing procedural compliance burdens.","Fixed short compliance window (100 hours after 30 June 1981) requires scheduling and potential aircraft downtime (Compliance).","No reliable field test to predict failure (Background) increases precautionary replacement volume and uncertainty about which units will fail.","Cross‑references to a manufacturer service bulletin and an FAA AD (Notes 1–2) add external compliance and documentation considerations."],"plain_english_summary":"This Airworthiness Directive requires specific Puritan‑Bennett oxygen masks to have their regulator diaphragm assembly replaced with a modified part and the mask serial number permanently marked with an “M”. Most masks must be returned to the manufacturer for the replacement, but certain ZMR 100 series masks may be serviced in the field using listed ATA maintenance manuals. It affects operators and maintainers of the listed masks and must be done within 100 flight hours after 30 June 1981 to prevent regulator leaks or positive face‑cone pressure."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is Amendment 1 to an existing Airworthiness Directive. The amendment expands the original scope by adding more serial numbers to the applicability list and introducing a field compliance method for certain mask models. However, this represents a routine technical update to address the same underlying safety issue, not a fundamental expansion beyond the original purpose of ensuring oxygen mask diaphragm integrity."},"complexity_factors":["Single, specific technical subject matter (one diaphragm replacement)","Limited applicability: only 4 specific part numbers with defined serial number ranges","Straightforward three-step requirement structure (remove, install, mark)","One conditional exception allowing field modification for specific ZMR 100 series masks","Minimal cross-referencing: only 2 external references (FAA AD and manufacturer service bulletin)","No nested definitions or interpretation section","Clear compliance deadline (100 hours time in service after fixed date)","Background section provides plain-language explanation of the safety risk"],"plain_english_summary":"This CASA Airworthiness Directive orders replacement of oversize diaphragms in specified Puritan‑Bennett aircraft oxygen masks because they can leak or pressurise the facepiece suddenly. It affects operators, maintenance organisations and aircrew who use the listed mask models. The fix requires installing the revised diaphragm assembly, marking the mask, and returning or servicing units as directed within 100 flight hours after 30 June 1981 to prevent sudden oxygen loss."}},"importantCases":[],"_links":{"self":"/api/acts/ad-oxy-3-amdt-1-puritan-bennett-oxygen-regulator-diaphragm-replacement","history":"/api/acts/ad-oxy-3-amdt-1-puritan-bennett-oxygen-regulator-diaphragm-replacement/history","analysis":"/api/acts/ad-oxy-3-amdt-1-puritan-bennett-oxygen-regulator-diaphragm-replacement/analysis","conflicts":"/api/acts/ad-oxy-3-amdt-1-puritan-bennett-oxygen-regulator-diaphragm-replacement/conflicts","importantCases":"/api/acts/ad-oxy-3-amdt-1-puritan-bennett-oxygen-regulator-diaphragm-replacement/important-cases","documents":"/api/acts/ad-oxy-3-amdt-1-puritan-bennett-oxygen-regulator-diaphragm-replacement/documents"}}