{"id":"F2006B07590","name":"AD/VIPER/8 - Oil Tank and Oil Pump Drain Valves","slug":"ad-viper-8-oil-tank-and-oil-pump-drain-valves","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":50239,"registerId":"commonwealth-F2006B07590-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/VIPER/8 - Oil Tank and Oil Pump Drain Valves","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)  \nRolls Royce Turbine Engines \\- Viper Series\n\nAD/VIPER/8 Oil Tank and Oil Pump Drain Valves 9/90 DM\n\nApplicability: Viper Mk 520, 521 and 522 engines.\n\nRequirement: Inspect oil tank and oil pump drain valve assemblies in accordance with Rolls Royce Viper Mks 520, 521 and 522 Service Bulletin No 72-A381.\n\nNote: CAA UK Airworthiness Directive 030-04-90 refers.\n\nCompliance: (1) Engines in service \\- Prior to 6 August 1990.\n\n(2) Uninstalled engines \\- Prior to installation in an aircraft.\n\nBackground: Failure to detect oil leakage at the oil tank drain valve may result in total loss of oil pressure. Investigation of a total loss of oil pressure on a test flight following engine installation revealed that the oil tank drain valve cap was not in position and the drain valve was stuck open allowing a rapid loss of oil tank contents.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive focused on a specific mechanical defect in specific engine models. It has not expanded beyond its original purpose of mandating inspections to prevent oil loss incidents."},"complexity_factors":["Very short document (approximately 150 words)","Only 3 defined engine models in applicability section","Single operational requirement referencing an external technical document","Simple two-part compliance deadline structure","No nested exceptions or conditional logic","No cross-references to other legislation beyond a single note about a UK directive","Straightforward cause-and-effect background explanation"],"plain_english_summary":"This is an **Airworthiness Directive** (a mandatory safety order) issued by Australia's Civil Aviation Safety Authority for specific Rolls Royce Viper aircraft engines.\n\n**What it does:**\n- Requires inspection of oil tank and oil pump drain valve assemblies on Viper Mk 520, 521 and 522 engines\n- Mandates following a specific Rolls Royce service bulletin (No 72-A381) for the inspection\n\n**Who it affects:**\n- Operators and maintainers of aircraft with Viper Mk 520, 521 or 522 engines\n- Applies to both engines currently in service and engines not yet installed\n\n**Why it matters:**\n- Prevents catastrophic engine failure from oil loss\n- Background explains a serious incident where a drain valve cap was missing and the valve stuck open, causing rapid oil loss and total loss of oil pressure during a test flight\n- Total loss of oil pressure can lead to engine seizure and potential aircraft accident\n\n**Compliance deadlines:**\n- Engines already in service: before 6 August 1990\n- Engines not yet installed: before they go into an aircraft"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive enforces an inspection requirement for Viper Mk 520, 521 and 522 engines to detect oil tank/pump drain valve faults. The text confines action to those engine types, prescribes the inspection be done per the Rolls Royce service bulletin, and sets deadlines for in-service and uninstalled engines. Nothing in the instrument expands or narrows that technical scope beyond the original stated purpose (preventing loss of oil pressure from a faulty drain valve). (Applicability; Requirement; Compliance; Background)"},"complexity_factors":["Narrow technical scope (only Viper Mk 520, 521 and 522 engines) (Applicability)","Single mandated action (inspection) but reliance on an external manufacturer service bulletin for procedural detail (Requirement)","Two clear compliance categories with fixed deadlines (in-service vs uninstalled) (Compliance)","Safety consequence is specific and technical (total loss of oil pressure from open/stuck drain valve) (Background)","Limited regulator-prescribed procedural detail creates dependence on service bulletin interpretation and maintenance execution (Requirement)"],"plain_english_summary":"What this instrument requires\n\n- The directive requires an inspection of the oil tank and oil pump drain valve assemblies on certain Rolls Royce Viper turbine engines. The inspection must be carried out in accordance with Rolls Royce Viper Mks 520, 521 and 522 Service Bulletin No 72-A381. (Requirement)\n\nWho it affects\n\n- Owners, operators and maintenance organisations responsible for Viper Mk 520, 521 and 522 engines. (Applicability)\n\nWhen it must be done\n\n- For engines already in service: inspection must be completed prior to 6 August 1990. (Compliance (1))\n- For engines not installed in an aircraft: inspection must be completed before installation. (Compliance (2))\n\nWhy it matters (official rationale and mechanical test)\n\n- The stated safety reason is that an oil tank drain valve left open or with its cap not fitted can allow a rapid loss of oil, which can lead to total loss of oil pressure and engine failure. The directive cites a test-flight incident in which the drain valve cap was not in place and the valve was stuck open, causing rapid oil loss. (Background)\n\nPractical effects, who pays and what changes\n\n- Who pays: the owner/operator or their maintenance provider will bear the cost of the inspection and any corrective work required (Requirement; Compliance). The service action references a manufacturer service bulletin, so costs include labour, parts and any aircraft downtime needed to access the drain valves. (Requirement)\n- What changes mechanically: operators must carry out the specified inspection procedure from the Rolls Royce service bulletin and remedy any defect found before returning engines to service or installing them. This is an operational pre-condition to continued use or installation of the affected engines. (Requirement; Compliance)\n\nIncentives, compliance burden and administrative discretion\n\n- Incentives: complying removes the immediate operational risk of undetected drain-valve leakage; non-compliance leaves operators exposed to the safety risk described in the Background. (Background)\n- Compliance burden: the action requires following an external manufacturer service bulletin, which creates dependence on that document for the correct steps and any parts specified. The burden includes scheduling maintenance, potential grounding of aircraft, and rectification costs if faults are found. (Requirement; Compliance)\n- Discretion: the directive prescribes inspection “in accordance with” the Rolls Royce service bulletin, so the substantive content of the inspection and acceptable remedial actions is delegated to the manufacturer document rather than set out in the directive text itself. The directive sets the mandatory deadline but does not specify tolerances, inspection detail or acceptance criteria beyond the service bulletin. (Requirement)\n\nTrade-offs, risks and opportunity costs (mechanics, not judgment)\n\n- The directive prioritises a short-term inspection intervention to reduce a specific failure mode (drain valve left open or stuck). The trade-offs are immediate maintenance costs and aircraft downtime versus reduced risk of in-service loss of oil pressure. (Background; Compliance)\n- There is a small operational window for compliance on in-service engines (deadline given), which concentrates scheduling pressure on operators and maintenance organisations. (Compliance)\n\nOther notes\n\n- The directive references a related United Kingdom airworthiness directive (CAA UK AD 030-04-90), indicating coordinated action with the manufacturer/other regulator. (Note)\n\nSource citations: Applicability; Requirement; Note; Compliance; Background."}},"importantCases":[],"_links":{"self":"/api/acts/ad-viper-8-oil-tank-and-oil-pump-drain-valves","history":"/api/acts/ad-viper-8-oil-tank-and-oil-pump-drain-valves/history","analysis":"/api/acts/ad-viper-8-oil-tank-and-oil-pump-drain-valves/analysis","conflicts":"/api/acts/ad-viper-8-oil-tank-and-oil-pump-drain-valves/conflicts","importantCases":"/api/acts/ad-viper-8-oil-tank-and-oil-pump-drain-valves/important-cases","documents":"/api/acts/ad-viper-8-oil-tank-and-oil-pump-drain-valves/documents"}}