{"id":"F2005L00236","name":"AD/M20/53 - O&N Bladder Fuel Cell Contamination","slug":"ad-m20-53-o-n-bladder-fuel-cell-contamination","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":33801,"registerId":"commonwealth-F2005L00236-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Mooney M20 Series Aeroplanes","sectionType":"division","heading":"Mooney M20 Series Aeroplanes","content":"### Mooney M20 Series Aeroplanes\n\n| AD/M20/53 | O&N Bladder Fuel Cell Contamination | 3/2005 |\n| --------- | ----------------------------------- | ------ |\n\n| Applicability: | Mooney Airplane Company Models M20B, M20C, M20D, M20E, M20F, M20G, and M20J aircraft, all serial numbers, that are equipped with an O & N Bladder Fuel Cell installed per Supplemental Type Certificate (STC) SA2277CE or STC SA2350CE.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |\n| -------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. On both the left and right wing, inspect the drain valve to assure that it was inserted fully into the drain nipple, using procedure described in O & N Aircraft Modifications Inc. Mandatory Service Bulletin (MSB) No. ON-100, dated1 February 1998.2. Modify any drain valve found not inserted fully into the drain nipple, using procedure described in MSB ON-100.3. Using procedure described in MSB ON-100, perform the following, on both the left and right wing:(a) Install a foam wedge to reduce the amount of trapped fluids in the centre fuel cell;(b) Install an anti-ice mast forward of the vent tubes to prevent icing of the fuel tank vents;(c) Drill a vent hole to prevent icing of the engine’s crankcase breathers; and(d) Replace the flush style fuel caps and adapters with raised style caps and adapters.Note 1: Instructions in paragraph (f) of the FAA AD 2004-25-04 Amendment 39-13891 is an alternative method of compliance for replacing the flush style fuel caps per requirement 3 (d). |\n\n| Compliance: | 1. Unless accomplished earlier, within the next 12 calendar months, after the effective date of this AD.2. Before further flight, if the drain valve is found not inserted fully into the drain nipple as per inspection requirement 1, unless accomplished earlier.3. Unless accomplished earlier, within the next 12 calendar months, after the effective date of this AD.                                      |\n| ----------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n|             | This Airworthiness Directive becomes effective on 17 March 2005.                                                                                                                                                                                                                                                                                                                                                  |\n| Background: | There have been reports of rainwater entering the O&N bladder fuel cells installed in Mooney Aircraft. Water contamination of the fuel could result in rough engine operation or complete loss of engine power.The actions specified in this AD are intended to assist in preventing water from entering the fuel bladders and thus address the identified unsafe condition associated with loss of engine power. |\n\n![](image.001.png)  \nJames Coyne  \nDelegate of the Civil Aviation Safety Authority\n\n1 February 2005","sortOrder":0},{"sectionNumber":"AD/M20/53","sectionType":"part","heading":"AD/M20/53","content":"## AD/M20/53","sortOrder":1},{"sectionNumber":"O&N Bladder Fuel Cell Contamination","sectionType":"part","heading":"O&N Bladder Fuel Cell Contamination","content":"## O&N Bladder Fuel Cell Contamination","sortOrder":2},{"sectionNumber":"3/2005","sectionType":"part","heading":"3/2005","content":"## 3/2005","sortOrder":3}],"analysis":{"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":3,"scope_assessment":{"changed":false,"description":"The AD remains aligned with its original safety purpose: preventing water ingress into O&N bladder fuel cells to avoid engine roughness or power loss. The measures (inspection, correcting drain valves, and modest tank/vent/cap modifications) are consistent with that purpose rather than expanding into unrelated regulatory areas. The AD does rely on an external MSB for execution and references an FAA AD as an alternate method for one item, but that is a procedural cross-reference rather than a substantive expansion of scope."},"complexity_factors":["Single-page Airworthiness Directive with a focused scope (inspection + a short list of modifications).","Three numbered operative requirements, with four short sub-items under Requirement 3 (3(a)–3(d)).","Three compliance timeframes (within 12 months generally; immediate pre-flight corrective action if drain valve defective).","Applicability tied to specific aircraft models and two specific STCs (SA2277CE and SA2350CE).","Cross-reference to an external Mandatory Service Bulletin (O & N MSB No. ON-100) for all procedures (dependence on a non-legislative technical document).","Cross-reference to an FAA AD paragraph as an alternative method for one element (cap replacement).","Low volume of defined terms and limited conditional logic (no multi-layered exceptions)."],"plain_english_summary":"**What this instrument requires (mechanical changes)**\n\n- Inspect the drain valve on both left and right wing fuel bladders to make sure the valve is fully inserted into the drain nipple, using the procedures in O & N Aircraft Modifications Inc. Mandatory Service Bulletin (MSB) No. ON-100 (Requirement 1).\n- If a drain valve is not fully inserted, modify it so it is fully inserted, using MSB ON-100 (Requirement 2).\n- Also, using MSB ON-100, carry out four modifications on each wing fuel tank (Requirement 3):\n  - install a foam wedge to reduce trapped fluids in the centre fuel cell (3(a));\n  - install an anti-ice mast forward of the vent tubes to reduce risk of vent icing (3(b));\n  - drill a vent hole to prevent icing of the engine crankcase breathers (3(c));\n  - replace flush-style fuel caps and adapters with raised-style fuel caps and adapters (3(d)).\n- The AD notes an FAA AD paragraph (f) as an alternative method for replacing the flush-style fuel caps (note to Requirement 3).\n\n**Who is affected**\n\n- Owners and operators of Mooney Airplane Company Models M20B, M20C, M20D, M20E, M20F, M20G and M20J (all serial numbers) that have an O & N bladder fuel cell installed under Supplemental Type Certificate (STC) SA2277CE or STC SA2350CE (Applicability).\n- Certified maintenance organisations and licensed mechanics who must perform the inspections and modifications per the referenced MSB.\n\n**When it must be done (compliance timing)**\n\n- Unless already done, the inspections and the required modification work must be completed within 12 calendar months after the AD’s effective date (Compliance 1 and 3).\n- If the drain valve inspection finds the valve not fully inserted, the valve must be corrected before further flight (Compliance 2).\n\n**Why it matters (stated safety concern and effect)**\n\n- The AD is prompted by reports that rainwater has entered O&N bladder fuel cells on affected Mooney aeroplanes. Water in fuel can cause rough engine operation or complete loss of engine power. The AD’s stated purpose is to prevent water ingress to the bladder fuel cells and thereby address that unsafe condition (Background).\n\n**Practical effects, costs, incentives and trade-offs**\n\n- Who pays: aircraft owners/operators pay for inspections, replacement parts (foam wedges, anti-ice masts, raised caps/adapters) and labour; maintenance providers supply labour and parts.\n- Who decides / who does the work: the owner/operator must ensure compliance; maintenance work must be carried out in accordance with MSB ON-100 by appropriately qualified personnel.\n- Compliance burden: the AD directs use of a specific MSB for the procedures, so operators must obtain and follow that non-legislative document. There is also a cross-reference to an FAA AD as an alternative method for one item (cap replacement). This creates operational dependency on external technical documents.\n- Operational impact: aircraft with a faulty drain valve must be grounded until the valve is corrected (must be fixed before further flight). Other modifications may be scheduled within the 12-month window.\n- Market effects: modest increased demand for replacement caps/adapters and parts for the O&N bladder installation; maintenance labour will increase for the affected fleet. No direct change to ownership, operation rights or competition law.\n- Implementation risks and trade-offs: carrying out physical modifications (drilling vent holes, installing wedges and masts) requires correct procedure to avoid introducing other issues; incomplete or inconsistent application of the MSB could reduce effectiveness. The AD leaves no discretionary waiver mechanism in its text other than the referenced alternative method for caps.\n\n**Source mechanics cited**\n\n- The AD’s operative instructions are listed as Requirement paragraphs 1–3 and the Compliance timing set out under \"Compliance.\" The safety rationale is summarised in the Background paragraph.\n\n**Bottom line**\n\n- If you operate an affected Mooney M20 with an O&N bladder fuel cell under the cited STCs, you must inspect drain valves and carry out specified modifications per MSB ON-100 within 12 months (or immediately fix any improperly seated drain valve before the next flight). The action is aimed at preventing water ingress that the AD says can cause engine power problems."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This AD maintains its original narrow scope. It addresses a specific unsafe condition (water contamination in O&N bladder fuel cells) in a specific aircraft fleet (Mooney M20 series with specific STCs). The requirements remain tightly focused on preventing that specific safety hazard through targeted inspections and modifications."},"complexity_factors":["Short, single-purpose directive with only 3 main requirements","Clear applicability table limiting scope to specific aircraft models with specific STCs","Simple conditional logic: immediate compliance for unsafe drain valves, 12-month window for other modifications","One cross-reference to an alternative FAA compliance method (Note 1)","Relies on external technical document (MSB ON-100) for detailed procedures rather than embedding them","No defined terms section — uses standard aviation terminology (STC, MSB, AD)"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's aviation regulator (CASA) that requires specific repairs or inspections on certain aircraft.\n\n**What it does:**\nThis directive orders owners and operators of specific **Mooney M20 series aircraft** (models B, C, D, E, F, G, and J) to fix a dangerous fuel contamination problem. The aircraft must have **O&N bladder fuel cells** installed under two specific modification approvals (called STCs — Supplemental Type Certificates).\n\n**The safety problem:**\nRainwater has been getting into the fuel bladders. Water in aircraft fuel can cause engines to run roughly or fail completely — a serious flight safety risk.\n\n**What must be done:**\n- **Inspect** both wing fuel drain valves to check they're fully inserted\n- **Fix** any drain valves that aren't properly inserted before flying again\n- **Install** four specific modifications within 12 months:\n  - Foam wedges to reduce trapped fluids in the fuel cell\n  - Anti-ice protection for fuel tank vents\n  - A vent hole to prevent engine crankcase breather icing\n  - Replace flush-style fuel caps with raised-style caps (or use an alternative FAA-approved method)\n\n**Who it affects:**\nOwners and operators of the specified Mooney aircraft with these particular fuel bladder modifications.\n\n**Why it matters:**\nThis prevents engine failure caused by water contamination. The 12-month compliance window gives owners reasonable time to schedule the work, but any improperly installed drain valves must be fixed immediately before the aircraft can fly again."}},"importantCases":[],"_links":{"self":"/api/acts/ad-m20-53-o-n-bladder-fuel-cell-contamination","history":"/api/acts/ad-m20-53-o-n-bladder-fuel-cell-contamination/history","analysis":"/api/acts/ad-m20-53-o-n-bladder-fuel-cell-contamination/analysis","conflicts":"/api/acts/ad-m20-53-o-n-bladder-fuel-cell-contamination/conflicts","importantCases":"/api/acts/ad-m20-53-o-n-bladder-fuel-cell-contamination/important-cases","documents":"/api/acts/ad-m20-53-o-n-bladder-fuel-cell-contamination/documents"}}