{"id":"F2006B08337","name":"AD/CESSNA 400/51 - Goodyear Fuel Cells - Inspection","slug":"ad-cessna-400-51-goodyear-fuel-cells-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115744,"registerId":"commonwealth-F2006B08337-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CESSNA 400/51 - Goodyear Fuel Cells - Inspection","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)  Cessna 400 Series Aeroplanes\n\n \n\nAD/CESSNA 400/51 Goodyear Fuel Cells - Inspection 6/78\n\nApplicability: All models 401, 402, 411, 414 and 421 fitted with Goodyear BTC-39 fuel cells. Document:               Cessna SL No. ME78-7.\n\nCompliance: Within 100 hours time in service after 30 June 1978 and annually thereafter as detailed in Cessna SL No. ME78-7.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"No evidence in the supplied text that the AD's scope has been altered from an earlier instrument: the directive as provided specifies its applicability (particular Cessna models with Goodyear BTC-39 fuel cells), the referenced technical document (Cessna SL No. ME78-7), and the compliance timing (within 100 hours after 30 June 1978 and annually thereafter). No prior version or comparative text was supplied for assessment of a scope change."},"complexity_factors":["Narrow, model- and component-specific applicability (models 401, 402, 411, 414, 421 with Goodyear BTC-39 fuel cells) — reduces complexity. (Applicability)","Mandatory reference to an external technical document (Cessna Service Letter ME78-7) for inspection detail — adds one dependency for implementation. (Document; Compliance)","Simple, fixed timing rules (within 100 hours after a specified date, and annually thereafter) — straightforward scheduling but creates recurring obligation. (Compliance)","Regulatory enforcement context (issued as an Airworthiness Directive under Civil Aviation Regulations and the Schedule of Airworthiness Directives) — creates legal force and administrative oversight. (Header)"],"plain_english_summary":"What this rule does (mechanically)\n\n- This is an Airworthiness Directive titled AD/CESSNA 400/51 (Goodyear Fuel Cells - Inspection). It requires owners/operators of certain Cessna 400-series aeroplanes to carry out inspections of installed Goodyear BTC-39 fuel cells. (See: Applicability; Compliance.)\n\nWho it affects\n\n- The rule applies to all Cessna models 401, 402, 411, 414 and 421 that are fitted with Goodyear BTC-39 fuel cells. (Applicability.)\n\nWhat the timing and source of the inspection requirement are\n\n- Inspections must be done within 100 hours time in service after 30 June 1978, and then annually thereafter, following the procedures and detail set out in Cessna Service Letter No. ME78-7. (Compliance; Document.)\n\nOfficial purpose-claim and how that maps to the mechanics\n\n- The directive is titled and framed as an inspection requirement for Goodyear fuel cells; the explicit mechanic is inspection at specified intervals and to the detail prescribed in the Cessna Service Letter ME78-7. (Title; Compliance; Document.)\n\nSimple account of who pays, who decides, and what behaviour changes\n\n- Who pays: aircraft owners/operators will bear the direct cost of performing the inspections and any subsequent maintenance or replacement that follows from inspection findings, because the obligation attaches to the specified aircraft. (Applicability; Compliance.)\n- Who decides: the Civil Aviation Safety Authority issued the AD under the Schedule of Airworthiness Directives; the technical inspection procedures and details are set by Cessna in Service Letter ME78-7, which the AD makes mandatory by reference. (Header; Document; Compliance.)\n- Behaviour change required: owners/operators must arrange and complete the initial inspection within the 100‑hour window after 30 June 1978 and then ensure an inspection every year thereafter in accordance with the service letter. (Compliance.)\n\nCosts, incentives, trade-offs and implementation points (mechanical and practical)\n\n- Compliance cost and burden: the directive creates a recurring compliance cost (initial inspection within the specified 100‑hour window and annual inspections afterwards) and possible follow-on repair or replacement costs if inspections reveal defects. The AD does not itself set repair standards; it points to the Cessna Service Letter for detail, which concentrates the technical compliance requirements in that external document. (Compliance; Document.)\n- Incentives: owners/operators are incentivised to schedule inspections and to repair or replace fuel cells if required to remain airworthy; maintenance providers gain work from the mandated inspections. (Applicability; Compliance.)\n- Trade-offs and opportunity costs: aircraft downtime for inspections/repairs and the money spent on inspections/repairs are the direct opportunity costs to owners/operators. The AD does not specify compensation or cost-sharing. (Compliance.)\n- Implementation risk and discretion: the AD delegates technical specification to Cessna Service Letter ME78-7, so the practical content of inspections depends on that service letter. Enforcement and interpretation sit with the authority that issued the AD, which references the service letter for procedural detail. (Document; Compliance.)\n\nEffects on private choice and market participants\n\n- The directive narrows actions available to affected aircraft operators by mandating a specific inspection regime and reliance on a manufacturer service letter. Operators must comply to keep the aircraft airworthy. Independent maintenance organisations may provide the inspections, but the AD fixes the required inspection content by reference to the service letter. (Applicability; Document; Compliance.)\n\nConcrete mechanism summary\n\n- Legal basis: issued under the Civil Aviation Regulations as a Schedule of Airworthiness Directives. (Header.)\n- Applicability: specific Cessna models fitted with Goodyear BTC-39 fuel cells. (Applicability.)\n- Action required: inspect within 100 hours TIS after 30 June 1978 and annually thereafter, as detailed in Cessna SL No. ME78-7. (Compliance; Document.)"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-bound safety directive from 1978 addressing a specific technical defect in specific aircraft. It has not expanded beyond its original purpose of mandating fuel cell inspections for the identified Cessna models."},"complexity_factors":["Extremely short document (under 200 words)","Only 4 operative elements: applicability, reference document, compliance deadline, and recurring requirement","No defined terms section — all terms are either common aviation parlance or reference external technical documents","No cross-references to other legislation beyond the parent Civil Aviation Regulations 1998","Simple conditional structure: if aircraft type X has component Y, then do Z","Single compliance pathway with no exceptions, exemptions, or alternative methods of compliance stated"],"plain_english_summary":"**What this is:** This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). Think of it as a \"recall notice\" for aircraft, but legally binding.\n\n**What it requires:** Owners and operators of specific Cessna twin-engine aircraft (models 401, 402, 411, 414, and 421) must inspect the **Goodyear BTC-39 fuel cells** (the rubber bladders inside the fuel tanks that hold aviation fuel). \n\n**Who must comply:** Anyone operating these specific Cessna models fitted with these particular Goodyear fuel cells.\n\n**When:** The first inspection had to be done within 100 flight hours after 30 June 1978, then repeated **every year** after that.\n\n**How to comply:** Follow the detailed instructions in **Cessna Service Letter No. ME78-7** — a technical bulletin from the manufacturer explaining exactly how to do the inspection.\n\n**Why it matters:** Fuel cell failures can cause fuel leaks, engine failure, or fire. This AD ensures potential defects in these specific fuel cells are caught before they cause accidents. Ignoring an AD is illegal and dangerous — aircraft cannot fly legally until compliance is proven."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cessna-400-51-goodyear-fuel-cells-inspection","history":"/api/acts/ad-cessna-400-51-goodyear-fuel-cells-inspection/history","analysis":"/api/acts/ad-cessna-400-51-goodyear-fuel-cells-inspection/analysis","conflicts":"/api/acts/ad-cessna-400-51-goodyear-fuel-cells-inspection/conflicts","importantCases":"/api/acts/ad-cessna-400-51-goodyear-fuel-cells-inspection/important-cases","documents":"/api/acts/ad-cessna-400-51-goodyear-fuel-cells-inspection/documents"}}