{"id":"F2006B08320","name":"AD/CESSNA 400/34 - Auxiliary Fuel Cells - Inspection and Replacement","slug":"ad-cessna-400-34-auxiliary-fuel-cells-inspection-and-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115727,"registerId":"commonwealth-F2006B08320-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CESSNA 400/34 - Auxiliary Fuel Cells - Inspection and Replacement","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)  \nCessna 400 Series Aeroplanes\n\nAD/CESSNA 400/34 Auxiliary Fuel Cells \\- Inspection\n\nand Replacement\n\n  \n6/72\n\nApplicability: All Model 411 with S/Nos. 411-0001 to 411-0300 and Model 421 with S/Nos. 421- 0001 to 421B-0048 fitted with Uniroyal Type US-932 or Goodyear Type BTC-39 Auxiliary Fuel Cells or any subsequent numbered aeroplanes which have been fitted with the above fuel cells as a replacement.\n\nRequirement: 1. Uniroyal Auxiliary Fuel Cell Type US-932 1.1 Before each flight inspect the external lower surface of the wings for evidence of fuel leakage. Pay particular attention to rivet heads, inspection covers and skin lap joints. Defective fuel cells shall be replaced with Goodyear Type BTC-54A fuel cells before further flight.\n\n1.2 Within 300 hours time in service or 6 months after 28 June 1972 whichever occurs first, the Uniroyal Type US-932 fuel cells shall be replaced by Goodyear Type BTC-54A fuel cells. 2. Goodyear Auxiliary Fuel Cell Type BTC-39 2.1 Before each flight inspect the external lower surface of the wings for evidence of fuel leakage. Pay particular attention to rivet heads, inspection covers and skin lap joints. Defective fuel cells shall be replaced with Goodyear Type BTC-54A fuel cells before further flight.\n\nNote 1: A pilot endorsed for the type may perform and certify for this inspection as detailed in paras. 1.1 and 2.1.\n\nNote 2: The repetitive inspections required by paras. 1.1 and 2.1 may be substituted by the normal daily inspection when Goodyear BTC-54A cells are installed.\n\nCompliance: As detailed in requirement document.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive applies to identified aircraft serial-number ranges and to any later aeroplanes fitted with the specified auxiliary fuel cells. Nothing in the text indicates an expansion or narrowing of scope beyond that identification and the replacement/inspection requirements."},"complexity_factors":["Applicability limited to specific models and serial-number ranges plus any later aircraft fitted with the listed fuel-cell types (identification burden).","Two different existing fuel-cell types are addressed (Uniroyal US-932 and Goodyear BTC-39) with a single mandated replacement type (Goodyear BTC-54A).","High-frequency compliance obligation: inspection required before each flight (paras. 1.1 and 2.1) imposes operational burden on pilots/operators.","Hard deadline replacement for Uniroyal cells: within 300 hours TIS or 6 months after 28 June 1972 (para. 1.2) creates a clear scheduling/maintenance cost.","Immediate grounding-like requirement for defective cells: defective units must be replaced before further flight (paras. 1.1 and 2.1).","Permitted delegations: a pilot endorsed for the type may perform and certify inspections (Note 1) affects who may lawfully carry out compliance.","Inspection substitution rule: once BTC-54A cells are installed, the repetitive inspections may be covered by the normal daily inspection (Note 2) changes ongoing inspection burden."],"plain_english_summary":"This airworthiness directive requires owners/operators of specified Cessna 411 and 421 aeroplanes fitted with certain Uniroyal or Goodyear auxiliary fuel cells to inspect for external wing fuel leaks before flight and to replace identified defective cells with Goodyear BTC-54A cells. It also mandates replacing Uniroyal US-932 cells within 300 flight hours or 6 months. Aircraft owners/operators pay for inspections and replacements; a pilot endorsed for the type may perform and certify the preflight inspections."},"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"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive focused specifically on defective auxiliary fuel cells in particular Cessna aircraft models. It has not expanded beyond its original technical safety purpose."},"complexity_factors":["Very short document (under 300 words)","Only 2 defined model/serial number ranges in applicability section","Simple conditional structure: 'if X, then Y' requirements","No cross-references to other legislation or regulations beyond the enabling authority (Civil Aviation Regulations 1998, Part 39)","Clear compliance deadlines (300 hours or 6 months)","Minimal exceptions: only two notes clarifying who can perform inspections and when requirements cease"],"plain_english_summary":"CASA’s Airworthiness Directive requires owners/operators of early Cessna 400‑series aircraft fitted with certain Uniroyal or Goodyear auxiliary wing fuel cells to perform pre‑flight underside inspections for leaks and to replace leaky or all Uniroyal US‑932 cells with the safer Goodyear BTC‑54A within a set timeframe. It addresses fuel‑leak fire/explosion risk and lets type‑rated pilots perform the routine checks until replacement."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cessna-400-34-auxiliary-fuel-cells-inspection-and-replacement","history":"/api/acts/ad-cessna-400-34-auxiliary-fuel-cells-inspection-and-replacement/history","analysis":"/api/acts/ad-cessna-400-34-auxiliary-fuel-cells-inspection-and-replacement/analysis","conflicts":"/api/acts/ad-cessna-400-34-auxiliary-fuel-cells-inspection-and-replacement/conflicts","importantCases":"/api/acts/ad-cessna-400-34-auxiliary-fuel-cells-inspection-and-replacement/important-cases","documents":"/api/acts/ad-cessna-400-34-auxiliary-fuel-cells-inspection-and-replacement/documents"}}