{"id":"F2006B08423","name":"AD/CESSNA 550/18 - Brake Shuttle Valve","slug":"ad-cessna-550-18-brake-shuttle-valve","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115896,"registerId":"commonwealth-F2006B08423-current","compilationNumber":null,"startDate":"2026-04-03","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CESSNA 550/18 - Brake Shuttle Valve","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 550 (Citation II) Series Aeroplanes\n\nAD/CESSNA 550/18 Brake Shuttle Valve 5/90\n\nApplicability: Model 550 and 551 with unit number \\-0002 through \\-0619 and \\-0621 through \\-0623 equipped with BF Goodrich brakes.\n\nModel S550 with unit number \\-0001 through \\-0160 incorporating SB S550-32-7, BF Goodrich brakes and wheels installation.\n\nRequirement: 1. For model 550 and 551:\n\nInspect in accordance with Cessna alert Service Letter SLA 550-32-38.\n\nFor model S550:\n\nInspect in accordance with Cessna Alert Service Letter SLA S550-32-15.\n\n2. Replace brake shuttle valves in accordance with BF Goodrich Service Bulletin SB 517.\n\nCompliance: 1. Within 50 hours time in service after 17 May 1990 and thereafter at intervals not to exceed 50 hours time in service, until BF Goodrich SB 517 is incorporated.\n\n2. Within 200 hours time in service after 17 May 1990.\n\nBackground: Reports of leaking shuttle valves have been received by the manufacturer. Leakage has been attributed to slow deterioration of shuttle valve o-ring material as a result of exposure to an incompatible seal lubricant.","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":2514},"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive maintains its original narrow scope addressing the specific airworthiness defect in brake shuttle valves for identified Cessna aircraft models. There is no indication of scope creep beyond the original safety concern regarding valve leaks caused by incompatible seal lubricant."},"complexity_factors":["Technical aviation terminology requiring specialized knowledge (e.g., 'time in service', 'shuttle valves')","Precise applicability criteria based on aircraft serial numbers and equipment manufacturer","Reference to external technical documents (Service Letters and Service Bulletins) without reproducing their content","Different inspection requirements for different aircraft sub-models"],"plain_english_summary":"This is a safety rule for owners of specific **Cessna Citation II business jets** (models 550, 551, and S550 with specific serial numbers) equipped with BF Goodrich brakes.\n\n**The safety issue:** The brake shuttle valves (components that direct hydraulic fluid pressure to the brakes) can leak due to deterioration of internal rubber seals (o-rings). The seals break down after exposure to an incompatible lubricant used during manufacturing.\n\n**Required actions:**\n- **Repeated inspections:** Check the brake shuttle valves every 50 flight hours until the parts are replaced\n- **Replacement:** Install new brake shuttle valves within 200 flight hours, following the manufacturer's specified procedure (BF Goodrich Service Bulletin 517)\n\n**Who it affects:** Only operators of specific Cessna 550 series aircraft identified by unit/serial number ranges (e.g., -0002 through -0619) that have BF Goodrich brakes installed."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cessna-550-18-brake-shuttle-valve","history":"/api/acts/ad-cessna-550-18-brake-shuttle-valve/history","analysis":"/api/acts/ad-cessna-550-18-brake-shuttle-valve/analysis","conflicts":"/api/acts/ad-cessna-550-18-brake-shuttle-valve/conflicts","importantCases":"/api/acts/ad-cessna-550-18-brake-shuttle-valve/important-cases","documents":"/api/acts/ad-cessna-550-18-brake-shuttle-valve/documents"}}