{"id":"F2006B04001","name":"AD/BEECH 55/57 - Fuselage Bulkheads FS 257.6 & FS 271.92","slug":"ad-beech-55-57-fuselage-bulkheads-fs-257-6-fs-271-92","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":43610,"registerId":"commonwealth-F2006B04001-current","compilationNumber":null,"startDate":"2026-04-02","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BEECH 55/57 - Fuselage Bulkheads FS 257.6 & FS 271.92","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)  \nBeechcraft 55, 58 and 95-55 (Baron) Series Aeroplanes\n\nAD/BEECH 55/57 Fuselage Bulkheads FS 257.6 & FS 271.92 3/79\n\nApplicability: All models 95-55, 95-A55, 95-B55 and 95-B55A with S/Nos. TC-1 to TC-349 and TC-351 to TC-2124.\n\nAll model 95-B55B with S/Nos. TF-1 to TF-70.\n\nAll models 95-C55, 95-C55A, D55, D55A, E55 and E55A with S/Nos. TC-350 and TE-1 to TE-1124.\n\nAll models 58 and 58A with S/Nos. TH-1 to TH-908. All models 58P and 58PA with S/Nos. TJ-2 to TJ-141. All models 58TC to 58TCA with S/Nos. TK-1 to TK-68.\n\nRequirement: Action in accordance with Beechcraft SI No. 0990.\n\nCompliance: Initially inspect within 100 hours’ time in service after 30 April 1979 and thereafter at intervals not exceeding 500 hours’ time in service or 1 year, whichever occurs first.\n\nBackground: Cracks may develop in the subject bulkheads in the areas of the horizontal stabiliser attachments.","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":2337},"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This directive maintains its original narrow scope as a targeted safety mandate addressing specific structural fatigue concerns in defined Beechcraft Baron aircraft models."},"complexity_factors":["Extensive model and serial number applicability lists (12 model variants with 17 distinct serial number ranges)","Reference to unspecified external technical standard (Beechcraft Service Instruction No. 0990) without reproducing procedural details","Technical aviation terminology requiring domain knowledge (fuselage bulkheads, frame stations, 'time in service')","Dual-threshold recurring compliance obligation (flight hours versus calendar time, whichever occurs first)"],"plain_english_summary":"This mandatory AD requires owners/operators of certain Beechcraft Baron twin‑engine piston models (55, 58 and 95‑55 series, specific serial-number ranges) to inspect two fuselage bulkheads where the horizontal tail attaches, using Beechcraft Service Instruction No. 0990. Initial inspection within 100 flight hours after April 30, 1979, then every 500 hours or 12 months, whichever is first. It addresses fatigue cracking that could lead to tail separation and catastrophic loss of control."}},"importantCases":[],"_links":{"self":"/api/acts/ad-beech-55-57-fuselage-bulkheads-fs-257-6-fs-271-92","history":"/api/acts/ad-beech-55-57-fuselage-bulkheads-fs-257-6-fs-271-92/history","analysis":"/api/acts/ad-beech-55-57-fuselage-bulkheads-fs-257-6-fs-271-92/analysis","conflicts":"/api/acts/ad-beech-55-57-fuselage-bulkheads-fs-257-6-fs-271-92/conflicts","importantCases":"/api/acts/ad-beech-55-57-fuselage-bulkheads-fs-257-6-fs-271-92/important-cases","documents":"/api/acts/ad-beech-55-57-fuselage-bulkheads-fs-257-6-fs-271-92/documents"}}