{"id":"F2006B03658","name":"AD/BEECH 1900/4 Amdt 2 - Engine Truss Assembly","slug":"ad-beech-1900-4-amdt-2-engine-truss-assembly","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":43248,"registerId":"commonwealth-F2006B03658-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BEECH 1900/4 Amdt 2 - Engine Truss Assembly","content":"![](image.001.png)  \n![](image.002.png)  \nBeechcraft 1900 Series Aeroplanes\n\nAIRWORTHINESS DIRECTIVE\n\n![](image.002.png)\n\n![](image.003.png)![](image.002.png)  \nFor the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/BEECH 1900/4 Amdt 1 and issues the following AD under subregulation 39.1 (1) of CAR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\nAD/BEECH 1900/4\n\nAmdt 2\n\n  \nEngine Truss Assembly 1/2002\n\nApplicability: Model Serial Number\n\n1900 UA-2 and UA-3\n\n1900C UB-1 through UB-74 and UC-1 through UC-174 1900C UD-1 through UD-6\n\n1900D UE-1 through UE-302\n\nRequirement: 1. If engine truss assembly part number (P/N) 129-910047-1, 129-910047-13, or 129-910047-17 (or FAA-approved equivalent part number) is not installed, accomplish the following:\n\n    Inspect the engine truss assembly for cracks in accordance with the Accomplishment Instructions in Raytheon Aircraft Mandatory Service Bulletin (MSB) No. 2255 Revision 10, Revised June 1999. If cracks are found, before further flight, replace with a part number truss specified in Requirement 1.b.\n\n    b. Replace the engine truss assembly with a P/N 129-910047-1, 129-910047- 13, or 129-910047-17 assembly.\n\n    2. For aircraft equipped with a P/N 129-910047-1 or 129-910047-13 engine truss assembly (of FAA-approved equivalent part number), inspect for linoil hole mislocation and cracks in Area A in accordance with Part I of the Accomplishment Instructions of MSB SB 71-3144 Revision 1, Revised April 1999. If any mislocated hole or crack is found, before further flight, replace the engine truss assembly.\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n    3. For aircraft equipped with a P/N 129-910047-1 or 129-910047-13 engine truss assembly, accomplish the following:\n\n    Inspect the engine cowling support bracket for cracks in accordance with Part III of the Accomplishment Instructions section of MSB SB 71-3144 Revision 1, Revised April 1999, and rework any cracked support bracket. If any cracked bracket is found, before further flight, accomplish any necessary engine cowling rework.\n\n    b. Install Kit No. 129-9017-1 reinforcements on the engine cowling support bracket.\n\n    4. For aircraft equipped with a P/N 129-910047-1 or 129-910047-13 engine truss assembly, replace all remaining linoil drive screws (those not in area A) in accordance with Part II of the Accomplishment Instructions section of MSB SB 71-3144 Revision 1, Revised April 1999.\n\n    5. For aircraft equipped with a P/N 129-910047-1 or 910047-13 engine truss assembly, install a P/N 129-910047-15 truss identification placard on the engine truss assembly in accordance with the Accomplishment Instructions section of SB 71-3024, Issued September 1997.\n\nNote: FAA AD 2001-22-16 Amdt 39-12495 refers.\n\nCompliance: 1.a. As specified in the Requirement document.\n\n1.b. Within 100 hours time in service after 24 January 2002.\n\n2. Upon accumulating 100 hours time in service on the engine truss assembly, or within 25 hours time in service after 24 January 2002, whichever occurs later; thereafter at intervals not to exceed 100 hours time in service until Requirement 4 is accomplished.\n\n    3.a. Upon accumulating 200 hours time in service on the engine truss assembly, or within 25 hours after 24 January 2002, whichever occurs later, unless already accomplished; thereafter at intervals not to exceed 200 hours time in service; until Requirement 3.b. is accomplished.\n\n    3.b. Upon accumulating 1,200 hours time in service on the engine truss assembly, or within 100 hours time in service after 24 January 2002, whichever occurs later.\n\n    4. Upon accumulating 8,000 hours time in service on the engine truss assembly, or at the next engine truss assembly removal, whichever occurs later.\n\n    5. Within 12 months after 24 January 2002 or upon installation of a P/N 129- 910047-1 or 129-910047-13 engine truss assembly, whichever occurs later.\n\nThis amendment becomes effective on 24 January 2002.\n\nBackground: Reports were received of cracks in the welded joints of the engine truss, which if detected, could lead to engine separation from the aircraft.\n\nAmendment 1 referenced later service information and required fluorescent penetrant inspection.\n\nAmendment 2 is issued in response to a new FAA AD which was prompted by further reports of engine truss fatigue cracks on Models 1900, 1900C, and 1900D aircraft.\n\nThe reports reference aircraft that are in compliance with FAA AD 95-02-18. The fatigue cracks are developing as a result of operational stresses in joints, welded bracketry, and linoil holes sealed by screws.\n\nAmendment 1 to this Airworthiness Directive became effective on 27 April 1995.\n\n![](image.004.png)The original issue of this Airworthiness Directive became effective on 5 September 1991.\n\n![](image.005.png)  \n\nDavid Alan Villiers\n\nDelegate of the Civil Aviation Safety Authority 4 December 2001\n\n![](image.002.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 9 January 2002.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":6,"scope_assessment":{"changed":true,"description":"This amendment expands and updates the original AD’s remedial program. The original AD (and Amendment 1) required inspections and fluorescent penetrant inspection references; Amendment 2: (a) adopts further FAA-directed measures prompted by additional fatigue reports; (b) prescribes a mix of recurring inspections for trusses already of certain P/Ns and mandatory replacement/installation actions (including reinforcement kit 129-9017-1 and replacement screws) as terminating or corrective actions; and (c) adds specific compliance intervals tied to hours-in-service and calendar deadlines. In short, the AD’s scope moved from inspection-only remedies to a more prescriptive combination of inspection, structural rework, parts replacement and reinforcement across a wider set of part numbers and service conditions (see Requirements 1–5 and Compliance)."},"complexity_factors":["Multiple specific part numbers (P/N 129-910047-1, -13, -15, -17 and kit 129-9017-1) requiring different actions","Applicability limited to multiple serial-number ranges across three models (1900, 1900C, 1900D)","Cross-references to three separate Raytheon service bulletins (MSB No.2255 Rev10; SB 71-3144 Rev1; SB 71-3024) for technical steps","Several conditional branches depending on which P/N is installed (inspect if not installed; different inspections/rework if specific P/Ns are installed)","Multiple compliance triggers tied to hours-in-service and a calendar benchmark (e.g. 25 hours/100 hours/200 hours/1,200 hours/8,000 hours and deadlines relative to 24 Jan 2002)","Revokes a prior amendment and follows an FAA AD (cross-regulatory linkage)","Actions of different types: inspections, rework, replacement, installation of reinforcement kit and placard — some are recurring until a terminating action is performed","Reliance on detection method quality (fluorescent penetrant and visual inspections referenced in previous amendments) which introduces procedural complexity and implementation variability"],"plain_english_summary":"**What this instrument does (mechanically)**\n\n- Applies to Beechcraft 1900, 1900C and 1900D aeroplanes listed by serial number in the Applicability box.\n- Requires operators to inspect, repair or replace the engine truss assembly and associated brackets/screws according to Raytheon/FAA service instructions (Raytheon Mandatory Service Bulletin No. 2255 Rev 10 and Service Bulletins SB 71-3144 Rev 1 and SB 71-3024). (See Requirement paragraphs 1–5.)\n- If an engine truss of the newer specification (part numbers 129-910047-1, -13 or -17, or an FAA‑equivalent P/N) is not installed, the operator must inspect for cracks and, if cracks are found, replace the truss with one of those P/Ns (Requirement 1).\n- For aircraft that already have trusses with P/N 129-910047-1 or -13, the AD mandates repeated inspections for mislocated linoil holes and cracks in Area A, replacement where necessary, inspection and rework of cowling support brackets, installation of a reinforcement kit (129-9017-1), replacement of remaining linoil drive screws outside Area A, and fitting a truss identification placard (Requirements 2–5).\n- Compliance is tied to hours-in-service thresholds and calendar deadlines (for example, some inspections start at 100 hours on the truss or within 25 hours after 24 January 2002, replacement within 100 hours after 24 January 2002, placard installation within 12 months after 24 January 2002, and other intervals such as 200, 1,200 and 8,000 hours). The AD revokes the earlier Amendment 1 and replaces it with this Amendment 2.\n\n**Who is affected**\n\n- Aircraft owners/operators and their maintenance organisations who operate or maintain the listed Beechcraft 1900 series aeroplanes (the serial ranges are set out in the Applicability).\n- Maintenance providers and parts suppliers who sell the specified trusses, screws and reinforcement kits; they will carry out the inspections, repairs and part replacements.\n- The regulator (CASA) enforces compliance; the required work must be done in accordance with the Raytheon service instructions cited.\n\n**Why it matters (stated safety risk and mechanical effect)**\n\n- The background says welds and other joints in the engine truss have developed fatigue cracks in service. If undetected, a crack could lead to engine separation from the airframe.\n- The AD therefore directs inspections and engineering changes intended to detect and correct cracks and mislocated linoil holes (which have been implicated in crack development), and to reinforce or replace affected structure.\n\n**How it changes behaviour and who pays**\n\n- Operators must establish and perform recurring inspections and, when required, remove and replace or rework structural components. That produces direct costs: labour, parts (replacement trusses, reinforcement kits, screws), and aircraft downtime. Maintenance organisations bear the execution burden and charge operators; parts manufacturers benefit from replacement part demand.\n- The CASA delegate (the regulator) sets the required actions and compliance timeframes; the specific inspection and repair steps are carried out under the Raytheon service instructions cited (the AD requires compliance “in accordance with” those instructions). FAA‑approved equivalent part numbers are permitted by the AD where noted.\n\n**Implementation, compliance and risk trade-offs**\n\n- The AD relies on service bulletins (MSB/SB) for technical detail; effective compliance depends on the quality of inspections (visual or fluorescent penetrant as referenced in prior amendments), inspector skill and access to appropriate tooling and parts.\n- Repeated inspection intervals before permanent modification is required mean ongoing operating cost and administrative tracking (recordkeeping of hours-in-service and inspection history).\n- There is an availability risk: if replacement trusses, reinforcement kits or approved screws are in short supply, operators may face extended downtime or need to source FAA‑equivalent parts subject to regulatory approval.\n\n**Concentrated benefits and diffuse costs**\n\n- The safety benefit (reduced risk of in‑flight engine separation) is concentrated for each aircraft and its occupants but the costs (inspections, parts, downtime) are borne directly by the aircraft operators. The service/parts industry sees concentrated demand for parts and maintenance services.\n\n**References in the AD**\n\n- Requirement steps and time-limits are set out at Requirements 1–5 and Compliance sections. The AD references Raytheon MSB No. 2255 Rev 10, MSB/SB 71-3144 Rev 1, SB 71-3024 and FAA AD 2001-22-16.\n\n(Section citations: Requirement 1–5; Compliance section; Background.)"},"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":6,"scope_assessment":{"changed":true,"description":"The original 1991 directive addressed engine truss cracks, but Amendment 2 (2002) significantly expanded the scope. It added requirements for inspecting linoil hole mislocations, reinforcing engine cowling support brackets, replacing drive screws, and installing identification placards. The compliance structure also became more complex with tiered deadlines and recurring inspections, moving beyond a simple 'inspect and replace' mandate to a comprehensive fatigue management program for the engine mounting system."},"complexity_factors":["Multiple conditional requirements based on which specific part number is installed (Requirements 1-5 have different triggers)","Extensive cross-referencing to external manufacturer documents (Raytheon MSB 2255 Rev 10, MSB SB 71-3144 Rev 1, SB 71-3024) — the AD cannot be understood without these external bulletins","Nested timing calculations for compliance (e.g., 'upon accumulating X hours, or within Y hours after date Z, whichever occurs later; thereafter at intervals not to exceed...')","Five distinct requirement streams with different compliance deadlines and recurring inspection intervals","Technical aviation terminology throughout (P/N, time in service, engine truss assembly, linoil holes, cowling support brackets)","Reference to FAA AD 2001-22-16 and previous amendments (Amendment 1, original 1991 issue) for full context"],"plain_english_summary":"This safety order addresses dangerous cracks in the welded engine-truss assemblies on Beechcraft 1900/1900C/1900D aircraft. Affected owners/operators must inspect, repair or replace trusses and related brackets and fasteners per manufacturer procedures, install identification placards, and meet specified compliance intervals. The measures—some urgent—prevent possible in-flight engine separation. Amendment 2 tightens requirements after continued crack reports despite earlier fixes, making compliance critical to avoid catastrophic failure."}},"importantCases":[],"_links":{"self":"/api/acts/ad-beech-1900-4-amdt-2-engine-truss-assembly","history":"/api/acts/ad-beech-1900-4-amdt-2-engine-truss-assembly/history","analysis":"/api/acts/ad-beech-1900-4-amdt-2-engine-truss-assembly/analysis","conflicts":"/api/acts/ad-beech-1900-4-amdt-2-engine-truss-assembly/conflicts","importantCases":"/api/acts/ad-beech-1900-4-amdt-2-engine-truss-assembly/important-cases","documents":"/api/acts/ad-beech-1900-4-amdt-2-engine-truss-assembly/documents"}}