{"id":"F2006B07062","name":"AD/SM-205/4 - Fuselage - Reinforcement","slug":"ad-sm-205-4-fuselage-reinforcement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":48803,"registerId":"commonwealth-F2006B07062-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/SM-205/4 - Fuselage - Reinforcement","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)  SIAI Marchetti S205 and S208 Series Aeroplanes\n\n \n\nAD/SM-205/4 Fuselage - Reinforcement 3/71\n\nApplicability: All S205 series with S/Nos. 001 to 4-173 except 103, 109, 217, 348, 351, 369, 4-101,\n\n4103, 4-121, 4-127, 4-137, 4-144, 4-149, 4-150, 4-151, 4-152, 4-153, 4-168 and 4-\n\n172.\n\n \n\nDocument:  SIAI Marchetti SB 205B20. Compliance: Before 31 March 1971.\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":"The provided AD text states a specific, time-limited requirement for fuselage reinforcement for a defined set of S205 serial numbers, references a single service bulletin for the required work, and sets a compliance deadline. The text contains no indication that its scope was altered from an earlier instrument or that it amends a prior AD within the excerpt supplied."},"complexity_factors":["Clear, narrow applicability by serial number (Applicability section)","Single mandated remedy referenced via a single manufacturer service bulletin (Document: SIAI Marchetti SB 205B20)","Fixed compliance deadline creates a clear temporal requirement (Compliance: Before 31 March 1971)","AD text does not include procedural details, requiring operators to obtain and follow an external document (Document)","No alternative compliance paths, exemptions (other than the listed excluded serial numbers) or administrative procedures are set out in the text"],"plain_english_summary":"What this instrument does (mechanics)\n\n- The Civil Aviation Safety Authority (under the Schedule of Airworthiness Directives) requires that certain SIAI Marchetti S205 aeroplanes receive a fuselage reinforcement. (Header and title: \"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - SCHEDULE OF AIRWORTHINESS DIRECTIVES\"; AD/SM-205/4 \"Fuselage - Reinforcement\".)\n- The AD makes compliance conditional on following the manufacturer service bulletin listed in the AD: SIAI Marchetti SB 205B20. (Document: \"SIAI Marchetti SB 205B20.\")\n- The work must be done by the date specified in the AD: before 31 March 1971. (Compliance: \"Before 31 March 1971.\")\n\nWho is affected\n\n- The direct targets are owners/operators of SIAI Marchetti S205 series aircraft with the serial numbers listed in the AD: all S205 series with S/Nos. 001 to 4-173 except the serial numbers expressly excluded (103, 109, 217, 348, 351, 369, 4-101, 4103, 4-121, 4-127, 4-137, 4-144, 4-149, 4-150, 4-151, 4-152, 4-153, 4-168 and 4-172). (Applicability section.)\n- The AD appears under a heading that also names S205 and S208 series aeroplanes, but the applicability text explicitly lists affected S205 serial numbers only. (Header and Applicability section.)\n\nWhy it matters (stated purpose and operational test of that purpose)\n\n- The document title and the mandated action indicate the AD's stated purpose: to have the fuselage reinforced by following SIAI Marchetti SB 205B20 (title: \"Fuselage - Reinforcement\" and Document: \"SIAI Marchetti SB 205B20\"). This is an explicit operational requirement rather than a recommendation.\n- Testing that stated purpose against costs and incentives: the AD imposes a one-off physical modification on a defined subset of aircraft by a fixed deadline. That creates direct costs for owners/operators (parts, labour, downtime) and creates demand for maintenance capacity. The AD centralises the choice of remedy by referencing the manufacturer service bulletin (the authority decides the required method of compliance); owners do not have a menu of compliance options set out in the AD itself. (See Document and Compliance sections.)\n\nWho pays, who decides, and how behaviour must change\n\n- Who pays: Owners/operators of the affected S205 aircraft must arrange and fund the reinforcement work required by the AD. (Applicability; Document; Compliance.)\n- Who decides: The Civil Aviation Safety Authority issued the AD and fixes the deadline; the AD references the manufacturer’s service bulletin as the required procedure. (Header; Document.)\n- Required behaviour change: Affected aircraft must undergo the reinforcement work as specified in SB 205B20 and complete it before the compliance date; until the work is done, operators must either defer operations or operate without compliance subject to any further regulatory direction (the AD itself sets the compliance obligation). (Document; Compliance.)\n\nTrade-offs, compliance burden and risks (mechanisms, not judgements)\n\n- Compliance burden and administrative tasks: operators must identify whether their aircraft are within the listed serial-number range and not excluded, obtain and follow the referenced service bulletin, schedule maintenance, and pay for parts and labour. (Applicability; Document; Compliance.)\n- Implementation risks and opportunity costs: the AD creates a near-term demand for maintenance capacity and replacement parts for the specified modification; that can cause aircraft downtime and scheduling costs. The AD does not enumerate alternative compliance methods or provide exemptions within the text provided. (Document; Compliance.)\n- Concentration of costs and benefits: the costs are concentrated on owners/operators of the listed S205 aircraft. Any safety benefit from a reinforced fuselage would accrue to operators, passengers and others who use or interact with those specific aeroplanes; the AD text itself specifies the obligation but does not quantify benefits or costs. (Applicability; title.)\n\nOther implementation notes grounded in the text\n\n- The AD references a single external procedural document (SIAI Marchetti SB 205B20) rather than describing the detailed steps in the AD itself; operators must obtain and follow that service bulletin to meet the AD requirement. (Document.)\n- A fixed compliance deadline is set (before 31 March 1971). The AD lists serial numbers that are excluded from the requirement; those exclusions narrow the affected population but do not explain the reason for exclusion in the text provided. (Applicability; Compliance.)"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue airworthiness directive from 1971 addressing a specific structural modification. It has not expanded beyond its original purpose of requiring fuselage reinforcement for a defined aircraft series."},"complexity_factors":["Very short document (approximately 150 words)","Only one substantive requirement (comply with manufacturer service bulletin)","Single applicability section with straightforward serial number exclusions","No defined terms section","No cross-references to other legislation beyond the parent Civil Aviation Regulations 1998","Clear deadline (before 31 March 1971)","No conditional logic or nested exceptions"],"plain_english_summary":"This is an **Airworthiness Directive** (AD) — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). It requires owners and operators of specific SIAI Marchetti aircraft to reinforce the fuselage (the main body of the plane).\n\n**Who it affects:**\n- Owners and operators of **SIAI Marchetti S205 series aircraft** with serial numbers 001 to 4-173, **except** for a long list of specific serial numbers that are excluded.\n\n**What it requires:**\n- The aircraft must be modified according to **Service Bulletin 205B20** issued by the manufacturer (SIAI Marchetti).\n- This modification must be completed **before 31 March 1971**.\n\n**Why it matters:**\nAirworthiness Directives are legally binding safety instructions. If you don't comply, you cannot legally fly the aircraft. This particular directive addresses a structural weakness in the fuselage that could affect flight safety if not reinforced."}},"importantCases":[],"_links":{"self":"/api/acts/ad-sm-205-4-fuselage-reinforcement","history":"/api/acts/ad-sm-205-4-fuselage-reinforcement/history","analysis":"/api/acts/ad-sm-205-4-fuselage-reinforcement/analysis","conflicts":"/api/acts/ad-sm-205-4-fuselage-reinforcement/conflicts","importantCases":"/api/acts/ad-sm-205-4-fuselage-reinforcement/important-cases","documents":"/api/acts/ad-sm-205-4-fuselage-reinforcement/documents"}}