{"id":"F2008L01913","name":"AD/B737/327 - SSI Damage Tolerance Rating","slug":"ad-b737-327-ssi-damage-tolerance-rating","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":74138,"registerId":"commonwealth-F2008L01913-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Boeing 737 Series Aeroplanes","sectionType":"division","heading":"Boeing 737 Series Aeroplanes","content":"### Boeing 737 Series Aeroplanes\n\n| AD/B737/327 | SSI Damage Tolerance Rating | 7/2008 |\n| ----------- | --------------------------- | ------ |\n\n| Applicability: | All Model 737-300, -400, and -500 series aircraft.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |\n| -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Action in accordance with the technical requirements of FAA AD 2008-09-13 Amdt 39-15494.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |\n| Compliance:    | As specified in the Requirement document, with a revised effective date of3 July 2008.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |\n|                | This Airworthiness Directive becomes effective on 3 July 2008.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |\n| Background:    | The FAA received reports of incidents of fatigue cracking in transport category aircraft that are approaching or have exceeded their design service objective. This Directive requires revising the FAA-approved maintenance inspection program to include inspections that will give no less than the required damage tolerance rating for each structural significant item (SSI), doing repetitive inspections to detect cracks of all SSIs, and repairing cracked structure. The actions required by this Directive are necessary to maintain the continued structural integrity of the entire fleet of Model 737-300, -400, and -500 series aircraft. |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n16 May 2008","sortOrder":0},{"sectionNumber":"AD/B737/327","sectionType":"part","heading":"AD/B737/327","content":"## AD/B737/327","sortOrder":1},{"sectionNumber":"SSI Damage Tolerance Rating","sectionType":"part","heading":"SSI Damage Tolerance Rating","content":"## SSI Damage Tolerance Rating","sortOrder":2},{"sectionNumber":"7/2008","sectionType":"part","heading":"7/2008","content":"## 7/2008","sortOrder":3}],"analysis":{"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":3,"scope_assessment":{"changed":false,"description":"This is a standard Airworthiness Directive with a clear, narrow scope: addressing fatigue cracking in specific Boeing 737 models. It has not expanded beyond its original safety purpose."},"complexity_factors":["Very short document (approximately 250 words)","Only 1 defined term used (SSI - Structural Significant Item, explained in context)","No nested legislative cross-references within the instrument itself","Single compliance pathway: follow the external FAA directive","No conditional logic or exceptions within the text","Relies entirely on incorporation by reference to external technical document (FAA AD 2008-09-13)"],"plain_english_summary":"This Airworthiness Directive requires Australian owners/operators of Boeing 737-300/400/500 aircraft to revise maintenance programs to add damage‑tolerance assessments for structural significant items (SSI), perform repeated inspections to detect fatigue cracking, and repair any findings. It adopts FAA AD 2008‑09‑13 to address age‑related fatigue risks and became mandatory on 3 July 2008."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"This instrument implements a focused safety measure: requiring revision of maintenance inspection programs and repetitive inspections/repairs for Structural Significant Items on the specified 737 series. That is consistent with the stated original purpose (addressing fatigue cracking and maintaining structural integrity). The instrument does not broaden the types of aircraft affected, add unrelated regulatory obligations, or extend enforcement beyond standard airworthiness directive powers; it therefore does not materially change the scope beyond its original safety-focused intent."},"complexity_factors":["Short instrument concentrated on a single technical action (revise maintenance program and carry out inspections/repairs).","Single clear applicability clause limited to three 737 model series (737-300, -400, -500).","Primary content is a cross-reference to an external technical document (FAA AD 2008-09-13) which contains the detailed inspection tasks, intervals and procedures.","No nested exceptions or multiple conditional branches within the Directive text itself.","Compliance timing is explicit (effective date 3 July 2008) but substantive compliance depends on interpreting the FAA AD (adds a layer of external complexity).","Administrative complexity concentrated in incorporation of the FAA AD into domestic maintenance approvals rather than in the AD's text."],"plain_english_summary":"**What this instrument changes (mechanically):**\n\n- It legally requires operators of Boeing 737-300, -400 and -500 series aircraft to revise their FAA-approved maintenance inspection programs to meet the damage tolerance requirements set out in FAA Airworthiness Directive (AD) 2008-09-13. (Requirement)\n- Operators must carry out repetitive inspections for every Structural Significant Item (SSI) to detect fatigue cracks, and repair any cracked structure found. (Requirement)\n- The Directive takes effect on 3 July 2008; compliance must follow the times, methods and intervals specified in the referenced FAA AD. (Compliance / Requirement)\n\n**Who this affects:**\n\n- Airlines, leasing companies and maintenance organisations that operate or maintain Boeing 737-300/400/500 series aeroplanes in Australia. (Applicability)\n- Civil Aviation Safety Authority (CASA) and its delegate are the enforcing authority (the notice is issued by the CASA delegate). (Header / Signature)\n\n**Why the rule exists (official rationale):**\n\n- The FAA reported incidents of fatigue cracking on transport-category aeroplanes that are near or have exceeded their design service objective. The Directive aims to ensure each SSI meets a required damage tolerance rating and is inspected regularly to preserve structural integrity. (Background)\n\n**What operators must actually do (practical effect):**\n\n- Update the operator’s FAA-approved maintenance inspection program to include the inspection tasks, intervals and procedures specified in FAA AD 2008-09-13 so that each SSI achieves at least the required damage tolerance rating. (Requirement)\n- Perform the specified repetitive inspections and carry out repairs where cracks are found. (Requirement)\n\n**Who pays, who decides, and how behaviour changes:**\n\n- Operators pay: the direct costs of revising maintenance programs, performing additional inspections, repairing cracked structure, and any associated aircraft downtime. (Requirement / Background) \n- The technical specifics (what to inspect, when, and how) are determined by the referenced FAA AD; CASA enforces compliance in Australia by making adherence to that FAA AD a legal requirement. (Requirement / Compliance)\n- Behavioural change: maintenance organisations will add or change inspection tasks and intervals, and operators will schedule more frequent structural inspections and repairs for SSIs on affected aircraft types. (Requirement)\n\n**Costs, incentives and implementation risks (mechanical analysis):**\n\n- Direct costs: extra inspection labour, tooling, non-routine repairs, and aircraft out-of-service time. These are borne by operators or their lessors. (Implicit from Requirement)\n- Incentives: regular inspections reduce the risk of undetected fatigue cracking and associated safety incidents; operators incur ongoing costs to manage that risk. (Background + Requirement)\n- Implementation risk and compliance burden: the Directive cross-references a foreign (FAA) technical document rather than reproducing inspection detail, so Australian compliance depends on operative access to and correct incorporation of that FAA AD into local maintenance manuals and approved maintenance programs. This raises a modest administrative burden for approved maintenance program holders and for CASA oversight. (Requirement / Compliance)\n- Concentration of benefits and diffuse costs: the safety benefit (reduced risk of structural failure) is broadly diffuse (public and passengers), while the costs are concentrated on operators and maintenance providers. (Background + Requirement)\n\n**Trade-offs and opportunity costs:**\n\n- Operators trade increased recurrent maintenance costs and potential aircraft downtime for a lower structural-failure risk. The directive does not provide exemptions or alternatives within the text itself; compliance must follow the FAA AD. (Requirement)\n\n**Source notes:**\n\n- The legal action is an Australian Airworthiness Directive that makes compliance with FAA AD 2008-09-13 mandatory for the listed 737 models in Australia. (Requirement / Applicability)\n- The stated justification is FAA-reported fatigue cracking on ageing transport aircraft nearing or exceeding their design service lives. (Background)\n\n(References in this summary refer to the labelled parts of the instrument provided: Applicability, Requirement, Compliance, and Background.)"}},"importantCases":[],"_links":{"self":"/api/acts/ad-b737-327-ssi-damage-tolerance-rating","history":"/api/acts/ad-b737-327-ssi-damage-tolerance-rating/history","analysis":"/api/acts/ad-b737-327-ssi-damage-tolerance-rating/analysis","conflicts":"/api/acts/ad-b737-327-ssi-damage-tolerance-rating/conflicts","importantCases":"/api/acts/ad-b737-327-ssi-damage-tolerance-rating/important-cases","documents":"/api/acts/ad-b737-327-ssi-damage-tolerance-rating/documents"}}