{"id":"F2006B02841","name":"AD/B737/14 - Forward Lower Cargo Doorway Frame","slug":"ad-b737-14-forward-lower-cargo-doorway-frame","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42183,"registerId":"commonwealth-F2006B02841-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B737/14 - Forward Lower Cargo Doorway Frame","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)  \nBoeing 737 Series Aeroplanes\n\nAD/B737/14 Forward Lower Cargo Doorway Frame 2/88\n\nApplicability: All model 737 aircraft, Line Numbers 1 to 509 inclusive.\n\nRequirement: Inspect in accordance with Boeing SB 737-53-1051 (Revision 3 or later) until modified in accordance with the Preventative Modification contained in that SB.\n\nNote: FAA AD 86-09-06 refers.\n\nCompliance: As detailed in the Requirement Document.\n\nBackground: There have been numerous reports of cracking in the fuselage frames which form the sides of the forward lower cargo doorway. Continued operation with undetected cracked frames could result in skin cracks and rapid decompression. This AD has been raised because SB 737-55-1051 has been listed in Section 9.0 of the 737 Supplemental Structural Inspection Document as having flight safety implications.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The supplied AD sets a clear, limited scope: it applies to Boeing 737 aircraft Line Numbers 1–509 and mandates inspections per Boeing SB 737-53-1051 until the Preventative Modification in that SB is implemented. The text does not indicate any expansion or narrowing of that applicability compared with the instrument as provided here."},"complexity_factors":["Narrow applicability (specific line numbers 1–509) reduces administrative breadth but requires accurate fleet identification. (Applicability)","Dependency on an external technical document (Boeing SB 737-53-1051, Revision 3 or later) for procedural detail increases operational complexity. (Requirement)","Ongoing inspection regime until a one-time modification is installed creates a temporal compliance burden for operators (scheduling, recordkeeping). (Requirement)","Reference to an external Requirement Document for compliance timing and procedures means legal compliance depends on obtaining and following that document. (Compliance)","Safety-critical technical inspections and potential repair work require qualified maintenance resources and may cause aircraft downtime. (Background)"],"plain_english_summary":"What this instrument does (mechanically)\n\n- Requires regular inspections of the fuselage frames that form the sides of the forward lower cargo doorway on certain Boeing 737 aeroplanes, and requires operators to implement a specified preventative modification when available. (Requirement)\n\nWho it affects\n\n- Applies to all Boeing 737 model aircraft with Line Numbers 1 to 509 inclusive — i.e. the specified set of early-production airframes. (Applicability)\n\nWhy it matters (safety risk and trigger)\n\n- The measure is prompted by multiple reports of cracking in the forward lower cargo doorway frames. The AD identifies the hazard: if these frames crack without detection, that could lead to skin cracking and rapid decompression. The AD therefore mandates inspections and a preventative modification to address that risk. (Background)\n\nHow it works in practice\n\n- Operators must carry out inspections in accordance with Boeing Service Bulletin (SB) 737-53-1051 (Revision 3 or later). They must continue those inspections until they implement the Preventative Modification described in that same SB. (Requirement)\n- The AD refers to the FAA Airworthiness Directive 86-09-06 for related material, and states compliance should follow the details in the Requirement Document. (Note; Compliance)\n\nWho pays and what incentives this creates\n\n- The aircraft operator or owner is the party that must perform and fund the inspections and the preventative modification, because the AD places the inspection/modification obligation on the operator via the Requirement (Requirement). Operators bear direct costs for labour, parts, and aircraft downtime. (Requirement)\n- The AD creates a clear operational incentive: carry out the Preventative Modification from Boeing’s SB to stop the recurring inspection requirement (\"inspect until modified\"), trading a one-time modification cost against ongoing inspection costs and associated downtime. (Requirement)\n\nCompliance burden and administrative points\n\n- The AD ties compliance to an external document (Boeing SB 737-53-1051, Revision 3 or later) and to a Requirement Document for procedural detail; operators therefore must obtain, retain, and follow those documents to demonstrate compliance. (Requirement; Compliance)\n- Scheduling recurring inspections and recording results will impose ongoing maintenance and administrative effort until the modification is installed. (Requirement)\n\nDiscretion and dependence on external material\n\n- The AD delegates the technical specification of inspections and the form of the modification to the Boeing Service Bulletin; it requires ‘‘Revision 3 or later’’ of that SB, so operators must track and apply the required revision level. (Requirement)\n- The AD’s compliance mechanics are ‘‘as detailed in the Requirement Document,’’ which requires operators and maintainers to follow that external document for exact compliance steps and timing. (Compliance)\n\nImplementation risks and trade-offs to consider\n\n- Practical implementation costs include the inspection effort, potential repairs if cracking is found, and aircraft downtime for both inspections and the modification. (Background; Requirement)\n- Operators may elect to schedule an earlier modification to avoid repeated inspections; conversely, delay in modifying keeps the inspection burden and exposure to in-service cracking. (Requirement)\n\nReference points in the source text\n\n- Applicability: All model 737 aircraft, Line Numbers 1 to 509 inclusive. (Applicability)\n- Requirement: Inspect in accordance with Boeing SB 737-53-1051 (Revision 3 or later) until modified in accordance with the Preventative Modification contained in that SB. (Requirement)\n- Note: FAA AD 86-09-06 refers. (Note)\n- Compliance: As detailed in the Requirement Document. (Compliance)\n- Background: Reports of cracking in the forward lower cargo doorway frames; risk of skin cracks and rapid decompression if undetected. (Background)"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific structural defect in early-model Boeing 737 aircraft. The scope remains precisely limited to the forward lower cargo doorway frame inspection and modification requirement as originally issued. No evidence of scope creep or expansion beyond the original airworthiness concern."},"complexity_factors":["Very short document (under 300 words)","Only 1 defined term implicitly referenced (Line Numbers)","Single, clear compliance pathway: inspect per SB, then modify per SB","No nested exceptions or conditional logic","Cross-reference to only one external document (Boeing SB 737-53-1051) and one related FAA directive","Straightforward applicability criteria (specific line number range)"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for aircraft.\n\n**What it does:**\nIt requires owners and operators of certain Boeing 737 aircraft to inspect a specific part of the plane — the **forward lower cargo doorway frame** (the structural frame around the cargo door at the front of the aircraft belly). They must check for cracks in this area following Boeing's official instructions (Service Bulletin 737-53-1051, Revision 3 or newer). Once the inspection is done, they must also install a permanent fix (called a \"Preventative Modification\") from that same bulletin.\n\n**Who it affects:**\n- All Boeing 737 aircraft with \"Line Numbers\" 1 through 509 (these are early production models, essentially the first 509 planes built)\n- Airlines, maintenance organisations, and owners operating these specific aircraft in Australia\n\n**Why it matters:**\nCracks have been found in the metal frames around the cargo door. If left unchecked, these cracks can spread to the aircraft's skin, potentially causing **rapid decompression** — a dangerous situation where the cabin suddenly loses pressure at altitude. This directive exists because Boeing identified this issue as having \"flight safety implications,\" meaning it could directly endanger passengers and crew if not addressed."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b737-14-forward-lower-cargo-doorway-frame","history":"/api/acts/ad-b737-14-forward-lower-cargo-doorway-frame/history","analysis":"/api/acts/ad-b737-14-forward-lower-cargo-doorway-frame/analysis","conflicts":"/api/acts/ad-b737-14-forward-lower-cargo-doorway-frame/conflicts","importantCases":"/api/acts/ad-b737-14-forward-lower-cargo-doorway-frame/important-cases","documents":"/api/acts/ad-b737-14-forward-lower-cargo-doorway-frame/documents"}}