{"id":"F2006B02648","name":"AD/B727/126 - Main Deck Cargo Door","slug":"ad-b727-126-main-deck-cargo-door","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41964,"registerId":"commonwealth-F2006B02648-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B727/126 - Main Deck Cargo Door","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)  Boeing 727 Series Aeroplanes\n\n \n\nAD/B727/126 Main Deck Cargo Door 3/91\n\nApplicability: Model 727 and 727-100 series aircraft equipped with main deck cargo doors installed in accordance with STC SA1368SO.\n\n \n\nRequirement: Action in accordance with the technical requirements of FAA AD 90-21-19 Amdt 39-6765.\n\n \n\nNote: Aeronautical Engineers, Inc. (AEI), Service Bulletin Report No R-690 refers.\n\n \n\nCompliance: Before 1 April 1991.\n\n \n\nBackground: The results of an FAA audit of the cargo door installation revealed that six cargo door latch lockpins were removed by virtue of a revision to STC SA1368SO.\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":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-limited safety directive addressing a specific technical defect in a specific aircraft modification. It has not expanded beyond its original purpose of mandating a safety fix for the cargo door latch issue."},"complexity_factors":["Very short document (under 200 words)","Only 4 operative sections: Applicability, Requirement, Note, and Compliance","Single cross-reference to external FAA directive (AD 90-21-19)","Single cross-reference to manufacturer service bulletin (AEI Report R-690)","No defined terms section — relies on standard aviation terminology","No conditional logic or nested exceptions","Clear, absolute compliance deadline with no alternatives"],"plain_english_summary":"**What this is:** This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for specific aircraft.\n\n**What it does:** It requires owners or operators of certain Boeing 727 aircraft to take specific safety action to fix a problem with the **main deck cargo door**.\n\n**Who it affects:** \n- **Boeing 727 and 727-100 series aircraft** that have been modified with a main deck cargo door installed under a specific design approval called **STC SA1368SO** (a \"Supplemental Type Certificate\" — basically official permission to modify the aircraft from its original design).\n\n**The problem:** The US aviation regulator (FAA) discovered that six **latch lockpins** (critical safety components that keep the cargo door securely closed) had been accidentally removed from the design when the modification was revised. This creates a serious safety risk — if the cargo door fails in flight, it could cause rapid decompression or structural damage.\n\n**What must be done:** Aircraft operators must follow the technical instructions in **FAA AD 90-21-19** (the original US safety order) to inspect and fix the cargo door latches.\n\n**When:** The fix had to be completed **before 1 April 1991**.\n\n**Why it matters:** Cargo door failures have caused fatal accidents in aviation history. This directive prevents a potentially catastrophic structural failure by ensuring the door latching system works as originally intended."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD addresses the specific installation issue identified in the FAA audit—removal of six cargo door latch lockpins following a revision to STC SA1368SO—and applies to 727/727-100 aircraft with that STC (Background; Applicability). The directive requires operators to comply with the FAA AD that prescribes the technical corrective actions and sets a compliance deadline; this is consistent with the AD's stated purpose and does not indicate a change in scope from that objective (Requirement; Compliance)."},"complexity_factors":["Cross-reference to an external FAA AD for the substantive technical requirements rather than including those details in the text (Requirement).","Limited and specific applicability: only Model 727 and 727-100 aircraft with the STC SA1368SO cargo door modification (Applicability).","Fixed compliance deadline (before 1 April 1991) that requires timely action but does not specify staged steps in this text (Compliance).","Reference to an industry service bulletin (AEI Service Bulletin R-690) as supplementary material (Note).","Background links the directive to a specific audit finding (six latch lockpins removed), which narrows the AD's remedial scope (Background)."],"plain_english_summary":"What this directive does\n\n- This Airworthiness Directive (AD/B727/126) applies to Boeing 727 and 727-100 series aeroplanes that have main deck cargo doors installed under STC SA1368SO (Applicability).\n- It requires operators to carry out the technical actions set out in FAA Airworthiness Directive AD 90-21-19 Amdt 39-6765; the CASA text incorporates those FAA technical requirements by reference rather than restating them in full (Requirement).\n- The AD also notes Aeronautical Engineers, Inc. (AEI) Service Bulletin Report No R-690 as a related reference (Note).\n- Compliance with the incorporated FAA AD is required before 1 April 1991 (Compliance).\n\nWho this affects\n\n- Operators (owners or operators) of Model 727 and 727-100 aircraft that have the main deck cargo door modification installed in accordance with STC SA1368SO (Applicability).\n\nWho pays and who decides\n\n- Operators of affected aircraft incur the direct costs of performing the mandated actions (Applicability; Requirement).\n- The Civil Aviation Safety Authority (CASA) imposes the obligation by issuing this AD and does so by requiring adherence to the FAA AD referenced above (Requirement).\n\nHow it works mechanically\n\n- CASA requires compliance with FAA AD 90-21-19 Amdt 39-6765; operators must obtain and apply FAA AD 90-21-19 Amdt 39-6765 and may reference AEI Service Bulletin R-690 (Requirement; Note).\n- The AD sets a deadline: the required actions must be completed before 1 April 1991 (Compliance).\n- The AD prescribes compliance with FAA AD 90-21-19 Amdt 39-6765 without setting alternate methods of compliance in this text (Requirement).\n- The AD incorporates FAA AD 90-21-19 Amdt 39-6765 by reference rather than restating technical requirements separately (Requirement).\n\nWhy the AD was issued (source statement)\n\n- The background provided states that an FAA audit of the cargo door installation revealed that six cargo door latch lockpins were removed by virtue of a revision to STC SA1368SO; the AD addresses that identified installation issue (Background).\n\nNotes on implementation risk and administrative mechanics (source-grounded)\n\n- The CASA AD directs operators to follow the FAA AD's technical requirements; the CASA text itself does not list those technical steps or alternate compliance methods (Requirement).\n- Operators will need to obtain the FAA AD (and may consult AEI Service Bulletin R-690) to determine the specific technical actions and to calculate the compliance effort and cost (Requirement; Note)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b727-126-main-deck-cargo-door","history":"/api/acts/ad-b727-126-main-deck-cargo-door/history","analysis":"/api/acts/ad-b727-126-main-deck-cargo-door/analysis","conflicts":"/api/acts/ad-b727-126-main-deck-cargo-door/conflicts","importantCases":"/api/acts/ad-b727-126-main-deck-cargo-door/important-cases","documents":"/api/acts/ad-b727-126-main-deck-cargo-door/documents"}}