{"id":"F2006B02759","name":"AD/B727/57 - Thrust Reverser Deflector Doors - Modification","slug":"ad-b727-57-thrust-reverser-deflector-doors-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42101,"registerId":"commonwealth-F2006B02759-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B727/57 - Thrust Reverser Deflector Doors - Modification","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/B727/57 Thrust Reverser Deflector Doors - Modification 8/68\n\nApplicability: All models.\n\n \n\nRequirement: 1. Modify the thrust reverser deflector doors in accordance with Boeing SB No. 78- 51, Rev. 1.\n\n \n\n2.    Modify the thrust reverser deflector doors in accordance with Boeing SL 6-7132- 3375 dated 1 March 1967 (or later revision).\n\n \n\n3.    Replace bolt P/N BAC-B30EK8-48 or P/N BAC-C30EK8-48C. Compliance: Forthwith.\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":3,"scope_assessment":{"changed":false,"description":"The instrument itself contains no language indicating a change from an earlier scope or from an original intent. It applies to all Boeing 727 models and mandates the listed modifications and bolt replacements with immediate effect. No amendment, supersession or deviation from an earlier stated scope is contained within the supplied text."},"complexity_factors":["References to external documents (Boeing Service Bulletin No. 78-51 Rev. 1 and Boeing Service Letter 6-7132-3375) require operators to obtain and interpret those documents rather than containing full instructions in the AD itself.","The Service Letter is allowed as “or later revision”, which creates a need to determine applicable revision status.","Precise part-number identification (BAC-B30EK8-48 and BAC-C30EK8-48C) requires parts procurement and verification.","Timing is specified as “Forthwith”, an operationally ambiguous term that imposes immediate action without a quantified deadline.","Applicability to “All models” widens scope and potentially increases coordination and parts-supply complexity across an operator fleet."],"plain_english_summary":"This AD from CASA mandates immediate modification of Boeing 727 thrust‑reverser deflector doors and replacement of specified bolt part numbers, to be done exactly as directed in two Boeing service documents. It applies to all Boeing 727 operators and requires compliance “forthwith.”\n\nIt matters because it’s prescriptive, leaves little operational flexibility, and imposes parts, labour and downtime costs on operators to address an airworthiness concern the AD implies but does not describe."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive focused specifically on thrust reverser deflector doors for one aircraft type. It has not expanded beyond its original technical safety purpose."},"complexity_factors":["Extremely short document (approximately 150 words)","Only 3 specific technical requirements with clear alternative compliance paths","No defined terms section — uses standard aviation terminology (SB = Service Bulletin, SL = Service Letter, P/N = Part Number)","No cross-references to other legislation or regulations beyond the enabling authority (Civil Aviation Regulations 1998, Part 39)","Single, unambiguous compliance deadline ('Forthwith')","No conditional logic, exceptions, or nested provisions"],"plain_english_summary":"**What this is:** This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) that requires specific repairs or modifications to aircraft.\n\n**What it does:** It orders owners and operators of **all Boeing 727 aircraft** to modify the **thrust reverser deflector doors** — the panels that redirect engine thrust forward to help slow the plane after landing. The directive requires three specific actions:\n- **Modification 1:** Update the doors following Boeing Service Bulletin No. 78-51, Revision 1 (official manufacturer instructions for fixing a safety issue)\n- **Modification 2:** Alternatively, update the doors following Boeing Service Letter 6-7132-3375 dated 1 March 1967 (or later versions)\n- **Replacement:** Swap out specific bolts (part numbers BAC-B30EK8-48 or BAC-C30EK8-48C) with corrected versions\n\n**Who it affects:** Anyone who owns, operates, or maintains Boeing 727 aircraft in Australia.\n\n**Why it matters:** Thrust reversers are critical safety equipment. If the deflector doors fail or malfunction, the aircraft might not be able to stop safely on wet or short runways. The \"Forthwith\" compliance deadline means **do this immediately** — no grace period.\n\n**The bottom line:** If you're flying or fixing a Boeing 727 in Australia, you must make these door modifications and bolt replacements right away to keep the aircraft airworthy."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b727-57-thrust-reverser-deflector-doors-modification","history":"/api/acts/ad-b727-57-thrust-reverser-deflector-doors-modification/history","analysis":"/api/acts/ad-b727-57-thrust-reverser-deflector-doors-modification/analysis","conflicts":"/api/acts/ad-b727-57-thrust-reverser-deflector-doors-modification/conflicts","importantCases":"/api/acts/ad-b727-57-thrust-reverser-deflector-doors-modification/important-cases","documents":"/api/acts/ad-b727-57-thrust-reverser-deflector-doors-modification/documents"}}