{"id":"F2006B02737","name":"AD/B727/36 - Flap Track - Modification","slug":"ad-b727-36-flap-track-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42079,"registerId":"commonwealth-F2006B02737-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B727/36 - Flap Track - 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/B727/36 Flap Track - Modification 11/66\n\nApplicability: All models. Document: Boeing SB No. 57-72. 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\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, single-issue airworthiness directive from 1966 (indicated by '11/66' in the reference number). It addresses one specific technical modification to one aircraft type. There is no evidence of scope creep — it does exactly what it says on the tin: mandates a flap track modification for Boeing 727s."},"complexity_factors":["Extremely short document (approximately 100 words of substantive content)","No defined terms section — uses plain aviation terminology","No cross-references to other legislation beyond the enabling regulation (CAR 1998, Part 39)","Single, unambiguous compliance requirement with no exceptions or conditions","No nested logic or procedural steps — simply 'do what Boeing says in SB 57-72'","Standardised AD format with only four fields: Applicability, Document, Compliance, and the directive number"],"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) under the Civil Aviation Regulations 1998.\n\n**What it does:** It requires owners and operators of **Boeing 727 aircraft** to modify the **flap track** (the mechanical component that guides the wing flaps during takeoff and landing) according to Boeing Service Bulletin No. 57-72.\n\n**Who it affects:** Anyone who owns, operates, or maintains Boeing 727 series aeroplanes in Australia.\n\n**Why it matters:** Flap tracks are critical for safe flight. If they fail, the flaps may not extend or retract properly, potentially causing loss of control during landing or takeoff. This directive addresses a known safety defect.\n\n**When it must be done:** **\"Forthwith\"** — meaning immediately, without delay. This is the most urgent compliance timeframe in aviation safety regulation.\n\n**Key details:**\n- **Applies to:** All Boeing 727 models\n- **Follow this document:** Boeing Service Bulletin 57-72 (the manufacturer's official repair instructions)\n- **Compliance:** Immediate action required"},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The text provides no indication that the AD alters or expands an earlier scope; it states applicability as \"All models\" and requires compliance \"Forthwith.\" There is no evidence within this AD that the scope has changed from any prior instrument or intent."},"complexity_factors":["Extremely brief text: AD contains only applicability, reference document, and compliance timing.","Reliance on an external technical document (Boeing SB No. 57-72) for procedural detail — AD does not include technical steps.","Immediate compliance requirement (\"Forthwith\") creates operational urgency and potential scheduling complexity for operators.","No explanatory material in the AD about reason for modification, acceptable alternatives, or exemptions — increases practical uncertainty.","Scope is broad (\"All models\"), so implementation must be applied across the entire 727 fleet rather than a subset."],"plain_english_summary":"### What this instrument does\n\nThis is an airworthiness directive (AD) issued under the Commonwealth Civil Aviation Regulations Part 39. It orders a modification to the flap track on Boeing 727 series aeroplanes. The directive is identified as AD/B727/36 — \"Flap Track - Modification\" (11/66). (See heading and AD number.)\n\nMechanically, the AD requires affected aircraft to be modified in accordance with the Boeing service bulletin it references: \"Boeing SB No. 57-72.\" The AD does not itself set out technical steps; it refers operators to the Boeing service bulletin for the modification instructions. (See \"Document: Boeing SB No. 57-72.\")\n\nWho is affected\n\n- All Boeing 727 models are in scope: \"Applicability: All models.\" This means any operator of a Boeing 727 must address this directive. (See \"Applicability: All models.\")\n\nWhat the timing and legal effect are\n\n- Compliance is required immediately: the AD states \"Compliance: Forthwith,\" which imposes an immediate obligation on operators to perform the required modification. (See \"Compliance: Forthwith.\")\n- The directive is issued under the Civil Aviation Safety Authority's airworthiness directive schedule (Part 39). That is the decision-maker that imposes and enforces the requirement. (See Part 39 and AD heading.)\n\nStated source of the technical requirement\n\n- The AD points to a manufacturer service bulletin (Boeing SB No. 57-72) as the technical authority for how to carry out the work. Operators must follow that bulletin to satisfy the AD. (See \"Document: Boeing SB No. 57-72.\")\n\nPractical implications, trade-offs and implementation points\n\n- Who pays: Aircraft operators (owners/lessees) are responsible for carrying out the modification and therefore bear the direct costs of parts, labour, and aircraft downtime. The AD text creates the obligation; the service bulletin supplies the technical actions. (See \"Applicability: All models\"; \"Document: Boeing SB No. 57-72\"; \"Compliance: Forthwith.\")\n\n- Compliance burden: The AD imposes an immediate operational and maintenance burden because compliance is required \"forthwith.\" The operator must obtain and follow Boeing SB No. 57-72 and schedule the work, which can cause aircraft out-of-service time and require technician hours and possibly replacement parts. (See \"Compliance: Forthwith\" and referenced service bulletin.)\n\n- Decision authority and discretion: The Civil Aviation Safety Authority (under Part 39) issues and enforces the AD. The AD itself gives no indications of exemptions, alternative methods of compliance, or extension windows; any such discretion would be exercised by the regulator or appear in further written guidance, but is not present in the AD text. (See Part 39 and the AD text.)\n\n- Information gaps and implementation risk: The AD text is short and does not state the safety deficiency or technical reason for the modification, nor does it include technical steps. It relies on Boeing SB No. 57-72 for instructions and does not specify timelines beyond \"forthwith.\" This creates implementation uncertainty about exact work content, parts needed, and expected downtime until the service bulletin is consulted. (See absence of explanatory material in the AD; reference to Boeing SB No. 57-72.)\n\n- Incentives and costs: Because compliance is mandatory, operators must prioritise the modification against other maintenance needs and commercial schedules. The AD creates a clear compliance cost for each operator of a 727 model; any benefits claimed by the manufacturer or regulator (such as increased safety) are not set out in this AD and would need to be assessed from supporting materials outside the AD text. (See AD reference to service bulletin only.)\n\n- Concentration of effects: The burden falls on the population of Boeing 727 operators (a defined, concentrated group). The AD does not create ongoing regulatory levies or subsidies; it imposes a one-off (or discrete) modification obligation carried out under the service bulletin. (See \"Applicability: All models\" and the reference to Boeing SB No. 57-72.)\n\nSummary conclusion (mechanical description only)\n\nThe AD requires every Boeing 727 operator to carry out a flap-track modification immediately by following Boeing Service Bulletin No. 57-72. The AD sets a binding compliance obligation but provides no technical description or stated rationale within its text; the detailed procedure and technical justification are contained in the referenced Boeing service bulletin. (See AD title and the three labelled lines: Applicability; Document; Compliance.)"}},"importantCases":[],"_links":{"self":"/api/acts/ad-b727-36-flap-track-modification","history":"/api/acts/ad-b727-36-flap-track-modification/history","analysis":"/api/acts/ad-b727-36-flap-track-modification/analysis","conflicts":"/api/acts/ad-b727-36-flap-track-modification/conflicts","importantCases":"/api/acts/ad-b727-36-flap-track-modification/important-cases","documents":"/api/acts/ad-b727-36-flap-track-modification/documents"}}