{"id":"F2006B02713","name":"AD/B727/189 - Engine Mount Forward Cone Bolt Flange Attachment","slug":"ad-b727-189-engine-mount-forward-cone-bolt-flange-attachment","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42029,"registerId":"commonwealth-F2006B02713-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B727/189 - Engine Mount Forward Cone Bolt Flange Attachment","content":"![](image.001.png)\n\n![](image.001.png)  \nAIRWORTHINESS DIRECTIVE\n\nFor the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\n![](image.001.png)  \n\nBoeing 727 Series Aeroplanes\n\nAD/B727/189 Engine Mount Forward Cone Bolt\n\nFlange Attachment\n\n  \n7/2004\n\nApplicability: All Model 727, 727C, 727-100, 727-100C, 727-200, and 727-200F series aircraft.\n\nRequirement: 1. Inspect the bolts that are used to attach the forward cone bolt to the engine flange to determine if they are H-11 steel bolts (part number (P/N) BACB30GU12-64), cadmium-plated bolts (P/N BACB30LM12-64), or corrosion resistant bolts (P/N NAS6712E64 or B27-53-031-111, not listed in the service bulletin), in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin (ASB) 727-71A0402, dated 18 January 2001.\n\n    If corrosion resistant bolts, P/N NAS6712E64 or P/N B27-53-031-111 are installed, no further action is required.\n\n    b. If any H-11 steel bolt or cadmium-plated bolt is found, before further flight, replace the bolt with a new corrosion resistant bolt, P/N NAS6712E64, in accordance with the Accomplishment Instructions of ASB 727-71A0402.\n\n2 No H-11 steel bolt, P/N BACB30GU12-64, or cadmium-plated bolt, P/N BACB30LM12-64 shall be installed to attach the forward cone bolt to the engine flange on any aircraft.\n\nNote: FAA AD 2004-09-36 Amdt 39-13627 refers.\n\nCompliance: 1. Within 18 months or 3,000 flight cycles after 8 July 2004, whichever occurs first.\n\n2. As of the effective date of this Directive\n\nThis Airworthiness Directive becomes effective on 8 July 2004.\n\nBoeing 727 Series Aeroplanes\n\nAD/B727/189 (continued)\n\nBackground: The FAA requires an inspection of the bolts used to attach the engine mount forward cone bolt to the engine flange to determine what bolts are installed, and replacement of certain bolts. This action is necessary to prevent undetected cracking of H-11 bolts or excessive wear of cadmium-plated bolts, which could compromise the load path of the engine support and could result in separation of the engine from the aircraft.\n\n![Signature of David Villiers, Delegate of the Civil Aviation Safety Authority.](image.002.png)  \n\nDavid Villiers\n\nDelegate of the Civil Aviation Safety Authority 28 May 2004\n\n![](image.001.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 16 June 2004.","sortOrder":0}],"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"},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"This AD stays within the original safety remit stated in its Background: identify and remove bolts that may crack or wear and could compromise the engine support. The requirements are limited to inspection, replacement with a specified corrosion‑resistant part, and a prohibition on reinstallation of the identified bolt types. It does not add unrelated obligations, new categories of aircraft, or broaden regulatory reach beyond the stated engine‑mount bolt safety issue."},"complexity_factors":["Short document (two action items + timing)","Clear applicability limited to defined Boeing 727 variants","Only a small set of part numbers to identify (4 PNs named)","Single external service bulletin referenced for technical steps (Boeing ASB 727‑71A0402)","Compliance window defined with a simple condition (18 months or 3,000 flight cycles, whichever first)","One absolute operational prohibition (no installation of two specified PNs)","No extensive defined‑terms section or multiple cross‑references","Reference to an FAA AD for background but not additional procedural complexity"],"plain_english_summary":"**What this Airworthiness Directive (AD) does**\n\n- Applies to: All Boeing 727 series aeroplanes listed (Model 727, 727C, 727‑100, 727‑100C, 727‑200, 727‑200F). (Applicability)\n\n- Mechanical requirement: Inspect the bolts that attach the engine mount forward cone bolt to the engine flange to identify their part numbers (PN). If the bolts already installed are corrosion‑resistant bolts (PN NAS6712E64 or PN B27‑53‑031‑111), no further action is required. If the bolts are H‑11 steel (PN BACB30GU12‑64) or cadmium‑plated (PN BACB30LM12‑64), each such bolt must be replaced with a new corrosion‑resistant bolt (PN NAS6712E64) before the aircraft’s next flight. (Requirement 1)\n\n- Ongoing restriction: From the AD’s effective date, operators must not install H‑11 steel or cadmium‑plated bolts to attach the forward cone bolt to the engine flange. (Requirement 2)\n\n- Timing: The inspection and any required replacements must be done within 18 months or 3,000 flight cycles after 8 July 2004, whichever happens first. The installation ban is effective immediately as of the AD date. (Compliance)\n\n- How to do it: The inspection and replacement must follow the Accomplishment Instructions in Boeing Alert Service Bulletin 727‑71A0402 (dated 18 January 2001). The AD also cites the related FAA AD for reference. (Requirement; Note)\n\n**Why the AD exists (stated purpose)**\n\n- The AD’s background explains the safety concern: H‑11 steel bolts may develop undetected cracking and cadmium‑plated bolts may experience excessive wear. Either condition could weaken the engine support load path and could lead to engine separation from the aircraft. The inspection and replacement requirements are intended to remove those unsafe bolts and prevent that outcome. (Background)\n\n**Who pays and who decides**\n\n- Who pays: Aircraft operators (airlines, lessors, maintenance organisations) bear the direct costs of inspections, parts and labour to replace bolts. Supply chains that provide the approved corrosion‑resistant bolts may see increased demand.\n\n- Who decides: The Civil Aviation Safety Authority (CASA) delegate issued the AD under CASR subregulation 39.1(1). The AD directs operators to follow Boeing’s service bulletin for the detailed work steps.\n\n**Practical effects and implementation considerations**\n\n- Direct actions required of operators: identify the PN on each forward cone bolt attachment, replace nonconforming bolts before next flight, and ensure maintenance procedures prevent future installation of the banned PNs. (Requirement 1–2)\n\n- Compliance burden: workhours for inspection, possible aircraft downtime while swapping bolts, procurement lead time for NAS6712E64 bolts, and recordkeeping to show compliance with the AD and the referenced service bulletin.\n\n- Supply and substitution risk: The AD specifies one approved replacement PN (NAS6712E64). If that part is scarce, operators may face delays or need to seek approved alternatives via regulatory relief or engineering approval.\n\n- Safety trade‑off and opportunity cost: The AD reduces the risk of bolt failure (stated safety benefit) at the cost of inspection and replacement expenditure and possible aircraft out‑of‑service time.\n\n- Enforcement and discretion: The AD sets a mandatory inspection/replace rule and an installation ban; any deviation requires regulatory approval. The CASA delegate enforced the requirement in line with CASR powers. (AD header)\n\n**Citations in the AD text**\n\n- Inspections and replacement: Requirement 1\n- Permanent ban on certain bolts: Requirement 2\n- Timing: Compliance\n- Detailed procedures: Boeing Alert Service Bulletin 727‑71A0402 (18 January 2001)\n- Stated safety rationale: Background (FAA/airworthiness concern)\n\nOverall, the AD prescribes a focused inspection and replacement program for a specific engine‑mount attachment bolt, prohibits future use of the problematic bolt types for that attachment, and anchors the detailed work to Boeing’s service bulletin. It shifts the immediate operational cost and logistical burden to aircraft operators while aiming to remove a potential cause of catastrophic structural failure."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This AD maintains its original narrow scope — addressing a specific unsafe condition in engine mount bolts on Boeing 727 aircraft. It has not expanded beyond its initial safety purpose."},"complexity_factors":["Short, single-purpose directive focused on one specific mechanical component","Only 4 defined part numbers to identify, with clear binary decision tree (inspect → if X then Y)","Minimal cross-referencing — only references one Boeing Service Bulletin (ASB 727-71A0402) and one FAA AD for context","Simple compliance structure with two distinct deadlines (one for inspection/replacement, one for installation ban)","No nested exceptions or conditional sub-clauses — straightforward if/then logic","Limited applicability (single aircraft type family, all variants included without exception)"],"plain_english_summary":"This AD requires operators of Boeing 727s to inspect the bolts attaching the engine‑mount forward cone to the engine flange and replace any H‑11 steel or cadmium‑plated bolts with corrosion‑resistant bolts before further flight. It also bans future installation of the unsafe bolt types. It affects airlines, owners and maintenance organisations and is critical because bolt failure could lead to engine separation; inspections were due within 18 months or 3,000 cycles from 8 July 2004."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b727-189-engine-mount-forward-cone-bolt-flange-attachment","history":"/api/acts/ad-b727-189-engine-mount-forward-cone-bolt-flange-attachment/history","analysis":"/api/acts/ad-b727-189-engine-mount-forward-cone-bolt-flange-attachment/analysis","conflicts":"/api/acts/ad-b727-189-engine-mount-forward-cone-bolt-flange-attachment/conflicts","importantCases":"/api/acts/ad-b727-189-engine-mount-forward-cone-bolt-flange-attachment/important-cases","documents":"/api/acts/ad-b727-189-engine-mount-forward-cone-bolt-flange-attachment/documents"}}