{"id":"F2005L03575","name":"AD/B737/269 - Engine Mount Cone Bolt Nuts","slug":"ad-b737-269-engine-mount-cone-bolt-nuts","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":39151,"registerId":"commonwealth-F2005L03575-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Boeing 737 Series Aeroplanes","sectionType":"division","heading":"Boeing 737 Series Aeroplanes","content":"### Boeing 737 Series Aeroplanes\n\n| AD/B737/269 | Engine Mount Cone Bolt Nuts | 13/2005 |\n| ----------- | --------------------------- | ------- |\n\n| Applicability: | All Model 737-100, -200, and -200C series aircraft.                                                                                                                                                                                                                                                                                                                                                                             |\n| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Inspect the engine mount cone bolt nuts and remove from service any nut that is not identified in FAA AD 89-21-02 Amdt 39-6342; or,Inspect the engine mount cone bolt nuts to establish conformity to the cone bolt nuts identified and described in Boeing Service Letter (SL) 727-SL-71-014-C.Note: FAA Letter, reference 97-120S-490 (FAA Alternate Method of Compliance for FAA AD 89-21-02), and SL 727-SL-71-014-C refer. |\n| Compliance:    | Before each cone bolt nut installation, effective 22 December 2005.                                                                                                                                                                                                                                                                                                                                                             |\n|                | This Airworthiness Directive becomes effective on 22 December 2005.                                                                                                                                                                                                                                                                                                                                                             |\n| Background:    | The FAA determined that bogus nuts have been introduced and sold to aircraft repair stations and parts distributors world-wide.This Directive also introduces an alternate method of compliance to FAA AD89-21-02, in order to use authentic cone bolt nuts manufactured by Standard Pressed Steel (SPS) Technologies that do not specifically conform to the part number description in AD 89-21-02.                           |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n11 November 2005","sortOrder":0},{"sectionNumber":"AD/B737/269","sectionType":"part","heading":"AD/B737/269","content":"## AD/B737/269","sortOrder":1},{"sectionNumber":"Engine Mount Cone Bolt Nuts","sectionType":"part","heading":"Engine Mount Cone Bolt Nuts","content":"## Engine Mount Cone Bolt Nuts","sortOrder":2},{"sectionNumber":"13/2005","sectionType":"part","heading":"13/2005","content":"## 13/2005","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"This Australian AD adapts and narrows the original FAA requirement by formally accepting an alternative compliance route: it allows the use of authentic cone bolt nuts manufactured by Standard Pressed Steel (SPS) Technologies even when those nuts do not precisely match the part-number description in FAA AD 89-21-02. In effect, the AD modifies the universe of \"acceptable\" parts from strictly those listed in FAA AD 89-21-02 to include SPS-manufactured nuts that conform to the Boeing Service Letter description (and the FAA alternate compliance letter). That broadens permissible replacement parts compared with a literal reading of the FAA AD while preserving the AD’s safety objective of excluding counterfeit or otherwise non-conforming nuts."},"complexity_factors":["Short, single-aircraft-family applicability (all 737-100, -200, -200C)","Simple core requirement: inspect and remove non-conforming nuts before installation (straightforward conditional)","Relies on 2 external FAA/Boeing documents for identification and alternate compliance (FAA AD 89-21-02; Boeing SL 727-SL-71-014-C)","Refers to an FAA Alternate Method of Compliance letter (97-120S-490) which adds a compliance pathway","No detailed inspection procedure in the AD text — identification criteria are in external documents (adds practical complexity)","Single effective date and single compliance timing (before each installation) — low procedural branching","Limited number of defined terms and no nested exceptions"],"plain_english_summary":"**What this instrument does (mechanically)\n\n- Requires operators of Boeing 737-100, -200 and -200C aircraft to check (inspect) the engine mount cone bolt nuts before installing them. (Applicability; Requirement.)\n- If an inspected nut is not one of the nuts identified in FAA AD 89-21-02 Amdt 39-6342, the nut must be taken out of service (removed). (Requirement.)\n- As an alternative, operators may inspect nuts and confirm they conform to the cone bolt nuts described in Boeing Service Letter 727-SL-71-014-C; that is an approved alternate method of compliance. The AD also refers to an FAA letter (97-120S-490) that sets out the alternate compliance route. (Requirement; Background.)\n- The inspection/verification must be done before each cone bolt nut installation. The directive took effect 22 December 2005. (Compliance.)\n\nWho this affects\n\n- Aircraft operators, maintenance organisations and approved parts distributors that service or supply cone bolt nuts for the engine mounts of Boeing 737-100/200/200C aircraft. (Applicability; Requirement.)\n- Parts suppliers and repair stations that supply or sell cone bolt nuts for these models, because they must ensure parts are either the part numbers listed in FAA AD 89-21-02 or conform to the Boeing Service Letter description. (Background; Requirement.)\n\nWhy it matters (official rationale and practical effects)\n\n- The stated purpose is to stop counterfeit or incorrect cone bolt nuts (\"bogus nuts\") entering service on these aircraft because such parts can compromise engine mount integrity. (Background.)\n- Practically, the rule forces operators to spend time and resources verifying the authenticity and conformity of cone bolt nuts before they are fitted. If nuts fail verification, they must be removed and replaced with acceptable parts. (Requirement; Compliance.)\n\nCosts, incentives and implementation mechanics\n\n- Who pays: operators and their maintenance suppliers bear the direct costs — inspection labour, possible replacement parts, and administrative verification. (Requirement; Compliance.)\n- Who decides: maintenance personnel or authorised inspectors must perform the inspections and make serviceability decisions; regulatory acceptance of an alternate method is achieved by following the referenced FAA letter and Boeing service letter. (Requirement; Background.)\n- Behaviour changes required: increased pre-installation checking, tighter parts sourcing discipline, possible changes to inventory (to hold approved parts), and possible supplier audits to ensure authenticity. (Requirement; Background.)\n- Trade-offs and opportunity costs: time spent on inspection and paperwork versus operating time; potential supply-chain friction if suppliers cannot readily prove parts conformity; but reduced risk of installation of counterfeit parts. (Requirement; Background.)\n- Implementation risks: distinguishing counterfeit from authentic parts depends on external documents (FAA AD, FAA letter, Boeing Service Letter). Reliance on those documents may create ambiguity for maintenance staff if identification guidance is technical or incomplete. (Requirement; Background.)\n- Effects on competition and prices: the AD potentially narrows acceptable suppliers to those who can demonstrate conformity (including Standard Pressed Steel (SPS) Technologies as explicitly acknowledged), which may raise procurement costs in the short term but also reduces market for non‑conforming/counterfeit parts. (Background.)\n\nConcise operational note\n\n- Before installing any engine mount cone bolt nut on a 737-100/200/200C: inspect it; if it is not listed in FAA AD 89-21-02 or cannot be shown to conform to Boeing Service Letter 727-SL-71-014-C (or covered by the FAA alternate compliance letter), don’t install it — remove from service. (Requirement; Compliance.)"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific counterfeit parts issue. It has not expanded beyond its original purpose of ensuring authentic engine mount hardware on specific Boeing 737 variants."},"complexity_factors":["Short, single-purpose directive with one specific mechanical component in scope","Only 2 compliance pathways (inspect against FAA AD 89-21-02, or inspect against Boeing Service Letter)","Cross-references to 3 external documents (FAA AD 89-21-02, Boeing SL 727-SL-71-014-C, FAA Letter 97-120S-490) but these are incorporated by reference rather than reproduced","No defined terms section — uses standard aviation terminology","Single applicability criterion (specific aircraft models) with no exceptions or conditional logic","Straightforward compliance deadline (before each installation, effective specific date)"],"plain_english_summary":"This CASA Airworthiness Directive requires inspection of cone‑bolt nuts used to secure engine mounts on Boeing 737‑100/‑200/‑200C aircraft before installation, after discovery of counterfeit nuts in the supply chain. Mechanics must remove and not use any nut that doesn’t meet approved specifications; parts from Standard Pressed Steel (SPS) Technologies are an acceptable alternative.  \n\nIt affects operators, maintenance organisations and parts suppliers and prevents catastrophic engine‑attachment failures from counterfeit hardware."},"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"}},"importantCases":[],"_links":{"self":"/api/acts/ad-b737-269-engine-mount-cone-bolt-nuts","history":"/api/acts/ad-b737-269-engine-mount-cone-bolt-nuts/history","analysis":"/api/acts/ad-b737-269-engine-mount-cone-bolt-nuts/analysis","conflicts":"/api/acts/ad-b737-269-engine-mount-cone-bolt-nuts/conflicts","importantCases":"/api/acts/ad-b737-269-engine-mount-cone-bolt-nuts/important-cases","documents":"/api/acts/ad-b737-269-engine-mount-cone-bolt-nuts/documents"}}