{"id":"F2006L03874","name":"AD/S-92/1 - Main Transmission Mounting Bolts","slug":"ad-s-92-1-main-transmission-mounting-bolts","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":60798,"registerId":"commonwealth-F2006L03874-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Sikorsky S-92 Series Helicopters","sectionType":"division","heading":"Sikorsky S-92 Series Helicopters","content":"### Sikorsky S-92 Series Helicopters\n\n| AD/S-92/1 | Main Transmission Mounting Bolts | 1/2007 |\n| --------- | -------------------------------- | ------ |\n\n| Applicability: | Model S-92A helicopters, with main transmission mounting bolt part number SS5211-10-47, installed.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |\n| -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Open the No. 1 and No. 2 engine work platforms to gain access to the main transmission mounting bolts. Remove each bolt, one at a time, and visually inspect the bolt shank and threads for wear or corrosion in accordance with paragraphs 3.A.(6)(a) of the Accomplishment Instructions in Sikorsky Aircraft Corporation Alert Service Bulletin No. 92-63-003, dated 1 February 2006.If wear or corrosion is detected, before further flight, replace an affected bolt, as well as the bolt barrel nut and cage, with a serviceable bolt part number SS5211-10-47, barrel nut part number RMLH2577-108, and cage part number NAS578-10B.Note: FAA AD 2006-11-14 Amdt 39-14618 refers. |\n| Compliance:    | Within 100 hours time in service after 18 January 2006, unless accomplished within the last 500 hours time in service.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |\n|                | This Airworthiness Directive becomes effective on 18 January 2007.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |\n| Background:    | The FAA received a report of a failure of a main transmission mounting bolt, detected during routine maintenance inspection. Undetected bolt failure could result in loss of support of the main transmission, and subsequent loss of control of the helicopter.                                                                                                                                                                                                                                                                                                                                                                                                                        |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n23 November 2006","sortOrder":0},{"sectionNumber":"AD/S-92/1","sectionType":"part","heading":"AD/S-92/1","content":"## AD/S-92/1","sortOrder":1},{"sectionNumber":"Main Transmission Mounting Bolts","sectionType":"part","heading":"Main Transmission Mounting Bolts","content":"## Main Transmission Mounting Bolts","sortOrder":2},{"sectionNumber":"1/2007","sectionType":"part","heading":"1/2007","content":"## 1/2007","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The AD remains narrowly focused on a specific hardware safety issue (main transmission mounting bolt P/N SS5211-10-47) for the S-92A. It does not expand into unrelated areas, additional components, or broader operational constraints beyond the single inspection-and-replace requirement. Therefore the scope has not grown beyond the original safety purpose described in the Background."},"complexity_factors":["Single helicopter model subset: only Sikorsky S-92A helicopters fitted with bolt P/N SS5211-10-47","Short, single-scope directive: one inspection requirement with a single remedial action (replace bolt, barrel nut and cage if wear/corrosion found)","Cross-reference to external documents: Sikorsky Alert Service Bulletin No. 92-63-003 (paragraph 3.A.(6)(a)) and FAA AD 2006-11-14","Simple compliance timing with one conditional exception: inspect within 100 hours TIS after 18 Jan 2006 unless already done within the last 500 hours TIS","Limited procedural detail in the AD itself (inspection protocol delegated to the manufacturer service bulletin), creating a dependence on that external document for technical specifics"],"plain_english_summary":"**What this instrument does**\n\n- This Airworthiness Directive (AD) requires operators of Sikorsky S-92A helicopters that have a specific main transmission mounting bolt installed (part number SS5211-10-47) to inspect those bolts for wear or corrosion, and to replace any bolt found to be worn or corroded together with its barrel nut and cage before further flight.\n\n**Who it affects**\n\n- Owners and operators of Sikorsky S-92A helicopters with main transmission mounting bolt P/N SS5211-10-47 installed.\n- Maintenance organisations and mechanics who perform the inspections and any required replacements.\n\n**How it works, mechanically**\n\n- Applicability: the AD applies only to S-92A helicopters fitted with the listed bolt part number (SS5211-10-47).\n- Access: it requires opening the No. 1 and No. 2 engine work platforms so the bolts can be reached.\n- Inspection: remove each bolt one at a time and visually inspect the bolt shank and threads for wear or corrosion, following paragraph 3.A.(6)(a) of Sikorsky Alert Service Bulletin No. 92-63-003 (dated 1 February 2006).\n- Remedy: if wear or corrosion is found, replace the affected bolt, and also replace the bolt barrel nut and cage with specified serviceable parts (bolt SS5211-10-47, barrel nut RMLH2577-108, cage NAS578-10B) before further flight.\n- Timing (Compliance): the inspection must be completed within 100 hours time in service after 18 January 2006, unless the required action was already done within the last 500 hours time in service.\n\n**Why it matters (stated purpose and operational effect)**\n\n- The stated safety reason (Background) is that the FAA reported a failure of a main transmission mounting bolt found during routine maintenance. If a bolt fails without detection, the main transmission could lose support and that could lead to a loss of control of the helicopter.\n\n**Who pays and who decides**\n\n- Costs are borne by the helicopter owners/operators: they pay for removing the work platforms (labour/time), the inspections, and the replacement parts if needed. The parts specified are identifiable by part numbers in the AD.\n- The decision-making is operational and technical: maintenance staff must follow the inspection steps in the Sikorsky Alert Service Bulletin and the AD; the regulator (Civil Aviation Safety Authority delegate) has issued the AD requiring compliance.\n\n**Compliance burden, trade-offs and implementation risks**\n\n- Compliance burden: the work requires access to engine work platforms and removal of each bolt for inspection. It may require aircraft downtime and standard maintenance labour. If replacements are needed, there is cost and parts procurement lead time.\n- Implementation risk: the AD relies on a visual inspection procedure in the Sikorsky service bulletin. Visual inspections can be subjective; different maintainers may reach different judgements about marginal wear. Availability of the specified replacement parts could affect the ability to return the helicopter to service quickly.\n- Incentives and choices: operators may choose to replace bolts proactively rather than risk detection of wear later. The AD encourages monitoring and replacement rather than continued operation with suspect hardware.\n\n**Relationship to other instruments**\n\n- The AD cross-references Sikorsky Alert Service Bulletin No. 92-63-003 for the inspection procedure and notes FAA AD 2006-11-14. This ties the requirement to manufacturer guidance and a related FAA directive.\n\n**Net effect**\n\n- Mechanically, the AD imposes a time-limited inspection requirement (100 hours TIS from the date specified) for a narrow set of helicopters and mandates replacement of any worn or corroded bolts together with specified companion parts before further flight. It aims to reduce the risk of in-service bolt failure by ensuring inspection and replacement where necessary."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This AD addresses a specific, isolated safety defect identified by the FAA. It has not expanded beyond its original purpose of ensuring the airworthiness of main transmission mounting bolts on affected S-92A helicopters."},"complexity_factors":["Single, discrete safety issue (one bolt type on one helicopter model)","Straightforward compliance pathway: inspect, and replace if necessary","Only one defined part number triggering applicability","Simple conditional logic: 100-hour deadline with 500-hour lookback exception","No nested definitions, no cross-references to other legislation beyond a note about the related FAA directive","Total length: approximately 200 words of operative text"],"plain_english_summary":"CASA requires operators of Sikorsky S‑92A helicopters with specific main transmission mounting bolts (P/N SS5211‑10‑47) to remove and inspect those bolts for wear or corrosion, replacing damaged bolts and associated hardware before further flight.  \n\nThis urgent AD follows an FAA-reported bolt failure; a failed bolt could let the main transmission lose support and lead to loss of control. Inspections are due within 100 flight hours after 18 January 2006 (unless already done within 500 hours)."},"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-s-92-1-main-transmission-mounting-bolts","history":"/api/acts/ad-s-92-1-main-transmission-mounting-bolts/history","analysis":"/api/acts/ad-s-92-1-main-transmission-mounting-bolts/analysis","conflicts":"/api/acts/ad-s-92-1-main-transmission-mounting-bolts/conflicts","importantCases":"/api/acts/ad-s-92-1-main-transmission-mounting-bolts/important-cases","documents":"/api/acts/ad-s-92-1-main-transmission-mounting-bolts/documents"}}