{"id":"F2007L01357","name":"AD/SA 315/15 - MGB Output Flange","slug":"ad-sa-315-15-mgb-output-flange","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":65627,"registerId":"commonwealth-F2007L01357-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Eurocopter SA 315 (Lama) Series Helicopt","sectionType":"division","heading":"Eurocopter SA 315 (Lama) Series Helicopters","content":"### Eurocopter SA 315 (Lama) Series Helicopters\n\n| AD/SA 315/15 | MGB Output Flange | 6/2007 |\n| ------------ | ----------------- | ------ |\n\n| Applicability: | Eurocopter SA315B (LAMA) helicopters fitted with MGB P/N 319A.62.00.000.1 through .4.                                                                                                                                                                                                                                                                                                                                                     |\n| -------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. Measure the play at the location of the assembly through measurement of the angular displacement on the MGB output flange, in accordance with Eurocopter Service Bulletin (SB) No. 05.16 or later approved revision.2. If the displacement measured exceeds 1mm the MGB must be removed for repair.Note: DGAC AD 80-194-20(B) dated 17 October 1980 refers.                                                                            |\n| Compliance:    | 1. For MGB’s accumulating more than 390 flight hours, within 10 flight hours of operation from the effective date of this AD, thereafter at intervals not to exceed 400 flight hours.For MGB’s having accumulated less than 390 flight hours at the effective date of this AD, before accumulating 400 flight hours, thereafter at intervals not to exceed 400 flight hours.2. Before further flight after the effective date of this AD. |\n|                | This Airworthiness Directive becomes effective on 7 June 2007.                                                                                                                                                                                                                                                                                                                                                                            |\n| Background:    | The measurement detailed in this AD determines the allowable wear limit within the splines on the MGB. The actions detailed in this AD are intended to prevent failure of the MGB and the subsequent loss of control of the helicopter.                                                                                                                                                                                                   |\n\n![](image.001.png)  \nDavid Punshon  \nDelegate of the Civil Aviation Safety Authority\n\n26 April 2007","sortOrder":0},{"sectionNumber":"AD/SA 315/15","sectionType":"part","heading":"AD/SA 315/15","content":"## AD/SA 315/15","sortOrder":1},{"sectionNumber":"MGB Output Flange","sectionType":"part","heading":"MGB Output Flange","content":"## MGB Output Flange","sortOrder":2},{"sectionNumber":"6/2007","sectionType":"part","heading":"6/2007","content":"## 6/2007","sortOrder":3}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard, narrowly-targeted Airworthiness Directive addressing a specific mechanical wear issue in a specific helicopter model. The scope remains tightly focused on the original safety purpose — preventing MGB output flange failure — with no evidence of scope creep or expansion beyond this technical safety requirement."},"complexity_factors":["Single, clearly defined applicability (one helicopter model, specific part number range)","Two straightforward requirements: measure wear, repair if over limit","Simple conditional logic (if >1mm then repair)","Clear compliance timeline with only two scenarios based on existing flight hours","No nested definitions or extensive cross-referencing to other legislation","Background explanation provided in plain language","Total length: approximately 200 words of substantive content"],"plain_english_summary":"This CASA Airworthiness Directive mandates operators of Eurocopter SA315B Lama helicopters with specified main gearbox part numbers to measure wear on the MGB output flange per the referenced Eurocopter Service Bulletin and remove/repair any gearbox with over 1 mm wear. Compliance is immediate (before further flight after 7 June 2007) and recurring every 400 flight hours. It prevents spline failure that could cause loss of control."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive is narrowly targeted to measure and limit wear on the MGB output flange and to require repair if wear exceeds 1 mm. It remains focused on that original safety objective and does not introduce additional regulatory areas, broader operational restrictions, or discretionary powers. Therefore the scope has not grown beyond its original purpose; it maintains a single technical safety remit (inspection cadence, measurement method, and repair requirement)."},"complexity_factors":["Short, single-issue directive focused on one component (MGB output flange).","Clear applicability: specific helicopter model and specific MGB part numbers listed.","Single numerical wear limit (1 mm) provides a straightforward pass/fail criterion.","Two-tier flight-hour timing rule (>=390 hours versus <390 hours) introduces a small conditional element to scheduling inspections.","Reference to an external document (Eurocopter Service Bulletin No. 05.16) creates a dependency on another technical document but does not add internal legal complexity.","One mandatory remedial action (remove MGB for repair) if threshold exceeded; no nested exceptions or discretionary carve-outs."],"plain_english_summary":"**What this instrument does (mechanics)**\n\n- It requires owners/operators of certain Eurocopter SA315B (Lama) helicopters to measure wear (play) at the main gearbox (MGB) output flange and to remove the MGB for repair if the measured angular displacement exceeds a fixed limit (1 mm). (Applicability; Requirement)\n- The measurement must follow Eurocopter Service Bulletin No. 05.16 (or a later approved revision). (Requirement)\n- Timing: helicopters whose MGBs already have more than 390 flight hours must be inspected within 10 flight hours of this directive, then every 400 flight hours thereafter; MGBs under 390 flight hours must be inspected before they reach 400 hours and then every 400 hours. If the displacement exceeds 1 mm the helicopter must not fly until the MGB is removed and repaired. (Compliance)\n\n**Who this affects**\n\n- Directly affects owners/operators of Eurocopter SA315B (Lama) helicopters fitted with MGB part numbers 319A.62.00.000.1 through .4. (Applicability)\n- Affects maintenance organisations and technicians who must perform the measurement and, where necessary, repair or remove the MGB in accordance with the referenced service bulletin. (Requirement)\n\n**Why it matters (safety mechanism and intended effect)**\n\n- The rule sets an inspection and wear limit for the splines on the MGB output flange to reduce the risk of gearbox failure and associated loss of helicopter control. The directive’s stated aim is to prevent MGB failure by catching excessive wear early and requiring repair before further flight. (Background; Requirement)\n\n**Who pays and who decides**\n\n- Owners/operators pay for the inspections, possible removal, repairs, and associated downtime. (Compliance; Requirement)\n- The regulator (Civil Aviation Safety Authority delegate) issues and enforces the directive; the measurement procedure referenced is Eurocopter’s Service Bulletin No. 05.16 (or later approved revision), which the operator must follow. (Requirement)\n\n**Practical effects and compliance burden**\n\n- Required actions are technical: measuring angular displacement on the output flange to a 1 mm criterion, following the specified service bulletin. This requires trained personnel and appropriate tooling to obtain a reliable measurement. (Requirement)\n- If the wear exceeds the limit the MGB must be removed for repair, which creates aircraft downtime and repair costs; frequency of inspections is tied to flight hours (every 400 hours after the first required inspection), which produces predictable recurring maintenance burden. (Compliance)\n\n**Costs, incentives, trade-offs and implementation risks**\n\n- Direct costs: inspection labour, measurement tooling, possible repair or overhaul, and aircraft downtime. These costs fall on the operator/owner. (Requirement; Compliance)\n- Timing incentive: because the inspection interval is tied to flight hours, higher-utilisation operators will face proportionally higher inspection frequency and associated costs. (Compliance)\n- Implementation risks include measurement variability (accuracy and repeatability of angular displacement checks), availability of the correct service bulletin revision or approved alternative, and capacity for repair/removal at maintenance providers—delays or limited MRO capacity could extend downtime. (Requirement)\n- Substitution effects: operators facing high repair costs or limited MRO access may reduce utilisation, defer flights (subject to safety and regulatory limits), or retire/replace affected airframes. The directive itself does not prescribe replacements or a mandatory parts change—only measurement and repair if threshold exceeded. (Requirement)\n\n**Notes and cross-references**\n\n- The directive references an earlier French AD (DGAC AD 80-194-20(B)) and requires using Eurocopter SB No. 05.16 as the measurement procedure; compliance therefore depends on following that manufacturer procedure or any later approved revision. (Requirement; Background)\n\nOverall, this is a targeted, technical maintenance requirement that sets a clear wear threshold and a flight-hour based inspection cadence to manage risk of MGB output flange spline failure. It places inspection and repair costs and operational impact on the helicopter owner/operator, while delegating measurement procedure detail to the manufacturer service bulletin cited (subject to regulator approval)."},"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-sa-315-15-mgb-output-flange","history":"/api/acts/ad-sa-315-15-mgb-output-flange/history","analysis":"/api/acts/ad-sa-315-15-mgb-output-flange/analysis","conflicts":"/api/acts/ad-sa-315-15-mgb-output-flange/conflicts","importantCases":"/api/acts/ad-sa-315-15-mgb-output-flange/important-cases","documents":"/api/acts/ad-sa-315-15-mgb-output-flange/documents"}}