{"id":"F2006L02214","name":"AD/T53/22 - Engine Fuel Pump Spline Failure","slug":"ad-t53-22-engine-fuel-pump-spline-failure","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":117542,"registerId":"commonwealth-F2006L02214-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AlliedSignal (Lycoming) Turbine Engines ","sectionType":"division","heading":"AlliedSignal (Lycoming) Turbine Engines - T53 Series","content":"### AlliedSignal (Lycoming) Turbine Engines - T53 Series\n\n| AD/T53/22 | Engine Fuel Pump Spline Failure | 8/2006 |\n| --------- | ------------------------------- | ------ |\n\n| Applicability: | Honeywell International Inc., (formerly AlliedSignal, Inc., formerly Textron Lycoming, formerly Avco Lycoming) T5311A, T5311B, T5313B, T5317A,T5317A-1, and T5317B series turboshaft engines and Lycoming former militaryT53-L-11B, T53-L-11D, T53-L-13B, T53-L-13B/D, and T53-L-703 series turboshaft engines using Goodrich Pump & Engine Control Systems, Inc. (GPECS) (formerly Chandler Evans Control Systems) engine fuel control regulator assembly modelsTA-2S, TA-2G, TA-2F, TA-7, or TA-10.Note 1: The T5311A, T5311B, T5313B, T5317A, T5317A-1, and T5317B turboshaft engines are installed on, but not limited to, Bell 204, 205, and Kaman K-1200 helicopters. Lycoming T53-L-11B, T53-L-11D, T53-L-13B, T53-L-13B/D, andT53-L-703 series turboshaft engines are installed on, but not limited to, Bell AH-1 and UH-1 helicopters.                      |\n| -------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. Remove the fuel control regulator assembly from the engine and perform an initial visual and dimensional inspection of the fuel control regulator assembly main and secondary drive shaft and pump gear splines for wear in accordance with paragraphs 2.A. through 2.D.(7) and 2.E. through 2.F.(2) of the Accomplishment Instructions of Goodrich Pump & Engine Control Systems, Inc. (TA series) Service Bulletin (SB) No. 73-42, Revision 1, dated 12 August 2004 or later FAA approved revision.2. Perform repetitive visual and dimensional inspections of the fuel control regulator assembly main and secondary drive shaft and pump gear splines for wear, as specified in requirement 1 of this AD.3. Do not install any engine fuel control regulator assembly that fails inspection.Note 2: FAA AD 2006-11-16 Amdt 39-14620 dated 23 May 2006 refers. |\n| Compliance:    | 1. Within 150 flight hours after the effective date of this AD, unless previously accomplished.2. Repetitively every 1,250 flight hours since-last- inspection.3. From the effective date of this AD.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |\n|                | This Airworthiness Directive becomes effective on 3 August 2006.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |\n\n| Background: | This AD results from several reports of loss of fuel flow from the engine fuel control regulator assembly due to failure of both main and secondary drive shaft and pump gear splines. The actions detailed in this AD are intended to prevent in-flight engine failure and forced autorotation landing. |\n| ----------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n\n![](image.001.png)  \nJames Coyne  \nDelegate of the Civil Aviation Safety Authority\n\n21 June 2006","sortOrder":0},{"sectionNumber":"AD/T53/22","sectionType":"part","heading":"AD/T53/22","content":"## AD/T53/22","sortOrder":1},{"sectionNumber":"Engine Fuel Pump Spline Failure","sectionType":"part","heading":"Engine Fuel Pump Spline Failure","content":"## Engine Fuel Pump Spline Failure","sortOrder":2},{"sectionNumber":"8/2006","sectionType":"part","heading":"8/2006","content":"## 8/2006","sortOrder":3}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a targeted safety directive addressing a specific mechanical failure mode (spline wear in fuel pump drives). The scope remains precisely focused on the identified safety risk without expansion into unrelated operational or maintenance areas."},"complexity_factors":["Single, specific mechanical issue addressed (fuel pump spline wear)","Clear three-part compliance structure (initial inspection, repetitive inspection, installation prohibition)","Only 5 specific fuel pump models and 11 engine variants covered","References one external technical document (Goodrich Service Bulletin 73-42) but provides specific paragraph references","Straightforward timeline: 150 hours initial, 1,250 hours recurring","No nested exceptions, conditional clauses, or alternative compliance methods","Limited cross-referencing (only one FAA AD mentioned in a note)"],"plain_english_summary":"This AD requires owners/operators of helicopters with certain Honeywell/Lycoming T53 engines and specific Goodrich fuel pumps to inspect and, if worn, replace the fuel control regulator assembly to address a design flaw that can cause sudden fuel flow loss. Mechanics must perform an initial inspection soon after the AD takes effect and repeat checks at intervals, replacing any failed parts.\n\nIt matters because simultaneous spline failure has caused complete engine shutdowns, risking forced autorotation and crashes."},"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":6,"scope_assessment":{"changed":false,"description":"The directive targets the spline wear failure mode on specified T53-family engines and particular Goodrich TA regulator models, matching the stated safety objective. The AD confines obligations to listed engine and regulator models and prescribes inspections, intervals and an installation prohibition; the source text contains no indication the scope was broadened beyond that original intent."},"complexity_factors":["Broad applicability across multiple engine models and military/civil variants (Applicability).","Applies to several Goodrich TA-series regulator assembly models, increasing parts-variability to inspect (Applicability).","Inspections require both visual and dimensional checks of main and secondary drive‑shaft and pump gear splines (Requirement).","Detailed inspection steps are performed by following Goodrich SB No. 73-42 Revision 1 (or later FAA-approved revision), adding an external-document dependency (Requirement).","Staggered compliance timing: initial action within 150 flight hours and repetitive checks every 1,250 flight hours, creating scheduling and tracking obligations (Compliance).","Explicit prohibition on installing any assembly that fails inspection, forcing replacement or refurbishment costs (Requirement).","Cross-reference to FAA AD 2006-11-16 creates inter-jurisdictional regulatory linkage (Requirement/Note 2).","Removal of the regulator from the engine is required for inspection, implying engine downtime and labor costs (Requirement/Compliance).","Authority issued by CASA delegate indicates administrative enforcement by the regulator (signature/date block).","Requirement that procedures follow an FAA-approved revision introduces potential need to monitor future approvals and revisions (Requirement)."],"plain_english_summary":"Requires removal and inspection of Goodrich TA‑series fuel control regulator assemblies on specified Honeywell/Lycoming T53 turboshaft engines. CASA mandates an initial inspection within 150 flight hours and repeat inspections every 1,250 flight hours; assemblies that fail the visual and dimensional spline checks must not be reinstalled. The stated aim is to prevent loss of fuel flow and in‑flight engine failure. Operators bear inspection, repair and downtime costs; CASA (via this AD) sets the mandatory inspection frequency and the installation prohibition."}},"importantCases":[],"_links":{"self":"/api/acts/ad-t53-22-engine-fuel-pump-spline-failure","history":"/api/acts/ad-t53-22-engine-fuel-pump-spline-failure/history","analysis":"/api/acts/ad-t53-22-engine-fuel-pump-spline-failure/analysis","conflicts":"/api/acts/ad-t53-22-engine-fuel-pump-spline-failure/conflicts","importantCases":"/api/acts/ad-t53-22-engine-fuel-pump-spline-failure/important-cases","documents":"/api/acts/ad-t53-22-engine-fuel-pump-spline-failure/documents"}}