{"id":"F2009L01129","name":"AD/CT7/13 - No. 3 Bearing","slug":"ad-ct7-13-no-3-bearing","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":121946,"registerId":"commonwealth-F2009L01129-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"General Electric Turbine Engines - CT7 S","sectionType":"division","heading":"General Electric Turbine Engines - CT7 Series","content":"### General Electric Turbine Engines - CT7 Series\n\n| AD/CT7/13 | No.3 Bearing | 4/2009 |\n| --------- | ------------ | ------ |\n\n```html\n

Applicability:

General Electric Company (GE) CT7-8A turboshaft engines that have a serial number (SN) listed in Table 1 of this AD.

Note 1: These engines are installed on, but not limited to, Sikorsky S92 helicopters.


Table 1 - Affected Engines by Serial Number

Engine Serial Number

947205

947215

947230

947243

947254

947265

947206

947217

947232

947244

947255

947274

947207

947218

947233

947245

947256

947277

947208

947219

947235

947247

947258

947278

947209

947220

947238

947248

947260

947279

947210

947221

947240

947249

947261

947280

947211

947223

947241

947250

947262

947284

947212

947225

947242

947253

947263

947285

947214

947228

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Requirement:

No further action is required if:

- The engine has a SN that is not listed in Table 1 of this AD; or

- The engine has a SN listed in Table 1 of this AD, but the engine log specifies that the front frame was flushed and the No. 3 bearing was replaced.

1. For engines with a SN listed in Table 1 of this AD, remove the engine from service and flush the front frame and replace the No. 3 bearing.

\n```\n\n| | GE CT7-8 Shop Manual, GEK 10517, contains information on replacing theNo. 3 bearing and GE Aircraft Engines Service Bulletin No. CT7-8 S/B 72-0017, Revision 02, dated 14 May 2008, or earlier revision, contains information on flushing the front frame and replacing the No. 3 bearing.2. Do not install any No. 3 bearing removed as detailed in Requirement 1 of this AD.Note 2: FAA AD2008-26-02 Amdt 39-15768 dated 9 December 2008 refers. |\n| ----------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Compliance: | For Requirement 1 - Within 6,200 cycles-since-new.For Requirement 2 - After the effective date of this AD. |\n| | This Airworthiness Directive becomes effective on 9 April 2009. |\n| Background: | This AD results from investigation for the root causes of two failures of the No. 3 bearing. The issuing of this AD is intended to prevent failure of the No. 3 bearing due to contamination by aluminium oxide, which could result in a possible in-flight shutdown of the engines and loss of control or forced landing of the aircraft. |\n\n![](image.003.png) \nJames Coyne \nDelegate of the Civil Aviation Safety Authority\n\n26 February 2009","sortOrder":0},{"sectionNumber":"AD/CT7/13","sectionType":"part","heading":"AD/CT7/13","content":"## AD/CT7/13","sortOrder":1},{"sectionNumber":"No.3 Bearing","sectionType":"part","heading":"No.3 Bearing","content":"## No.3 Bearing","sortOrder":2},{"sectionNumber":"4/2009","sectionType":"part","heading":"4/2009","content":"## 4/2009","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD confines its scope to engines with the serial numbers listed in Table 1 and to the specified remedial actions (flush front frame and replace No. 3 bearing). It implements the original safety objective stated in the Background—to prevent No. 3 bearing failure from aluminium oxide contamination—without expanding applicability beyond the listed engines or adding new regulatory categories (Background; Applicability; Requirement 1–2)."},"complexity_factors":["Narrow, serial-numbered applicability requires checking engine serials against Table 1 (Applicability: Table 1).","Prescriptive maintenance action: removal from service, flushing front frame and replacing No. 3 bearing (Requirement 1).","Compliance metric measured in cycles‑since‑new (6,200 cycles) rather than calendar time (Compliance).","Reliance on engine logbooks to establish prior compliance (no further action if log shows prior flush and replacement) (Requirement text).","Prohibition on reinstalling removed No. 3 bearings creates a parts-disposition obligation (Requirement 2 / Note).","Cross-references to manufacturer shop manual and service bulletin for procedures raise technical implementation dependency (GE CT7-8 Shop Manual; Service Bulletin CT7-8 S/B 72-0017).","Limited regulatory discretion: prescriptive remedy with little room for alternative mitigations, increasing operational downtime but simplifying enforcement (Requirement 1–2)."],"plain_english_summary":"This airworthiness directive requires operators of specific GE CT7-8A turboshaft engines (listed by serial number) to remove affected engines from service, flush the front frame and replace the No. 3 bearing within 6,200 cycles‑since‑new, and forbids reinstalling the removed bearing. The measure addresses aluminium‑oxide contamination identified as a root cause of No. 3 bearing failures, aiming to prevent engine shutdowns. Owners/operators pay for the maintenance, parts and downtime and must record compliance in engine logs (Requirement 1–2; Compliance)."},"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This AD maintains its original narrow scope — addressing a specific bearing contamination issue in specific engine serial numbers. There is no evidence of scope creep; it targets exactly the safety risk identified in the background (aluminium oxide contamination causing No. 3 bearing failures)."},"complexity_factors":["Single, clearly defined applicability table with 48 specific serial numbers","Two straightforward requirements with simple conditional exemptions (OR logic)","No defined terms section or complex interpretation provisions","Minimal cross-referencing — only refers to two external technical documents (GE manual and service bulletin)","Clear compliance timeline (6,200 cycles-since-new and 'after effective date')","No nested exceptions or conditional logic beyond the initial exemption clause","Short, self-contained document without multiple parts or divisions"],"plain_english_summary":"This CASA Airworthiness Directive mandates removal, front-frame flushing, and replacement of the No.3 bearing on 48 listed General Electric CT7-8A engines (commonly on Sikorsky S‑92s) due to two failures traced to aluminium oxide contamination. If not on the serial-number list or the work is already recorded, no action is needed. The main compliance action is required within 6,200 flight cycles; the AD is effective 9 April 2009 and prohibits reinstalling old bearings once active."}},"importantCases":[],"_links":{"self":"/api/acts/ad-ct7-13-no-3-bearing","history":"/api/acts/ad-ct7-13-no-3-bearing/history","analysis":"/api/acts/ad-ct7-13-no-3-bearing/analysis","conflicts":"/api/acts/ad-ct7-13-no-3-bearing/conflicts","importantCases":"/api/acts/ad-ct7-13-no-3-bearing/important-cases","documents":"/api/acts/ad-ct7-13-no-3-bearing/documents"}}