Airworthiness Directive · Amendment 39-15768 · General Electric Company (GE) CT7-8A Turboshaft Engines
General Electric Company (GE) CT7-8A Turboshaft Engines
This AD applies to General Electric Company (GE) CT7-8A turboshaft engines that have a serial number (SN) listed in Table 1 of this AD. These engines are installed on, but not limited to, Sikorsky S92 helicopters.
| 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 |
The FAA is superseding an existing airworthiness directive (AD) for certain GE CT7-8A turboshaft engines. That AD currently requires initial and repetitive inspections of the electrical chip detectors for the No. 3 bearing. This AD requires removing from service certain GE CT7-8A turboshaft engines within 6,200 cycles-since-new. This AD results from investigation for the root causes of two failures of the No. 3 bearing. We are issuing this AD to prevent failure of the No. 3 bearing due to contamination by aluminum oxide, which could result in a possible in-flight shutdown of the engines and loss of control or forced landing of the aircraft.
You are responsible for having the actions required by this AD performed within the compliance times specified unless the actions have already been done.
(f) No further action is required if:
(1) Your engine has a SN that is not listed in Table 1 of this AD, or
(2) Your 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.
For engines with a SN listed in Table 1 of this AD, within 6,200 cycles-since-new, remove the engine from service and flush the front frame and replace the No. 3 bearing. GE CT7-8 Shop Manual, GEK 10517, contains information on replacing the No. 3 bearing and GE Aircraft Engines Service Bulletin No. CT7-8 S/B 72-0017, Revision 02, dated May 14, 2008, or earlier revision, contains information on flushing the front frame and replacing the No. 3 bearing.
After the effective date of this AD, do not install any No. 3 bearing removed as a requirement of paragraph (g) of this AD.
