As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) ON A FLIGHT, THE LT ENGINE EXPERIENCED THREE TORQUE DECAY SURGES ON DESCENT. MAINTENANCE WAS NOTIFIED AND AFTER SEVERAL COMPONENT CHANGES AND TEST FLIGHTS AS THIS WAS AN INTERMITTENT RECURRING EVENT. THE ENGINE HAS BEEN REMOVED FOR A SHOP VISIT/O/H.