As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) ON CLIMB PILOTS EXPERIENCED TORQUE FLUCTUATIONS ON RT ENGINE. THEY RETURNED TO THE AIRPORT WITH NO FURTHER PROBLEMS. ON TAXI THEY BLEW THE FIRE BOTTLES ON THE RT ENGINE. WHEN MAINTENANCE REMOVED THE COWLS THEY DISCOVERED HEAT DAMAGE TO SOME WIRING. ON FURTHER INVESTIGATION THEY DISCOVERED THAT THE EXHAUST PIPE STUB HAD BROKEN AND FOLDED OVER PARTIALLY BLOCKING THE EXHAUST GAS FLOW. FURTHER INVESTIGATION IS REQUIRED. (TC NR 20070502015)