SR22
Flight Crew Commercial; Flight Crew Instrument
Flight Crew Last 90 Days 20; Flight Crew Total 1000; Flight Crew Type 500
Training / Qualification
Aircraft Equipment Problem Less Severe
Air Traffic Control Provided Assistance; Flight Crew Diverted; Flight Crew Landed As Precaution; General Maintenance Action
Aircraft; Human Factors
I was in cruise flight when I suddenly heard a 'thump;' felt a slight vibration; and heard the engine sounds change. It also felt like the engine power decreased slightly. The engine indications on the MFD were all in the green. I had been taught that any sudden decrease in engine power should be assumed to be caused by a fault in the turbo normalizing system. This could cause hot exhaust gases to enter the engine compartment and possibly cause a fire. I immediately informed TRACON of my rough running engine and received vectors to [a nearby airport]. The controller gave me the weather and asked the skydiving operation on the field to hold their jumpers until I was on the ground. The airport was close and I was unable to lose enough altitude to make a normal approach to the best runway for the wind. I joined the pattern after broadcasting my intentions and made a downwind landing on [the opposite runway]. I stopped on the runway and pulled off into the transient parking area.The company that manages the airplane sent a mechanic out to the airport and he gave the engine a brief examination and did a run-up. He was unable to find any anomalies. The airplane is going to be ferried back to its home base and will be checked out by the A&Ps there. I am still glad that I made a precautionary landing because I had no idea what caused the changes in the engine sound. I am lucky that the winds were not strong and the runway was long enough to do a downwind landing without an overrun; but I have already contacted my instructor to get more instruction in emergency descents; steep spirals; and downwind landings. The controllers did an outstanding job in getting me to a field where I could get on the ground safely.
An SR-22TN pilot reported he diverted because of a rough running engine. No anomalies were found by the mechanic.