PA-24 Comanche
Flight Crew Private; Flight Crew Instrument
Flight Crew Last 90 Days 32; Flight Crew Total 366; Flight Crew Type 366
Aircraft Equipment Problem Critical
Air Traffic Control Provided Assistance; Air Traffic Control Issued New Clearance; Flight Crew Diverted; Flight Crew Landed in Emergency Condition; Flight Crew Requested ATC Assistance / Clarification
Aircraft
I was in communication with Center. Engine ran rough briefly then plane shook violently. Immediately assessed flight situation and started to run through checklist of potential issues.  Switched fuel to most full tank and started fuel pump. Pushed in mixture and prop to full. Looked for a place to land. By then we were directly over a private landing field.  I asked the Controller could we land there. He was not aware of that airfield and suggested [another airport] just north. By then I had lost about 1;000 ft in altitude. When I applied throttle; the plane shook.  By my engine monitor it appears that we lost cylinder 1 and cylinder 6 was not performing. As I turned to the north; the passenger door then popped open; most likely from extreme vibration.  This added to distraction and increase in ambient noise. I located the airport environment and made preparations for a 'normal' landing. When I began to slow plane down for gear extension; I began losing more altitude than normal.  I could not apply throttle to regain altitude.  I extended gear and then waited until I had airport made until I put in 10 degree of flap to slow us down to landing speed. Once on ground; I contacted Center and cancelled flight plan. Kudos to Controller who helped guide me to safe landing.
PA-24 pilot reported successfully diverting to an alternate airport after experiencing power loss and a rough running engine.