Narrative:

I was flying in smooth air uneventful since takeoff from home base. All of a sudden I heard two soft pops and noticed that I was losing power and descending. I immediately switched tanks turned on aux fuel pumps and told center I was declaring an emergency for loss of power due to engine malfunction or fuel issue. I asked for nearest airport and was told it was approximately 8 miles away. Looking in the area of my GPS I noted there were some low clouds limiting visibility of the ground. I asked about distance to an airport where I was familiar from numerous prior landings. Told that was 20 miles. I was unable to recover power and continued a descent toward the selected airport. ATC was very helpful giving me instructions on where to look as I cross checked with GPS and was able to concentrate on controlling my glide speed and descent. Clouds below began to dissipate and I could see runway 32 markings ahead of me and below and by then most of the runway. I told ATC I was going to land on 32 and would begin to circle down. They told me to switch to unicom 122.8. I did this and then noted complete loss of power on downwind. Although high I decided I would not have altitude for another circle on downwind so dirtied up the plane and dropping gear on turn to final I decided I had more than enough speed and altitude so put in full flaps and speedbrakes. I landed smoothly I did not want to brake hard to make the ramp turn so let speed bleed off on runway until full stop. I then got out of plane with my wife and got the tow bar out to move plane off the runway. A local pilot came up to me and said ATC wanted to talk to me to make sure things were fine. I told them that we were alright but had no power. The person I spoke to said he was [the] supervisor and heard the conversation with the controller. I said he did a wonderful job and allowed me to concentrate on flying the plane. We then pulled the plane by hand onto the ramp. No mechanic could come until sunday. The mechanic called first to say that it was the magnetos that failed but when he pulled them late this evening he said they were fine but whatever controlled the magnetos either a crankshaft lobe or camshaft lobe was broken off and so magnetos were not functioning all pistons and valves appeared to move correctly. Engine is lycoming 0 time 2 years old with only 200 to 250 hours on it.

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Original NASA ASRS Text

Title: A M20J engine failed in flight because the magnetos ceased to function after the controlling cam shaft lobe apparently broke.

Narrative: I was flying in smooth air uneventful since takeoff from home base. All of a sudden I heard two soft pops and noticed that I was losing power and descending. I immediately switched tanks turned on aux fuel pumps and told Center I was declaring an emergency for loss of power due to engine malfunction or fuel issue. I asked for nearest airport and was told it was approximately 8 miles away. Looking in the area of my GPS I noted there were some low clouds limiting visibility of the ground. I asked about distance to an airport where I was familiar from numerous prior landings. Told that was 20 miles. I was unable to recover power and continued a descent toward the selected airport. ATC was very helpful giving me instructions on where to look as I cross checked with GPS and was able to concentrate on controlling my glide speed and descent. Clouds below began to dissipate and I could see Runway 32 markings ahead of me and below and by then most of the runway. I told ATC I was going to land on 32 and would begin to circle down. They told me to switch to Unicom 122.8. I did this and then noted complete loss of power on downwind. Although high I decided I would not have altitude for another circle on downwind so dirtied up the plane and dropping gear on turn to final I decided I had more than enough speed and altitude so put in full flaps and speedbrakes. I landed smoothly I did not want to brake hard to make the ramp turn so let speed bleed off on runway until full stop. I then got out of plane with my wife and got the tow bar out to move plane off the runway. A local pilot came up to me and said ATC wanted to talk to me to make sure things were fine. I told them that we were alright but had no power. The person I spoke to said he was [the] Supervisor and heard the conversation with the Controller. I said he did a wonderful job and allowed me to concentrate on flying the plane. We then pulled the plane by hand onto the ramp. No mechanic could come until Sunday. The Mechanic called first to say that it was the magnetos that failed but when he pulled them late this evening he said they were fine but whatever controlled the magnetos either a crankshaft lobe or camshaft lobe was broken off and so magnetos were not functioning all pistons and valves appeared to move correctly. Engine is Lycoming 0 time 2 years old with only 200 to 250 hours on it.

Data retrieved from NASA's ASRS site as of July 2013 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.