Narrative:

The flight was mostly uneventful up to about 10 miles before landing. It was challenging to keep engine temps at 380 and below 400F cht without throwing a lot of fuel at it; but I worked on that most of the flight (cowl flaps opened). I had 82 gallons of fuel; enough for a return flight as long as I was burning closer to 15 gallons than 20 gallons per hour (there was virtually no headwind). I checked that I had 8qt of oil before takeoff. During the flight; the fuel totalizer failed; so I didn't know what my fuel flow was and I tried to use fuel based on cht temperatures only without knowing what the flow was. This was a known fault with this plane that was going to be fixed eventually.when I got over the mountains; we got smoke in the cockpit. Strangely it felt like it came from the back of the plane and because I was carrying a lot of batteries (lipo and lithium); I had my passenger look in the back to make sure none were on fire (they were in a fire proof lipo safe bag; but still; I wanted to be sure). He looked through all the luggage and couldn't find anything. By then; the smoke had stopped things were back to normal and I figured it was probably one battery I was carrying that shorted and things were back to normal. I was busy with the approach since I had to follow a specific route and altitude; and unfortunately at the time; I didn't think about looking at the alternator; but I got no low voltage warnings. It's possible the alternator did die and that I was running on batteries. I made the mistake of not checking electrical systems or oil pressure/temperature; mostly because after I felt confident that I didn't have an active fire in the plane; and no more smoke; I was close enough to my destination that I had to concentrate on the approach.at the time; I didn't think/know anything was wrong with the airplane (clearly; I made a mistake there); but soon I could tell the engine sounded a bit differently; something like a pinging sound when I was a lowered throttle (maybe 20'). I saw cht go to 410F and added more fuel (more than needed); and unfortunately I was too busy worrying about not busting airspace and being over the right places to approach landing to think about looking at oil pressure and temperature when I heard the pinging; but I'm guessing they were bad.the pinging soon (maybe within 2 minutes at most; I didn't time it) changed to what felt like a cylinder that failed and very heavy shaking. I feathered the prop and just shut off the engine because of how bad the vibrations were. I believe the prop stopped on its own. On the ground; it was not possible to turn the prop by hand. I was able to make a perfect glide to the runway numbers and land smoothly at the airport. Because of the location I likely could have landed safely anywhere else; but given the choice of gliding to a hard runway; I went for that).I had enough speed to turn on a taxiway before the plane stopped entirely; and it then had to get towed. I had a bit of oil on the windscreen (not a lot thankfully); and after landing took this picture which was my first strong hint that the smoke did come from the cockpit and likely the alternator that shorted; or some other wires that went loose and shorted. I don't know if this in turn caused a failure that messed with oil delivery and killed the engine; hard to say; but it would be a possible outcome. It is also possible that I had a failure with the oil system that caused a leak that caused an electrical short and the smoke we got. Clearly; I got so concerned about lipo batteries being in fire that I totally forgot to check those systems unfortunately.I'm happy that I did remember to put the gear down and that I had enough electrical power for it to go down because I don't think I could have pumped it fast enough. I was able to coast off the runway and was later towed to the airport parking. There we no injuries; the landing was perfect; but the plane likely has an engine that isdestroyed. I hope that I didn't cause it to die by not keeping it cool enough (I've been told under 400F cht is ok; but maybe that was too close to the limit; or the engine had other issues that caused it to be marginal and more likely to be damaged by any temperatures above 380F).

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Original NASA ASRS Text

Title: After crossing a high mountain range; a C182RG had an apparent engine failure. The pilot saw smoke in the cockpit earlier and felt vibrations severe enough that they shut the engine down before landing.

Narrative: The flight was mostly uneventful up to about 10 miles before landing. It was challenging to keep engine temps at 380 and below 400F CHT without throwing a lot of fuel at it; but I worked on that most of the flight (cowl flaps opened). I had 82 gallons of fuel; enough for a return flight as long as I was burning closer to 15 gallons than 20 gallons per hour (there was virtually no headwind). I checked that I had 8qt of oil before takeoff. During the flight; the fuel totalizer failed; so I didn't know what my fuel flow was and I tried to use fuel based on CHT temperatures only without knowing what the flow was. This was a known fault with this plane that was going to be fixed eventually.When I got over the mountains; we got smoke in the cockpit. Strangely it felt like it came from the back of the plane and because I was carrying a lot of batteries (lipo and lithium); I had my passenger look in the back to make sure none were on fire (they were in a fire proof lipo safe bag; but still; I wanted to be sure). He looked through all the luggage and couldn't find anything. By then; the smoke had stopped things were back to normal and I figured it was probably one battery I was carrying that shorted and things were back to normal. I was busy with the approach since I had to follow a specific route and altitude; and unfortunately at the time; I didn't think about looking at the alternator; but I got no low voltage warnings. It's possible the alternator did die and that I was running on batteries. I made the mistake of not checking electrical systems or oil pressure/temperature; mostly because after I felt confident that I didn't have an active fire in the plane; and no more smoke; I was close enough to my destination that I had to concentrate on the approach.At the time; I didn't think/know anything was wrong with the airplane (clearly; I made a mistake there); but soon I could tell the engine sounded a bit differently; something like a pinging sound when I was a lowered throttle (maybe 20'). I saw CHT go to 410F and added more fuel (more than needed); and unfortunately I was too busy worrying about not busting airspace and being over the right places to approach landing to think about looking at oil pressure and temperature when I heard the pinging; but I'm guessing they were bad.The pinging soon (maybe within 2 minutes at most; I didn't time it) changed to what felt like a cylinder that failed and very heavy shaking. I feathered the prop and just shut off the engine because of how bad the vibrations were. I believe the prop stopped on its own. On the ground; it was not possible to turn the prop by hand. I was able to make a perfect glide to the runway numbers and land smoothly at the airport. Because of the location I likely could have landed safely anywhere else; but given the choice of gliding to a hard runway; I went for that).I had enough speed to turn on a taxiway before the plane stopped entirely; and it then had to get towed. I had a bit of oil on the windscreen (not a lot thankfully); and after landing took this picture which was my first strong hint that the smoke did come from the cockpit and likely the alternator that shorted; or some other wires that went loose and shorted. I don't know if this in turn caused a failure that messed with oil delivery and killed the engine; hard to say; but it would be a possible outcome. It is also possible that I had a failure with the oil system that caused a leak that caused an electrical short and the smoke we got. Clearly; I got so concerned about lipo batteries being in fire that I totally forgot to check those systems unfortunately.I'm happy that I did remember to put the gear down and that I had enough electrical power for it to go down because I don't think I could have pumped it fast enough. I was able to coast off the runway and was later towed to the airport parking. There we no injuries; the landing was perfect; but the plane likely has an engine that isdestroyed. I hope that I didn't cause it to die by not keeping it cool enough (I've been told under 400F CHT is ok; but maybe that was too close to the limit; or the engine had other issues that caused it to be marginal and more likely to be damaged by any temperatures above 380F).

Data retrieved from NASA's ASRS site 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.