What happens if the turbo were to seize?

[mike20sm]

Just what'ifing what would happen to the engine if the turbo bearings were starved of oil and suddenly stopped spinning. Would enough air slip past to allow the engine to still run with enough power to make a safe landing?

[Bryan Cotton]

I only know this one academically as I have never flown a turbo. I believe you would see a loss of boost and suddenly you would be flying behind a normal aerovee. There is probably some power loss from the non-spinning turbo parts.

[Rynoth]

It would probably run just like a normal aerovee with a partially obstructed air filter.

That said, I don't see how the turbo would be any more likely to be starved of oil than any other bearing in the engine. If the oil line to the turbo were to come loose, all that oil is going overboard anyway.

[marsolgp]

As a matter of fact, I actually had this happen several months ago…..(sort of), the airplane had sat for a couple weeks and when I finally got it out to fly, did my runup and ignition checks (all OK), then started T/O roll…. RPM would only get to 2600 (normally 2900+) and 26" MAP. Needles to say, T/O was aborted and back to hangar I went. I immediately suspected turbo and pull the down pipe off….. turbine was not 'seized' per se, but very difficult to turn. Once I rotated it a bit, it freed up. Did not appear to be damaged, maybe just lead deposits… anyway, put it back together and went flying. It's been OK since (70+ more hours so far).

So, based on that experience, if the turbo stays intact, I would expect to see 2600 RPM and 26" at full throttle….. hopefully this would be enough to get you to an airport.

[Rynoth]

Interesting report! What was your density altitude? 26" doesn't seem half bad, even at sea level I wouldn't expect a normally aspirated aerovee to be much higher than 26" MAP at full throttle. The lower RPM was probably due to the coarse prop on the turbo, slap a regular aerovee prop on and I bet you'd be getting 3000+.

[marsolgp]

Don't recall DA for that day…. all I really noticed initially was the lack of acceleration. 26" is a long way from 40-41"…. And you are probably correct, with a finer pitched prop, it may have acted more like a NA Aerovee .