Plane crash on Rt. 287 in NJ

On a King Air 200 that I use to fly we had ice vein doors on our Pratt and Whitney engines that we would deploy causing heavy air (rain, ice, etc) to not be able to make it into the induction. Everytime we depoly the doors, power was reduced and more throttle was needed to keep the same amount of power if it was available.

 

I'm not sure if the TBM has ice doors (I suspect that it does too) but you lose ram pressure on the engine inlet when you open them. If you aren't going that fast it isn't as big a deal, but at higher speeds inlet ram is considerable. Still an additional power loss that they didn't need at the time.

 

I remember when a King Air 90 was doing low level agriculture missions of some sort. The plane flew through a swarm of bugs and did not have the ice veins down (and there was no reason to have the doors open for the conditions) and the bugs cause flame outs on both engines. So flying fast or slow you dont want heavy objects like swarm of bugs, water or ice going into the engine. Some king air pilot i know only close those doors for takeoff and landings.

 

Roger..

They are ICE VANES. I have blood in my veins.

 

It still reduced power. I was instructed that you should pull it on all the way even if it seemed to make things worse and sweat it out until the carb ice melted. It cost power even in non-icing conditions when you turned it on for landings.

Cold air = good power. Hot air = less power. Carb blocked = no power.

 

The PT6 is an odd duck in that the compressor is at the back of the engine and the air turns around, after running under the engine, and enters the inlet. This results in more inlet losses and that costs you power and fuel all the time. Most PT6's have a screen around the inlet and that could get clogged, but the mesh is big, it would have to be a swarm of locust to clog one up. The long inlet also has the potential to have ice on the inlet walls, so that is a disadvantage of the design in that you have to heat more of the inlet.

Opening the doors dumps the pressure in the inlet and lets the air pass through the inlet and out the back. Most of the time FOD does get trapped at the back of the inlet, it would take a whole lot of junk to clog up the inlet on a King Air, and the pilot should know if he is in a situation where he should open it.

The ram pressure that you gain at 120 knots isn't much, about a 3% loss of power with the doors open, and since the engine is flat rated, at low altitude you wouldn't miss the power at all. At high speed and altitude you really should keep the doors closed unless you are in an icing situation. At 300 kts you lose about 18% of ram pressure that you would recover with the doors closed, and the engine has to make that up by burning more fuel and running hotter, which shortens engine life.

While I'm sure there have been situations where engines got clogged, it's exceedingly rare and certainly not a reason to cruise with the doors open all the time.

 

I see that the basic question has already been answered. The TBM has both a heated inlet and ice vanes, so it's a double whammy. And, this was a TBM-700, not an 850. I believe that means it has even less power.