I had a sudden high pitched noise start while at altitude (IMC) and after spending some time trying to track down the problem an inspection of the turbo showed significant damage to the turbine blades caused by FOD. Assuming the damage happened when the sound started (which seems reasonable) what else could it be other than ice? Anybody else experienced a turbo being damaged by ice ingestion?
How common is turbo damage caused by ice ingestion?
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docmirror
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Welcome. First, the turbine wheel is the one in the exhaust stream, and surely would not be hit with ice. I think you meant the compressor wheel(intake side). They do break apart on their own, and the blade exiting the housing will cause plenty of problems.
Clark1961
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The intake side (compressor) should be protected by an air filter. If the filter is clogged then AUX air (a suck-in door or a manual door) may be bypassing the filter. I would not expect ice damage on any installations that I have seen but I certainly haven't seen them all.
...and welcome to POA
...and welcome to POA
Ted
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Like doc said, compressors can break on their own, it happens. I would just figure age.
It's probably actually been breaking for a while, you just didn't notice until it got bad.
It's probably actually been breaking for a while, you just didn't notice until it got bad.
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Note to the O.P. - since you're new here, a little background knowledge on Ted is that he used to destroy engines for a living so he knows just a bit about them and usually what he types is true
Ted
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Thanks for the welcome. The engine (and turbo of course) is only 200 hours old and still under warranty. Dealer is saying the damage is due to FOD and it sure looks that way to me. One blade has a large chunk missing with some lesser damage on the other ones. But I'm certainly no expert. So has anyone ever heard of ice damaging the compressor? I was in ice and was using alternate air which bypasses the air filter.
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It happens a lot on the PA46 series. The whine is always the first sign. With the PA46 they recommend that you don't touch the door after selecting alternate air until you are on approach or have landed.
Ice will build up on the back side of the air filter in even the lightest icing. If you select primary before the ice has thawed the pieces will get sucked up into the compressor blades as it begins to break up.
What kind of an airplane do you have?
Ice will build up on the back side of the air filter in even the lightest icing. If you select primary before the ice has thawed the pieces will get sucked up into the compressor blades as it begins to break up.
What kind of an airplane do you have?
docmirror
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Did you see ice anywhere on the airframe? In the corner of the windscreen, or leading edge, was there vibration from the prop? If so, you sure could have had some ice accretion in the intake path. Who's to say it's FOD or just a busted wheel at 200 hours? He says FOD, I say maybe, but maybe a blade came off too. He's seen the damage, none of us have seen it.
Docmirror, yes I went through light ice and had to cycle the boots, etc, about 40 minutes or so before this happened.
Kevin yes you nailed it. It's a PA46. This is the first time I've heard to stay on alternate air once selected until down on the ground. This is not in the POH or in my training materials (I just checked). I've owned this plane less than a year so I guess this is an expensive lesson for me.
Any suggestions on what else I should tell them to look for?
Kevin yes you nailed it. It's a PA46. This is the first time I've heard to stay on alternate air once selected until down on the ground. This is not in the POH or in my training materials (I just checked). I've owned this plane less than a year so I guess this is an expensive lesson for me.
Any suggestions on what else I should tell them to look for?
I agree with docmirror. Something could have gone through the open alternate air door, taken out the compressor blades and found it's way into one or more cylinders.
Borescope the engine.
Borescope the engine.
Ted
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I agree with borescoping the engine, good idea.
Who did the overhaul on the engine? The turbos may or may not have been touched, and if they were, they may have just gotten new bearings and new seals, may not be new turbos.
Interestingly, the turbos I roasted in the lab were on a TIO-540-AE2A - Malibu engine. But I've roasted Navajo turbos in the field.
Who did the overhaul on the engine? The turbos may or may not have been touched, and if they were, they may have just gotten new bearings and new seals, may not be new turbos.
Interestingly, the turbos I roasted in the lab were on a TIO-540-AE2A - Malibu engine. But I've roasted Navajo turbos in the field.
It's 200 hours since new. The plane is still under the factory warranty. They've inspected the cylinders and the aftercooler on the side where the turbo was damaged. Also inspected the other good turbo to check if it got damaged on the exhaust turbine side. They didn't see anything luckily.
kmead
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Normally no cylinder damage will occur with a failed turbo compressor.
The inlet system and alternate air box has been an issue since 1984. We started off damaging the turbos with pieces from the flapper valves in the induction air box breaking apart and trashing both turbos. Piper issued SB961 that installed thicker valves and large coverage washers. That was a good fix until people failed to tighten the two flapper valve attach bolts. The bolts and valve pieces make junk out of both turbos, not just one.
PA46 induction icing will occur with no visible accumulation on the wings or tail. Addressing play issues in the valve linkage and proper rigging will go a long way in preventing the issue with ice ingestion while operating on alternate air.
You will be unhappy if you are flying along in the flight levels and the MAP starts to drop even with alternate air selected. ( I've been there ). This happens when the alternate air door valve will not stroke fully, leaving the filtered side open. Ice will build on the back side of the filter and up to the turbos.
The inlet system and alternate air box has been an issue since 1984. We started off damaging the turbos with pieces from the flapper valves in the induction air box breaking apart and trashing both turbos. Piper issued SB961 that installed thicker valves and large coverage washers. That was a good fix until people failed to tighten the two flapper valve attach bolts. The bolts and valve pieces make junk out of both turbos, not just one.
PA46 induction icing will occur with no visible accumulation on the wings or tail. Addressing play issues in the valve linkage and proper rigging will go a long way in preventing the issue with ice ingestion while operating on alternate air.
You will be unhappy if you are flying along in the flight levels and the MAP starts to drop even with alternate air selected. ( I've been there ). This happens when the alternate air door valve will not stroke fully, leaving the filtered side open. Ice will build on the back side of the filter and up to the turbos.
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So what is the preventative measure for that scenario? To make sure you select alternate air early?
kmead
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Descend if possible to stop the icing, richen the mixture if the TIT is rising or the engine wont run smoothly LOP. This really hurts on the PA46-310P when you can't descend and you are forced to bring the fuel flow from 16 GPH to 21 GPH. You might be looking for a fuel stop.
Preventive measures, it all comes down to good maintenance and proper rigging of the valve. This really means that you should learn as much as possible about the maintenance needs and insure that the maintenance shop is doing the right work.
Do you belong to the MMOPA?
Preventive measures, it all comes down to good maintenance and proper rigging of the valve. This really means that you should learn as much as possible about the maintenance needs and insure that the maintenance shop is doing the right work.
Do you belong to the MMOPA?
gismo
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IME a major cause of compressor wheel damage is coked and/or insufficiently lubricated bearings. The floating bearings wobble and the wheel contacts the scroll.
Ted
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I'd say you're likely right. I managed to fail turbos on AE2As in pretty short order, and we were running them very hard. High oil temps, etc., all of which impacts lubrication to the turbos.
Part of the issue I think is that we have old turbo designs in our engines. Turbos have improved significantly, but the FAA being what it is makes it very difficult to upgrade to a better turbo.