? for Garrett 331 pilot's

[King Nothing]

Has anyone experienced compressor stall on a Garrett TPE-331 (any dash #) and if so what was the cause? Another question, "shaft bow," what are your experiences?

KN

 

[reaperman]

I don't have an answer to your question about compressor stalls, but I can't help but wonder why, in the space of one day I've suddenly seen on two different forums, a well known Dan Quayle quotation attributed to Bill Clinton. A quick search on the web turns up this quote being attributed also to George W. and to Al Gore.

 

[banned username 2]

I don't have an answer to your question about compressor stalls, but I can't help but wonder why, in the space of one day I've suddenly seen on two different forums, a well known Dan Quayle quotation attributed to Bill Clinton. A quick search on the web turns up this quote being attributed also to George W. and to Al Gore.

Who Cares? This is an Aviation board, not a Political board...

 

[mar]

Thank you Falcon Capt

What's up Mr. Reaperman? Attention Deficit Disorder?

Compressor stalls on the -331? Never heard of it happening. Putting the fire out due to water, slush, snow, ice--you bet.

Putting the fire out due to turbulence--occasionally.

I can't imagine how the compressor would stall on the -331 unless you had a huge pitch attitude and low power setting maybe.

Shaft bow: I've never experienced it myself but I've known pilots who have claimed they could hang off the prop with their feet off the ground the engine was seized so bad.

Apparently it's a real phenomenon. You can imagine how small the tolerances are on an engine of that size and rotational speed.

 

[BAe3100FO]

C-STALL?

I've never heard of a compressor stall concern with Garrett TPE331-10/12 engines. Although I only have 250 hours or so with them strapped to my back. (I'm by no means an expert)
Where did you hear about it?
All I know is that they are LOUD.

 

[ArcticFlier]

3500 hours in Metro 3's with the -11's never a problem with compressor stalls nor shaft bow.

AF

 

[up frnt]

I have a few hours powered by Garrett 331-5/-10 engines. I have not heard of a compressor stall with the 331. I do know that you will see Garrett drivers out spinning the props to cool down the engine and prevent "shaft bowing". The Main and only shaft in the Garrett will tented to wrap if not turned over a couple of times. I had an engine that was trashed because it was not turned over several times after shut down. Some owner/pilots know everthing. NOT. The bowing has to due with the location of the bearings and the weight of the compressors. They also have a danger area in the starting rpm around 20-28 %. If the engine stopped accelerating in this area it would cause severe damage and a loss of a job.

 

[100-1/2]

things that make you go hmmm

What is the basis of the question(s). For the most part, Garretts are the best run (performance and efficiency) when properly operated. The turning of the props is required as a result of the installation of the EPA Can that purges the system with air on shut-down. Used to be purged with fuel unburnt and having a cooling affect as it travels (pushed) rearward through the gas turbine stages. This air spikes the temperatures as the motor shuts down and trapsthis hotter air in the burner can and gas turbine stages making restart difficult if not impossible and risks damage to components not meant to be static in those temperatures. Turning a Metro Motor -8 or -10: 20 Blades or so takes the ambient air through the intakes and first stage compressor (26:1 ratio) and pushes that much cooler air completely through the motor and purges this Hot air from the system leaving residual component temperatures degrees cooler and free from this warmer air.

As for Compressor stalls or flow reversal, Garrett motors' air intakes are usually inches from the props and very small openings over or under the prop hub. This allows for relatively unrestricted and sufficient airflow to the first stage compressor in all flight regimes. Never flown a turbo commander, but by the looks of the wing, if it is anything like the Metro, you DO NOT engage in flight at slow speeds and high angles of attack, as they do not recover well from stalls nor do they have to with the stick shaker/pusher installation. I have heard of a Conquest II Pilot experiencing a Compressor Stall by his account, however, familiar with his blase approach to a/c limitations with regard to performance and a history of anecdotal accounts to flying outside the envelope, I must question his integrity and need for this sense of accomplishment. In Caravan training we discussed these anamolies but never gave mush weight to their threat or temperment in this airplane and suspect similar feelings of most other PT&W engines.

The vibration on start/acceleration through certain % RPM is experienced on all turbines as they are spooled up to ground idle. Some % windows are small and others larger. It has to do with the size and design of the turbine. It is a frequency resonating that occurs with any gyroscopic mass hinged on more than 2 points (shaft bearings). A "hung" start in these regions will increase in amplitude and shake the shaft right out of the bearings if left unaddressed.

"Bow or shaft sag" taught in theory with Garrett typically will occur in larger motors with longer shaft segments where the heaviest part of the gas turbine is located Compressor stages) Most Garrett motors are relatively short and contain multiple bearing/shaft supports to deter this threat. Allowing residual heat from shutdown to remain in these areas increasing the risk on this phenomenon. Usually, accessories and powerpacks will get hosed before this happens.

As for political viewpoints: It is a given that anytime some well to Politician Like "I did not have sexual relations with that woman..." makes a flub and great soundbite like that previously quoted and commented upon, they will never live it down until some awful liberrally fact-void constituant tries to insist it originated from the lips of a well spoken and educated Republican.

But, hey, we're all family here and can vote anyway we want to and still have a beer together prior to beginning our duty day.

100-1/2

 

[King Nothing]

Thanks for all the reply's. I have serveral thousands of hours operating Garrett TPE-331's and have never experienced a compressor stall, however, I have fodded (is that a word?) them and they have just kept right on running.

With respect to "shaft bow," I've experienced this on several occasions. I've been told several different ways to handle this problem, one is to pull it through, as most of you have mention, the other is to move thr prop one blade width and leave it, and last, don't do a thing. Nothing works in my opinion, if it's locked up just go inside and have a soda and wait it out.

The reason I asked is a friend of mine was telling me about his friend who claimed to have had a compressor stall with a 331. I thought for a few minutes and really had no response. My friend had very few details and I tried after we departed ways to figure out what this guy did and why the compressor stall. Any idea's would be nice. I'm wondering if the clearance has been eaten away on the compressor and shroud do to shaft bow and that's the reason.

KN

 

[Skank]

I don't mean to be offensive, but it sure is nice not to listen to the roar of the TPE 331 anymore. They are nice and reliable, but that noise.....