Turbo High Altitude Engine Flooding?

[Paul Sharp]

This past weekend I have the front engine kill on me at LaPlata/Durango airport on start of takeoff roll.

Mine is a turbo, but it takes a little time for the turbo to spool up when you apply throttle from an idle. Could it be that the engine is just getting flooded?

I taxied back to the start and thinned out the mixtures, then applied throttle and all ran fine. Once the RPMs got up I went ahead and advanced the mixture to full rich again about halfway down the runway.

I have had this happen before at Flagstaff, AZ - another reasonably-high airport.

Anyone else with turbos have something like that happen?

[kevin]

I fly out of high altitude airports frequently (Cheyenne and Laramie WY for example) and I do not experience this behavior. I would have your mechanic look into it. While looking to purchase my current airpline, I flew some turbo 337s with fuel flow set much too high, so high that the fuel flow needle went 90 degress past the vertical into the OTHER engine's fuel flow range. Even those airplanes did not stumble or die as you describe...

Kevin

[Bob Cook]

Paul

Appears you have a problem that is not normal.

1) You should check fuel flow and make sure you are in the correct range of approx 140 lbs /hr or about 24 gph. This should occur at full throttle.

2) There is a barometric fuel control that compensates for altitude. This could be out of adjustment or not working properly.

3) You should get the engines checked on the ground with a proper fuel flow meter and make sure the controller is set up properly. You should be able to take off with full throttle at any altitude and still maintain 37 inches of manifold pressure.

Last thing you want is to "nurse" an engine on takeoff... more important things to do such as flying the aircraft.

fyi

Bob

[Jerry De Santis]

Interesting problem Paul! I was about to post similar problem and ask for help. My plane is a 1975 P337G with TSIO-360 engines with Riley Intercoolers. I know my problem is in fuel system but stuck where to start the debug process. Here's what is happening.

In flight, regardless of alt. it first showed up when I started to lean the front engine. The engine ran real rough with some coughing. Sounds like the engine is missing such as bad mags or Plugs. Plegs were removed cleaned and regapped. Fuel filter checked and clean and mags checked okay. Problem still appeared. We cleaned all injectors, which were okay anyway, ran engine on ground test and now it gets to about 26 inches manifold pressure and starts to die. Almost as though either lack of fuel or flooding engine. When this happends upon spool up, fuel flow does not go over 13 to 14 gph. We are going to do a fuel pressure test next to determine if adjustment has to be made.

Wondering if anyone else experienced this same problem and what was the solution.

Thanks and Cheers
Jerry

[Bob Cook]

Jerry

First test is to run with boost pump on low and see if this helps.

You need to go thru the fuel flow / pressure measurement / test per TCM.

My guess would be the barometric controller that governs the amount of fuel based on the upper deck air pressure. It is a closed loop and is probably the fuel pump or the controller.

Just out of curiosity did you try running on one mag while airborne to see if this could be a problem or at least eliminate a potential problem?

Do you have a jpi to see if there is one or two cylinders causing the problem in flight (roughness). Roughness is usually caused by an inbalance of fuel to cylinders or a mag(s) problem.

fyi

bob

[kevin]

Although not related to the problem describes, this reminds me of a congenital defect that I *have* seen in both my Skymasters, and which my instructor, who used to fly checks in a variety of them, said they all have.

On very hot days (maybe "normal" days for you air conditioned guys), when power is first applied on takeoff, the rear fuel flow will be about 20 lbs lower than it should be. It recovers to normal within about 10 seconds.

FYI.

Kevin

[rick bell]

i have had the same problem aqt times. at sea level and also in flagstaff. usally i have advanced the throtles a little to quickly. i retard the throttles while still rolling and the slowly adavnce them again and all is well. on short field i stop the a/c reduce them and readvance. there seem to be a very ine line between advancing and boging down the engines

[Jerry De Santis]

Hi Bob,

I did do mag check while flying and all tested out okay. I do have JPI and three cylinders were running a little cooler then they should have. #2 290 F, #5 270F and #6 270 to 280F. All others about 320 to 340F. As such, I thought it was due to partial blocked injectors, but they turned out to be okay. Also when we ran flow check on ground,with low boost electric pump and flow into cups, it appeared all injectors flow were equal. I did not attempt to run low boost while flying. Should have but didn't think of it at the time. I agree that it is either the upper deck controller or fuel pump. However, also can be a hung fuel relief valve. Dirt or something may be holding it open more than it should be. We will do pressure test tomorrow night. I'll keep you posted what we find.
Cheers
Jerry

[Paul Sharp]

I had my aircraft checked with one of the rent-able systems from that place that makes them about 2 years ago. No one around here that I know of has one and I'm reluctant to have mechanics mess with the fuel settings without it - (maybe I shoudl rent it for them). Sometimes they end up getting things worse instead of better.

The auto altitude adjuster that Bob mentioned might be a culprit. Don't know exactly how I'm going to approach this at the moment. Enjoying the input and comments.

[Bob Cook]

Paul

There was someone on the board living in Calif that purchased one and let his mechanic use it. Perhaps he is willing to rent it for a few days.

Yes I agree with you that I would hesitate to play with the fuel without proper equipement.

Regarding the fuel controller, it can be sent out for testing, calibration and/or service. This is the only way to really find out.

You should be able to determine it the fuel being supplied is either too little or too much. How is the compression on the three low temp cylinders?

Another possibility is do the GAMI check and reduce the fuel flow and monitor where each cylinder is peaking .. then see the spread!. My cyls run about 50 degs. deltal when leaned properly and 125 degrees when running rich. This is a good determination of fuel flow balance. I do NOT have Gami injectors.

My guess would be barometric fuel flow controller. Call TCM support and ask them.

I have never experienced this condition. Took off full gross today in 90 degree wx at SGJ and climbed to 17k ft without touching anything.

fyi

bob

[Jerry De Santis]

Problem solved!

Sent the fuel pump out and had all seals replaced and recal. on bench for $270.00 plus over night freight. Installed it back in the plane and made minor adjustments. At first solved mixture problem and was able to lean to proper fuel flow. However, once in cruise setting of 2450 RPM and 30 inches of MP, when I advanced the throttle to 32 inches MP, engine would die than return rapidly until I reset throttle back to 30 inches on MP. Advancing the mixture to rich did not help nor low pressure boost pump. Drove me crazy for a couple of days. This evening, took the flow divided apart and cleaned it with air pressure and made sure the check valve was operating. Put it back in plane and ran the engine....problem solved. Must have been a speck of dirt under the check valve that was to small to see with the eye.

Thanks for suggestions.
Cheers
Jerry

[Paul Sharp]

Here's some new info, FWIW: I can't find any "barometric controller" on my turbo model in the diagrams, etc.

But I did talk to the mechanics, who said that with Piper Aerostars, for example, this is a common attribute: at high altitudes the pilot needs to reduce the mixture somewhat until the turbos begin to spool up, and then add the rest of the mixture.