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 Post subject: Re: 441 Conquest II Torque split
PostPosted: 23 Sep 2021, 14:12 
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The EGT comp can be adjusted quite a bit. What the RH side is showing is exactly what I would expect if it was adjusted incorrectly.


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 Post subject: Re: 441 Conquest II Torque split
PostPosted: 23 Sep 2021, 20:13 
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Borescope came back with no issues apart from erosion on first stage blades, which they said was within limits, and trailing edge cracks on first stage turbine nozzles which they said was also acceptable.

I think the fuel flow just needs a k factor adjustment, so that leaves only the torque split and the plane being slow for the airspeed.

If anyone can share what torque they see at 450C with -10s at a specific alt, temp, and rpm, that would be helpful for me to compare. They are sending the data from the MVP and Txi.


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 Post subject: Re: 441 Conquest II Torque split
PostPosted: 23 Sep 2021, 20:35 
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Location: Owosso, MI (KRNP)
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This is the best I have. We ran 20 degrees below redline EGT as a normal policy for several reasons, so it will be slightly slower than someone running right at 450.

The airplane was likely heavy as we tanker fuel home since we don't have Jet-A at home. We were probably at 9850# at takeoff...

Attachment:
2017-09-22 17.22.17.jpg


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 Post subject: Re: 441 Conquest II Torque split
PostPosted: 23 Sep 2021, 22:29 
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Username Protected wrote:
This is the best I have. We ran 20 degrees below redline EGT as a normal policy for several reasons, so it will be slightly slower than someone running right at 450.

The airplane was likely heavy as we tanker fuel home since we don't have Jet-A at home. We were probably at 9850# at takeoff...

Attachment:
2017-09-22 17.22.17.jpg


Why 430? I’m told 100%rpm and 450C is fine (how this guy ran it for years), which can’t be true.


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 Post subject: Re: 441 Conquest II Torque split
PostPosted: 24 Sep 2021, 09:00 
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Username Protected wrote:
This is the best I have. We ran 20 degrees below redline EGT as a normal policy for several reasons, so it will be slightly slower than someone running right at 450.

The airplane was likely heavy as we tanker fuel home since we don't have Jet-A at home. We were probably at 9850# at takeoff...

Attachment:
2017-09-22 17.22.17.jpg

OMGosh that’s literally the temp and fuel flow we see on the ground in solitaire lol.
Solitaire -10 limit is something like 650* egt.

I don’t know much about 441.

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 Post subject: Re: 441 Conquest II Torque split
PostPosted: 24 Sep 2021, 22:10 
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It’s been a couple years since my crappy training in the 441 (2500 hours of 331 experience and another 2000 of Twin Cessna experience will get you that), but from what I remember from teaching the 331’s, the EGT indications in the Conquest are only an index and not representative of real temperatures. Don’t quote me on that as I haven’t looked at the manuals in a few years. I’m not current at the moment in that airplane.


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 Post subject: Re: 441 Conquest II Torque split
PostPosted: 27 Sep 2021, 03:31 
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Aircraft: C560, Extra NG, FX3
Hi John,

My plane, and I heard most/all 441's are 10 to 15 knots slower than the -10 numbers at 96% RPM, but they are still 300knot+ airplanes most of the time. I get about book speeds at 100% at lower altitudes, say 280 and below.

(I have hubcaps and Strakes, which worked really great wonders on my previous 421, so I installed them right away on the 441, so I don't know exactly how much difference they make)

The compensating resistor is added to make both engines perform the same, have the same indications (at one altititude...?). I do not worry about the indication splits very much.

I suspect the indication on the EI instrument of 273 lbs/hr at FL320 is very wrong, not calibrated. According to book, the fuel flow is supposed to be around 205lbs/hr at 96% RPM and ISA +10.... If the right engine is burning so much more fuel, why are the tanks almost balanced? I think the gauges are wrong.. Did the avionics shop program the calibration factor from each fuel sender into the EI box? On the right side?



Here is my 441 at FL350 (ISA +15)

The analog FF is "just for entertainment", look at the Shadin numbers instead, 161lbs/hr/side. Torques have a 50 split. At altitudes above FL300 it does not seem it makes a difference in airspeed if RPM is 100 or 96%.

Attachment:
N184VB FL350 Isa+15.JPG



and at FL270 (ISA+10) Still a split in FF, running both engines at temp limit, and a 50 split in Torques. But at FL 270 I am only able to burn 232/239 lbs/side/hour. Same as yours at FL320! Seems something is not calibrated, and your numbers are far from the -10 book numbers. (If you don't have them PM me and I can send)

When I fill full fuel, set the Shadin, and then fly off several hundred gallons, and fill up again, the Shadin is always within a few percent of the metered fuel. So my Shadin numbers are very close. Has this been done with the EI? Other than indications being off, it seems the plane is performing.


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2014-10-14 16.49.23.jpg


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Last edited on 27 Sep 2021, 12:30, edited 1 time in total.

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 Post subject: Re: 441 Conquest II Torque split
PostPosted: 27 Sep 2021, 10:12 
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Username Protected wrote:
and at FL270 (ISA+10) … able to burn 232/239 lbs/side/hour.

FWIW, in my MU2 installation, my -10 numbers are very similar to Max’s. At roughly 98% RPM and near the EGT limit, I’m burning between 230-240 lbs/hr/side.

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 Post subject: Re: 441 Conquest II Torque split
PostPosted: 27 Sep 2021, 15:20 
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Thank you Max and Jon.

As it was explained to me this morning, the way the EI is setup is there is a separate engine data box for each MVP unit, and each box is connected to both engines. Where it sounds like they erred is the K-factor for the fuel flow is set per box, not per side, so you can only set it so one fuel flow transducer is correct. They moved the sensors from one side to the other and the same side was wrong (in the image the right side is showing more fuel flow than it actually is). Apparently the STC holder for the MVP in the 441 is not EI, it is Carpenter avionics, so this will require some phone calls to sort out. It makes all of the computed numbers for range, etc. wrong.

I think with the EGT, you want the limit set such that the gas temperature hitting the turbine wheel is a certain value as determined by Garrett, no less for max power and no more for engine health. Since this cannot be measured directly, I don't understand the mechanism they use to get there. The EGT out of the computer is not a real number, and my understanding is the value coming out of the engine has been calibrated on a test stand to something.

At any rate one engine is making over 100 ft lbs less, which seems like an awful lot to wave away.


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 Post subject: Re: 441 Conquest II Torque split
PostPosted: 27 Sep 2021, 15:34 
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Username Protected wrote:
I think with the EGT, you want the limit set such that the gas temperature hitting the turbine wheel is a certain value as determined by Garrett, no less for max power and no more for engine health.

Not exactly.

The subject is called "compensation" and is very confusing to understand. The goal is that engine developing the same power under the same conditions have the same EGT. The idea is that engines are interchangeable and produce the same results in torque and EGT.

On my former TPE331-10AV engines, they were tested on the test stand and the actual EGT was measured under the running conditions. They were found to be 28 C and 38 C *lower* than limits for that test condition. So the engines were fitted with compensators adjusted to those numbers. Now when my engines reach the EGT limit on the gauge, they are actually 28 C and 38 C from the actual EGT limit that would damage the engines. I have that much margin before I truly bust temp limits.

The 28 C and 38 C values are published in a "DSC", data sheet customer, document in the engine log book. If, as an engine ages, it is found the EGT compensation needs to be adjusted, the DSC gives the maximum change than can be allowed. In most cases, you should never need to do this.

A person could "cheat" if they have a bad engine by adjusting the compensation to make it look okay. You can tell this by disabling the compensation and noting the EGT change (on MU2, you did this by pulling L/R ENG CTRL circuit breakers, no idea how that is done on a 441). The EGT reading should move as much as the DSC value if you have the same compensation. If it moves differently, then someone has messed with it and you should be suspicious.

The compensation varies from engine to engine due to all sorts of variables. The tightness of the compressor section, the goodness of the turbine section, and even the probes themselves are all part of the variability.

Mike C.

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 Post subject: Re: 441 Conquest II Torque split
PostPosted: 27 Sep 2021, 16:05 
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Username Protected wrote:
I think with the EGT, you want the limit set such that the gas temperature hitting the turbine wheel is a certain value as determined by Garrett, no less for max power and no more for engine health.

Not exactly.

The subject is called "compensation" and is very confusing to understand. The goal is that engine developing the same power under the same conditions have the same EGT. The idea is that engines are interchangeable and produce the same results in torque and EGT.

On my former TPE331-10AV engines, they were tested on the test stand and the actual EGT was measured under the running conditions. They were found to be 28 C and 38 C *lower* than limits for that test condition. So the engines were fitted with compensators adjusted to those numbers. Now when my engines reach the EGT limit on the gauge, they are actually 28 C and 38 C from the actual EGT limit that would damage the engines. I have that much margin before I truly bust temp limits.

The 28 C and 38 C values are published in a "DSC", data sheet customer, document in the engine log book. If, as an engine ages, it is found the EGT compensation needs to be adjusted, the DSC gives the maximum change than can be allowed. In most cases, you should never need to do this.

A person could "cheat" if they have a bad engine by adjusting the compensation to make it look okay. You can tell this by disabling the compensation and noting the EGT change (on MU2, you did this by pulling L/R ENG CTRL circuit breakers, no idea how that is done on a 441). The EGT reading should move as much as the DSC value if you have the same compensation. If it moves differently, then someone has messed with it and you should be suspicious.

The compensation varies from engine to engine due to all sorts of variables. The tightness of the compressor section, the goodness of the turbine section, and even the probes themselves are all part of the variability.

Mike C.


We're overloading the term EGT, I meant to say you want the EGT signal coming out of the engines, after the resistor, to indicate 450 degrees when the temperature of the gas hitting the first stage is what Garrett determined the materials can handle.

I don't get why you would want to run an engine at the "wrong" temperature, if I am reading the above correctly. If the materials can handle that, I'd like that to be the limit, then I can as the pilot determine how conservative I want to be. I understand the displayed number is just a number generated by the computer for the benefit of the pilot under some conditions, and that the number from the engine is adjusted on a test stand. I believe there is actually a ring of 7 (8?) EGT probes.

Maybe for practical reasons it is better to have consistent torque and operate +Zero/-X so you have room to adjust the engine to match?

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 Post subject: Re: 441 Conquest II Torque split
PostPosted: 27 Sep 2021, 16:08 
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Finally started digging into the data. One engine temps out before the other. This would seem to indicate the EGT is not adjusted correctly?

GPS-SPEED is mislabelled, it is altitude. Interestingly the gap drops to nothing at 36,600 geometric altitude (FL350). Not sure what that means :scratch:

Also there are two fields named TCOMP1 and TCOMP2. Also not sure what those are.


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 Post subject: Re: 441 Conquest II Torque split
PostPosted: 27 Sep 2021, 16:24 
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Here is a different flight with OAT (I think it's actually TAT). This pilot ran everything up to the stop, this shows no split at altitude then a gap. Very confused.


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 Post subject: Re: 441 Conquest II Torque split
PostPosted: 27 Sep 2021, 17:00 
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Here is something on the temp compensation.


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 Post subject: Re: 441 Conquest II Torque split
PostPosted: 27 Sep 2021, 23:41 
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`Searching online to refresh my memory and trying to help to explain, I found this, Conquest Performance Verification:


https://support.cessna.com/custsupt/con ... s_id=23365

This requires the shop to make some ground and flight measurements and send the data to Honeywell. It is for a -8 engine, the shop and/or Honeywell should know whether the same or similar is applicable to the -10 conversion.

Compensated EGT was discussed above. Compensated EGT is further massaged in the computer using several variables, including a delta p/p transducer input, to give indicated single redline EGT. It might be instructive to fly a test point in manual mode, where the indication will be compensated EGT.


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