C90 GTx Aircraft Performance Discrepancies

[KingAir76]

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ISSUE DESCRIPTION

Description of the issue: C90 Gtx Aircraft Performance Discrepancies.

I am currently employed as a C90 GTi pilot. For comparison, there are minor differences between the C90 GTi and C90 GTx. For example, the GTx has winglets and slightly different tires. However, they are essentially the same aircraft with the same engines (PT6A-135A) resulting in nearly identical performance numbers.

I performed a test flight in the sim and found the following results., The test flight temperature was 9 degrees C at 6,000 ft (ISA) at full torque (~1,520 pounds per side).

When I compare the simulator’s C90 GTx values vs. the real life GTi’s performance charts, the simulator version is significantly off. It is burning 100 pounds of fuel per hour higher per engine (200 pounds of fuel per hour higher total) and is 35 knots slower. This means the simulator aircraft is burning more fuel and goes significantly slower than the actual aircraft.

If applicable, which aircraft is experiencing this issue: C90 GTx

[PC Only] Did you remove all your community mods/add-ons? If yes, are you still experiencing the issue?

Not Applicable

FREQUENCY OF ISSUE

How often does this occur for you (Example: Just once, every time on sim load, intermittently)?

Persistent

REPRODUCTION STEPS

Please list clear steps you took in order to help our test team reproduce the same issue:

1. Fly the simulator C90 GTx and copy performance values such as fuel flows and indicated airspeed
2. Compare these values to C90 Pilots Operating Handbook performance charts for these atmospheric conditions
3. Correct differences

YOUR SETTINGS

If the issue still occurs with no mods and add-ons, please continue to report your issue. If not, please move this post to the User Support Hub.

What peripherals are you using, if relevant: Not relevant

[PC Only] Are you using Developer Mode or have you made any changes to it?

No

[PC, MSFS 2020 Only] Are you using DX11 or DX12?

PC

[PC Only] What GPU (Graphics Card) do you use?

RTX 4080

[PC Only] What other relevant PC specs can you share?

I9- 14th gen

MEDIA

Please add a screenshot or video of the issue occurring.

[END OF FIRST USER REPORT]

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[SunkPigeon35371]

FYI…I have corresponded with Carenado, and they said they are working with Asobo to get a fix in for many of the issues with the King Air GTX.
Just letting you know that they are aware.
How realistic they will get with correct performance is anyone’s guess. My experience tells me it will take a community member who is interested enough to build a fix.

[KingAir76]

Thank you for the update. I appreciate it.

[CaptainRude2025]

SU 1 seems to have fixes for the C90 but high fuel flow and low speed are not among those (at least according to change log).

I used to fly the C90GTi some 15 years ago, I also came to the same conclusions. About 50% higher fuelflow and 20% slower than should be. Along with some other inaccuracies.

[MSFS2024] Beechcraft C90 GTX King Air

For me the L and R green down lock lights are only visible from a certain angle: [image] Little further back: [image] Same for TCAS, PROP SYNCH green lights. Engines don’t start without BOOST PUMPS ON, this is incorrect behavior. You can dispatch and fly around for 100 hrs without working boost pump before engine driven pump needs to be overhauled. AUTOFEATHER lights shouldn’t be ON at idle power: [image] PITOT HEAT lights should be ON when PITOT HEAT in OFF position (so now working i…

[SunkPigeon35371]

It’s encouraging to see that did something with the model, but obvious need for improvement.
I’ll reach out to them again, and give them a thorough list of needed fixes. I’ll have time this coming week to test this updated model further. Just gave it a quick flight tonight.

[SunkPigeon35371]

Items that I have so far to be fixed:

1. Side windows should not open in flight/Pressurization would prevent that.
2. Windshield heat starts in “Normal” position. Should start “Off”, although if the aircraft had a saved from previous state, that would fix the problem.
3. Push to reset Caution/Warning buttons are silent now. I believe they made a click noise previously.
4. LOD issues(Have to be too close for function) on the standby instrument display knobs and Nav/Comm center panel.
5. Electrical indication issues on rotary display. Particularly, when turning one generator on after start it shows a 100% load indefinitely when it should charge the battery and start to show a reduction in draw/load.
6. Recall in route menu is greyed out and not functional. This was functional atleast part of the time when attempting to download a flight plan from Simbrief.
7. Fuel XFR lights will still not extinguish when wing tanks are empty and switches turned off.
8. Autofeather lights on all the time, instead of being on only with advancement of 90% N1 or more.
9. VNAV functionality when attempting any change to VNAV, including a “Direct to” VNAV Altitude, changing a VNAV angle in a flightplan, or having it use the default angle you set in VNAV defaults.
10. Fuel use is 50% too high.
11. Speed is 20% too slow.
12. HSI formats for FMS input on the PFDs do not work. Interestingly, the MFD is fine, and the “Active leg” indication on the MFD map format indicates properly, but not on the PFD. Autopilot follows FMS Nav fine, its just the display issues on the PFD not working properly. I believe it was on the previous build.

Also, “Ground Fine” actually works fine, but I can’t get a controller bind setting set to use it. If anyone has luck in getting it to work with a controller please let us all know.
Let me know what else you have for a list, anything that contradicts this, etc…

[CaptainRude2025]

There shouldn’t be any chime in connection with master cautions or warnings and the master caution / warning flashers don’t reset on the real aircraft even if the fault causing it to activate is rectified, they keep flashing until pressed.

For example, if there is a nuisance, like a caution light coming on for just 1 second while not paying attention, you would find the master caution flashing without cause.

PITOT HEAT caution light is working in reverse (should be illuminated if not ON).

Should be able to start engines with boost pumps off. The aircraft can fly 100 hrs without working boost pumps before engine driven pump needs to be replaced.

Torque effect (left turn tendency) on ground at beginning of the take-off roll missing. Torque and ITT not going over redline at full throttle.

Not enough drag at flight idle (insufficient deceleration) noticable during flare.

Unless some of these got fixed with SU1, I didn’t check.

[SunkPigeon35371]

Noted on the master cautions/warnings(I only meant that when you press the master warning/cautions there was not button press-click noise anymore.), Torque effect, and flight idle drag are also noted. Both need work.

It appears the pitot heat caution lights are fixed and the boost pump issue.

I’m sending out another email to hopefully get some of these items addressed.

[CaptainRude2025]

@SunkPigeon35371

I only meant that when you press the master warning/cautions there was not button press-click noise anymore

Yes, I got that.

I believe the C90 gives a chime in FS2024 when the master caution / warning activates? It shouldn’t, all warnings and cautions are silent on Kingairs, and the second odd design choice is that the flasher will not reset until pressed, solving the cause that triggered the flasher will not cancel the flasher on the real aircraft.

But again, maybe this got solved already.

[SunkPigeon35371]

It does chime and still stops flashing when solved and shouldn’t. I’ll add them as items to notify them of.
I bombarded them with the list above. Looks like they opened it, but no response yet. Hopefully they will entertain us with more improvements. For now, I’m happy that the autopilot has been fixed and follows the flight director reasonably well.
After testing on several flights, the speed is low at low altitudes and higher than normal at high altitudes by around 20 knots either way. This may be a torque calibration issue as you can maintain max torque past FL260. Fuel use appears to be tweaked, but it’s still off since torque is off and who knows what else.

[CaptainRude2025]

I believe this is a bug as well:

Beechcraft C90 GTX King Air Malfunction

What doesn’t help either is that torque and probably ITT needle as well do not turn red as they should when exceeding limits. I came across this post: [image] I just realized a thing! This ITT redline (plus symbol) should ONLY be there for engine start, it shouldn’t be visible during flight. The single redline counts as both the torque and ITT redline. This might also cause people to get these engine failures. Neither torque nor ITT should exceed the first redline.

[SunkPigeon35371]

Carenado did respond and will look at the list of items and consider for the subsequent Sim update, so keep fingers crossed.

[CaptainRude2025]

Another one, I didn’t check but apparently autofeather limits the torque and ITT:

Beechcraft C90 GTX King Air Malfunction

Ok, that is a bug then. Autofeather should NOT prevent overtorque or exceeding ITT limits, that is not its function and that is not how it works on the real aircraft. The only thing autofeather is capable of doing is dumping oil pressure from the propeller dome which feathers the propeller of an inoperative engine. It has no means to limit torque or ITT. The Kingair simply does not have a torque / temperature limiter. The torque / temperature limiter is sitting on the pilot seat …

[SunkPigeon35371]

Your description of how autofeather works is correct, but I am not able to duplicate any issue where turning the switch on in the model limits torque or ITT. In fact, have been unable to get ITT to exceed limits in any circumstance, which is a modeling issue. Torque is always able to exceed limits, even above FL260(Still max), which is a modeling issue as well. The GTX would normally “Torque out” at altitudes in the mid to high teens.
This modeling issue is probably exacerbating the performance issue where speed is slower than it should be(20 knots or so) at lower altitudes, and higher than it should be(20 knots or so) at higher altitudes. This is also contributing to fuel flow accuracy issues.
I sent Carenado the GTI cruise chart from KingAir76, so hopefully that all can be tweaked.

[SunkPigeon35371]

Amendment…it should torque out in the low 20’s.

[CaptainRude2025]

Ahah, thanks for checking. I don’t know how the reporter got that result. Maybe in carreer mode it behaves differently?

I remember when I tested the C90 (pre-SU1) I couldn’t get the torque to exceed redline during take-off with full throttle.

I have the GTi full manuals for you if it helps.

[CaptainRude2025]

Guess change over from torque to ITT limited can be found somehwere in the cruise performance tables.

[TomLamarre]

I don’t suppose they mentioned anything about looking into the Saab 340, too, did they? As mentioned over here [MSFS2024] Saab 340B - #112 by doriel0726 its performance is also pretty far off the mark.

[SunkPigeon35371]

Could be different in career mode. Bugs can be variable and mind-bending. Yeah, it will over-torque anytime now, but never over-temp even at 40c on takeoff.
Sure and thanks.

[SunkPigeon35371]

No, but try contacting them directly through the website. I’ve had good luck so far. They seem appreciative and responsive if you have good/accurate and knowledgeable info that can help improve their models.