Random hot start causing engines to fail

[henrik.bergvin]

Today when I spun up my engines after an overnight stop I got a hot start. I'm using the "current conditions" setting, and I'm on the 23rd of April release.

So let me explain what happened. I did the normal preflight procedure from powered down, no avionics running. Bat on, props to full, condition to fuel cutoff. Power to idle.

I hit ignition for the right engine, and watch as the N1 rises. 15%, fuel on. Immediately, ITT rushes to 1200 for 2 seconds before going down to normal temperatures (around 600). Torque never went over 20 as far as I can remember.

This only happened on the right engine, but not on the left.

I started the flight, and unfortunately had a sim crash. Restarted the simulator, loaded up the flight on the ground again, same procedure but now hot start.

However, on climb out first the left engine failed, and shortly after the right. Both were in "Fail Condition" in MVAMS.

What could be causing this? Bug or did I do something wrong on startup?

Edit: Only thing I can think of is that I had 8kt tailwind (give or take, it wasn't straight on the tail) when starting, but that makes no sense for the second start where I was standing in the same position with the same wind.

[Bushido]

Wait untill n1 stabilise (around 20%) before injecting fuel.
15% seems a bit too early.

[brett.cummings]

I had this as well, updating from 1.1.7 to 1.1.8. My engine condition was about two thirds remaining prior to the flight, but following the same engine start procedure (stable above 20%) I had hot starts on both engines.

I didn't un-install and re-install entirely between updates, I only installed 1.1.8 over the top. I've since completely removed and re-installed but have yet to test again.

[henrik.bergvin]

Wait untill n1 stabilise (around 20%) before injecting fuel.
15% seems a bit too early.

The guide and procedures included says after N1 reaches 12% minimum, which is what I was following in detail.

[henrik.bergvin]

I had this as well, updating from 1.1.7 to 1.1.8. My engine condition was about two thirds remaining prior to the flight, but following the same engine start procedure (stable above 20%) I had hot starts on both engines.

I didn't un-install and re-install entirely between updates, I only installed 1.1.8 over the top. I've since completely removed and re-installed but have yet to test again.

I suspect that the 8kt tailwind was actually my issue here, do you know if you were pointing your tail into the wind?

[brett.cummings]

Not exact winds, but there was at least some headwind factor, and I've never experienced anything as significant as this. Both engines both rapidly rose above 1000 degrees in the first start after install. Ive seen ITT vary during start depending on atmospherics, but not the way it rose in this case.

[KenG]

Wait untill n1 stabilise (around 20%) before injecting fuel.
15% seems a bit too early.

The guide and procedures included says after N1 reaches 12% minimum, which is what I was following in detail.

12% N1 is minimum, but the other half of that is N1 is also stabilized! If N1 is still accelerating then there may still be eddies in the combustion chamber that can cause scorching of the walls or turbine section.

I know people who dump the fuel into the engine at 12% every time and I also know people who wonder why they are spending so much money on hot ends.

I have also seen a pilot torch a -60A (exceed 1000C) at KAPA when they dumped the fuel in at exactly 12%.

My advice has always been to wait until N1 stops rising and if it stops anywhere near 12% then to discontinue the start and hook up a GPU.

[henrik.bergvin]

Wait untill n1 stabilise (around 20%) before injecting fuel.
15% seems a bit too early.

The guide and procedures included says after N1 reaches 12% minimum, which is what I was following in detail.

12% N1 is minimum, but the other half of that is N1 is also stabilized! If N1 is still accelerating then there may still be eddies in the combustion chamber that can cause scorching of the walls or turbine section.

I know people who dump the fuel into the engine at 12% every time and I also know people who wonder why they are spending so much money on hot ends.

I have also seen a pilot torch a -60A (exceed 1000C) at KAPA when they dumped the fuel in at exactly 12%.

My advice has always been to wait until N1 stops rising and if it stops anywhere near 12% then to discontinue the start and hook up a GPU.

Thank you for the insight, Ken, I really appreciate it. From now on, I'll make sure to wait until it is stable before giving it fuel.

I still don't quite understand it happening though, considering that the engines have less than 20 hours on them, and were in perfect condition. Is it normal, in the situation I describe, for the engine temp to go down to normal levels immediately after bursting over 1000, and then work fine up to FL310 with no indication of issue?

Also, I understand some engines don't like having the wind in the wrong direction, how susceptible is the KA to this, and is the Milviz one simulating it?

[Taguilo]

Hi,

I guess something like this is what happened to you ?:

- You switched the starter to the down position (Starter Only), moved CL to Low Idle, noticed that combustion was not coming, then moved CL lever back to Fuel Cutoff. After that you switched the starter Up (Ign and Eng Start), when passing 12 % N1 moved CL to Low Idle and ITT rose towards 1000 C.

Now, Starter position in Starter Only does not prevent Fuel Flow to engine, the only difference with the Up position is that ignitors are not automatically fired. But if CL is moved to any fuel on position, fuel is injected and will soak the combustion chamber. Any time you notice that, the proper procedure is to put CL back to fuel off and hold the Starter in down position for ~30 seconds to vent the excess of fuel before attempting a regular start.

Tomas

[henrik.bergvin]

Hi,

I guess something like this is what happened to you ?:

- You switched the starter to the down position (Starter Only), moved CL to Low Idle, noticed that combustion was not coming, then moved CL lever back to Fuel Cutoff. After that you switched the starter Up (Ign and Eng Start), when passing 12 % N1 moved CL to Low Idle and ITT rose towards 1000 C.

Now, Starter position in Starter Only does not prevent Fuel Flow to engine, the only difference with the Up position is that ignitors are not automatically fired. But if CL is moved to any fuel on position, fuel is injected and will soak the combustion chamber. Any time you notice that, the proper procedure is to put CL back to fuel off and hold the Starter in down position for ~30 seconds to vent the excess of fuel before attempting a regular start.

Tomas

No, that's not how I did, I switched starter to ON (I have this bound to a button for each engine on my HOTAS, using the TOGGLE_STARTER1 and TOGGLE_STARTER2 actions), waited until N1 passed 12% and moved CL to Low Idle. ITT went over 1000C. As Ken mentioned though, I probably should have waited until it settled.

[Victory103]

Also, I understand some engines don't like having the wind in the wrong direction, how susceptible is the KA to this, and is the Milviz one simulating it?

I've started with the wind in all directions and while not ideal, never had an issue using the same method KenG mentioned of letting the N1 stabilize before introducing fuel, around 20-25%.

[henrik.bergvin]

Ok, so now I know for sure I am not doing something wrong.

I flew a flight from VTCC - VVPQ, parked and shut the plane down completely. Had the sim running for roughly 2 hours when I was out for a walk, came back to perform a flight from VVPQ to VTSG.

Full preflight, following the checklist to the t. I check that condition is set to cutoff, starter + ignition (switch in the up state). Wait until stable above 20 N1 (usually about 21). Introduce fuel to low idle and bam, ITT spikes to 1200 and the engine is immediately set to fail condition in mvams. This is where I feel like flipping the table and giving up simming.

3-5 seconds after the hot start, temperature dives back to ~500 again, and stays stable, but obviously it would be stupid to even try flying after this.

I know for sure that the engine was at around 95% when doing the flight from VTCC to VVPQ, and I did not overtorque or overtemp it, everything was in the green for the entirety of the flight.

This can *not* be as intended. If this was the case, then every King Air would be permanently on ground needing engine repairs.

I follow the procedures to load up the plane as per directions in the post (using the "current conditions" option in MVAMS, and picking a previously saved game with the aircraft. It doesn't seem to load up exactly the same (battery is always on, even if I switch it off, also engine anti-ice is on when the plane is loaded), but I switch it off to cold and dark before doing anything.

Can someone tell me what I'm supposed to do? Only way of getting it back to functioning again after this to not use "Current Conditions" in MVAMS and only load it cold and dark, then save after the next flight, switch to current conditions, and yeah... It's a chore.

Someone *please* help me figure this out.

[Taguilo]

Hi,

Other users have reported FSUIPC5 as the cause of the engine misbehavior.
You can start by checking that.


Tomas

[henrik.bergvin]

Hi,

Other users have reported FSUIPC5 as the cause of the engine misbehavior.
You can start by checking that.


Tomas

I am using fsuipc5, yeah, but never seen issues with this.

This may be connected to my axis binding to CL though, maybe causing the levers to hop into low idle at some point when I’m not looking. I’m going to remove the binding to that axis and see if that solves the issue.

I will report back.

[henrik.bergvin]

Since I stopped using an axis to control condition levers, I’ve had zero hot starts. The engines still feel like they fail way too often with very little reason.

I’m starting to feel like we should have a way to disable engine failures in the aircraft. I get it that it is supposed to be realistic, but it feels far from it. I keep my numbers below limits, and I still get failures for no apparent reason.

Would it be too much to have a “service based engine failures” option? Or do I have to reset the engines after each flight to avoid them failing because of the sim having a hiccup or I accidentally nudge my power levers and god forbid happen to reach exactly ITT 820 for less than three seconds?

Yesterday I had an engine out again (right engine, it’s always that one I feel). This was during climb. My N1 was at around 98, props were reduced to 1600, ITT sat at about 805-810 (within max cont limits), and torque was probably 80-85 (don’t remember exactly here).

Before the flight I had checked MVAMS, and the engines were not at approximately 95%. I did a good preflight, nothing was off. Temps good on start. Then at about 1000-2000ft the engine shut down. Again no indication why it would.

Did I just have a bad roll on the randomizer?