reported EGI restarts mid-attack (Multiple occurences)

[adirtynurse]

Hello!

I'd like to start off by saying that I don't think this is a bug. But for the life of me this happened twice in a row in the same mission during a diving attack in Grayflag Persian Gulf. This has never happened before.
I've got the track file. Now I don't know how to chop it up, but I'll link my drive and I know the timeslots when they happened. I'll also link tacview if needed.
TRACK TACVIEW

1st occurence (TWITCH CLIP)
Approximately 2:59:00 I start a steep dive gun attack against a truck-mounted ZU-23-2. In the file you'll see I don't shoot. This is because as soon as I was about to press the trigger, my pipper disappeared and HUD went nuts. Found out my EGI was done for. I started inflight alignment and noticed the CDU screen displayed WARM START on the top left.

2nd occurence (TWITCH CLIP)
Approximately 4:20:30 I start another steep dive attack, this time with rockets against Rapier launchers. I shoot my rockets and as I'm doing so exactly like last time, HUD goes nuts and EGI restarts. This time there's a difference. The left engine shuts down as well. I go through the EGI inflight alignment again and start the left engine. At which point the server crashed ending my sortie.

I'm fairly certain its not a bug and that its me doing something wrong. I'd just like some help figuring out what that is, so I'd know what not to do in the future.

 

Thanks in advance for all of y'all's help. Have a good one.

Edited December 30, 2023 by adirtynurse
Added Twitch clips

[ASAP]

EGI going nuts probably is it switching over to HARS mode, which is what I'd expect if the EGI dies. Either its a random failure or maybe you have a key bound to the EGI switch that cycled?

[adirtynurse]

I don't know about the HARS. The HARS light next to the EGI light in the center dash behind the stick didn't light up.

As it was during a diving attack. No other button was pressed then the weapon release button. There were other attacks in between, but nothing happened during those. The two attack where the problems presented themselves were the only high-angle diving attack though.

[ASAP]

When you say the HUD wigged out, did you lose the flight path marker and all you had was the altitude airspeed and pitch ladders?

[Yurgon]

2 hours ago, adirtynurse said:

I'd just like some help figuring out what that is, so I'd know what not to do in the future.

It looks as if in both cases engine RPMs drop down to very low values, leading to both engine generators cutting out for a short moment, which in turn messes up your INS and then leads to follow-on faults like SAS and EAC cutting out as well.

I had a dual engine flameout some years ago during a steep dive with engines idle. As far as I'm aware, that shouldn't happen and I haven't managed to reproduce it on purpose. However, I made it my personal SOP to always have the engines a fair bit above idle during steep descents. For whatever reason, that keeps them from spooling down and eventually flaming out altogether.

Edit: And thanks for the videos, track and TacView, these are extremely helpful!

Edited December 30, 2023 by Yurgon

[adirtynurse]

10 hours ago, ASAP said:

When you say the HUD wigged out, did you lose the flight path marker and all you had was the altitude airspeed and pitch ladders?

Pitch ladder wasn't there. Only the sides of the HUD were there. Airspeed, Altitude and steerpoint info (which reset to the default DTC spawn ones, meaning the waypoint I input after startup were missing). Pitch ladder on the HUD was gone and the one on the HMD was going all over the place

9 hours ago, Yurgon said:

It looks as if in both cases engine RPMs drop down to very low values, leading to both engine generators cutting out for a short moment, which in turn messes up your INS and then leads to follow-on faults like SAS and EAC cutting out as well.

I had a dual engine flameout some years ago during a steep dive with engines idle. As far as I'm aware, that shouldn't happen and I haven't managed to reproduce it on purpose. However, I made it my personal SOP to always have the engines a fair bit above idle during steep descents. For whatever reason, that keeps them from spooling down and eventually flaming out altogether.

Edit: And thanks for the videos, track and TacView, these are extremely helpful!

 

Thanks next time I'll know to keep engines idle during steep attacks.

Could that be it though? Overspeed leading to engines going nuts? I was going way fast for an A-10 in those. Over 400kts.

[ASAP]

10 hours ago, Yurgon said:

 I made it my personal SOP to always have the engines a fair bit above idle during steep descents. For whatever reason, that keeps them from spooling down and eventually flaming out altogether.

That's either a random failure or a bug, definitely not an ops limit of the aircraft. 

[Yurgon]

2 hours ago, adirtynurse said:

Thanks next time I'll know to keep engines idle during steep attacks.

Just to clarify, in a steep dive with engines idle, they sometimes flame out.

To avoid the issue, keep both throttles above idle (like at 25% of their full range of motion or thereabouts, or more).

Edited December 30, 2023 by Yurgon

[jaylw314]

Weird, I could not get the track file to load.  I have PG so it's not the terrain.

is there any chance you're pulling the throttle back to idle during those steep dives and accidentally hitting the engine off bindings, even momentarily?  

[adirtynurse]

3 hours ago, jaylw314 said:

Weird, I could not get the track file to load.  I have PG so it's not the terrain.

is there any chance you're pulling the throttle back to idle during those steep dives and accidentally hitting the engine off bindings, even momentarily?  

Nope. Definitely not hitting the cutoffs.

[Lord Vader]

Hi @adirtynurse

I agree with the analysis that the engines appear to enter a shutdown/cut-off status when this occurs. In the second clip the left engine is even completely shutdown. 

I tried following your videos as best as I could and could not replicate the issue. I performed steep dives from high altitudes and never have engine shutdowns or cutting-off. 

I would review you keybindings and/or axis, maybe clear the fuel cut-off switches bindings and test some dives, then remap them.

[adirtynurse]

Thanks guys

[Yurgon]

On 1/4/2024 at 2:48 PM, Lord Vader said:

I tried following your videos as best as I could and could not replicate the issue.

In the current DCS 2.9.1 Stable I could get one engine to drop its RPM, together with the associated R-GEN warning and a master caution. See associated track.

I was careful to keep the current airspeed needle below the maximum airspeed needle, avoided prolonged flight below 0 g and I'm very sure I didn't accidentally hit any cut-off switches or anything of that kind.

Do you need further tracks to show a complete spooldown of an engine? Not sure yet how to provoke that kind of behavior, but it's probably only a few more seconds of high speed flight at idle throttle going by the issue shown in the track here.

A-10C_II_RPM_drop.trk

[Lord Vader]

This requires a bit more investigating, then. I have raised this internally.