CHT overheat issues with 1.2.1 Release

[mtbparker]

Hello Folks,

With this latest release, I'm experiencing extremely unusual CHT overheat issues in the turbo version.  I fly this plane religiously, so I'm quite familiar with it's normal behavior and know that it's something with the release.  Even though nothing is mentioned in the Change Log, were the engine settings tweaked?

Thanks in advance,
Tom

[Coop]

Hi Tom,

The engine behaviors were not tweaked in the last update, I'd recommend running engine maintenance through the SR22 Maintenance dialog to see if something there has gone wrong. 

[mtbparker]

Hi Coop. 

Thanks for the response.  I dug in a bit and see some needed maintenance that looks like it's related.  It says:

Quote

Inspected Engine Accessories.  The following serviced needed to be performed:
ENGINE ENTRIES

SYSTEM ENTRIES

These messages persist after every possible attempt at engine maintenance available.  Is there some way to clear these?

Thanks again,

Tom

 

[Coop]

That is what it shows when there isn't anything being caught on the inspection (nothing under Engine Entries or System Entries).

[mtbparker]

Ah!  Ok.  I was interpreting it to mean there might be something in the engine intakes.  Nevermind then.  I'll keep plugging away at it.  Unfortunately, I don't get very far into my flight before the cylinders overheat and shutdown one-by-one.  This will limit my use of the plane until I get it figured out.

[Coop]

How are you leaning the engine? Is this the SR22 Normally Aspirated or SR22TN?

[mtbparker]

Hi Coop,

I'm leaning the engine per the climb checklist (17.5 FF) and am climbing at the suggested minimum of 130KIAS.  I've also tried climbing at full rich which brings down the EGT/TIT and consequently has a minor cooling effect on the CHT as well.  Same problem.  It's always cylinder 1 that fails first.  If I don't level out and gain speed, then cylinder 4 is next.  If I do level out, I'm able to keep it so that only cylinder 1 fails.  I've been able to reliably reproduce this every flight since installing 1.2.1. 

Another thing to note is that even if I level out immediately upon getting the warning, the C1 temp continues to rise to the point of failure and shutdown.  It's almost as if it's getting into a thermal runaway situation.

Out of curiosity, I reverted back to 1.2.0 this morning and was able to climb per the checklist without any problems on a test flight this morning.

This only is an issue with the SR22TN.  The SR22 seem to be okay (on the one flight I tried.)

Tom

Edited August 16, 2021 by mtbparker

[Coop]

Hmm, that is really obscure behavior, especially since nothing changed between 1.2.0 and 1.2.1 with the plugin, I'm guessing something got corrupted in the engine files. We can try deleting these (this will reset the aircraft's physics/mx model entirely)

The files to delete are in X-Plane 11/Output/SR22: "TN_Record.txt" and "TN_State.txt"

[mtbparker]

Hi Coop,

I've only gotten two flights in with the 1.2.0 version since reverting.  I'd like to get 2 or 3 more in before making any REAL claims about CHT & version.  It will help eliminate Wx as a possible influence.  Then I'll try the experiment that you suggest.  Please bear with me.  It may take a few days to get that done. 

I did get a 2nd flight in last night with 1.2.0 and I did have CHT issues.  However, I took off with 36*C OAT / +22* ISA.  Those are significantly warmer conditions than the other cases so far.  In this case, I was able to level off and bring the CHT temps back down -- which is notably different.

Thanks for your patience and thanks for working with me on this.

Tom