231 LOP TIT fluctuating

[flynboy]

Had a couple of times with something strange with TIT at cruise that has me confused, looking to see if anyone else has seen this.

Level at cruise, usually for more than 1/2 hour or so.  about 2500 rpm, 32" MP, 9.5-10 gph lop.  TIT between 1575 and 1585, steady.  Then the tit starts to climb slowly with no changes towards 1600.  Try to lean a little more causes it to climb, richening causes it reduce, then climb toward the peak.  All chts 350 or lower and not climbing.  Usually after it goes through 1600, I'll go rop, let it cool back down and then relean and usually it doesn't occur again.

Thoughts?

 

Joe

[carusoam]

Joe,

Did I mention how much I like my NA engine? 
 

Are you familiar with Mouse Milk?

What do you have for an MP controller on your ship?

Do you have an engine monitor with data you can share?

A JPI can generate some really nice pics... to describe in detail what is going on...

You did a great job of describing the issue...

If you can download the engine data, upload to Savvy.com, push the share button, copy link here....

I can invite a great M20K pilot, that has deep engine knowledge, along with the ordinary CFII skills of a transition trainer...

Lets see if Paul @kortopates is cruising through the neighborhood... (M20K with TIT drift)

Best regards,

-a-

[aviatoreb]

18 hours ago, flynboy said:

Had a couple of times with something strange with TIT at cruise that has me confused, looking to see if anyone else has seen this.

Level at cruise, usually for more than 1/2 hour or so.  about 2500 rpm, 32" MP, 9.5-10 gph lop.  TIT between 1575 and 1585, steady.  Then the tit starts to climb slowly with no changes towards 1600.  Try to lean a little more causes it to climb, richening causes it reduce, then climb toward the peak.  All chts 350 or lower and not climbing.  Usually after it goes through 1600, I'll go rop, let it cool back down and then relean and usually it doesn't occur again.

Thoughts?

 

Joe

Do any of your EGTs do any fluctuating while this happens?

[ziggysanchez]

18 hours ago, flynboy said:

Had a couple of times with something strange with TIT at cruise that has me confused, looking to see if anyone else has seen this.

Level at cruise, usually for more than 1/2 hour or so.  about 2500 rpm, 32" MP, 9.5-10 gph lop.  TIT between 1575 and 1585, steady.  Then the tit starts to climb slowly with no changes towards 1600.  Try to lean a little more causes it to climb, richening causes it reduce, then climb toward the peak.  All chts 350 or lower and not climbing.  Usually after it goes through 1600, I'll go rop, let it cool back down and then relean and usually it doesn't occur again.

Thoughts?

 

Joe

What happens with your FF & MP while this is happening? 

[flynboy]

I have a jpi 800, I'll try to go out and see if I can download the info later today.  To answer the other questions:

No noticeable rise in other egts, but only going by the bars here, I didn't cycle through each as I was watching the tit / ff part of the edm at the time.

ff is steady (within +- .1 gph), no noticeable change in mp.

 

Thanks,

Joe

[Andy95W]

2 minutes ago, flynboy said:

 

No noticeable rise in other egts, but only going by the bars here, I didn't cycle through each as I was watching the tit / ff part of the edm at the time.

ff is steady (within +- .1 gph), no noticeable change in mp.

I would suspect your TIT probe is starting to go bad.  It lives a pretty hard life where it’s at.

[jlunseth]

It does sound like a probe, but just as a precaution, the next time you preflight, open the turbo inspection door and then push on the tailpipe. Both watch and feel for movement at the inlet V clamp.

If the EGT’s are not moving, then I would guess probe. However, the fuel flow and throttle in the 231 are not exactly accurate to the tenth and the ff in particular does like to climb a few tenths after you make your cruise setting. it does not take much to cause TIT changes.

[flynboy]

Thanks for all the suggestions.  I went to try and pull the data from the 800, but I apparently have an older one and couldn't find a usb anywhere.  Good news is plane is going in the shop next week and one of the upgrades is replacing the 800 with an 830 (along with a pair of gi275s to replace the ai / hsi).

JL, the v clamp comment was interesting.  They replaced this during my annual in November.  I pushed on the exhaust but couldn't feel or see any movement, I'll keep an eye on that.  

once the plane comes out of the shop, I'll try to get some followup data and see if it's still happening.

 

Thanks!

Joe

[aviatoreb]

On 2/23/2021 at 3:04 PM, flynboy said:

Had a couple of times with something strange with TIT at cruise that has me confused, looking to see if anyone else has seen this.

Level at cruise, usually for more than 1/2 hour or so.  about 2500 rpm, 32" MP, 9.5-10 gph lop.  TIT between 1575 and 1585, steady.  Then the tit starts to climb slowly with no changes towards 1600.  Try to lean a little more causes it to climb, richening causes it reduce, then climb toward the peak.  All chts 350 or lower and not climbing.  Usually after it goes through 1600, I'll go rop, let it cool back down and then relean and usually it doesn't occur again.

Thoughts?

 

Joe

I had some tit fluctuations about a year ago, that made me worry about my turbo, about my induction, and so on, but none of the EGTs were reacting in any way to suggest it was real related to induction. But still plausibly the turbo.  In level cruise at various settings it would sort of skip for 20 seconds, from say 1580 to maybe 1650 briefly.

Turned out to be the sensor itself.  The tit probe was old and on last legs and this seemed to be the failure mode that this one displayed.  After a new tit probe, it was rock solid. 

[flynboy]

That sounds almost exactly like what I'm seeing.  If it keeps doing it I'll have them replace the probe.  No idea how old the one in there is.

[aviatoreb]

4 minutes ago, flynboy said:

That sounds almost exactly like what I'm seeing.  If it keeps doing it I'll have them replace the probe.  No idea how old the one in there is.

Yeah - give it a try.  I didn't find it by logic but by exhaustive search.  We were poking around inspecting the induction, looking at the injectors, looking at the data, which is never a bad thing, but we just replaced the tit as a Hail Mary why not - but that was the trick.  It is not an expensive thing to do.  They don't last forever giving accurate measurements living I that incredibly high temp environment.