Jump to content

Failing exhaust valve in Savvy?


Recommended Posts

Hey everybody,

Merry Christmas and Happy Holidays!  I just took a nice flight from Denver down to Colorado Springs and back and noticed something in my EGT data that I've not seen before.

The Savvy file is here: https://apps.savvyaviation.com/flights/4599237/f87a4cd4-5142-4d16-9175-0c6a837759a9

According to what I've read, a failing exhaust value will exhibit "A slow, rhythmic EGT oscillation (often on the order of one cycle per minute) is the unique signature of a failing exhaust valve."  The FEVA algorithm wasn't tripped on my flight but it still looks odd.

The part of the flight I'm interested in is from about 0:52 to about 1:08:

image.thumb.png.6ec5a9fd1cbb0fba4c9e1492419623a8.png

During this period I was running LOP at 2400, probably about 21", 9500 feet, 8.6 GPH, TAS of about 147k which is my normal.

Zooming in, you see something like this.  The temperature delta is about +- 10 degrees but it is happening rhythmically on roughly a one minute interval.

image.thumb.png.be555d74f5693d4042232dd679bc649f.png

 

Anyone better than me at this stuff see anything interesting?

Thanks!

 

Link to comment
Share on other sites

2 hours ago, kortopates said:

10 degrees isn’t enough magnitude to trip our algorithm. But don’t hesitate to open an analysis ticket and I’ll take a real look next week for you and let you know.


Sent from my iPhone using Tapatalk

Paul, Curious to know what magnitude EGT swings you usually see with valve issues.

Skip

Link to comment
Share on other sites

It does look interesting, but that egt looks like it’s varying earlier in the flight too.  The sensor isn’t loose or the exhaust pipe vibrating, is it?  It kinda looks like it has some issues from the beginning.

Edited by Ragsf15e
  • Like 1
Link to comment
Share on other sites

3 hours ago, PT20J said:

Paul, Curious to know what magnitude EGT swings you usually see with valve issues.

Skip

Sure Skip,

A sinusoidal oscillation in EGT of frequency .75 cycle(s) per minute with an amplitude of 40º F ± 10º peak-to-peak.

Correlation is high, but not 100%. When we see it we advise borescoping the valve. When caught early enough, we've have had very good results lapping the valve in situ to correct the issue. The trick is to catch it early enough with a hot spot before being burnt. 

Edited by kortopates
  • Like 2
  • Thanks 3
Link to comment
Share on other sites

Borescope of the cylinder is in order. Any available oil analysis results would also be useful, increasing nickel trends indicate valve guide wear.

I have an Insight G4 monitor in my plane, it has an exhaust valve analysis feature built in. You can check it live, no need to send data out.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.