Jrob Posted April 5, 2016 Report Posted April 5, 2016 (edited) Good morning all, I posted last week about my 231 that blew a SCAT hose connecting the exhaust from one side to the other (see pic). That has been repaired and signed off but I decided to leave the cowl off and spend some time cleaning the engine and do and oil change. I noticed several areas of bronzing around various EGT probes and the TIT probe and wanted to know if that was expected and acceptable. Also, there was a fair amount of white residue on the exhaust side of the turbo which was completely overhauled at last annual. The slip joint immediately above it is shown. The plane has been running fine with all parameters in the green. I have started to do my own oil changes as I have had a lot of problems with the local shop (crushing hoses, not hooking up the landing lights, taking forever) and as a way to get to know the plane. Thanks for any advice. Judge Edited April 5, 2016 by Jrob Quote
Bob Posted April 5, 2016 Report Posted April 5, 2016 May be a good idea to loosen the clamp on #1 EGT probe and see how it is seated. It looks like the thimble may be 90 deg. off and the probe has backed out a little. Also looks like someone bent the probe to clear the induction pipe that you have removed for the picture. Keep that in mind when reinstalling. You may want to look at an install manual on JPI's site. It is very common for guys to install them wrong! Not sure about the turbo, but I feel that it may be getting real hot, but not sure?? What are your TIT numbers at? Here is a pic from when my engine was removed at 850hrs. My turbo looked pretty even and without a light color. 1 Quote
carusoam Posted April 5, 2016 Report Posted April 5, 2016 Great picture, Bob! Best regards, -a- Quote
Jrob Posted April 5, 2016 Author Report Posted April 5, 2016 Bob. Thanks for the input and the picture of the engine off the mounts. I'm thinking it might be an exhaust leak around the gasket in the turbo itself. The unit was completely rebuilt in October (115 hours ago) and it is a very rare occasion I run the TIT to 1600 and more often it is closer to 1550 (@150 ROP). There was one occasion about a month ago when I had to go around on very short final due to geese on the runway. I didn't push the mixture in immediately and the JPI showed TIT of 1700 for 4 seconds. Other than that screw up, I tend to run pretty conservative. Have a call in to Dugosh as he has done the last couple of annuals. Thanks again. J Quote
jlunseth Posted April 6, 2016 Report Posted April 6, 2016 Rub the coating on the turbo with your finger (obviously not when the turbo is hot). If it is a powder residue then get the turbo looked at right away before flying anymore. It can be a crack and therefore leak in the turbo. If it is a coating, I get the same coating on mine and it is harmless. I don't know what it is, but the turbo has operated fine for years and passed several annuals. While you're at it, rub the inside of the exhaust pipe with your finger (again, not when it is hot, but during your next preflight). There will be residue, that is normal, but it should be dry. If it is grimey/oily then you may have an oil leak in your turbo and you don't want an oil leak in your turbo. Also, get down on your hands and knees next to the turbo port during your next preflight, open the port, and push on the tailpipe (the part of it after it exits the cowling). Watch the clamp and joint between the tailpipe and turbo, it should be stiff and not move at all. If there is movement in that joint at all, don't fly until you get it checked. Quote
peevee Posted April 9, 2016 Report Posted April 9, 2016 (edited) we get a similar white powder looking coating, mechanic swears it's nothing to worry about, I'd sure like to know what it is Edited April 9, 2016 by peevee Quote
carusoam Posted April 10, 2016 Report Posted April 10, 2016 Take a picture of it. See if we recognize it... Best regards, -a- Quote
Marauder Posted April 10, 2016 Report Posted April 10, 2016 we get a similar white powder looking coating, mechanic swears it's nothing to worry about, I'd sure like to know what it is I thought it was lead residue. Lead boils a little over 600°F and fully vaporizes at close to 1800°F. Quote
peevee Posted April 10, 2016 Report Posted April 10, 2016 I'll try, I'll see if I can stick a camera in the turbo inspection door. My first thought was exhaust leak as others have mentioned but our a&p swears it's OK. We've had two shops do work on the plane this month and neither flagged it so..... Quote
carusoam Posted April 10, 2016 Report Posted April 10, 2016 Grab a snapshot, and post... See what else could be in there according to MS eyes. How much exhaust leak is OK? Best regards, -a- Quote
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