Very High EGTs on finals

[andrewbutler]

Hello All,

I fly out of a very short field in the West of Ireland (about 350 yards with high obstacles at one end), and was pracitising slide slip final approaches today, as one end of the field has several high obstacles on finals. The point of the exercise is to come in as steeply as possible (heavy slide slip, little or no power) until the threshold, then level off with a burst of power to arrest the sink rate and touch down.

Powerplant is an IO360 with one P-MAG and one Slick, with a CS MT 3 blade prop out front. When on finals if I pull the power completely, my EGTs shoot up to over 1500, and I have to apply some power to get them down again.

I run LOP, and have read and understood John Deakin's articles so have learned a lot about what is going on inside the engine during different modes of operation. However, I haven't really been able to figure out what exactly is happening to cause the EGTs to shoot up like this when I pull the power on finals.

Can anyone help me? Is it normal or may I have a problem? Is it damaging?

Thanks for your help,
Andrew Butler,
RV7 EI-EEO 38hours
Galway, Ireland.

[Dragonfly]

Idle mixture too rich and still burning as it exits the exhaust valve elevating the EGT's?? Just a guess.
Timing not quite right for the low RPM and causing the same as above?? Again just a guess.

[RV10inOz]

my EGTs shoot up to over 1500, and I have to apply some power to get them down again.

So what!!!!!!! If you have read again the various articles you will not be so worried.

Are you full rich during this operation?

There is no need to be, mind you if you richen up a bit from LOP settings in your cruise and descent this will ensure a good margin from a cough, just remember the go around is red knob first. There is no GA that requires anything faster than red knob/black knob assuming RPM is either fine or OK where it is.

Previous post has some good things to check also.

[kiwipete]

Andrew

You should have a 30-50 rpm rise when you sloooowly pull the mixture at idle. On the same engine mine was quite rich and had to be adjusted after the engine had run in.

Cheers

Peter

[AltonD]

What are the chances that on the extended side slip, your have selected the tank where the fuel is moving away from the pickup. You could be on the edge of fuel starvation but it is picking back up just as you come out of the slip. I would think this could only happen with fuel tanks drawn down pretty good.

Just a thought.

[jjconstant]

I may be proposing a physical impossibility but is it possible that with a very heavy side slip angle and idle power it is harder for the exhaust to leave the pipes and thus increasing egt? Increasing the power and/or reducing the side slip angle would "unplug" the exhaust.

It may be too wild an idea...

Jeremy

[David-aviator]

With a constant speed MT prop set to fine pitch (go around setting) and engine at idle, you should be coming down like a boat anchor. At least that was the case with an electric MT prop. It was a huge speed brake.

The side slip may not be necessary.

I don't look at EGT's on final.

[frazitl]

engine does the same thing as I'm letting down for a relatively steep approach into KHND. My GRT EGT graph shows very erratic EGTS with some cylinders going cold, and some with high EGTs. First of all, at these low power settings I don't think I can hurt anything. Second, It looks to me like lean misfire and fuel burning in the hot exhaust pipe caused by the prop driving the engine (resulting in lots of air) at very low manifold pressure and very low fuel flows.

I'd like to understand this better, but I don't think we can hurt the engine with the throttle all the way out (just like leaning at idle).

What say the experts???

[Jamie]

What engine monitoring system are you using? Almost all of the engine monitors allow you to dump the data. If you could provide the data to the group (especially with a system like the Dynon that allows you to get engine and flight data) it may give folks a clearer picture of what is happening.

Cheers.

[andrewbutler]

Boat anchor, you are absolutely right. The MT is a great speed brake and perfect for short fields. However, if I am a little high, I still need the option of pulling the power all the way back. I don't normally monitor the EGTs either, but my EFIS gives me verbal warnings when they go over 1500 - and that kinda forces to me to look!

I always slideslip with right rudder, and have a mandatory "select right tank" check in my prelanding procedure. Prop is set to Max RPM, and mixture is set to full rich. My idle mixture setting is not quite correct yet. It may be still too rich.

My EFIS is an AFS3500 with Enginer Monitor. I will download yesterday's data, graph it and post it.

Thanks for all the replies.

Andrew.