Rv-10 Lycoming 540 D4A5 High EGT’s & CHT

[simpsonstu]

Hi All,

Been a little toasty in the UK recently with temps around 80 F. With full throttle on take off the No1 cylinder indicates the hottest but 1,2,4 reach 1550F the rest just under 1500, pretty much stays that way even when RPM reduced to 2500 until airflow increases to around 125kts indicated. The No1 CHT also peaked momentarily at about 420F albeit for a few seconds, which I have never seen before. Fuel flow on take off is around 88 l or 23 ish gallons an hour, so it’s getting enough fuel on take off according to Vics video on base leg.

Cruise is all fine but I have noticed I cannot move the mixture very far without EGT’s going into the high 1500’s again, so leaning is almost a non starter, it used to lean absolutely fine with a fair amount of movement to see any spikes.

I appreciate CHT is the important one and the no1 is normally the hottest but surely I shouldn’t be seeing these high temps on take off with temp outside in the 80’s F. Is it a case of checking fuel nozzles, baffling around the engine or a hazard of a 540 on a hot day, I never noticed any of this with external temps in the low 70’s. Or poor control of RPM etc after take off? I do not use the Dynon leaning setups.

Sorry rubbish picture but 225C is 437F, 840 is 1562, the peaks.
Cheers Stu

 

[lr172]

You are running WAY too lean at WOT. I have to question the accuracy of your FF instrument. 23 should be plenty, but no way that 23 GPH nets EGTs in the 1500-1550 range

 

[lr172]

You are running way too lean. I have to question the accuracy of your FF instrument. 23 should be plenty, but no way that 23 GPH nets EGTs in the 1500-1550 range

If this just popped up out of the blue, my first guess is a fuel leak downstream from the red cube. Youare reporting 23 gph, but 1/3 of it is going somewhere else other than the cylinders. given the even distribution, i would suggest the leak is between the red cube and the servo. it is not related to a 10* increase in ambient temps.

 

[DCBrown198]

Is this FF reading with the electric fuel pump on? In many cases, with fuel pumps positioned prior to the FF sensor, erroneously high FF readings can occur. Does the FF show the same with the fuel pump off?

As Larry suggested, somehow the engine is short on fuel in your condition. Have you seen any dye remnants from the fuel anywhere along the fuel routings in the engine compartment?

 

[dmattmul]

You can create a zip file for your engine data and post it. Lots of viewers know how to troubleshoot this on the forum.

 

[simpsonstu]

Ok thanks chaps, suspected as such , fuel flow with the pump off drops from 25 to 13 ish gph , it’s definitely not getting the fuel , I’ve seen no leaks other than a recent small drip from one of the drains under the wing , will give the Engineer a call and get the cowlings off. Also I’ll get some data downloaded.

Many thanks
Stu

 

[lr172]

fuel flow with the pump off drops from 25 to 13 ish gph ,

Many thanks
Stu

while that could mean you have an issue with the mech pump, it doesn't necessarily explain the symptoms you stated. you were indicating 23 during the phase when the egts were 1500, correct? assuming the boost pump was on; is that correct? in that case, a failing mech pump should have no bearing as the boost pump is doing the work. flow is flow unless there is a reason to suspect an inaccurate flow reading or the fuel is flowing somewhere other than the cylinders.

am i missing something here? were you getting the 1500 while showing a 23 flow rate?

 

[BobTurner]

840 C =1,544 °F. But don’t get distracted from the real issue. I’d suggest the ‘coke bottle test’ (flow fuel from the injectors into 6 bottles.)