yankee-flyer
Well Known Member
912 ULS Rotax installed in an RV-12. 22 months/127 hours on the engine. Everything OK at 100-hour inspection.
This morning on taxi out the left EGT readout spiked up to 2000+ degrees in just a couple of seconds. I shut everything down waited a minute and re-started-- everything normal. Flew 1.2 hours to a family reunion with no problems and the airplane sat fro almost 4 hours.
About 15 minutes after takeoff the left EGT reading spiked; I reduced power from 5200 to about 4200 and the temp started to drop slowly and then instantaneously dropped to normal, Back to cruise power/altitude (Density altitude 7700 and yes, the fuel flow was reading 5.9 again) and about 15 minutes later the same thing happened, including instantaneous return to normal ( the display actually blinked as it changed) I noted the conditions as follows:
EGT L 1265 then up to 2079
EGT R 1240 (Normally seem to read 25-50 deg cooler than left side)
RPM 5200
MP 22.7/8 (reading fluctuates rapidly in the decimal digit)
Oil Pressure 68
Oil Temp 214
CHT L 187
CHT R 186
OAT about 55 F
There was NO CHANGE in engine sound, power output, manifold pressure, RPM, or anything else I could see while the EGT was climbing (less than 10 seconds from baseline to 2079), 3-4 seconds to instantaneous drop).
Same thing happened a third time with me keeping a close eye on alternate airports along route.
Then during descent from cruise altitude to home base at about 4500 RPM it spiked again. Pulling power all the way back had no affect, Going to FULL power brought an instantaneous return to normal.
I can't think of any mechanical problem that would cause this other than something hanging up a carb float (lean mixture) but it happens most often after 10-15 minutes at constant power setting>Need input on what to look at. Loose EGT probe? Loose connection back at the firewall? Or ????
On the positive side, at about 1025 Lbs gross weight, take off from a not particularly manicured grass strip at 2500 density altitude was not more than 1000 feet ground roll-- what a change from my AA-1!!!l
Thanks guys-- need to fix this before flying Young Eagles Saturday.
Wayne 120241/143WM
This morning on taxi out the left EGT readout spiked up to 2000+ degrees in just a couple of seconds. I shut everything down waited a minute and re-started-- everything normal. Flew 1.2 hours to a family reunion with no problems and the airplane sat fro almost 4 hours.
About 15 minutes after takeoff the left EGT reading spiked; I reduced power from 5200 to about 4200 and the temp started to drop slowly and then instantaneously dropped to normal, Back to cruise power/altitude (Density altitude 7700 and yes, the fuel flow was reading 5.9 again) and about 15 minutes later the same thing happened, including instantaneous return to normal ( the display actually blinked as it changed) I noted the conditions as follows:
EGT L 1265 then up to 2079
EGT R 1240 (Normally seem to read 25-50 deg cooler than left side)
RPM 5200
MP 22.7/8 (reading fluctuates rapidly in the decimal digit)
Oil Pressure 68
Oil Temp 214
CHT L 187
CHT R 186
OAT about 55 F
There was NO CHANGE in engine sound, power output, manifold pressure, RPM, or anything else I could see while the EGT was climbing (less than 10 seconds from baseline to 2079), 3-4 seconds to instantaneous drop).
Same thing happened a third time with me keeping a close eye on alternate airports along route.
Then during descent from cruise altitude to home base at about 4500 RPM it spiked again. Pulling power all the way back had no affect, Going to FULL power brought an instantaneous return to normal.
I can't think of any mechanical problem that would cause this other than something hanging up a carb float (lean mixture) but it happens most often after 10-15 minutes at constant power setting>Need input on what to look at. Loose EGT probe? Loose connection back at the firewall? Or ????
On the positive side, at about 1025 Lbs gross weight, take off from a not particularly manicured grass strip at 2500 density altitude was not more than 1000 feet ground roll-- what a change from my AA-1!!!l
Thanks guys-- need to fix this before flying Young Eagles Saturday.
Wayne 120241/143WM