P-70 EGT Probe Possible Issues
04-05-2016, 01:47 PM
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P-70 EGT Probe Possible Issues
Helping a friend with his P-70. EGT probe cracked and nearly broke in two back near the engine exhaust. The crack was more than far enough outside the exhaust tail cone that I was able to wrap it with some fine steel wire (about like you find in a bread twist tie) to give it strength and support and silver soldered the wrapped wire for further support. Wasnt sure this would work but after doing so the EGT readout on the GSU was reasonable (20 to 22 degrees c ) in my work shop which would be about right for ambient. I then took my monocote heat gun and it read a reasonable temp for having been blown with the hot air of the blower. I decided it was going to work and reinstalled the probe and mounted the engine back in the plane. I made four or five short test runs on my driveway at home and all seemed to be fine. Made a couple of short runs to full throttle and all seemed well. At this point the probe was sticking into the tail cone a 1/4' to 5/16" inch which is quite a bit and a little farther than we had been running it. Normally we had it in 1/8" to 3/16". We found that the engine started better (more reliably) with the probe stuck in about 3/16 ".
At this point I went to the field and made one flight which was normal and fine. After landing and shutdown the engine went into the cooking or slow down phase but got stuck in this mode. The green light on the I/O board continued to blink. At this point I plugged in the GSU and the readout showed EGT of 107, but was also flashing the 107 or 108 temp and would alternatly replace the 107 or 108 temp with an "E" like looking symbol ( which I assume means e for error). No matter what the temp always reads 107 or 108. I can cool the robe or heat the probe but the temp readout stays the same. I cannot start the engine right now because the engine is still stuck in cool down mode and because I am not getting an accurate temp readout from my repaired probe, or what I thought was a repaired probe. I do note that the EGT readouts (before it quite working) were quite high, like 800 or 850 at or near full power. I attribute this to the probe being in farther than normal. I did pull off the engine cowl and the front end of the probe is still secure. Please let me know what might be going on here. I will probably order a new probe in the next day or two if we cant figure out why this probe is not working right now.
At this point I went to the field and made one flight which was normal and fine. After landing and shutdown the engine went into the cooking or slow down phase but got stuck in this mode. The green light on the I/O board continued to blink. At this point I plugged in the GSU and the readout showed EGT of 107, but was also flashing the 107 or 108 temp and would alternatly replace the 107 or 108 temp with an "E" like looking symbol ( which I assume means e for error). No matter what the temp always reads 107 or 108. I can cool the robe or heat the probe but the temp readout stays the same. I cannot start the engine right now because the engine is still stuck in cool down mode and because I am not getting an accurate temp readout from my repaired probe, or what I thought was a repaired probe. I do note that the EGT readouts (before it quite working) were quite high, like 800 or 850 at or near full power. I attribute this to the probe being in farther than normal. I did pull off the engine cowl and the front end of the probe is still secure. Please let me know what might be going on here. I will probably order a new probe in the next day or two if we cant figure out why this probe is not working right now.
