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Sounds like the timing is more advanced on the EI than the mag. I'd recommend checking the mag timing to verify that it is at the proper setting. During the runup the EI could be advancing the timing from the base setting, as the manifold pressure is relatively low. I'm not surprised that there is very little drop when running EI only - it's a function of the timing, not the "strength" of the spark. And I agree with the reply that suggested upping the warning limit - 1475 is very low. I have mine set at 1500 and I should raise it to prevent co-pilot anxiety. Another suggestion: Play around with the mixture during the runup - I find that I get a more consistent result with the mixture a little lean. Full rich and very lean mixtures will give high mag drops. Gary
Hello all, Hope you don’t mind I may be a pain in the butt for a while. I’m breaking in this new Barrett Precision Engines TSIO 550 and hope some of you won’t mind answering niggling questions that will come up as I go through the process. I have about 6.5 hours on it now and the CHT’s are coming down nicely. Still running full rich and cycling the power in cruise from about 33 inches MAP down to 25” in gradual increments. Today I got to 12,500 and stayed there about an hour with CHT’s never going to 400 and after the initial climb and level off, they stayed below 380. Previous flights, I could not seem to keep #3 below 400 above about 10,000 ft, even when powering back. So it
looks like the rings are seating well and break in is on track. I did notice one thing that I don’t recall seeing before during engine run up before takeoff. The EGT’s all went to caution temps when I switched to the MAG at 1700 RPM. The drop on the MAG has been a bit high – usually over 100 RPM and inconsistent. Sometimes it could be 95 RPM and it has been as high as 145 RPM. Today I think it was close to the higher number. I have
the EGT caution warning go off at 1475. I know that’s not particularly high but it’s the first time bitching Betty has gone ballistic six times in a row in short order like that. As expected there is no drop on the Lightspeed ignition and the EGT’s don’t seem to change much when selecting only that ignition source. Any thoughts on that? Regards, John Barrett, CEO |
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