netsurfr
Well-Known Member
- Joined
- Jun 15, 2014
- Messages
- 1,311
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So went up for an IFR phase check today and during the climb at 5500 shortly after takeoff the engine momentarily hesitated (as best as I can describe it) and lost a bit of power during the climb. Conditions were cold (28F on the ground) but we were not and had not flown through moisture. Full throttle, prop, and mixture with fuel pump off & carb heat off. Engine indicators all in the green. Carb temp was about 22F during the climb and OAT was about 36F. I turned on the fuel pump and applied carb heat. The engine felt like it rumbled a little and after a bit carb heat and fuel pump off and no other problems for the duration of the 2.5 hour training flight. One thing I noticed in the JPI is that CHT of Cyl 1 was 275F where the rest were in the low to mid 300's. BTW - Both tanks were full w/ fresh gas and plane is in a heated hangar so no condensation/moisture in the fuel sumps.
JPI data showed the slight and momentary drop in RPM and EGTs but nothing else I can see (except Cyl 1 CHT being colder and dropping temp more than the rest) out of the ordinary.
Here's a link to the JPI data. If you add RPM data on the right to the EGT chart and go to 22 minutes into the flight you'll see the slight RPM and EGT drop.
https://www.savvyanalysis.com/flight/834410/b3b04d01-4705-4ae5-8740-fdc212472c97
Here's a very short video clip. At 6 seconds you can sort of hear the change in engine noise & when you see me turn on the fuel pump and then carb heat you can hear some slight roughness.
http://youtu.be/GThj7Chd2qs
So what could cause a "hiccup" like that? If this could have been carb ice I'm surprised because it was cold (36F) and DP spread on the ground about 15F (50% relative humidity)plus no clouds/moisture. Carb Temp was 22F but with those conditions I would not expect carb icing so wondering what else it could be and what to do next????
So now I'm freaked out!!!
JPI data showed the slight and momentary drop in RPM and EGTs but nothing else I can see (except Cyl 1 CHT being colder and dropping temp more than the rest) out of the ordinary.
Here's a link to the JPI data. If you add RPM data on the right to the EGT chart and go to 22 minutes into the flight you'll see the slight RPM and EGT drop.
https://www.savvyanalysis.com/flight/834410/b3b04d01-4705-4ae5-8740-fdc212472c97
Here's a very short video clip. At 6 seconds you can sort of hear the change in engine noise & when you see me turn on the fuel pump and then carb heat you can hear some slight roughness.
http://youtu.be/GThj7Chd2qs
So what could cause a "hiccup" like that? If this could have been carb ice I'm surprised because it was cold (36F) and DP spread on the ground about 15F (50% relative humidity)plus no clouds/moisture. Carb Temp was 22F but with those conditions I would not expect carb icing so wondering what else it could be and what to do next????
So now I'm freaked out!!!
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