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higher fuel flow in hot weather?


207WF

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I just got back from an 11 hour multileg trip around California. It has been very hot (over 100F on the ground, 77F at 9500 feet), and I had to reduce power quite a bit in the climb for oil temps. Even with so much time at reduced power (30-40 minutes to claw my way up), and then using my normal cruise power settings(more throttle then I had on in the climb) my fuel flow was 5.6 gph hobbs. Normally, I see only 4.6 gph. Should I be worried, or could the hot temps do this? WF

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Trying to climb out from N. Arkansas (Walnut Ridge) after Oshkosh I hit 31C (88F) air at 5000 feet. One of my CHTs read 239 F and stayed there even in cruise. Never had this problem before the hose replacement. Oil temp never got over 210F. Would this be expected?

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Hi Scott,

 

It could have been a one time thing and 239F isn't overly bad. You may just need to keep an eye on it for a flight or two.

 

OR

 

If a hose got a little soft and and developed a reduced radius then the answer is yes this could happen. The Rotax hose in the replacement kits seems to be a little more pliable than the hose FD used in its place. FD changed the routing and configuration of all the top coolant lines and reservoir at the FD factory from the Rotax original configuration.

It could happen with a loose CHT connection too. Check the offending CHT connector. It should be fairly snug to turn. If it moves easily crimp it down with some pliers. I would pop the cowl after a flight when the hoses are hot and check top and bottom hoses for roundness and to see if someone got over zealous with a wire tie and put it around a coolant hose too tight. I have found about halve dozen like this which reduces the radius.

If you are having a some what high oil temp then that may be the oil return line coming off the bottom of the engine and back to the reservoir tank and is making too tight a turn which cause a reduced radius. The oil return slows down and the oil gets hotter. FD had a SB out on this years ago. I'm sure most have forgotten about it. I have lengthened and re-routed my hose to make a more gentle S turn.

 

 

I hope this helps some.

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