It's Summer Prime Again

[Blake Wheaton]

Hello All,

Hoping someone could shed some light on the reasoning behind using less prime on hot days. To put into context, I'm renting fuel injected Cessna 172S's whenever I fly.

I understand why you usually don't need to prime if you or someone else just flew the airplane since the fuel hasn't vaporized in the lines yet, but why less prime on a general hot day when the airplane has not been flown recently?

Any comments/answers will be much appreciated!

Plenty of fuel and fast tailwinds,

Blake

 

[jsstevens]

Even the modest (I say modest because compared to 350 degrees of a just shut down engine, 60 degrees is modest...) difference in temperature between, say 20 degrees F and 80 degrees F will make a huge difference in fuel vaporization. Priming when cold is (partly) compensating for that difference.

 

[Blake Wheaton]

Even the modest (I say modest because compared to 350 degrees of a just shut down engine, 60 degrees is modest...) difference in temperature between, say 20 degrees F and 80 degrees F will make a huge difference in fuel vaporization. Priming when cold is (partly) compensating for that difference.

Thank you!