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Loss of Power on Takeoff

in General Tech Discussion 11 years ago

  • Re: Loss of Power on Takeoff

    by » 11 years ago

    Why would you warm a 912 up to 285F CHT when using mogas that tends to vaporlock?
    The indicator of vaporlock is abnormally high fuel pressure reading upon startup. Fix is to run boost pump for 30 sec to bring cold fuel into system and eliminating vaporlock, then takeoff.

    I had loss of power on takeoffs before I realized what was doing it and now run the boost pump during takeoff on hot days until fuel pressure comes down to normal.
      
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  • Re: Loss of Power on Takeoff

    by » 11 years ago

    I agree that too hot an under the cowl temp and letting the engine just sit can speed up any vapor lock. If you don't have your fuel lines in fire sleeve like you should that will speed the process up even more. I haven't seen any high fuel pressures from vapor lock. Actually just the opposite. My plane will do that when I fly out for breakfast and let it sit for 45 min. and then when I come back instead of a 4.5 psi fuel pressure I may see 1.5-2.2. The pump and fuel pressure sender don't do well with vapors they need a liquid. After start up and running a little cooler fuel during my check out pressures return to normal. Everyone that calls me from around the country have all reported low fuel pressure with their vapor lock. Then after running, i.e. taxi to position, it tends to go away after the cooler fuel gets into the lines. I have tested running at those low pressures with take offs and have had people call me and say they have taken off with low pressure, but I haven't had any reports of an engine out. Fire sleeve not only protects the hose from fire, but it does help some from the extra heat build up. I have found header wrap to help cut down internal heat also, but that's another personal choice.

    Some things work for some folks due to design and some don't.

    That said I would tell someone to taxi for a minute and vapor lock should (maybe not 100% of the engines) clear up. I wouldn't advise anyone to be a test pilot.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

      
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  • Re: Loss of Power on Takeoff

    by » 11 years ago

    45 mins for breakfast? :-)
      
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  • Re: Loss of Power on Takeoff

    by » 11 years ago

    Hi Mark,

    Your right, 45 min. wasn't enough. I'm sure I'm in the restaurant for at least an hour. :) No use denying a good thing. ;) We have a group of LSA's that fly out some where in Arizona once a week for breakfast.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

      
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  • Re: Loss of Power on Takeoff

    by » 11 years ago

    We do the same, but I'm sure it's a bit nicer over there.

    I've only ever flown across Florida, and that was awesome.
      
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