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Using Boost Pumps

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    Using Boost Pumps

    This is how I manage the use of the boost pumps on the DC=6A (C-118A).

    Operate on LOW boost when -

    1. Engine Start
    2. Take Off
    3. Climbing
    4. Selecting a New Fuel Source
    5. Fuel pressure drops below 22 psi or fluctuation.

    More trivia. I'm not sure if this matters with the PMDG model, but it's fun to pretend.
    Bode Bridges
    I Earned my Spurs in Vietnam

    #2
    Please more of this, thank you!
    Klaus Schmitzer

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      #3
      Also recommended in the C-118A TO are for fuel conditioning and oil dilution. From the tech order: Since the boiling point ... of fuel vary ... it is difficult to predict the exact moment ... that booster pumps should be applied. Conditioning the fuel for 1.5 hr by booster pump agitation overs most of the critical fuel conditions that my occur in the.. system. This may be an extremely liberal period of time under some conditions; therefore, make the following test for fuel stability: After the aircraft is stabilized at cruise altitude, momentarily turn one of the selected booster pumps off and watch pressure. If pressure drops or fluctuates, leave booster pumps on for a longer period. If pressure remains steady, the booster pump may be turned off.
      Dan Downs KCRP

      Comment


        #4
        Originally posted by Bluestar View Post
        This is how I manage the use of the boost pumps on the DC=6A (C-118A).

        Operate on LOW boost when -

        1. Engine Start
        2. Take Off
        3. Climbing
        4. Selecting a New Fuel Source
        5. Fuel pressure drops below 22 psi or fluctuation.

        More trivia. I'm not sure if this matters with the PMDG model, but it's fun to pretend.
        Did those prop liners have issues with aerated fuel ? Was it the cause of fuel pressure fluctuations ?

        best regards,

        Paulo M Soares
        SBSP

        Comment


          #5
          Originally posted by PMSoares View Post

          Did those prop liners have issues with aerated fuel ? Was it the cause of fuel pressure fluctuations ?

          best regards,

          Paulo M Soares
          SBSP
          The issue is related to the vapor pressure variance in avgas, the pressure at which the liquid will start to change state to vapor (same as boiling point but function of both temperature and pressure). At high altitudes, the avgas may start to form bubbles in pockets. The boost pump will circulate the fuel because the fuel supplied to the engine driven pump in excess of what the engine needs flows back into the tank. This circulation will help inhibit the formation of bubbles.
          Dan Downs KCRP

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