Managing Fuel during flight

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  • #83861

    Well after just two long flights, this is what I think happens with the fuel but like to share it to see if I am on the right track.

    We started with all 5 tanks full.
    Stay on tip tanks for about 1.15 min and then switched to AUX. TIPS fuel remaining aprox. 22gals.
    We stayed on the AUX tanks for about 1.30min (31.5 gals @ 21 gal/hr) until the engines cough and them move to the tips.
    There was actually 7 min. difference between the engines on every flight.
    Left engine ran longer.

    THe TIPS showed then 29gals. So there was about 7 to 8 gals more due to the return from the engines.
    Is that a reasonable number of gals?

    We then stayed on the TIPS and started transferring fuel from the Locker tank.
    Since we had no idea about the rate of transfer, we left it on only 20 min only as we had enough
    to arrive at destination.
    Is that the right time to move the fuel from the locker to the TIP tank?
    Or is it better to do it while using the AUX tanks?

    THanks for your comments

    Reiner

    #96546

    What kind of aircraft is this? The return flow is dependent on the engine size and power being applied.

    Most of the locker type tanks I have seen pump around 15 gal per hour…so depending how the system is plumbed I would start pumping it on the AUX or when back on the tips (assuming it pumps into the tips).

    You have to do the math for your set up (tank size, pump rate etc) but you should try to pump all the locker fuel into a tank before descent (since most systems are only rated for pumping in level flight). In my case this is 1.5 hour before descent. Also you want to consider crossfeeding if it is a system that only pumps into one wing, because you dont want to have to cross feed on a missed and you dont want to run out of gas on one engine because all the extra gas is in the opposite wing….

    #96548

    Reiner,

    When I have my nacelle/locker tank filled and plan on needing that fuel, I transfer it as soon as there is room to take the transfer in the main (right main on my plane).

    My locker tank pump will transfer the 20 gallons in 48 – 50 minutes and I typically start the transfer after leveling off. During the transfer I do use the Cross-Feed from the left engine to the Right Main to keep the two main tanks even plus not over filling the Right Main.

    I do the nacelle fuel right away as the only way to count on that fuel is to have it out of the nacelle tank and in the mains. If the pump is not going to go (it happened to me) at least I know early in the flight and can plan accordingly.

    As for the Aux tanks, when I need to know exactly how much fuel I have remaining, I run them till they are empty. But my gauges are accurate, when they indicate zero, the tank is dry, so it is usually my mistake if the engine coughs.

    Jim

    #96550

    In the 340 I run the aux tank transfer pump(one in left nacelle)in the climb as soon as I have about 10 gal burned off the mains. My pump is 40gph so it takes me 30 min to run my nacelle dry. As soon as I see the main tank gauge start to rise with additional fuel from the nacelle I xfeed my right engine over to the left main. I burn roughly 30gph in the climb per side so I run in this confit for roughly 15 minutes hence 15 gal burned off the left main….and this seems to balance things out well. I switch back to the normal config and let the transfer pump run dry. I like getting this done early so I know I have the gas transferred for the reasons mentioned
    by other posters…..that way the rest of the flight there is no need to crossfeed or worry that my pump might fail.

    I generally have long climbs so this process gets the crossfeed and transfer out of the way
    quickly so the rest of the flight can be focused on other things….

    #96553

    Derek, this sounds like the best option. I will try it in my next flight.
    The only question I have is if there is any limitation on Xfeed on climb.
    I have flown an Aerostar for 14 years and there is a limitation of Xfeed
    at level flight only. THat is why I did not entretain the idea of Xfeed
    during climb.

    I will time my locker tank transfer also to see what rate of transfer I get.
    For what people have shared they seem to vary quite a bit…. from 40 min
    to well over an hour to transfer.

    #96560

    I wrote a small table in EXCEL that allows you to place 1 or 0 to activate TIP Tanks
    AUX Tanks, X-Feed and Locker transfer. You can then place the FF, time and speed
    for the diffent times in the flight like Climb, Cruise, descent to get at the end the
    amount of fuel on each tank at any time of the flight.
    It anyone wants to look at it and also see if what is doing its right, let me know.
    You can send me an email and I will reply back with the attachment.
    The fixed variables that I used is the Aux transfer pump 30 gph and the return rate
    to the Tip tank set to 8 gph
    I wrote it because it did not seem that simple to me to calculate in the top
    of my head

    Reiner

    #96563
    quote JODAY:

    Reiner,

    When I have my nacelle/locker tank filled and plan on needing that fuel, I transfer it as soon as there is room to take the transfer in the main (right main on my plane).

    My locker tank pump will transfer the 20 gallons in 48 – 50 minutes and I typically start the transfer after leveling off. During the transfer I do use the Cross-Feed from the left engine to the Right Main to keep the two main tanks even plus not over filling the Right Main.

    I do the nacelle fuel right away as the only way to count on that fuel is to have it out of the nacelle tank and in the mains. If the pump is not going to go (it happened to me) at least I know early in the flight and can plan accordingly.

    As for the Aux tanks, when I need to know exactly how much fuel I have remaining, I run them till they are empty. But my gauges are accurate, when they indicate zero, the tank is dry, so it is usually my mistake if the engine coughs.

    Jim

    I do the same as Jim

    Jim

    Is that shiny new paint on your 340? 😀 You must have better pictures!

    #96564

    Hey Doug -It is all your fault. I thought my plane was pristine until you rolled onto the ramp with yours.

    Shine….not yet.

    I was told that the plane would be completed in 3 weeks. That seemed about right. As I use the plane every week I thought that I could survive. I dropped the plane off 7/20 and I took this picture yesterday. So much for the3 week promise. I expected it to be completed by the new “drop dead” date of 8/31 but I think it will be another week.

    One thing I learned, there is an incredible amount of preparation to refinishing a plane. Even the VG’s come off.

    I will write up a report and pictures when this is all finished. I have owned 7 aircraft and this is the first one I have painted. But, this is my favorite and I have owned it much longer than any of the others.

    #96583
    rwelsh
    Participant
      quote :

      We stayed on the AUX tanks for about 1.30min (31.5 gals @ 21 gal/hr) until the engines cough and them move to the tips.
      There was actually 7 min. difference between the engines on every flight.
      Left engine ran longer.

      Depending on how strong your Aux inline pumps work can vary the time of draining the Aux tanks. If you see an increase in fuel flow on the Shadin on either side when you switch to the AUX tanks, then you have an inline pump with a little more pressure and that will drain that tank a few minutes earlier then the other side. If your 340 is pre 1975, you won’t have the inline pumps.

      #96584
      rwelsh
      Participant

        Hey Jim, what are those boards hanging down from the tail?

        #96587
        quote JODAY:

        Hey Doug -It is all your fault. I thought my plane was pristine until you rolled onto the ramp with yours.

        Shine….not yet.

        I was told that the plane would be completed in 3 weeks. That seemed about right. As I use the plane every week I thought that I could survive. I dropped the plane off 7/20 and I took this picture yesterday. So much for the3 week promise. I expected it to be completed by the new “drop dead” date of 8/31 but I think it will be another week.

        One thing I learned, there is an incredible amount of preparation to refinishing a plane. Even the VG’s come off.

        I will write up a report and pictures when this is all finished. I have owned 7 aircraft and this is the first one I have painted. But, this is my favorite and I have owned it much longer than any of the others.
        ]

        Glad that I could help you spend some of that moldly money 😛
        I’m sure that it will turn out great!

        #96588
        quote RWELSH:

        Hey Jim, what are those boards hanging down from the tail?

        If it is what I think you are looking at-new VG’s getting installed. I guess as they were installed on top of the paint that came off, they had to go to get back to the base aluminum.

        #96592

        Congratulations Jim.

        Can we have the paint scheme? I am planning to paint my 340 and looking for some ideas. The interior modification is in the ideas time too. I love the paint scheme and color of the Pipistrel Pantera. A 340 would look out of this world.

        So far I am thinking about the cinamon color you can see on some BMWs and Diamond Jet for the seats. Chocolate color thin carpet and white half pannels up and ceiling. I don’t like the table look. I want to hide it. I live in a city with a lot of shoe industry, so I will have perfect interior done. I did it in my last 340 and sold it in 3 days. The interior finish was amazing. I already have a new metalic control wheel “340” plaque done with red numbers and satin finish. In fact I have 100 of them done (100 for the Cessna 310 too). If somebody is interested…

        I don’t know what to do with with the curtains. I surely like the window electric shades that block at the touch of a buton.

        We have to keep our Twin Cessnas top notch. There is nothing in the market to replace them.

        Rodolfo
        1978 C340A RAM VII

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