Fuel Exhaustion Question

Discussion in 'Flight Following' started by Jack C-137, Aug 9, 2018.

  1. Jack C-137

    Jack C-137 Filing Flight Plan

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    Not that anyone here would ever make this kind of error but just for arguments sake:

    If you were flying an aircraft that required switching between tanks (as opposed to a Cessna 172 that has a "both" option) and you ran a tank empty and the engine quit in flight what would you have to do to re-establish fuel flow to the engine. Assuming you had time/altitude, of course.

    Would it be as simple as switching the fuel tank and cranking the engine? Would you use the electric fuel pump if you had one? Prime the engine?
     
  2. Stingray Don

    Stingray Don Pattern Altitude

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    If the prop is windmilling, there would be no need to crank the engine. Once fuel flow is restored, the engine should fire right up.
     
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  3. Capt. Geoffrey Thorpe

    Capt. Geoffrey Thorpe Touchdown! Greaser!

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    Switch tanks. Wait.
    I have hit the electric boost, but I don't think it really matters.
    Never had a need to crank. By the time you get to the primer, it will already be running.
    Snot a big deal.

    Just ask John Denver.
     
    Last edited: Aug 9, 2018
  4. MauleSkinner

    MauleSkinner En-Route

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    Switch tanks. If you can get to the boost pump switch before the engine is running again, switch it on.
     
  5. Ryanb

    Ryanb Final Approach PoA Supporter

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    This. If you’ve ever leaned the engine a little too far while in flight and the engine dies...ahem.. not that I have or anything...than you’ll know that once the fuel flow resumes, the engine will restart if the prop is windmilling.

    Some engines may need the fuel pump to be triggered for a second or two, but other than that just restore the fuel supply.
     
  6. jaymark6655

    jaymark6655 Pre-takeoff checklist

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    Use the checklist, should run something like:
    1.Fuel Shut-Off Valve On
    2. Selector to the fullest tank
    3. Aux Fuel Pump On
    4. Mixture Full Rich
    5. Ignition to Both or Start if prop has stopped.
     
  7. Jack C-137

    Jack C-137 Filing Flight Plan

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    Very cool stuff! Consider me educated
     
  8. ejensen

    ejensen Pattern Altitude

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    Happened often in my Mooney. Ran each an hour and when a tank went dry the other had 1 hr. I did run out for real once in the jabiru but that's another story
     
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  9. Zeldman

    Zeldman Final Approach

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    They didn't have fuel problems, they landed on a deserted island in a storm....:)
     
  10. Cluemeister

    Cluemeister Pre-takeoff checklist

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    What does Gilligan have to do with this?
     
  11. JCranford

    JCranford Pattern Altitude

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    Switch tanks at first sputter, hit the emergency pump, keep flying.
     
  12. Ryanb

    Ryanb Final Approach PoA Supporter

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    Happy I could be of assistance, that’s what I’m here for.
     
  13. Let'sgoflying!

    Let'sgoflying! Touchdown! Greaser!

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    Use the POH instructions first, if they cover the topic.
     
  14. Capt. Geoffrey Thorpe

    Capt. Geoffrey Thorpe Touchdown! Greaser!

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    OK, youse guys got me.

    And, he was Maynard G. Krebs before he was Gilligan.
     
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  15. James331

    James331 Touchdown! Greaser!

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    9/10 time switch tanks.

    Did a hard and long slip (not like that) in my last plane (S108) engine coughed as I had the low wing selected, flipped over to the other tank, didn’t even loose a knot.
     
  16. sarangan

    sarangan Pre-takeoff checklist

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    One time I stopped the prop to experiment with the glide performance. Stopping the prop is hard. You need to get near stall speed. But restarting was impossible. It would not start at all. My instructor at that time thought it may be due to shock cooling. We were doing this over an airport (instructor was a glider pilot), so it was not a big deal, but the glide ratio was distinctly different than a windmilling prop. A very valuable experience.
     
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  17. kgruber

    kgruber En-Route

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    No! It is not a checklist or POH item.

    It is a memory item from the emergency checklist.

    Don't go reading something. If it isn't already in memory......quit flying.
     
  18. Jack C-137

    Jack C-137 Filing Flight Plan

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    Wow, that's a good insight- what kind of aircraft.
     
  19. 455 Bravo Uniform

    455 Bravo Uniform Pattern Altitude

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    That checklist is an easy one to turn into a flow just by switching the order around.

    C182-
    -Fuel on/both (on the floor)
    -Mixture rich (go up to the panel right side)
    -Fuel pump on (move left)
    -Ign both (all the way left)

    Memorization done!

    The engine out checklist is similar items but opposite actions, and just add Master off.
     
  20. asicer

    asicer Pattern Altitude

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    Preferably quit while on the ground and not in the air. :)

    Start with a flow, back it up with a checklist. Belt and suspenders.
     
  21. Squirrelfury

    Squirrelfury Filing Flight Plan

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    Maybe consider doing what the airplane’s POH* directs?

    Some airplanes (mine, for example) can be reluctant to restart without boost pump activation. In others, the boost pump can deliver an excess of fuel, and inhibit restarting.

    There isn’t a one-size-fits-all answer.

    * That’s assuming it’s a certificated airplane, where the manufacturer has had to actually demonstrate air starts as part of its certification program. Experimental airplane? Then you’re the test pilot - go for it.
     
  22. overdrive148

    overdrive148 En-Route

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    Loose knots aren't good - keep them tight!
     
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  23. Zeldman

    Zeldman Final Approach

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    I would have mentioned that, but it would have been, like, work....
     
  24. Tom-D

    Tom-D Taxi to Parking

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    "T"----------------- handle in
    Mags-------------- on
    Mixture----------- auto rich
    feather button---in
    Feather -----------pump on

    The positive Torque is indicated--- set cruise power.

    Probably forgot a step, It's been 45 years.
     
  25. James331

    James331 Touchdown! Greaser!

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    Meh, it’s rote, ain’t pretty, but more or less for the average sea levelish DA type, sure
     
  26. Ken Ibold

    Ken Ibold Final Approach

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    Would not start due to shock cooling? That's one idiotic instructor.
     
  27. champ driver

    champ driver Line Up and Wait

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    I've run tanks dry a number of times when I used to fly Aztecs. We had Aztecs that had the Met-Co-Aire tip tanks and we would run them first, and even though you knew it was going to run dry in a couple of minutes, it always surprised you when it happened. With two pilots on board, we would almost knock our heads together when both of us reached down to switch tanks at the same time. It only shut down for a couple of seconds and I think the procedure was switch tanks, hit the boost pump, and keep on flying, nothing to it.
    A standard Aztec has 4 36 gallon tanks and with the tip tanks you had another 24 per side, making it 192 total.
     
    Last edited: Aug 10, 2018
  28. timwinters

    timwinters Touchdown! Greaser! PoA Supporter

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    Back when I was building across the east 1/2 of the US and traveling a lot in my 182, I would regularly "dry tank" the left tank. My 182 has 5 gallons unusable per side. But, in straight and level flight, almost all is usable. So, I picked up about 25 minutes of flight.

    It definitely always got my attention if I wasn't watching the fuel flow at the time. In my plane I simply had to switch tanks to restart, although it would never really die, rather just start to sputter.

    The fuel flow gave ample warning if I was watching. It would go from reading a rock solid flow (usually 10.9 gph) to wildly vacillating as the line would start sucking air. 6gph...20gph...4gph...etc. It would do this for a minute or two before the engine would sputter.
     
    Last edited: Aug 10, 2018
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  29. tawood

    tawood Pattern Altitude

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    Good to know about the fuel flow...I have a JPI450 that I always seem to be watching...I even use it to set engine power, as it is more precise than the RPM gauge.
     
  30. Lance F

    Lance F Pattern Altitude

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    I run my aux tanks dry (well really just to engine stumble) just about every flight. Switch selector from aux to mains and engine goes right back to normal. They are certified to do this. I strongly suggest that every pilot intentionally do this, so you gain confidence and know what its like. Do it 5,000' over an airport with a 10,000' runway if that would make you feel more comfortable the first time. Also, a number of posters above have said "mixture rich" for the restart procedure. I suppose do what the POH says, but this makes no sense to me. If the air/fuel ratio had the engine running smoothly when one tank went dry, why on earth would you want to change that ratio just because the fuel is now coming from a different tank???
     
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  31. bradg33

    bradg33 Cleared for Takeoff

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    I run the tanks dry, intentionally, all the time in my Viking and in my Twin Bonanza. It's really a non-event. In both airplanes, just switch to a good tank, hit the boost pump, and the engine comes back immediately. It's routine and nothing to worry about. The engine was just running, the only thing that went missing was fuel. Add fuel back in, and it starts running again. The only reason some airplanes need or benefit from the boost pump is to quickly purge any air in the lines.
     
  32. bradg33

    bradg33 Cleared for Takeoff

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    Had the exact same thought. "Your instructor is an idiot."
     
  33. Fearless Tower

    Fearless Tower Touchdown! Greaser!

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    Exactly. If you are cruising high up, going full rich on the mixture is asking for trouble restarting.

    Go to a place like Santa Fe and try starting with the mixture full rich and see how well that works for you.

    You might just experience that ‘shock cooling’ the boneheaded CFI was talking about....
     
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  34. sarangan

    sarangan Pre-takeoff checklist

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    This was 25 years ago, when shock cooling was a thing. In any case, all I remember is that it would not start. Never looked into it further. Whats your theory?
     
    Last edited: Aug 10, 2018
  35. Dan Thomas

    Dan Thomas En-Route

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    Were you expecting the prop to start windmilling once you reestablished normal glide speed? It won't. The compression is holding it easily because the prop blades are stalled in an inverted airflow. I dove a 150 to Vne in that configuration and it wouldn't start. I hit the starter and away it went.

    You'd have to shock cool it so bad that it seized to prevent restart. Shock cooling does not affect fuel or ignition. And shock cooling is an extremely rare phenomenon anyway.
     
  36. sarangan

    sarangan Pre-takeoff checklist

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    May be I didn't describe it clearly. We were not trying to turn the prop with airspeed (as you mentioned, that would require a very high speed), We wereusing the starter, like a normal start procedure on the ground. The starter ran fine, the prop was being turned (but not enough to start windmilling), but the engine did not fire. A few minutes after landing, it started right up. This was in a N-model 172.
     
  37. sarangan

    sarangan Pre-takeoff checklist

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    I did a most of flying in NM and CO, and full rich has a different meaning there. Everyone there knows full rich is not mixture knob pushed to the firewall. Full rich is what give you max power, with a couple of extra turns to run slightly on the rich side, at least for takeoff anyway. After that, you lean as usual.
     
  38. James331

    James331 Touchdown! Greaser!

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    It’s still a “thing” just not when it comes to restarting.