I intentionally ran a tank dry today

Kiddo's Driver

Kiddo's Driver

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Jim
I intentionally ran a tank dry today. I knew it was coming. I still jumped, tossed the iPad, pulled the throttle back a bit (I have no idea why), pushed the mixture full rich, and then remember "oh yea, the tank is empty!"...then I switched tanks and started the electric pump.

It was a very weird sensation. I was expecting sputtering, instead the RPM just smoothly dropped. The engine never quit, nice to know.

Even knowing it was coming you get distracted and forget it is coming. Then the sound grabs your attention!

I was at 5,000 agl on a nice clear day with lots of airports/fields around.

I'm a bit miffed at myself for not looking in the tank once I got on the ground to see what an empty tank looked like! I just added fuel without thinking about it.
 
Kiddo's Driver said:
I intentionally ran a tank dry today. I knew it was coming. I still jumped, tossed the iPad, pulled the throttle back a bit (I have no idea why), pushed the mixture full rich, and then remember "oh yea, the tank is empty!"...then I switched tanks and started the electric pump.

It was a very weird sensation. I was expecting sputtering, instead the RPM just smoothly dropped. The engine never quit, nice to know.

Even knowing it was coming you get distracted and forget it is coming. Then the sound grabs your attention!

I was at 5,000 agl on a nice clear day with lots of airports/fields around.

I'm a bit miffed at myself for not looking in the tank once I got on the ground to see what an empty tank looked like! I just added fuel without thinking about it.
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I would have thought it would have surged in power before it dropped off..like my lawn mower. You know its coming, it surges and I make a b line for the gas tank so I don't have to lug the gas can to me. yeah im lazy.haha

What was the purpose for running it dry?
 
Yeah, I did that on a trip recently. I wanted to know where on the fuel gauges the aux tanks ran out... I just forgot to tell the wife what I was doing...:yikes:
The look on her face reminded me that I should always communicate when I turn test pilot...:yes::yes::yes:

I was also surprised when they didn't cough or anything. they just stopped making power....:rollercoaster:
 
I did it once. Even though I knew it was coming, it still scared the **** outta me.
 
I really want to do this in my Mooney. I've just not set up the conditions yet where I'd feel comfortable doing it.
 
Possible reasons why?
-Check the gauge to see how it tracks down that low.
-To even the plane out when my fat butt is in the pilot seat and there is no other ballast (people or cargo) to balance the plane out. (Not really true, but possible.)
-You are going to end up landing with minimum legal fuel and you would like all of it to be in the tank you are using when landing. Run it dry at altitude and use the other one for the rest of the flight. Better than coming in with two almost empty tanks and then uncovering the suction port maneuvering to land...
-For the fun of it...
 
I ran the aux tanks dry in my K35 Bonanza all the time. The fuel injection system drew about double the rate of fuel that was used by the engine at cruise, and excess fuel from the aux tanks was sent back to the left main. Also, aux tanks were placarded unusable for landing. So every extra minute of time spent using fuel from the aux tanks meant an additional two minutes of range.

I knew the aux tanks (18 gallons) would be dry after about 42-45 minutes of use. I'd watch the fuel pressure gauge and flip the selector at the first twitch of the needle, and usually passengers never noticed any blip in engine operation.
 
All aircraft designed since the CAA have been required to test running a tank dry in flight, switching tanks, and without touching any controls, have the engine restart. I do it all the time to maximize fuel utility.
 
I'll try that next time if I can keep my mind from running down the loss of engine procedure. Too much time as a Reactor Operator in the navy I guess. You see the first indication and then go through the memorized procedure, stabilize the situation, then pull out the printed procedure and verify that you did not miss anything.

Everything I listed in the first post I did before the RPM got below 1500.

Next time I lead off with switch tanks... Heck, I bet that is what it says in the procedure anyway. Time to get the whiteboard out and re-memorize the procedures...
 
Possible dumb question,

Why run the engine out in the air? Could you do it on the ground?
 
FloridaPilot said:
Possible dumb question,

Why run the engine out in the air? Could you do it on the ground?
Click to expand...

For the reason stated by Cowboy and Jim. I run a tank dry pretty frequently if I am cutting it close to my minimum fuel on landing. I want to be running on the tank that has ALL of my fuel when I am maneuvering and close to the ground. Run one dry when you are high and have options and that way you know exactly how much you have on the tank you are running when on approach/in the pattern. This is particularly useful if you have a good fuel totalizer and know down to the gallon or less how much total fuel you have but not in which tank.

I do admit that it kind of surprised me the first time even though I knew it was coming. Now I'm pretty used to it.
 
Slight thread hijack: How do you guys remind yourselves to switch tanks? The Mickey pointing to the right or left trick or something else?
 
In a section titled "Fuel Management", my Mooney M20E manual says:

Code: 
After  take-off with both tanks full, use one tank only until one hour of fuel  is depleted from it. Then switch to the second tank and record the  time... Use all the fuel in the second tank. Then, the time of fuel  remaining in the first tank is the time it took to deplete the second  tank, less one hour.


Kiddo's Driver said:
...pulled the throttle back a bit (I have no idea why),
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You followed the procedure in the Mooney manual. It says that restarting with an advanced throttle may cause engine over-speeding.
 
Pulling the throttle back is not a bad move as it helps moderate the surge when the power comes back up.
 
asicer said:
You followed the procedure in the Mooney manual. It says that restarting with an advanced throttle may cause engine over-speeding.
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Each aircraft is a bit different. Some of them say use the elec pump, say say reduce throttle, etc.

I was flying over N AZ once and the right tank went dry, so I just reached down and twisted the handle to the aux, and it fired off just fine -- for about 5 seconds then it went silent again, and my sphincter slammed shut so tight I think I tore something down there. By the time I was grabbing, and pulling, and twisting and messing with things it started right back up again. Bubble in the selector valve line I guess, never had trouble again.
 
RalphInCA said:
Slight thread hijack: How do you guys remind yourselves to switch tanks? The Mickey pointing to the right or left trick or something else?
Click to expand...

When I searched before starting this thread I found lots of threads that talk about fuel management and switching tanks. I change when I start having to hold aileron input to keep the plane level. Works out to around every 30 minutes or so.

asicer said:
In a section titled "Fuel Management", my Mooney M20E manual says:

Code: 
After  take-off with both tanks full, use one tank only until one hour of fuel  is depleted from it. Then switch to the second tank and record the  time... Use all the fuel in the second tank. Then, the time of fuel  remaining in the first tank is the time it took to deplete the second  tank, less one hour.

You followed the procedure in the Mooney manual. It says that restarting with an advanced throttle may cause engine over-speeding.
Click to expand...

Henning said:
Pulling the throttle back is not a bad move as it helps moderate the surge when the power comes back up.
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Makes sense. I think I was doing it to reduce fuel flow while I was switching tanks to keep from sucking air completely through the lines. I don't know if I was at that point already or if I was getting reduced flow due to loss of Net Positive Suction Head (NPSH) due to the loss of elevated fuel level in the tank. You do things so quickly in "emergency" (real or perceived) situations that looking back I "think" I remember why I did it, but who knows why I really did it. Maybe it is in my procedure also and I just subconsciously remembered it.
 
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RalphInCA said:
Slight thread hijack: How do you guys remind yourselves to switch tanks? The Mickey pointing to the right or left trick or something else?
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We have a cheap battery power timer in the plane. Normally I switch every hour. On long trips I switch the first time at 30 min than every hour after this keeps the tanks within 5 gal of each other.
 
RalphInCA said:
Slight thread hijack: How do you guys remind yourselves to switch tanks? The Mickey pointing to the right or left trick or something else?
Click to expand...

On a long trip, I plan out airports as waypoints every 30 minutes and switch when I'm over one that's on the plan. It sure beats being over a bunch of pointy rocks when you go to switch tanks and the handle breaks off in your hand.
 
430W tells me every 30 min.......
 
Kiddo's Driver said:
When I searched before starting this thread I found lots of threads that talk about fuel management and switching tanks. I change when I start having to hold aileron input to keep the plane level. Works out to around every 30 minutes or so.




Makes sense. I think I was doing it to reduce fuel flow while I was switching tanks to keep from sucking air completely through the lines. I don't know if I was at that point already or if I was getting reduced flow due to loss of Net Positive Suction Head (NPSH) due to the loss of elevated fuel level in the tank. You do things so quickly in "emergency" (real or perceived) situations that looking back I "think" I remember why I did it, but who knows why I really did it. Maybe it is in my procedure also and I just subconsciously remembered it.
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You are already sucking air which is why the engine starts to stumble, as you noticed, it clears itself just fine, most of the time no pump is required.
 
RalphInCA said:
Slight thread hijack: How do you guys remind yourselves to switch tanks? The Mickey pointing to the right or left trick or something else?
Click to expand...

Cirrus alerts me every 9 gal burned.
I am sure the newer models switch automatically :)
 
Henning said:
You are already sucking air which is why the engine starts to stumble, as you noticed, it clears itself just fine, most of the time no pump is required.
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Mine didn't stumble. It just sounded like someone pulled the throttle back. It was smooth from the beginning, down to the lowest RPM it got to (1500) and back up to normal again. No pop. No snarle. Just a smooth reduction in RPM and then a smooth return to power.
 
RalphInCA said:
Slight thread hijack: How do you guys remind yourselves to switch tanks? The Mickey pointing to the right or left trick or something else?
Click to expand...
The GPS reminds me to. I also sometmes set a timer for 30 minutes.
 
I run the aux tanks dry in the travel air as SOP on almost every flight. There's nothing more useless than little bits of fuel left scattered around in different tanks.
 
Kiddo's Driver said:
Mine didn't stumble. It just sounded like someone pulled the throttle back. It was smooth from the beginning, down to the lowest RPM it got to (1500) and back up to normal again. No pop. No snarle. Just a smooth reduction in RPM and then a smooth return to power.
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Then you didn't run it dry.;) That's really the best time to catch it, especially if you have bladders. You probably have at least a quart left, which is enough to keep the bladder good.:yes:
 
Mine just goes from normal operation to silence without any warning. Running the tips dry isn't too bad. Running the main dry puts you in the realm of experimental operation.
 
RalphInCA said:
Slight thread hijack: How do you guys remind yourselves to switch tanks? The Mickey pointing to the right or left trick or something else?
Click to expand...

The 496 on the yoke has an alert on the half hour. Quite handy actually. I think running on one tank extensively in a Cherokee or Mooney is ill-advised unless you rally like flying an unbalanced airplane.
 
I generally do one hour on the first tank, then two hours on the second. By then I've usually got other reasons to land.
 
Henning said:
Then you didn't run it dry.;) That's really the best time to catch it, especially if you have bladders. You probably have at least a quart left, which is enough to keep the bladder good.:yes:
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Yea, that goes back to my comment about kicking myself for forgetting to look in the tank and see what was left in there. I just added fuel and didn't think about it. I'll try it again another time and see.

No bladders. Nice metal tanks that slope to the suction.
 
Kiddo's Driver said:
Yea, that goes back to my comment about kicking myself for forgetting to look in the tank and see what was left in there. I just added fuel and didn't think about it. I'll try it again another time and see.

No bladders. Nice metal tanks that slope to the suction.
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You can suck them bone dry if you want, and if you're ever in a bind for fuel, I suggest you do. I'm constantly surprised how many people come up 1000' or less short of a runway on fuel exhaustion. :dunno:
 
Henning said:
You can suck them bone dry if you want, and if you're ever in a bind for fuel, I suggest you do. I'm constantly surprised how many people come up 1000' or less short of a runway on fuel exhaustion. :dunno:
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That was the purpose of me doing this. Not running it out and crashing, but running it to "eek, I'm out of fuel" and then seeing what that looks like inside of the tank...but I forgot to look. :(
I'll try it again and see. If it turns out that there is a quart left when RPM drops then I will know that I should run it farther before switching if I am really concerned about getting everything out.
This kind of goes back to the people asking why you do something like this. In a plane with lots of tanks (>2) it makes sense to run the aux tanks dry as normal practice. In a two tank plane you (I) don't normally get low enough on fuel that I should ever have to run one tank completely dry. I like to land with an hour reserve. That is 8 gallons for me. With one tank dry and 8 in the other I have to hold aileron input to keep it level. For me, there is really no normal reason to run one dry. That does not mean that I should not know how the plane will react and how to do it safely to get every ounce of fuel out of the tank and through the engine in an emergency.
 
I've never ran one dry (yet), but for those who have.. Do you just switch tanks to one with fuel, turn on the fuel pump if you have one and the windmilling prop restarts the engine? Or do you have to use the starter?
 
Kiddo's Driver said:
That was the purpose of me doing this. Not running it out and crashing, but running it to "eek, I'm out of fuel" and then seeing what that looks like inside of the tank...but I forgot to look. :(
I'll try it again and see. If it turns out that there is a quart left when RPM drops then I will know that I should run it farther before switching if I am really concerned about getting everything out.
This kind of goes back to the people asking why you do something like this. In a plane with lots of tanks (>2) it makes sense to run the aux tanks dry as normal practice. In a two tank plane you (I) don't normally get low enough on fuel that I should ever have to run one tank completely dry. I like to land with an hour reserve. That is 8 gallons for me. With one tank dry and 8 in the other I have to hold aileron input to keep it level. For me, there is really no normal reason to run one dry. That does not mean that I should not know how the plane will react and how to do it safely to get every ounce of fuel out of the tank and through the engine in an emergency.
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Your concern is unfounded (I have run hundreds of tanks "DRY" and have never failed to have the engine fire right back up with a flick of the valve. The only times I recall getting to the pump switch before the engine was back up and smooth was at high altitude with fuel injection) but if you place yourself within gliding range of a runway for the run dry, you will cover your bases and you may as well let the engine die totally and bring it back on line so you see how much altitude it costs you, and give you the knowledge that it will come back online so you have the confidence to use the knowledge.

The goal is to have the last 45 minutes of fuel in one tank (per engine if a normally split system).
 
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FredFenster said:
I've never ran one dry (yet), but for those who have.. Do you just switch tanks to one with fuel, turn on the fuel pump if you have one and the windmilling prop restarts the engine? Or do you have to use the starter?
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I don't bother with the fuel pump, engine fires right back up after the tank switch.
 
In the 310 and all the early tip tank twin Cessnas, you always run the auxes dry because you're never quite sure how long they'll last since the fuel return goes to the mains. All of them you start on the mains (tips) and run for an hour+ to make room for the return fuel (otherwise it pumps overboard out the vent) then switch to auxes and run them dry. If you have Pax you try to catch it watching the gauges, but that's hit and miss, and the fuel totalizer is no good because the return flow varies with the mixture so you don't know how much is consumed and how much bypassed, just what was consumed. The 15 gallons tanks may be dry in an hour, but 5 gallons on each side went to the mains.
 
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The fuel gauges on my 140 are placarded below 1/4 tank as "no take off." That means that with 12 1/2 gallons on each side, if you run both of them to 1/4 tank, you are operating with 6 gallons of potentially unusable fuel. If you keep the fuselage level, you can use it all. If you wheel land you probably won't have trouble. If you take off, you could lose power before the tail picks up.

SO, on the few lengthy trips I've done, I run the left tank dry and switch. That way I have used that last three gallons while it is still completely usable. To most of you, three gallons probably doesn't sound like much, but at 5.6 GPH it's over a half hour of fuel.

The fuel selector has left, right and both. I have learned to take off and land on both for safety reasons.
 
MBDiagMan said:
The fuel gauges on my 140 are placarded below 1/4 tank as "no take off." That means that with 12 1/2 gallons on each side, if you run both of them to 1/4 tank, you are operating with 6 gallons of potentially unusable fuel. If you keep the fuselage level, you can use it all. If you wheel land you probably won't have trouble. If you take off, you could lose power before the tail picks up.

SO, on the few lengthy trips I've done, I run the left tank dry and switch. That way I have used that last three gallons while it is still completely usable. To most of you, three gallons probably doesn't sound like much, but at 5.6 GPH it's over a half hour of fuel.

The fuel selector has left, right and both. I have learned to take off and land on both for safety reasons.
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I think you are misinterpreting the meaning of the 'no takeoff' restriction into being unusable fuel.
 
they say in the turbo aircraft if the engine quits in the flight levels or high teens it won't restart so I don't think I'll tempt it.
 
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