Ever Run a Tank Dry In Flight

[AlanA]

Has anyone ever purposely or accidently completely run one tank dry in flight?  (Hopefully you've never run TWO tanks dry).  How many "sputters" did you experience before you switched tanks and had the engine going normal again?  Did the engine stop completely?  How fast were you able  to restart the engine?   I don't plan on getting to that point but still want to be prepared in case of an emergency.    Was it simply switch tanks, boost pump and back in business?

[Mooneyjet]

For myself with a m20c, is not a big deal at all just watch the fuel pressure flicker and then switch tanks.

[Lood]

Never done it, because I simply haven't had the need to do so. However, should I find myself in a situation where endurance is of critical importance, I will.

[tony]

I did.  It was not as dramatic as I thought it would be.  There was no sputter, no warning, the engine RPM just started to decrease rather quickly; just like you turned the key off.  Reached down, switched the tanks and the engine came right back to life.  When I refilled the tank with fuel I recorded the level after every 4 gallons to make myself a graph of fuel level vs fuel quantity.

 

Its not something I would do everyday but I had to experience it at least once. 

[sleepingsquirrel]

I did it in my M20B. Needed the tank empty for a leak repair. Expect to lose about 500 ft during the event. Really a non event.

[lahso]

For myself with a m20c, is not a big deal at all just watch the fuel pressure flicker and then switch tanks.

 

Same with me. When the pressure steadily declines, change tanks. No sputter or dramatics.

[David Brown]

Never done it, because I simply haven't had the need to do so. However, should I find myself in a situation where endurance is of critical importance, I will.

 

TOO LATE!!!!

 

When it is of critical importance is when you need the knowledge, and a bad time to be wrong wouldn't you say.

 

This is another topic very close to the hearts of my APS mentors and I must say if provoked I will copy and past the stories told by George Braly (GAMI & APS) who refuelled and took to lunch John Deakins former colleague and friend, prior to him crashing fatally just because of this attitude toward running a tank dry.

 

If you do not run all your tanks tank dry (not all at once) at least just before your annual, you can not say for certainty what your in flight usable fuel is. Anything in the POH, or anywhere else is just a guess unless you prove it regularly. This is more important with tanks with bladders, tanks with flop tubes, or older tanks with a possible pickup issue.

 

THIS IS A SAFETY OF FLIGHT MATTER!

 

For long range flying you may want to balance the tanks down a bit then run one out knowing exactly that you have used it all, and thus knowing that you have X amount available in the other. Knowing what you have helps ease the anxiety and decision making process when after you arrive at your destination the weather is worse, or the runway is unavailable, and you know what reserves you have and exactly where.

 

Diverting with an uneasy feeling of not knowing for sure forces the human brain to start making poor decisions and that is how the lines in the swiss cheese start lining up.

 

With modern fuel totalizers this makes for very accurate fuel planning. I know within a 1/4 USG typically how much the pump will show when I refuel. And I know to the litre how much each tank holds that I can actually burn. Often it is more than advertised in some aircraft types. That "B"-word plane for example.

 

If you know roughly when it should run out the fuel pressure gauge will alert you, however there is nothing serious about letting it run dry, touch nothing and change tanks, if you want the boost pump will speed up the process, but it takes about 2 seconds. and you will hardly notice a speed loss.

 

If your wife or passenger is not at ease with the procedure, brief them 5 minutes ahead, explain that for their safety we want all the fuel known to be left in the other tanks so we will use all the fuel from this tank, in the next few minutes we may feel a slight deceleration or maybe a few coughs, but we will change tanks straight away and the engine will keep running. If we are really good we might not even feel a thing as we will catch it on the pressure gauge. Have them part of the process so it is not a shock to them.

 

It is a non event and it was SOP in the piston airliners on every flight.

 

Anyone with a turbine……this is not for you!   

[David Brown]

I did it in my M20B. Needed the tank empty for a leak repair. Expect to lose about 500 ft during the event. Really a non event.

 No way……last one I did I was hand flying and I gained 100'. I am serious, and if you have done a few you will know why 

 

If the A/P is on you will lose about 5 knots.

 

If you lose 5' maybe OK, but even 50' you are doing it wrong. 

 

KNOW YOUR AEROPLANE!! 

[aaronk25]

Yep non event. Just brief passengers first . Don't even need boost pump.

[neilpilot]

I've run tanks dry intentionally in both the C and E models.  With the sTec in altitude hold, no altitude lost, just a moderate speed reduction during tank switch.  Sometimes fuel pressure or a bouncing level gauge was an imminent warning that the engine was about to quit, but not always.  Note that the injected IO-360 in the E would quit immediately, while the O-360 in the C would continue to sputter and never quite stop during the tank switch.  I suggest you retard the throttle before refiring, if possible, to prevent overspeed on restart.

[201er]

Has anyone ever purposely or accidently completely run one tank dry in flight?  (Hopefully you've never run TWO tanks dry).  How many "sputters" did you experience before you switched tanks and had the engine going normal again?  Did the engine stop completely?  How fast were you able  to restart the engine?   I don't plan on getting to that point but still want to be prepared in case of an emergency.    Was it simply switch tanks, boost pump and back in business?

Never by accident. Always on purpose. It can take as long as 5-12 seconds to restart. The main gotcha I found is when flying LOP, the engine will not restart at that mixture with the prop windmilling. How's that for a seat wetter? However, at altitude throwing the mixture in can over enrich too and kick it out. So the secret is to swap tanks, throw the pump on, wait 10 seconds. If that doesn't help, leave the throttle and prop alone (full) and slowly enrich the mixture till it restarts. Whatever you do, don't panic and DON'T SWITCH BACK to the empty tank!

[Mooneymite]

I've run my left and right tanks dry once each at altitude to verify the gauge does, in fact, read empty.

Engine stumbled, switched tanks, engine smoothed out...non-event.

I do not subscribe to the idea that this is a routine way to manage fuel.

[201er]

I do not subscribe to the idea that this is a routine way to manage fuel.

It's not a routine way to manage fuel because most flights I'm landing with enough fuel in the tanks that I would not be tapping into that critical reserve. However, once below 20 gallons and with more than 10 minutes flying time remaining or questionable conditions ahead, I want to use every drop from the low tank while in cruise rather than wish I had access to it on a 3rd missed approach.

Another reason burning the tank dry is so important is because I time between when the red fuel low light comes on and when it burns out. This gives me a good ballpark of how much I will have left when the the 2nd fuel low light comes on. I think I have only once flown with both lights on and I was already landing. Under all normal circumstances I do not land with less than 0 in one tank and 15 in the other.

[Bob]

I never ran one dry, but did test the gauges.  Waited for the "dummy" light to come on, saw where the fuel gauge needle was, then ran till gauge read "0".  I learned a few things.  My gauges are accurate at empty, but not when full.  I have 3 gallons of useable fuel left after the dummy light comes on.  I never want to see the dummy lights come on during a flight, but if one does come on, I know what minimum fuel I have.  See no need to run one empty. 

[201er]

Can't find anything about not running a tank dry but my POH does say to use takeoff flaps!

[John Pleisse]

This is getting to be like MAPA....same threads over and over again. There is a search bar in the upper right corner of the home page. Topic suggestion........"Pushing a plane by the prop" (talk amongst yourselves).......Yawn........

[John Pleisse]

Not being facetious...just bored. Sorry All.

[pinerunner]

Its happened to me once. I had plenty of altitude. Engine sputtered a little and then just stopped. I knew I was operating close to the end of that tank and so was expecting it. I was running LOP at the time. Switching to full tank and throwing in boost pump didn't bring it back as quick as I'd hoped. After maybe 15 seconds of rough running and discomfort I went to full rich and it settled down. It wasn't too bad but don't ever let it happen to you at low altitude. Approaching low altitude, switch to fullest tank. I think you should do this on purpose with plenty of altitude to learn how your system acts. 

 

And yes the threads here seem to repeat.

 

One comment I'll add to this. The reason for doing it on purpose is to get good old-fashioned data on how your fuel-flow is really doing that you can't get quite as reliably any other way. Putting a known amount of fuel in a tank and seeing how it takes to get used is the simplest, most obvious way to get a firm hand on how much time you can count on from it. If someone says there's no reason to do it when, in fast, the reason is obvious, then I know how to approach their comments.

 

Dave

[Bob - S50]

Not being facetious...just bored. Sorry All.

If you're bored, don't read it.

 

Has anyone ever purposely or accidently completely run one tank dry in flight?  (Hopefully you've never run TWO tanks dry).  How many "sputters" did you experience before you switched tanks and had the engine going normal again?  Did the engine stop completely?  How fast were you able  to restart the engine?   I don't plan on getting to that point but still want to be prepared in case of an emergency.    Was it simply switch tanks, boost pump and back in business?

I have not yet done so but I plan to run both tanks dry on separate solo flights or with one of my partners (not with my wife on board).  We have an FL202 digital fuel gauge and I want to see two things: 1) Will the gauge get all the way to zero before the engine quits and 2) assuming it does, how long will the engine run after that before it quits?  Based on draining the tanks for calibrating the gauge, and how much we got out of the sump after the boost pump quit pumping, I'm thinking it may run up to 5 minutes after the gauge says zero.

 

My POH says for an Air Start I should: 1) Prop full forward 2) Switch tanks 3) Mixture cutoff 4) Check fuel pressure (boost if needed) 5) Throttle 1/4 open 6) Mags both 7) Mixture slowly toward rich until it starts 8) re-establish power settings.  However, I think for reasons mentioned above I'll probably switch #2 and #3.  However, from a 'flow pattern' point of view which I've grown accustomed to in my line of work it might make it easier to flow left to right and top to bottom twice like this: Throttle 1/4, Prop forward, Mixture cutoff, Tank switch, Pressure check/establish, Mags both, Mixture advance, Power set.  I don't see that it would hurt anything to do it in that order.

[Bob]

At some point, a quality forum will get to a level of almost being complete with not many untouched subject areas.  It is also very important to repeat subjects from 6 months or later to help the new members.  As this may bore you, it also gets new members excited.  I think that if I get bored, I should start a new subject thread.  Now that I have made 2 posts on a subject that I know has been covered, since I am bored too, I think I should leave and go for a nice flight, work on a motorcycle or do some research on a subject that will expand my knowledge or interests, or just drink some beer in the garage.  This time, I am leaving thread to go for a nice flight!

[RJBrown]

Many times on purpose. A non event used to verify fuel used and leave all fuel in one place. Once not on purpose. Startling but not serious. I was planning on running the tank dry but became distracted with other duties. It still ran dry without my help. Because I had seen it before and was expecting it there was no "panic".

[John Pleisse]

I agree...subject threads are too broad and confined. Splintering into relevant niches would really spark interest and contribution.

 

Suggestions: IFR/WX, Panel Pics, Paint jobs, A&P/gear heads, FCC/Regulatory/Legal, new product reviews, Monney-centric (wet wings-bladders, landing gear, empanage-trim issues, steal tubular cage), Mooney Service Centers-Great shops, STC's Mods, Cheap fuel, Prop-Talk, Trip destinations, CFI-II resource.

 

Back on topic. I fly 4.0 hour legs, switch every hour and always land with significant reserve (IFR, too). I see no reason to run a tank dry and ever let an engine stop. It serves no purpose.

[RJBrown]

 

 

My POH says for an Air Start I should: 1) Prop full forward 2) Switch tanks 3) Mixture cutoff 4) Check fuel pressure (boost if needed) 5) Throttle 1/4 open 6) Mags both 7) Mixture slowly toward rich until it starts 8) re-establish power settings.  However, I think for reasons mentioned above I'll probably switch #2 and #3.  However, from a 'flow pattern' point of view which I've grown accustomed to in my line of work it might make it easier to flow left to right and top to bottom twice like this: Throttle 1/4, Prop forward, Mixture cutoff, Tank switch, Pressure check/establish, Mags both, Mixture advance, Power set.  I don't see that it would hurt anything to do it in that order.

In most instances this procedure would be unneccesary and a bad idea. When the fuel stops flowing the engine does NOT quit turning. Simply switching to the other tank should get it running again. Has anyone here ever got an engine to quit spinning while in the air? I tried a precautionary shut down once and the prop kept spinning. I even tried to slow the plane down enough to stop the prop but could not stop the spinning. I gave up on stopping it and landed the plane.

[1964-M20E]

I ran a tank dry intentionally once nonevent.  The fuel injected engine quit rather quickly with not sputtering.  Backed out on the throttle switched tank and added boost pump for 30 seconds or so.  The engine fired right up.

[chrisk]

In most instances this procedure would be unneccesary and a bad idea. When the fuel stops flowing the engine does NOT quit turning. Simply switching to the other tank should get it running again. Has anyone here ever got an engine to quit spinning while in the air? I tried a precautionary shut down once and the prop kept spinning. I even tried to slow the plane down enough to stop the prop but could not stop the spinning. I gave up on stopping it and landed the plane.

The POH may have a good reason for this procedure.   I suspect there is a concern that there are conditions where to much fuel may end up in the exhaust system, before your engine starts.  Once the engine restarts, the fuel in the exhaust might explode.   Granted this is probably more of an issue with a turbo at high altitude.   1) engine runs out of fuel.  2) Loss of manifold pressure, 3) you switch tanks and the engine gets fuel, but is way to rich for the MP.   4) engine finally starts,  5) fuel in exhaust ignites.   However, I can imagine this could happen in a normally aspirated engine at high power settings.