Running a tank dry in flight

[jetdriven]

Let me tell you, in 8500 hours, I have hoped and wondered about my fuel supply exactly once.

[John Pleisse]

Quote: jetdriven

Let me tell you, in 8500 hours, I have hoped and wondered about my fuel supply exactly once.

[jetdriven]

Nope,  Cessna 210, 1998 near Cherry Point, NC. i switched from one tank than ran empty to one that ran empty as i turned off the runway 8 minutes later.   After analyzing the situation, came to the conclusions I use today. Cheifly that you need to know your remaining fuel and especially how much per tank.

[John Pleisse]

Quote: jetdriven

Nope,  Cessna 210, 1998 near Cherry Point, NC. i switched from one tank than ran empty to one that ran empty as i turned off the runway 8 minutes later.   After analyzing the situation, came to the conclusions I use today. Cheifly that you need to know your remaining fuel and especially how much per tank.

[jetdriven]

This  was a 1961 Cessna 210. NO fuel totalizer.  Fuel flow meter in PSI.  No "both" fuel selector.  Fuel guages in pounds and goes to zero at half tanks anyways.

These planes csn burn 25 GPH or 13, it depends on how it is being run.

 

Point is I siwtched to that tank expecting 10 gallons in it and was surprised when it ran dry 2 minutes later.  I knew then the other tank did not have 1/2 what I thought it had left.

[1964-M20E]

When flying home from ORL the other day I did an experiment.  Being the only one in the plane and fighting a head wind I decided to run the right tank completely dry after the first hour of flight on the left tank.  By the way this is the recommended procedure in the OM for the 64 E model.

1. 
   
2. The engine quit pretty quickly when the right tank ran out right at 2.5 hours +/- no spitting and sputtering.  I was at varying altitudes during the trip searching for smooth air with fewer headwinds.
   
3. The prop kept wind milling hit the boost pump, switched tanks and pushed the throttle in some. 
   
4. The restart came quickly.  Reset the MP and mixture
   
5. I did notice a slight roughness for about a minute or two and then it cleared up.
   
6. This was a non event at 6500MSL.  I’m not sure I’d like to do this at 1500 or on final.
   
7. This strategy did work well since I arrived at my fueling point with 0.5 hours +/- of fuel on board in one tank.
   
8. I was able to determine the total usable fuel in the right tank 25.7 gallons +/-
   
9. I was also able to determine where full is on the tanks and it is right at the filler neck on my plane.
   
10. My plan has always been counting on 50 gallons usable and 10GPH.
    

[Shadrach]

A few things that are escaping my pea brain in this whole argument...

1) What are the increased risks in running one tank dry in cruise? Anyone who's seen the inside of a Mooney fuel cell should know that the "tank debris" argument is ignorant. So what is it?

2) A few of you state that you do XXXnm (300, 400, 500, whatever) legs when flying XC. If you destination is 150nm past your typical XC leg, do you still stop at you typical leg length? stop sooner? What is the logic in adding both an additional 40-80 mins in time and an additional 5- 10 gals in burn to your trip? 

3) I occasionally fly non-stop legs of 6-700nm or more. Approaching to land after being in cruise for hours a long flight I want to be done worrying about managing my tanks. I prefer to know that what I have left is in one place whether things go as planned or if I have to go to an alternate. Putting it down of airport because I ran out ran the engine out of gas would be stupid, humiliating and possibly deadly. Doing so with useable fuel on board would be twice as stupid, twice as humiliating and possibly deadly.

4) What is the benefit to having 2 containers with 15gals over 1 container with 15 gals? There is in fact an increased risk for unporting a tank while maneuvering (especially in turbulence or in a slip) as it gets closer to empty... If this happens, I guess you can always switch tanks, but would it not be safer to do this at altitude.  

The NTSB database is full of fuel exhaustion accidents/incidents involving planes with fuel remaining on board. It'd be easy to say that these pilots were all idiots, but I think that's a rather simple few of the situation. Everone makes mistakes/miscalculations. Running a tank dry does not eliminate this risk, but it atleast cuts the variable to total remaining vs total remaining left tank and toatal remaining right tank...

[crxcte]

Quote: 1964-M20E

When flying home from ORL the other day I did an experiment.  Being the only one in the plane and fighting a head wind I decided to run the right tank completely dry after the first hour of flight on the left tank.  By the way this is the recommended procedure in the OM for the 64 E model.

The engine quit pretty quickly when the right tank ran out right at 2.5 hours +/- no spitting and sputtering.  I was at varying altitudes during the trip searching for smooth air with fewer headwinds.

The prop kept wind milling hit the boost pump, switched tanks and pushed the throttle in some. 

The restart came quickly.  Reset the MP and mixture

I did notice a slight roughness for about a minute or two and then it cleared up.

This was a non event at 6500MSL.  I’m not sure I’d like to do this at 1500 or on final.

This strategy did work well since I arrived at my fueling point with 0.5 hours +/- of fuel on board in one tank.

I was able to determine the total usable fuel in the right tank 25.7 gallons +/-

I was also able to determine where full is on the tanks and it is right at the filler neck on my plane.

My plan has always been counting on 50 gallons usable and 10GPH.

[1964-M20E]

I did not go for best glide my mistake.  I guess I was focused on getting fuel back to the engine since I knew what was happening.  The plane did appear to slow down quick with the loss of thrust.  I'll make a mental note to go back to may early training and that is engine stops best glide, trim for that and then worry about the problem unless you are real close to the ground.  I was aware of running the pump dry and switch the tanks should be first, of course I suspect the pump was not totally dry.

Would I normally run one tank dry the answer to that is NO.  Most of my flights are 1 to 3 hours long.  Occasionally I will have a longer flight due to distance or winds.  This trip is gong to be a fairly common one for me and I’m trying to learn the limits of my particular plane and I’d rather do this in good VFR weather than IMC.

Finally I have never experienced a total engine shutdown in flight until this trip and even when it is expected it still gets your heart running.

[Shadrach]

Quote: crxcte

 The only thing different on your procedure would be to not turn on the pump.  Just turn the switch to the other tank and let gravity work.  Turning on a dry pump could do damage to the pump and what is another couple seconds of wait time.   If you set the speed to best glide did you notice your descent rate?  Make note of that rate and you could approximate your maximum flight distance with the ground speed should you have an engine failure.

[jetdriven]

The plane isn't going to slow down appreciably in the 4 or 6 seconds it takes to re-establish fuel flow.   Pull the throttle back to 1/3rd so you don't overspeed the engine also. 

[Immelman]

I've run a tank dry when needed several times now. If you can get a passegner to stare at the fuel pressure for about 10 minutes until it budges, running one dry is a complete non-event. The pressure budges, you switch tanks, and you won't know any difference. Wait a few seconds after the gauge budges, and you'll lose power. I do advocate retarding the throttle about half-way in case of any surges.

I second the comment to leave the boost pump off. If you ever take the access panel off that exposes the electric fuel pump - at least in the case of the Dukes pump - there is a nice yellow placard stating that it should not be run dry. In an emgerency? Sure, I'd turn it on, but not in the routine event of running a tank dry.

[fantom]

The REAL question is how many have run a tank dry without planning to do it?

[FloridaMan]

Bringing up this old thread after finding a reference to it elsewhere. This thread was just a few months before I bought my Mooney. Thank God I ran away from that 177RG that I was looking at when this thread was made. 

My grandfather was a fighter pilot in WW2. He supposedly flew "all" of them, and from what I've researched it was certainly most of them, and was invited to be a test pilot after the war. I know that for a while he was in the ferrying group that flew the Alaska route to deliver fighters to the Russians. My grandmother loved to bitch about things. She complained about how he would run the tank until the engine quit in his Bonanza when he'd fly. She says he told her it was to prevent moisture from getting in the tanks. I don't know the significance of all of that and whether the extreme cold weather and high altitude experience he had learned something that I haven't heard elsewhere, but I thought I'd mention it. 

[Hank]

Huh

That's why I like to fill mine all the way after a trip . . .

[jamesm]

With all the fuel exhaustion situations across all airplanes....

I am surprise that someone has come up with fuel tank timer. Where you would have a magnetic prox sensors embedded in the tank selector valve handle so every time you switched tank the timer  would count down telling  you  how much time  that you had flown on a tank. Then  could derive  much time you have remaining    on a particular tank if you had fuel flow.  You probably also  need something like a fuel pressure or oil pressure  switch sensor so  the timer would know when the engine is running. This would be to enable the timer to count down.  I guess too much bureaucratic  red tape to making the idea not feasible. 

James

[carusoam]

1) Digital senders

2) digital displays

3) FF gauge

4) digital fuel used display

5) all available on your Mooney today.

6) All accurate to within a gallon...

Any more than that you didn't fill the tank...

draining tanks in flight is a good way of knowing where your fuel is.  Mooney tanks are designed for this.

Be familiar with your selector valve.  They can fail making it difficult to change tanks.  They can also be OH'd...

PP thoughts only, not a mechanic.

Best regards,

-a-

Edited March 25, 2017 by carusoam

[moosebreath]

On 10/4/2011 at 11:24 PM, jetdriven said:

A challenge to all of those "run a tank dry it won't restart" believers.   Can anyone find an accident report where a pilot ran  a tank dry and could not restart the engine on the other tank containing fuel? This seems to be a big fear of the pilots who have never ran a tank empty.

 

 

 

 

 

 

 

 

 

I don't have to find a report because I have HAD this problem, in my Mooney.  I can therefore tell you from experience that gliding to the airport with a dead engine and passengers onboard is not fun.  In an effort not to repeat this unsatisfactory life experience I personally do not run tanks dry purposely and prefer to land with a generous fuel margin.  

[Shadrach]

24 minutes ago, moosebreath said:

I don't have to find a report because I have HAD this problem, in my Mooney.  I can therefore tell you from experience that gliding to the airport with a dead engine and passengers onboard is not fun.  In an effort not to repeat this unsatisfactory life experience I personally do not run tanks dry purposely and prefer to land with a generous fuel margin.  

Huh? Do tell? This thread is about running ONE tank completely dry on that tank's final fuel leg when making long X-county trips. Doing so ensures that all remaining usable fuel is in one tank. It is not about intentional or unintentional fuel exhaustion.   

Please expand on your experience and confirm that you had to glide to an airport with fuel on board because the engine would not restart?  

[jetdriven]

Then the airplane wasn't airworthy, or didn't comform to its type certificate.  Certification rules require the engine to restart within 10 seconds after selecting a tank with fuel.   Far 23.955(e)

[Hank]

4 minutes ago, jetdriven said:

Then the airplane wasn't airworthy, or didn't comform to its type certificate.  Certification rules require the engine to restart within 10 seconds after selecting a tank with fuel.   Far 23.955(e)

Except our Mooneys are CAR 3 aircraft, designed before this rule was promulgated. 

[jetdriven]

Good point. Here's the relevant CAR.  It's the same.  Ten seconds. Perhaps you should give it a try over your home airport first to verify your airplane meets the certification requirements. If you have a conforming airplane, it's  no big deal  

CAR 3.437 (b) 4 (e)

from http://www.navioneer.org/riprelay/Yet More Navion Files/car_part3.pdf

 

 

[carusoam]

We had an MSer that had a stuck fuel valve a ways back...

my google-fu isn't very strong today...

 

Moosebreath,

First, congrats on your airmanship...

Did you get a finding on what happened?

Unfortunately, my memory isn't strong enough to recall.

 

best regards,

-a-

Edited March 27, 2017 by carusoam

[jetdriven]

Presumably before running a tank low or empty, that you've cycled the fuel valve several times during that flight. So I have a hard time thinking there is a big hazard in a fuel valve suddenly sticking without warming.

[jlunseth]

I did it intentionally/inadvertently in my 231.  The intentional part was that I meant to.  The inadvertent part was that it ran dry a couple of gallons before I expected it to.  I had my hand near the switch and was watchiing fuel flows, etc., so the pilot component of the aircraft automatically and instantaneously switched tanks and the engine was back in action immediately.  That alone was a good reason to do it, I would hate to be making a landing expecting just a gallon or two more and finding it is not there.  

I will reiterate what I have said before though, a K driver at high altitude should probably think twice given the difficulty of restarting if the turbo has a chance to slow down before the switch is made.