Fuel management

[Brandt]

Just out of curiosity, how many of you have run a tank dry before switching? Inadvertently or by design? I’ve never been willing to do so.  

[Hank]

Whenever I'm flying near max range. Make sure you don't run both dry . . . When you're expecting it, it's a non-event.

[RoundTwo]

Once you get comfortable, it’s no big deal. Just make sure passengers are prepared for it.

[Shiny moose]

I have to pee long long before I would need to run a tank dry!! 67F 

[Greg Ellis]

I have done it many times.  Run first tank for an hour, switch tanks, run the second tank dry then switch to the first tank (although after running the second tank dry, I am usually close to landing because I have been in the airplane for over 3 hours and really need a stretch).  When you run the second tank dry, you get some warning.  My C model gives me 10 seconds or so of the fuel pressure slowly dropping.  When I switch it is really like nothing ever happened.  I had a friend who owned an A model at one time and he did not let his run dry.  After doing it once, his fuel pressure dropped fast enough for the engine to stumble and he did not much care for that.  His is the only airplane I have heard of to drop that quickly.  Normally it is a non-event.

One thing that it does make me appreciate is the efficiency of the C model.  It may not get you there as fast as an Ovation or Acclaim but it sure is efficient.  I flew from Texas to Florida.  Was in the air for 4 1/2 hours (I normally do not fly that long at a time) and when I landed and refueled I still had over an hour left of fuel.  Not bad for 48 gallon tanks!!!!!

 

[201er]

1 hour ago, Brandt said:

Just out of curiosity, how many of you have run a tank dry before switching? Inadvertently or by design? I’ve never been willing to do so.  

Yes. And my J takes 100 gallons.

[Hank]

18 minutes ago, bluehighwayflyer said:

When I paid my fuel bill I was bragging to the girl behind the counter about how little fuel I had burned.  A biz jet pilot was behind me in line and, overhearing our conversation, remarked that I must be the guy flying the Mooney because no one else does that.    

Because no one else can!!   

[skydvrboy]

I personally think it's a good idea to run each tank dry at some point (just not on the same flight ).  Then you will know your exact useful fuel in each wing.  Since each plane is hand crafted with wet wings, there is no guarantee that each side holds the same amount of fuel. 

My POH says each side should hold 32 gallons useful, which is what I use for fuel planning.  Some knucklehead stuck stickers on each wing that says 31 gallons useful, but when I run a tank dry, I can put in just a bit over 33 gallons in either tank.

Running a tank dry is also how my POH recommends monitoring fuel consumption, though I don't like the method it recommends.

[M20F-1968]

18 minutes ago, skydvrboy said:

I personally think it's a good idea to run each tank dry at some point (just not on the same flight ).  Then you will know your exact useful fuel in each wing.  Since each plane is hand crafted with wet wings, there is no guarantee that each side holds the same amount of fuel. 

My POH says each side should hold 32 gallons useful, which is what I use for fuel planning.  Some knucklehead stuck stickers on each wing that says 31 gallons useful, but when I run a tank dry, I can put in just a bit over 33 gallons in either tank.

Running a tank dry is also how my POH recommends monitoring fuel consumption, though I don't like the method it recommends.

I do not like the thought of fuel planning down to 1 gallon.  Knowing how much fuel is in the tank is essential and can be coupled with a fuel totalizer and paper and pen quite nicely.  CIES senders help as well.  But, a left hand turn to final with 1 gallon in your left tank will get your attention quickly.

John Breda

[Floyd]

Would you rather have 5 gallons left in one tank or 2.5 gallons in each?

[Tom 4536]

20 minutes ago, M20F-1968 said:

I do not like the thought of fuel planning down to 1 gallon.  Knowing how much fuel is in the tank is essential and can be coupled with a fuel totalizer and paper and pen quite nicely.  CIES senders help as well.  But, a left hand turn to final with 1 gallon in your left tank will get your attention quickly.

John Breda

Does anyone know how much fuel we need in the left tank to make a left turn to final without running out of fuel?

[M20F-1968]

This is one example where standard rate turns, or less, are imperative.  I do not like turning toward a tank with less than 10 gallons.  A more precise answer would be nice to have.

John Breda

[Skates97]

9 hours ago, Brandt said:

Just out of curiosity, how many of you have run a tank dry before switching? Inadvertently or by design? I’ve never been willing to do so.  

On every long flight I run a tank dry, the same MO that @Greg Ellis outlines below. And if you are paying attention to the fuel pressure in a carbureted model you can keep the engine from ever stumbling because there is the fuel in the carb bowl. My understanding is that in a fuel injected model you will have the engine stop on you. The good news is that the prop is still spinning so switching tanks will have you back running again. I have had the engine stop on me a couple times when I didn't notice the fuel pressure dropping, switching tanks brings everything back online in about 2-3 seconds (although it feels like about 30 seconds).

8 hours ago, Greg Ellis said:

I have done it many times.  Run first tank for an hour, switch tanks, run the second tank dry then switch to the first tank (although after running the second tank dry, I am usually close to landing because I have been in the airplane for over 3 hours and really need a stretch).  When you run the second tank dry, you get some warning.  My C model gives me 10 seconds or so of the fuel pressure slowly dropping.  When I switch it is really like nothing ever happened.  I had a friend who owned an A model at one time and he did not let his run dry.  After doing it once, his fuel pressure dropped fast enough for the engine to stumble and he did not much care for that.  His is the only airplane I have heard of to drop that quickly.  Normally it is a non-event.

 

 

[A64Pilot]

38 minutes ago, Tom 4536 said:

Does anyone know how much fuel we need in the left tank to make a left turn to final without running out of fuel?

So long as the ball is centered, the fuel won’t move.

 

‘You can however move the full side to side with no turn, just by being out of trim

Edited October 11, 2021 by A64Pilot

[Tom 4536]

4 minutes ago, A64Pilot said:

So long as the ball is centered, the fuel won’t move.

 

‘You can however move the full side to side with no turn

What keeps the fuel from flowing downhill toward the end of the left tank in a left turn turn? In your video he was able to pour the tea, which shows the fuel will flow from side to side in a turn. Seems that the fuel could flow away from the tank outlet.

[Ragsf15e]

59 minutes ago, Floyd said:

Would you rather have 5 gallons left in one tank or 2.5 gallons in each?

Well neither.  Personally I use 10 gallons as my minimum for ~1 hour of fuel reserve, but you’re right, day vfr, 5 might meet the requirements.  If I’m going all the way down to 10, I’ll want it all in one tank.  0 in the other.

[Ragsf15e]

6 minutes ago, Tom 4536 said:

What keeps the fuel from flowing downhill toward the end of the left tank in a left turn turn? In your video he was able to pour the tea, which shows the fuel will flow from side to side in a turn. Seems that the fuel could flow away from the tank outlet.

Well he’s showing the tea pour just like when he’s level.  Look in the glass, it doesn’t move side to side at all.  He’s flying a perfect 1 g, coordinated roll so it’s just like he’s in level flight the whole time.

[skydvrboy]

2 hours ago, M20F-1968 said:

I do not like the thought of fuel planning down to 1 gallon.  Knowing how much fuel is in the tank is essential and can be coupled with a fuel totalizer and paper and pen quite nicely.  CIES senders help as well.  But, a left hand turn to final with 1 gallon in your left tank will get your attention quickly.

John Breda

Nor do I, but I will fuel plan down to 10 gallons remaining.  However, when I do, I want it all in one tank.  Perhaps I wasn't clear when I said I use 32 gallons per side for fuel planning.  I use that as my total, thus I plan for 54 gallons of useful fuel, even though in reality I have 56 gallons useful onboard.  If my fuel is consumed perfectly as planned, I'll land with 12 gallons on board, which gives me some wiggle room for planned vs actual fuel consumption.

[skydvrboy]

2 hours ago, Tom 4536 said:

What keeps the fuel from flowing downhill toward the end of the left tank in a left turn turn?

The short answer is that the turn is coordinated.  In fact if you skid a turn, the fuel will flow uphill toward the end of the right tank in a left turn, though that is certainly not something I would recommend as it's lead to many fatal accidents in the traffic pattern.  It's much better to have your remaining fuel in the uphill wing and plan to slip your turn if needed... or just fly coordinated, though slipping turns to lose altitude aren't unsafe when performed correctly.

[A64Pilot]

2 hours ago, Tom 4536 said:

What keeps the fuel from flowing downhill toward the end of the left tank in a left turn turn? In your video he was able to pour the tea, which shows the fuel will flow from side to side in a turn. Seems that the fuel could flow away from the tank outlet.

A coordinated turn will impose no side loading, it will usually increase G of course, a 60 bank being 2G, but it’s not like a car which when going around a flat curve will impose side loads. A weight hung from the ceiling will not move in a coordinated turn, the trim ball is identical to that weight hung from the ceiling, it’s nothing more or less than a simple level, it does not sense aerodynamic trim, just level fuselage.

Bob Hoover was not an ordinary pilot, few can replicate his feats, so just because he could doesn’t mean others can.

My little C-140 if you are down to 1/4 tank, you can put the aircraft into a side slip and it will unport the fuel pickup and the engine will quit, my old 46 model doesn’t, but newer 140’s I believe have on the fuel gauge a prohibition of not taking off with less than 1/4 tank of fuel.

If you kick my 140 out of trim and run it out of fuel, the engine picks up within just a few seconds of putting the aircraft back in trim.

Most worthless things in aviation.

1. runway behind you

2. altitude above you

3. fuel in the truck

Edited October 11, 2021 by A64Pilot

[Guest]

3 hours ago, Tom 4536 said:

What keeps the fuel from flowing downhill toward the end of the left tank in a left turn turn? In your video he was able to pour the tea, which shows the fuel will flow from side to side in a turn. Seems that the fuel could flow away from the tank outlet.

Notice that you don’t fall out of your seat in a turn?  The fuel is the same as long as the ball is centred.

Clarence

[carusoam]

Running a tank out of fuel intentionally…

For some people it takes getting used to…

For others… they know how the systems were designed and built to do exactly that…

Study the system, train on the system, use it the way it is designed for…

 

My first flight in a Mooney… I turned the fuel off during the pre-flight….  The label wasn’t very clear on the valve… L, R, but the B seemed to be missing….  

Kind of the first lesson on not assuming anything….  
 

Read, look at drawings, get trained, practice… follow the procedure…

The reason you want to follow the procedure closely… so during practice, you don’t send raw gasoline to the exhaust system… that can be kinda expensive…

NA Mooney engines always restart when the fuel comes back… the pumps are designed to work this way…

 

Specific for @Brandt…. Turbo engines above a certain altitude have procedures for that… because the turbo wants to slow down when the exhaust stops flowing… don’t let the turbo slow down if you don’t have to…  know the restart procedure for when it does occur…  (are you familiar?)  this is a challenge to practice during Transition Training…  it isn’t easy to turn a pair of TNs off and back on…

 

+1 coordinated turns keep fuel where it is supposed to be… 

-1 uncoordinated turns in the traffic pattern… running out of fuel turning to final isn’t the first concern is it…?

 

If you are flying with only a gallon or two left in the wing… switch to the tank with the most fuel in it…. If that is the wing with the most fuel in it… Know that lowering the nose for the descent… causes the fuel to generally move forwards, away from the fuel pick-ups… a steep descent on final… things will get quiet when the fuel level is low enough…

The fuel pick-up location was selected to keep the engine running during the climb…. You can always descend with the engine out…. You can’t climb very long with it out…

Check to see how well your fuel valve operates… if there is anything wrong with it… they can be OH’d or replaced…  none will come with a Both option…  

PP thoughts only, not a CFI or mechanic…

Best regards,

-a-

An invite for @mike_elliottto stop by… (comments about TT, and turbo engines, and running tanks out of fuel, and the rest…)

[mike_elliott]

An engine stoppage in a turbo is different than a NA, as you are suddenly set up for a much more rich condition. POH procedures suggest getting to a lower altitude so the now forward CG counterweight can breath again and do something other than keep it aerodynamically stable. This takes time as will the climb back up to altitude. In other words, why put yourself in a situation you are one step closer to executing the emergency landing checklist, and end up burning more fuel up to get back to cruise? Yes, they can be restarted and the procedures work well, but it is something I personally don't do as a practice just to maximize my range, the only valid reason I can come up with for doing it. I have done this over an airport in both NA and Turbos, and generally switch tanks within gliding distance of a safe landing spot.  I wont plan a leg that cuts it to less than 10 remaining, as others suggest, my personal range is also less and my bride would go into defcon 3 mode if I were to stay up as long as an Acclaim can if she is on board. This isn't to say it is not safe to do and doable, but it does introduce one more variable into a flight regime that brings you one step closer to making an off field landing. YMMV, but Im in the camp do not bust something because you can. @Brandt, keep the wife happy and keep the lawyers yearning

[201er]

18 minutes ago, mike_elliott said:

my personal range is also less and my bride would go into defcon 3 mode if I were to stay up as long as an Acclaim can if she is on board.

[mike_elliott]

I am not even going to go there with her. I have spent 3 months in rehab once already....