Switch Tanks Before Takeoff

[Schllc]

2 minutes ago, Shadrach said:

It’s certainly not a very conservative way to distribute fuel. I have found that Mooneys are not very sensitive to fuel  imbalance. At least not those with 64gl useable or less.

I have never noticed different handling with an imbalance in the acclaim or ovation 

but having more fuel in one tank when you are at or below 10 a side is probably a smart idea. 

[Shadrach]

1 hour ago, Fly Boomer said:

Have you had or heard of issues running a tank dry?  I know guys with carbureted engines that do it, but I also know guys with fuel injection who say that the engine has a tendency to just crap out.  With turbocharging, it could be a long glide down to an altitude with enough air for a relight.

I fave been running tanks dry for decades without issue. I do try to catch it at the first dip in fuel pressure to avoid concerning passengers. Turbo is a different story. That being said, I’d think you’d have to be well above 20k for a restart to be problematic.

[Shadrach]

1 hour ago, GeeBee said:

With Continental fuel injection you are being really hard on the mechanical fuel pump by running it dry. Not something you want to make a habit.

Why? Are the rotary pumps sensitive to brief bouts of fuel starvation?

[A64Pilot]

I don’t make a regular habit of running one dry, but have never had an issue of one actually quitting, always it’s gone rough, you know why and switch tanks, in just a few seconds at most it picks up again, it’s never lost thrust as in quit and windmilling. I’ve never even turned boost on, It’s really a non issue unless you don’t realize your low on fuel, then you wake up real quick

Turbines you don’t want to run dry, because once the fire goes out you don’t want to be pumping fuel in, it could relight once you have too much in there, you know right away because it’s like airshow smoke, lots of white smoke, so you have to turn the fuel control off, engage the starter and igniter, check ITT and Ng, then place condition lever back to idle and restart, can take 20 sec or so maybe, and the prop feathers of course when oil PSI goes away.

[802flyer]

On 12/9/2023 at 9:31 AM, Pinecone said:

Somewhere on MS there is a 3D design for a holder that uses a spring clamp to hold onto the nose gear door and holds a GATS jar to catch the fuel. 

My friend had to modify the design a bit as it was a bit too small for a recent GATS jar.

https://www.printables.com/model/207825-mooney-m20-gats-jar-holder

 

For those that are interested

[Shadrach]

32 minutes ago, A64Pilot said:

I don’t make a regular habit of running one dry, but have never had an issue of one actually quitting, always it’s gone rough, you know why and switch tanks, in just a few seconds at most it picks up again, it’s never lost thrust as in quit and windmilling. I’ve never even turned boost on, It’s really a non issue unless you don’t realize your low on fuel, then you wake up real quick

Turbines you don’t want to run dry, because once the fire goes out you don’t want to be pumping fuel in, it could relight once you have too much in there, you know right away because it’s like airshow smoke, lots of white smoke, so you have to turn the fuel control off, engage the starter and igniter, check ITT and Ng, then place condition lever back to idle and restart, can take 20 sec or so maybe, and the prop feathers of course when oil PSI goes away.

We’re talking about turbo charged engines, not turbines.  I have never heard of someone intentionally running a tank dry (unless it’s with a transfer pump) while flying a turbine.

[GeeBee]

1 hour ago, Shadrach said:

Why? Are the rotary pumps sensitive to brief bouts of fuel starvation?

"FAILURE OF THE DRIVE SHAFT IS ALMOST UNHEARD OF UNLESS THE PUMP IS ALLOWED TO OPERATE DRY. VANES IN ANY TYPE OF PUMP NEED A FLUID FOR PROPER LUBRICATION AND TO SEAL THE PUMP CAVITY DURING OPERATION."

 

https://www.avweb.com/ownership/continental-io-360-fuel-injection/

[N201MKTurbo]

None of these pumps are going to be harmed by a few seconds of no fuel. There is enough residual fuel in the pump to lubricate it. The one thing you don't want to do is try to prime a dry fuel system using one of these pumps (aux or engine driven) after the fuel system has been opened up for service. I always remove the fuel hose at the firewall and let the system fill with fuel by gravity before turning the pump on, and then using the aux pump to prime the engine driven pump.

[PeteMc]

So not to drag on this thread, but....  Question on automobile engines vs aircraft engines and water.

Was listening to the NY news on the radio and some gas station had an issue and with the heavy rains the tank filled with a lot of water.  The water, of course, ended up in some cars.  Engines quit as expected, but the news is talking about "Expensive Repairs" for the cars.

In all my training, if you were dumb.. er.. forgetful enough to take off without checking the tanks, you switch tanks somewhere along the flight and shortly afterwards you discover there is water in the other tank when the engine quits.  So, you simple switch back, wait a few seconds and the engine typically starts right back up.

So for those that are in the know, what's the big difference that makes it such an expensive fix for a car engine?  Is the fuel injection that much different than my TSIO360?  I figured they'd pump through good gas or maybe a solvent first, then gas and you're done. 

 

[GeeBee]

Expensive because in a car you have to drop the tank to empty it out and thanks to safety standards, tanks are well buried in the vehicle.

[PeteMc]

10 minutes ago, GeeBee said:

Expensive because in a car you have to drop the tank to empty it out

So you can't pump it out?  I could see lifting the side/front just a bit with jacks so everything ran to one corner, then pumping it dry.  

 

 

[GeeBee]

1 hour ago, N201MKTurbo said:

None of these pumps are going to be harmed by a few seconds of no fuel. There is enough residual fuel in the pump to lubricate it. The one thing you don't want to do is try to prime a dry fuel system using one of these pumps (aux or engine driven) after the fuel system has been opened up for service. I always remove the fuel hose at the firewall and let the system fill with fuel by gravity before turning the pump on, and then using the aux pump to prime the engine driven pump.

The issue we have is the pump vanes are carbon and they heat quickly without lubrication. While a dry vacuum pump operates in a similar way, it also has cooling. A fuel pump has no radiating fins and indeed when ran dry even momentarily fuel inside evaporates quickly under the heat. Continuous fuel lubrication and cooling are essential for pump longevity.

[GeeBee]

1 minute ago, PeteMc said:

So you can't pump it out?  I could see lifting the side/front just a bit with jacks so everything ran to one corner, then pumping it dry.

You can but water will remain. in the lowest points without physical manipulation. Round a corner and fuel sloshes. My daughter just went through this with her Honda Odyssey.

  

 

 

 

[Shadrach]

2 hours ago, PeteMc said:

So you can't pump it out?  I could see lifting the side/front just a bit with jacks so everything ran to one corner, then pumping it dry.  

 

 

New DFI engines run under very high pressures (4000psi). Some of them will need to be bled after draining. Modern Diesel engines run with pressures >30,000psi. Most of those systems will also need to be drained and bled.

[EricJ]

6 hours ago, PeteMc said:

So you can't pump it out?  I could see lifting the side/front just a bit with jacks so everything ran to one corner, then pumping it dry.  

You can get the water out of the tank pretty easily in most cars.   It's the same access as changing the fuel pump, which is in the tank in nearly all cars these days and there's usually an access hatch under the seat or some other reasonable place.

As mentioned, though, fuel injection pressures are much higher in cars than in airplanes, and the fuel injectors are electrically-switched pintles rather than the relatively large fire hoses our airplanes have.   That said, I bet most cars would be fine with just draining the water out of everything and refilling with clean gas, but if something got hydrolocked it may require more effort.

[as350]

Interesting thread. it made me think about the advantage of ensuring prior to getting airborne that both tanks can sustain engine operation. I will have to think about this a bit more.

 

My standard procedure: Land on fuller tank. Start, run up, take off on same tank. 1 hour into flight, or while near an airport, I switch tanks. 

[cliffy]

On newer Ford trucks (250,350) if the tank pump fails you have to remove the entire body and bed

by hanging it above the chassis to get access to the pump in the top of the tank

Can't be done any other way that I know of. Can't just drop the tank out.

No back to our regularly scheduled program-

[Fly Boomer]

Just now, cliffy said:

On newer Ford trucks (250,350) if the tank pump fails you have to remove the entire body and bed

by hanging it above the chassis to get access to the pump in the top of the tank

Can't be done any other way that I know of. Can't just drop the tank out.

No back to our regularly scheduled program-

Cut an access hole in the bed.  Patch later.

[cliffy]

Cut up a $100,000 truck for a $400 PUMP?  :-)

And Ford dealers won't do it that way.

My local dealer does a lot of them. 

Now maybe here is an opening for a good after market product!

[Fly Boomer]

11 minutes ago, cliffy said:

Cut up a $100,000 truck for a $400 PUMP?  :-)

And Ford dealers won't do it that way.

My local dealer does a lot of them. 

Now maybe here is an opening for a good after market product!

Last time I heard of someone doing this, trucks didn't cost 100k, so maybe you are right.  I remember when guys bought pickups because it was the cheapest form of transportation you could get.  I guess something has changed.

[cliffy]

100K is just getting started in a big truck today

[Shadrach]

3 minutes ago, Fly Boomer said:

Last time I heard of someone doing this, trucks didn't cost 100k, so maybe you are right.  I remember when guys bought pickups because it was the cheapest form of transportation you could get.  I guess something has changed.

New pickups are no longer inexpensive.
And old ones don’t ever fully depreciate. A 15  year old  F250 with over 100,000 miles can push $20k

[EricJ]

11 hours ago, Fly Boomer said:

Last time I heard of someone doing this, trucks didn't cost 100k, so maybe you are right.  I remember when guys bought pickups because it was the cheapest form of transportation you could get.  I guess something has changed.

Those are bigger trucks, 3/4 ton and larger, that are being mentioned here.    I recently changed the fuel pump (hanger, actually) on my older Ford Ranger, which requires lifting the bed and sliding it back about a foot, which is easy to do by yourself.

It was normal on older Ford cars (80s, 90s) to cut a hole in the floor under the back seat, fold up the metal, change the pump, fold the metal back, and then put sealing tape over the cuts.    Most other manufacturers at that time (Honda, BMW, etc., etc.) included a hatch that you unscrewed to get tank access and get to the pump.   I think even Ford does that now.

The bigger trucks have a lot of stuff that is difficult to access, so the way to get to a lot of things is lift the cab.   It's made to be done as a normal procedure in a shop, so they just include the fuel pump as one of the things you get to that way.   It just means it's less practical to do by yourself at home.

[McMooney]

On 12/15/2023 at 8:51 AM, cliffy said:

I flew a Navajo  for a few years and we would fly the aux tanks (at cruise) until empty by watching the fuel pressure gauge to see when it started to fluctuate (air being drawn into the system-empty tank). Never lost power doing it that way and the aux tanks were completely empty. Tank valves were right by our right hand below the seat so they were easy to get to and we were watching the FP gauge like a hawk. In a couple thousand hours never had an issue. 

Had a friend who did the same thing in a Twin Beech with its 5 tanks also. Running them dry can be done without problems IF you watch what you are doing. I wouldn't make it a practice to run them dry to the point of engine shutdown though. Besides it scares the crap out of the passengers. 

In the case of the Mooney I have no idea why one would need to run a tank that dry on a regular basis. I can see in it in an emergency where you might need to do that but then you've got other problems to deal with  lack of planning for contingencies or say ferry across the ocean!  If you have regular flights where the fuel required is so close to the limit that you need to always run a tank dry then again you're pushing the envelope too close. IMO   Someday that will bite you. 

I've flown a Mooney with one tank empty and one full for maintenance (tank patch) and you really can't tell the difference between that and both full. 

Just because its legal to plan a 30 min reserve doesn't make it a smart idea. 

i tend to run one of the tanks dry on all my xcntry's over 450 miles per the POH. 1 hour on start tankm switch, run second tank dry, switch back and land.   actually it's closer to 500+ miles before the second tank goes dry but i plan for 450.  usually land with 16+ gallons in tank 1

 

 

[Hank]

23 minutes ago, McMooney said:

i tend to run one of the tanks dry on all my xcntry's over 450 miles per the POH. 1 hour on start tankm switch, run second tank dry, switch back and land.   actually it's closer to 500+ miles before the second tank goes dry but i plan for 450.  usually land with 16+ gallons in tank 1

My Owners Manual is the same. On long trips, I fly an hour on each tank, then another 1:20 or so on the first tank before switching for the last time. I've gone 4:45 like that twice, both times topping off with 41-42 gallons (52 gal capacity).

Distance traveled is too dependent on winds aloft for meaningful discussion. One trip was 2:20 outbound and 4+ return, with groundspeed rarely above 105 knots and bottoming out at 68 knots . . . .

My Performance Tables show I should be good for 750-800 statute miles plus 45 minute reserves in no-wind conditions. But I fly by my watch, not by distance.