Switching Tanks on the Ground?

[201er]

A) Do you ever switch tanks on the ground?

Do you ever test/ues the fuel shut off on the tank selector?

C) Do you purposefully switch tanks before takeoff to test the system?

D) In what situation do you not switch tanks for sure?

E) If switching tanks is destined to cause a problem, what is the longest amount of time you are in the "caution" zone where you are still running on residual fuel before the switch really kicks in. Ex switching to an empty tank, switching to water contaminated tank, etc.

[carusoam]

Switch on the ground, but two minutes before departure.   Not because it is required.  I feel better this way.

My first mooney experience was turning the fuel switch to the "both" position.  the engine ran for about two minutes while we taxied to the runway.

Best regards,

-a-

Lesson learned, low wing aircraft don't usually have a "both" position.

[jetdriven]

As a rule I do not switch tanks on the ground because you might not be able to sample enough fuel before takeoff. I had a friend takeoff in a Cherokee 180 and the engine failed at 400' because of water in the tanks, and they crashed.  So, if I had a really long taxi, I might switch tanks a few minutes before the runup. Otherwise, one tank from start to to top of climb.  Likewise if doing several full stop takeoffs and landings.  On taxi back is probably the safest time to switch.  

A. almost never. 

B.  once a year, in flight

C. no

D. After parking outside overnight, after refeuling, night, or IFR. 

E. I would guess the fuel line holds 1 quart of fuel, and that lasts a little less than one minute at takeoff power, 1.5 minutes at cruise, and 8 minutes on the ground. 

[scottfromiowa]

Quote: carusoam

Switch on the ground, but two minutes before departure.   Not because it is required.  I feel better this way.

My first mooney experience was turning the fuel switch to the "both" position.  the engine ran for about two minutes while we taxied to the runway.

Best regards,

-a-

Lesson learned, low wing aircraft don't usually have a "both" position.

[201er]

Quote: jetdriven

As a rule I do not switch tanks on the ground because you might not be able to sample enough fuel before takeoff. I had a friend takeoff in a Cherokee 180 and the engine failed at 400' because of water in the tanks, and they crashed.  So, if I had a really long taxi, I might switch tanks a few minutes before the runup. Otherwise, one tank from start to to top of climb.  Likewise if doing several full stop takeoffs and landings.  On taxi back is probably the safest time to switch.

[jetdriven]

I try to drain 10 sec each tank before flight.  our plane gets fuel form the same pump all the time and sits under a covered tie down. We wash it frequently and the fuel caps are watertight.  But XC trips, yes, I am fanaatic about preventing water in the fuel.

[201er]

Quote: jetdriven

I try to drain 10 sec each tank before flight.  our plane gets fuel form the same pump all the time and sits under a covered tie down. We wash it frequently and the fuel caps are watertight.  But XC trips, yes, I am fanaatic about preventing water in the fuel.

[carusoam]

Scott,

This was a demo flight for the plane I eventually bought.  The PIC at the time, is now our airport manager.  The flight school that i learned my expert pilot skills from, was run by his mother.  The incident was not a confidence builder for any of us.

There is so much to learn.  At least mooneyspace is available to help bring these topics out into the open.

From that flight I learned Fuel mis-management is easy, and Mooneys are awesome, all at one time.

Water in tanks is bad.  Ice in tanks is not much better, and more difficult to drain out, and can turn back into water without consulting the pilot.  Follow the checklist for draining procedure.  Visually make sure each valve has stopped draining prior to flight.  Some of these devices tend to drip when micron sized dirt get stuck in them.

Best regards,

-a-

[jetdriven]

I know from testing the fuel gascolator in an early 201 drains at the rate of 10 GPH. 

[WardHolbrook]

Personally, I would simply shut the engine down a couple of times using the fuel selector instead of the mixture. Once or twice from the left tank then once or twice from the right tank. Note the time it takes for the idling engine to quit after selecting off and you now have an idea just how long you need to wait after switching tanks for a fuel continuity issue to become apparent. Just to be on the safe side, I'd add 15 to 30 seconds to the longest time you come up with. It's going to take a while, but it's a number you really need to know. Granted, it won't take so much time if you're at takeoff power - the engine in guaranteed to run long enough to get you about 50' in the air.  Personally, I'll start it on one tank then switch to the other prior to taxi and runup. Takeoff is also on that tank, unless of course you're willing to wait the prescribed time to ensure fuel continuity.

[WardHolbrook]

I remember reading something, somewhere that water would settle out of avgas and work it's way to the low point of the fuel system at the rate of about 18" per hour. How true that is, I have no idea; but it sounds about right. It makes you wonder how long you should wait to sump the tanks after fueling. Fueling and airplane, then immediately sumping it and blasting off might not be the best idea.

 

Quote: 201er

Wow, 10 secounds really? I only do about 3 on each unless I have any suspicion. Whenever possible I have someone hold a cup under the pee hole (this is how I know my plane is a she) to get a sample. It seems like 3-5 seconds would already give me a cup full. Most of the time I'm on my own and can't expect the plane to go into the cup if I place it underneath (wind, drippage, etc), so I only go for 3. Of course if I so much as find a drop in the tanks, I'll be more vigerous on the gascalator.

Although bad for the engine, isn't this the least dangerous of places to have water? I would think the engine would quit before you could take off if it were in the gascalator whereas water in the wings may take some time to make its way to the engine...

[scottfromiowa]

Quote: carusoam

Scott,

This was a demo flight for the plane I eventually bought.  The PIC at the time, is now our airport manager.  The flight school that i learned my expert pilot skills from, was run by his mother.  The incident was not a confidence builder for any of us.

There is so much to learn.  At least mooneyspace is available to help bring these topics out into the open.

From that flight I learned Fuel mis-management is easy, and Mooneys are awesome, all at one time.

Water in tanks is bad.  Ice in tanks is not much better, and more difficult to drain out, and can turn back into water without consulting the pilot.  Follow the checklist for draining procedure.  Visually make sure each valve has stopped draining prior to flight.  Some of these devices tend to drip when micron sized dirt get stuck in them.

Best regards,

-a-

[jetdriven]

I did forget to add in my long winded rant, that I do switch tanks before startup to the fullest tank. If already on the fullest tank I cycle the valve to the other tank and back to verify its working.  

[Mooney65E]

Quote: WardHolbrook

[mulro767]

I learned a technique a long time ago that I still use today.   Assuming my tanks are close to being even on each side I will normally start up with the right tank.  As part of my after start or just prior to taxi, I will switch to the left tank.  Now I now it's working.  I should have enough time during taxi and run-up to confirm that my fuel is good, no contaminants. 

I like this technique because at a low altitude engine failure, I can reach down without looking, and switch the tanks to the right tank easily.  Just swing it over to the stop.  If I take off in the right tank and need to switch, I have to look down and stop the lever on the left tank precisely.  If I move it too far I could inadvertently shut it off.

Just a technique.

[Hank]

Wow. My C has a positive stop at each tank--point to the left until it stops for left tank, point to the right til it stops for the right tank. There's a pretty noticeable detent at OFF, but I never stop there in flight . . . makes it easy to take off on fullest tank with no worries. It is a good idea before takeoff to verify that the lever moves freely to both positions.

In fact, it's such a good idea that the last line of the Engine Start Checklist in my Owner's Manual says:

Fuel Selector Handle--CHECK right and left.

[carusoam]

Mulro makes a good point.  If possible, always start with the same tank knowing where to go when things get quiet on departure.

Funny thing, I always depart on right tank.  This is more important for those who have to bend down to their knees with their head under the i strument panel to reach the valve (from my 65c experience).

Best regards,

-a-

[jetdriven]

A 12" long piece of 1.5" PVC with a notch cut in one end makes a good fuel valve turner.  Dowel rod glued in the other end aligned with the notch gives more leverage and makes it easy to identify the orientation of the slot and valve. 

 

[jlunseth]

I always sump the right and left tanks.  I used to sump the gascolator also, but learned the hard way it can jam if opened with a sump cup pin from the bottom.  Had it replaced and the new one did it, so I don't think it is the quality of the part, but the design.  I normally call the FBO and have the plane fueled up before I get there, which builds in a good deal of wait time.

I do switch during ground ops, one tank for starting and taxi, another for runup, then back to the original tank for takeoff and climb.  I normally do not switch frequently in flight at cruise.  My fuel flow meter is much more accurate than the tank gauges, and I just like to let the meter do its job.  So I will use 20 something gallons out of the tank used for takeoff and climb, then switch to the other tank and run it down to empty on the gauge, which typically means there is 2-5 gals. useable left, then go back to the first tank for approach and landing.  Don't remember ever using more than 55 gallons from the 75.6 gal system, am usually either at the destination or a fuel stop by then. 

I have never had the switch to the off position, I should probably try it. 

I have seen water in a Mooney, it was an older rental J that had the ring gaskets in the gas caps leaking.  Quite a bit of water, was sort of brownish gunk.

I refuel at all sorts of places, many small fields with self serve and you never know how much fuel they go through and how long it sits in storage, so am sort of manic about sumping every time.

[Immelman]

I second what Ward said.

My practice is to start the engine on the tank I don't want to take off from, and switch to the takeoff tank before runup. I usually run through the "CIGARS" mnemonic (contols, instruments, gas, attitude, runup), before each takeoff, and in absense of a long taxi or other delays I usually take off about 5 minutes after engine start. To me, this is enough time to verify operation on each tank. I get to "G" for gas after taxiing a minute or so, checking flight introls, and figure this is long enough to test the first tank. I then switch leaving at least 2-3 minutes of operation, to include runup, from the tank I'll use for takeoff.

When doing a long range flight where I will need fuel from both tanks, I do not want a surprise!

[Lood]

I always dip both tanks before flight to determine fuel quantity in each. Then I sump both. After pulling the ring inside the cockpit, I always start, warm up and taxi on the tank with the least fuel. Before I do my run up's and power checks, I switch to the fuller tank, which I also take off with. This way I'm sure that fuel flow and -condition is good from both tanks.

I always put the fuel selector in "off" after shut down. This way I keep up the good habbit and won't get caught loosing fuel due to crossfeed when flying a Cessna once in while. My Mooney doesn't even start when the fuel selector is turned off. It might give a few coughs, but that's it.

[flyboy0681]

Everyone has offered excellent suggestions here. The only one I can add is that when switching tanks, I always start off by moving the lever to the right regardless of which tank I'm on. Doing so will guarantee that I don't go from Left to Off if I'm switching from right to left.

[Shadrach]

I typically check both tanks before take to establish fuel continuity. I think it's a good SOP.  Especially for those of us that run tanks dry (running until the needle blips), because I have had situations were a small amount of air in the system has caused a burp after switching to a tank that is full but was previously run dry. This can be mitigated by starting on the tank that was previously empty. However, no ones perfect, and it's redundant way of confirming continuity at the possible operating regime...on the ground.

[Shadrach]

Quote: Mooney65E

[1964-M20E]

I sump both tanks and the collator  for a 5 count but generally I do not switch tanks on the ground.  I will swap tanks from the last time I flew the plane to burn gas out of the other tank.  Only on longer cross countries >=1.5 hrs do I switch tanks in the air.  The majority of my flying has been <= 1.5hrs.

I once went to fly a 152 before I owned my Mooney and when I sumped the left tank a bunch of water came out.  None came out of the right tank and plenty out of the collator.  I shook the plane several times until I could not get any more water.  I drained a lot of fuel that day in little bites to make sure the water was out.  Weird thing was someone had just flown that airplane earlier in the day.  I went flying and had no problems but was on edge for a while.  Maybe I should not have flow it but in the end the collators can hold a fair amount of water and that is what they are there for to catch the water before it goes into the engine.