Procedure for switching fuel tank

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IlyaK18

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IlyaK18
Good day,
I am currently training on a Piper Warrior . I am getting mixed opinions about the procedures to change fuel tanks. Some say first switch tanks, then turn on electric fuel pump, and others say Electric pump first. I have always learned that electric pump goes on first. Also , in the Warrior 2 POH, on the approach/Landing checklist , which I attached below. It says fuel selector to proper tank, and the Electric Fuel Pump ON is later. So if you are not on the proper tank, and need to switch , do you put the fuel pump on first ? or put it to the proper tank and then turn on the pump? Kind of confused here. :mad2::mad2:
 

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My first training experience was in an 1970 Cherokee.

That instructor always taught the following routine for switching tanks in flight.

Check Fuel Pressure Gauge
Turn on electric pump
Check Fuel Pressure Gauge
Switch Tanks
Check Fuel Pressure Gauge
Turn off pump
Check Fuel Pressure Gauge
Fly

The frequent check of the pressure gauge was his reinforcing to determine if something is awry right away rather than waiting for the engine to hiccup from starvation.
 
It doesn't matter, if the engine stumbles turn on the pump, or turn on the pump first. The likelihood of the engine stumbling during a tank switch is really low and most likely it won't be from the pump not running and you'll have to switch back tanks.
 
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AggieMike88 said:
My first training experience was in an 1970 Cherokee.

That instructor always taught the following routine for switching tanks in flight.

Check Fuel Pressure Gauge
Turn on electric pump
Check Fuel Pressure Gauge
Switch Tanks
Check Fuel Pressure Gauge
Turn off pump
Check Fuel Pressure Gauge
Fly

The frequent check of the pressure gauge was his reinforcing to determine if something is awry right away rather than waiting for the engine to hiccup from starvation.
Click to expand...


I am training in a PA28 and this is exactly how my CFI has me do it. We have not switching tanks in the downwind, but before entering the pattern if needed. As for landing the checklist I am using is...

1. throttle 1500
2. mixture full rich
3. full pump on
4. landing lights on/ collison lights on
5. flaps to 1st notch. (this is the downwind setup procedure)
 
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I follow the POH for the aircraft I'm flying. So, if I were flying that Warrior, I'd hit the pump first, then switch, then watch the fuel pressure gauge for a few seconds before turning it off, and keep my finger on the fuel pump switch and my eye on the fuel pressure gauge for a few more seconds before turning my attention to other tasks.

OTOH, my Grumman Tiger does not say anything about using the fuel pump unless I've emptied the tank and the engine has stopped. So, for a routine tank change, I just reach down and switch -- but keep my eye on the fuel pressure gauge for a few seconds after I do with my hand ready to go "pump-on, tank-back to the original".
 
POH is the rule for a check ride. But, with a good reason, you can override it. It does no harm to have the pump on for a short time when you don't need it, so you can turn it on first.

Something that hasn't been mentioned -- and there is a potential error here.

If you arrive in the pattern and you're on the wrong tank, it is TOO LATE. Switch only while you have altitude. Every configuration change has the possibility of an error or other problem. For most changes, the results are easily recoverable. If you switch the tank and don't move the selector all the way (for instance) or you turn it the wrong way, or there happens to be undetected water in the other tank, you can cut off the fuel and make the engine quit close to the ground. As a rule of thumb, it takes 2000 feet or so of altitude to troubleshoot, so if you're less than 2000 AGL when a problem hits, you're landing right now, wherever you happen to be.

An examiner may not like that, but that's the place where you tell him what the book says and assert PIC authority. The POH is not the PIC and neither is the examiner, and they will understand that.

Now, if you fly a good pattern, you can make the field with the fuel cut off. So, it's not always a hazard, it's a potential hazard. But believe me, passengers do not like to see the engine quit on final even if you have the field made (BTDT -- but due to mixture at high altitude, not fuel starvation). Where this really can bite you is when you switch tanks right before takeoff. The POH language is ambiguous here, but as a rule, you should do your run-up and takeoff on the same tank.

Also pay attention to where you are when you switch during cruise. If you're in a high pass with no good emergency landing spots or over open water or a dense urban environment, wait until you've cleared to switch tanks.
 
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I fly an Archer 3. Pressure, Pump, switch tanks, pressure, turn pump off except prior to landing where pump would stay on.
 
Following the POH is a good idea.

That said, it really doesn't matter. If you get a stumble one way or the other (you shouldn't) then use the way that doesn't have the stumble.

Signed,

-An engineer who would know
 
With fuel...

Add a source, lose a source.

As you advance in equipment this will serve you well. Before you kill a fuel pump you open a transfer valve. Before you close off a fuel source you start a new one.

Add a source, lose a source.

With a SE aircraft I'd guess that adding pressure from a fuel pump would be good before you switch between two available tanks. That way the tanks switch under pressure...

Add a source, lose a source.

Hope this helps.


BTW...post #5 is spot on too.
 
IlyaK18 said:
Good day,
I am currently training on a Piper Warrior . I am getting mixed opinions about the procedures to change fuel tanks. Some say first switch tanks, then turn on electric fuel pump, and others say Electric pump first. I have always learned that electric pump goes on first. Also , in the Warrior 2 POH, on the approach/Landing checklist , which I attached below. It says fuel selector to proper tank, and the Electric Fuel Pump ON is later. So if you are not on the proper tank, and need to switch , do you put the fuel pump on first ? or put it to the proper tank and then turn on the pump? Kind of confused here. :mad2::mad2:
Click to expand...

Why are you asking for opinions? The POH rules.

Bob Gardner
 
Ted DuPuis said:
Following the POH is a good idea.

That said, it really doesn't matter. If you get a stumble one way or the other (you shouldn't) then use the way that doesn't have the stumble.

Signed,

-An engineer who would know
Click to expand...

That philosophy I agree with.
 
POH is easy - especially when there's 2 tanks. I fly a Cherokee 235 which has 4 tanks...no 'both' or 'all' option so you really have to keep an eye out and know how long you're going to fly to properly balance the tanks.

For me, I always start on the right main (25 gallons) and on my cruise checklist I switch to the left main for 45 minutes. I never go back to the right main until I'm doing my landing GUMPS - that way I always know I have over an hour of fuel in there when it's time to land.

From that point it's basically just how long am I going to be flying. I don't think I physically could take much more than 3-4 hours which is about half the endurance of the plane so it's just a matter of balancing the tanks at that point.

I use the POH for guidance and it calls for turning on the pump prior to switching tanks and then leaving it on for a bit after the tanks have been switched.

The partners in my plane run the tips out of gas before switching...I'm not brave enough to do that yet...but they basically let them get down dry and then start watching the fuel pressure gauge. It'll start dropping once the tank is empty and once it bottoms out they'll turn on the boost pump and switch tanks.

Big thing to watch out for my in my plane is hammering the fuel tank selector all the way back to the left when switching to the left tip tank. Go to far not paying attention and you'll be at the "OFF" position. Not good. I actually did that on my last flight - luckily I caught it before I even took my hand off the switch...but kinda freaked me out for a minute. Definitely lesson learned now when I'm reaching down there...nice and slow...look at where you want to go first...then slowly switch it.
 
From the 1976 Warrior POH, page 2-7:

"The electric pump should be ON for all takeoffs and landings and when switching tanks."

So in order to have it on when switching the tanks, you'd need to turn it on first.

But yes, it doesn't really matter much.
 
Captain said:
With fuel...

Add a source, lose a source.

As you advance in equipment this will serve you well. Before you kill a fuel pump you open a transfer valve. Before you close off a fuel source you start a new one.

Add a source, lose a source.

With a SE aircraft I'd guess that adding pressure from a fuel pump would be good before you switch between two available tanks. That way the tanks switch under pressure...

Add a source, lose a source.

Hope this helps.


BTW...post #5 is spot on too.
Click to expand...

Thing is, in most small planes that's not possible, the valving system is all set up to be 'lose a source, add a source'.
 
AggieMike88 said:
My first training experience was in an 1970 Cherokee.

That instructor always taught the following routine for switching tanks in flight.

Check Fuel Pressure Gauge
Turn on electric pump
Check Fuel Pressure Gauge
Switch Tanks
Check Fuel Pressure Gauge
Turn off pump
Check Fuel Pressure Gauge
Fly

The frequent check of the pressure gauge was his reinforcing to determine if something is awry right away rather than waiting for the engine to hiccup from starvation.
Click to expand...
:yeahthat:
 
The Cherokee POH is the rule to follow.

Keep your hand on the fuel selector for 15 seconds after the switch. If the engine quits on the new tank your hand is already in position to switch back, and the fuel pump is already on via the POH.

A good friend of mine switched tanks in the pattern at Pearson in a Super Cub. The engine quit and he didn't have the where-with-all to switch back to the good tank. He landed short, but luckily didn't do much damage.
 
kgruber said:
The Cherokee POH is the rule to follow.

Keep your hand on the fuel selector for 15 seconds after the switch. If the engine quits on the new tank your hand is already in position to switch back, and the fuel pump is already on via the POH.

A good friend of mine switched tanks in the pattern at Pearson in a Super Cub. The engine quit and he didn't have the where-with-all to switch back to the good tank. He landed short, but luckily didn't do much damage.
Click to expand...

And when you fly twins, that rule gets modified to "wait 15 seconds between switching tanks on the second engine."
 
POH says put the pump on...you're probably fine without it.

I think what's most applicable here is:

-Do something.
-If things go downhill, undo that something.
 
I agree with the POH.

The way I do is pump on, switch tanks, put finger on fuel pressure gauge for five to ten seconds, and then pump off.

I think it's crazy to switch tanks entering the pattern, YMMV.
 
Captain said:
With fuel...
Before you close off a fuel source you start a new one.
Add a source, lose a source.
Click to expand...
Illegal in most designs, the regs will not permit a configuration that will allow you to pump from two tanks.
With a SE aircraft I'd guess that adding pressure from a fuel pump would be good before you switch between two available tanks. That way the tanks switch under pressure...
Click to expand...
Well, it depends on the plane (or even more precisely which engine / fuel system you have). While my old Gopher engine in the Navion and older Bonanzas you would turn on the fuel pump prior to switching tanks YOU SURE AS HELL DO NOT WANT TO DO THAT on an IO-550 powered engine in the later models. You can kill the engine running the aux pump when the engine driven one is working. You *NEVER* turn on the boost pump unless you think there is something wrong with the engine driven one has failed.

Hope this helps.
Click to expand...
Not in the least. This is one of those dangerous things that certain people "know" to be true that is not.

As every sane person says... LOOK AT THE POH!
 
JimNtexas said:
I think it's crazy to switch tanks entering the pattern, YMMV.
Click to expand...

Well you need to be on the "fuller" tank in some planes and on mine, you need to be on the mains for landing. You can plan to switch over some ways out but frankly, having the engine die in the pattern isn't usually a disaster, you're not that far from the runway.

Of course the scary time was when my wife turned the fuel selector to OFF rather than MAIN on downwind. That woke me up.
 
flyingron said:
Illegal in most designs, the regs will not permit a configuration that will allow you to pump from two tanks.

Well, it depends on the plane (or even more precisely which engine / fuel system you have). While my old Gopher engine in the Navion and older Bonanzas you would turn on the fuel pump prior to switching tanks YOU SURE AS HELL DO NOT WANT TO DO THAT on an IO-550 powered engine in the later models. You can kill the engine running the aux pump when the engine driven one is working. You *NEVER* turn on the boost pump unless you think there is something wrong with the engine driven one has failed.


Not in the least. This is one of those dangerous things that certain people "know" to be true that is not.

As every sane person says... LOOK AT THE POH!
Click to expand...

Then how do all the Cessnas get away with having a "Both" position?
 
I tend to agree with Jim…no reason your "switch to fuller tank" (or "switch to main") can't be on the descent from at least 2000 AGL.

Of course, you're right that you should be able to make a good landing on the runway if the engine dies in the pattern. But it uses up your backup plan -- no go-around if a deer runs across the runway, etc. And passengers REALLY don't like it, even if it's otherwise flawless.

The bigger problem is switching tanks right before takeoff and finding out about that water you missed when sumping or that the detents aren't quite seated, etc. I prefer to set on the fullest tank (or whatever the POH says for takeoff) and do the taxi, run-up and takeoff all on the same tank. Then, 30 minutes out, switch to the other tank. If there is a problem, switch it back and RTB.

I also advocate not switching tanks in cruise if an engine failure "right now" might be a problem, such as crossing a ridge close to the ground or flying over water. It can usually wait a few minutes. If it can't, declare your fuel emergency and do what you need to.
 
bartmc said:
They don't pump.
Click to expand...

Some do. Fixed gear 172s do not.

There is a boost pump on 172 and 177 RGs that "can" be on for takeoff (but is not required), and also a "both" position. I'm not convinced that it does much aside from prime the engine (177RG) or purge vapor (172RG).
 
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