I intentionally ran a tank dry today

[weilke]

We have the aux tanks directly plumbed into the fuel selector. To get the 20gallons per tip-tank, you pretty much have to run them dry. If I switch the moment the fuel pressure drops, the engine doesn't even stumble. The only 'problem' is that the next time someone switches to the tip tank, they are going to pull 17ft of air column in the fuel line through the fuel pump and that will make the engine go quiet for a very long 10 seconds. So anytime someone runs tips dry, we let the next guy to fly the plane know so he can avoid having the engine go quiet with a skiddish passenger on board.

 

[Henning]

they say in the turbo aircraft if the engine quits in the flight levels or high teens it won't restart so I don't think I'll tempt it.

Only with a Deisel. Gas engine will restart no worries, it runs ROP.

 

[PeeGee]

Only with a Deisel. Gas engine will restart no worries, it runs ROP.

Wish I could find the post about it, guy accidentally put the fire out at FL220 and had to drift down to the low teens to get it back.
I was advised to run one tank until the low fuel light comes on, plus 5 minutes, then switch.

edit, well this guy put the fire out at 230 and said it came right back with full throttle. I won't do it with the wife on board but I might try it some time on a max endurance flight. Hate to leave those few cups of fuel in the tank.
http://mooneyspace.com/topic/11210-high-altitude-operations/

 

[tmyers]

Routine event on a long flight at altitude. Don't want to run them dry down low. I have a fuel totalizer and this is the best way to know how much fuel is actually in the tank with fuel. Pretty much a non issue

 

[Henning]

Wish I could find the post about it, guy accidentally put the fire out at FL220 and had to drift down to the low teens to get it back.
I was advised to run one tank until the low fuel light comes on, plus 5 minutes, then switch.

edit, well this guy put the fire out at 230 and said it came right back with full throttle. I won't do it with the wife on board but I might try it some time on a max endurance flight. Hate to leave those few cups of fuel in the tank.
http://mooneyspace.com/topic/11210-high-altitude-operations/

Likely forgot to lean. Regardless, unless you're over the Hymalayas, you have room to glide down.

 

[docmirror]

they say in the turbo aircraft if the engine quits in the flight levels or high teens it won't restart so I don't think I'll tempt it.

If it's a turbocharged 4 stroke piston engine it will restart. There is a procedure in your plane books somewhere. If it's an actual turbine, that's different, as it's a free air engine.

 

[PeeGee]

Likely forgot to lean. Regardless, unless you're over the Hymalayas, you have room to glide down.

It's embarrassing though

I think he over leaned, you can climb to altitude in a turbo full rich and it'll run fine, most people do I would say from what I've read.

 

[BigBadLou]

On a long trip, I plan out airports as waypoints every 30 minutes and switch when I'm over one that's on the plan. It sure beats being over a bunch of pointy rocks when you go to switch tanks and the handle breaks off in your hand.

 

[weilke]

There are occasional cases where someone can't restart after running a tank dry. Broken fuel selector, some gunk dislodged etc. That happening is much less likely than fuel starvation short of the destination because your fuel is spread across 4 tanks.

 

[jesse]

I think he over leaned, you can climb to altitude in a turbo full rich and it'll run fine, most people do I would say from what I've read.

Yes, you can, because the the turbo is online. If the engine isn't running, the turbo isn't going to be slamming more air into your engine, and the available intake air isn't going to be any better than a non-turbo engine would be for restart.

 

[kenjr]

A couple of the guys that are Partners in my plane do it on long trips where they need as much gas as possible. No sense in leaving 4-5 gallons in the tips just for the helluva it when you need it. I never could get up the nerve to do it myself...but I did let it happen on accident once...and unfortunately had 3 passengers with me.

We were flying out to the Big Bend area from Austin and I flew direct to an airport as a waypoint and then turned south from there because a straight shot from home would have cut the corner and taken me over Mexico. So, I had it planned out perfectly that I was going to switch tanks over this airport (there's **** nothing out there...so I'm switching tanks over a place where i can land) once I turn south.

We get over the airport and I start turning south and then Albq Center calls me and tells me that they are going to lose comms with me in about 10 minutes so heads up on that...then as we're turning my passengers start gawking about how that's Mexico over there and I'll admit the scenery was quite nice...my passenger in the co-pilot seat sticks his phone in my hands with the camera at the ready to snap a few pics and then just as the OP described...the engine loses about 300 RPM. I immediately knew what was going on - but it still startled me. As for my passengers I could feel the tension...my wife and sister-in-law were in the back and they embraced each other. I know they all thought they were going to die. I only regret that I didn't have my GoPro's on at the time. As for me, I switched the pump on and slammed the fuel selector all the way to the right to pick up from the right tip tank and without hesitation she came back up to full RPM. Fun times. I still don't have plans to do that on any regular basis - but it's good knowing what to expect.

Another funny story about that - my CFI owned a 235 at one point and was flying in the co-pilots seat with one of his partners in the pilots seat and 2 other pilots in the backseat. They had a discussion early on in the flight about how they were going to handle switching tanks, letting them run out, etc... and agreed that they weren't going to run them out but that my CFI was going to be in charge of monitoring the fuel pressure gauge. When it starts dancing around...that's when it's time to turn on the aux pump and switch. Well, of course, they all get to chatting and what not and vrooomp...engine drops 300 RPM and instinctively both he and the pilot reach down to the floor to switch the tanks and crash each other right in the temples and about knock each other out.

He says to me, "How messed up would that have been to crash that plane with 4 pilots on board and 4 hours of fuel with the two of us out cold in the front seat...".

Good times...

 

[weilke]

There is no need for rash actions if your engine looses power in cruise due to a tank running dry. If you 'slam' the ful selector, you just risk breaking the handle off the capstan. For the time being, dont change anything, it'll fire back up once it gets fuel. If it doesn't start back up after 10-15 seconds you'll have to start thinking about doing something.
I tell my pax during planned tank changes that the engine may go quiet for a couple of seconds due to air in the fuel lines.

 

[flyingron]

To avoid unnerving passengers when switching tanks in flight I always run fuel out of the aux tanks on the ground to prime them.

 

[Pilawt]

FAR §23.955 ("Fuel flow"):

(e) Multiple fuel tanks. For reciprocating engines that are supplied with fuel from more than one tank, if engine power loss becomes apparent due to fuel depletion from the tank selected, it must be possible after switching to any full tank, in level flight, to obtain 75 percent maximum continuous power on that engine in not more than—

(1) 10 seconds for naturally aspirated single-engine airplanes;

(2) 20 seconds for turbocharged single-engine airplanes, provided that 75 percent maximum continuous naturally aspirated power is regained within 10 seconds; or

(3) 20 seconds for multiengine airplanes.

The earlier CAR 3 3.4221(d) had an even stronger requirement for single-engine airplanes.

If an engine can be supplied with fuel from more than one tank, it shall be possible to regain the full power and fuel pressure of that engine in not more than 10 seconds (for single-engine airplanes) or 20 seconds (for multiengine airplanes) after switching to any full tank after engine malfunction becomes apparent due to the depletion of the fuel supply in any tank from which the engine can be fed. Compliance with this provision shall be demonstrated in level flight.