Anyone ever run a tank dry in flight...on purpose?

[N941WR]

I've been following this thread with great interest. Back in the dark ages when I got my PPL we were taught never to run a tank dry as you might suck up some junk that keeps the engine from restarting. In thinking about this logic, I would think that "junk" has to be something floating in the fuel because if it sinks, the engine would have already sucked it up.

... If you never run a tank dry inflight, how do you verify the accuracy of the gauge? During testing on all three of my airplanes I built I tested the accuracy of the gauges at a safe altitude by running a tank dry. It's a non-event.

Smokyray, I verified the accuracy of my gauges with the plane in a level flight attitude when I calibrated my capacitance senders. Then I watched the gauges go down as I drained each tank.

(PS. I'm not judging those who have done this test. Just commenting on what I was taught and how I tested my plane.)

 

[smokyray]

One man's junk...

Bill,
Your technique works well for your application, but what if you fly and or inspect many different airplanes? When you don't have the luxury of having built every one you fly, there has to be a way to verify fuel levels versus gauge readings if you fly long distance and need to extract every bit of fuel. What if your fuel gauges failed or lose your DC bus? My technique works for ANY airplane and done properly, the engine never quits. It also gives you a very useful time gradient for simple wristwatch fuel calculations. It's also nice to know how your engine restarts when it does get quiet.
BTW, if you're worried about junk in the tanks, checking them periodically by removing the drains is a good technique...

Smokey
HR2


Having spent quite a few long nights over bad guy land, I can appreciate having enough gas to get home...

 

[N941WR]

Smokey,

True on all counts. Sometimes I forget that people didn't build the plane(s) they are flying.

 

[jdmunzell]

In my early days of Part 135 flying, I used to fly freight in a Cherokee Six with 4 main wing tanks. Because of weight restrictions, we routinely were at max weight with payload and required legal fuel on board.

We routinely would run the tips dry at cruise, so that when you were down to marginal fuel, at least it was in only the two inboard tanks. Back in those days I was a young whipper-snappin' low time pilot building flight time in order to move on to bigger, faster,etc.. didn't think much about shock cooling in those days....

Now that I have owned airplanes and payed their maintenance bills, I think about all that stuff now!

Of course, I don't peal out with the family car anymore either!

 

[dmaib]

When I was sixteen, the family car was a VW bus with no hope of peeling out!
I kept hoping Dad might see the light and bring a Corvette home some day, but it was not to be!

 

[Steve Brown]

If you don't empty it, then how low?

As I've written before, I had an M20E in the early 90s that had this procedure in the POH. So, its not some crazy new idea or something only to be used on record flights.

I understand that some are concerned about running a tank dry, but what is the alternative?

How much then is it "safe" to run the tank down to? 4 gallons, 3 gallons, 2 gallons? In a pinch do you really want to switch over to a tank with only 2 gallons in it? Do you want to throw away an extra 4 gallons (10%) of fuel by making it essentially "unusable"?

I think if pilots want to run larger fuel margins so this is never a factor, that is a personal choice. However, if you want to actually utilize the range of the airplane this is SOP, and the most beneficial discussion should really be about doing it safely rather than whether it should be done.

FYI: Like several have written, I used the fuel pressure as an indicator of empty tank. When the tank was near empty I turned on the electric pump. When the pressure dropped I switched tanks. Engine never missed a beat.

 

[asav8tor]

..... In a pinch do you really want to switch over to a tank with only 2 gallons in it?

In a pinch, (Fuel stopped feeding from selected tank and engine quit) yes I really would want to switch over to a tank with ANY amount of fuel in it. 2 gallons is better than zero gallons. It's all about having options available.

 

[Ron Lee]

Steve, what are your reserves when you stop to Refuel? If around eight gallons that could be four in each tank. Reserves are not unusable fuel.

Don't run out of fuel like one person may have done here a month ago and caused major damage to the aircraft (non-RV).