Sr20 & 22 fuel management

Guest Discussion
#1

Has anyone tried John Deakin’s technique for determining the true fuel capacity and endurance of the Cirrus airplanes? If so, please share the results. Of course, YMMV.

See “Run that Fuel Tank Dry” at http://www.avweb.com/articles/pelperch/pelp0007.html

Here’s the blurb: “AVweb’s John Deakin takes aim at yet another OWT (Old Wive’s Tale). While running a fuel tank dry in your recip powered plane may serve to increase your heart rate, John explains why it’s not such a bad thing at all, and it is probably a really good idea for most of us. In fact, John explains why it’s one of the first things you ought to do with a new plane and how it could save your life someday”

#2

I agree with John 100%. I also do it with a new car (new or used). I had a Commanche that one wing would run out .5 hrs before the other and the gauge never got close to empty. May sound scary to some of you, but it will only make you a better pilot by actually doing the emergency procedures. Just like this one. When was the last time you shut your engine off using the fuel shut off valve? Well, I make sure mine works every now and then. If you have a real fire and your fuel valve does not work because you have never tried, I hope you brought some hot dogs for the cook-out. Have a great Cirrus 4th of July day.

Woor

Has anyone tried John Deakin’s technique for determining the true fuel capacity and endurance of the Cirrus airplanes? If so, please share the results. Of course, YMMV.

See “Run that Fuel Tank Dry” at http://www.avweb.com/articles/pelperch/pelp0007.html

Here’s the blurb: “AVweb’s John Deakin takes aim at yet another OWT (Old Wive’s Tale). While running a fuel tank dry in your recip powered plane may serve to increase your heart rate, John explains why it’s not such a bad thing at all, and it is probably a really good idea for most of us. In fact, John explains why it’s one of the first things you ought to do with a new plane and how it could save your life someday”

#3

I agree with John 100%.

I tend to agree too, but would like one question answered before trying this.

The auxiliary fuel pump on the 550N is not to be operated when there is no fuel pressure. In various maintenance routines, one manual warns to turn the pump off as soon as cavitation begins. I presume the no-load condition on the pump allows it to operate too fast, but maybe there are other harmful conditions that develop in the pump. Of course, you wouldn’t have the fuel pump on during a fuel starvation routine in flight.

But the question is: Does the engine driven fuel pump suffer any similar trauma when operated dry? I assume its speed is unaffected by the lack of fuel pressure. But I’d like to hear an AME say that the pump is happy pumping dry before I’d experiment with the last drops of fuel.

Steve

#4

I’m as close to an avid desciple of John Deakin as you can get, but as he cautions, you have to read and THINK aboyut his comments before you follow them blindly in your aricraft.

I can only speak for the SR22 - SR20 drivers, this may or may not apply. I also mus tnote that this is just my opinion.

The '22 is very sensitive to unbalanced fuel loading. The POH calls for (reguires?) that the fuel load not be unbalanced by more than 10 gallons. My experience is that I change tanks more often than require to keep the fuel levels very close. Add to this that if a wing is low (typical if the fuel load is imbalanced) or the aircraft is at all uncoordinated the fuel gauges read very inaccurately. After assuming a straight and level, coordinated attitude for a few minutes everything balances out and the gauges look very accurate. I’ve seen the gauge vary by as much as 5 gallons due to the airplanes attitude. I assume using the last bit of fuel ‘unuseable’ would be difficult unless you are very straight and level.

The problem is that as soon as the fuel load becomes inbalanced, the aircraft flies quite a bit heavy wing low. Therefore to suck out the last remaing fuel, the ‘full’ tank would also have to be very low. Not something that Deakin recommends.

I’d definately recommend running (or draining a tank) and filling it to see how much it really holds, and maybe calilbrate a dipstick along the way.

I also have no problem with his advice that there is nothing wrong with running a tank dry - just his method would not work well in the SR22.

Finally, if I ran a tank dry with my wife inthe plane, I would probably hope that I couldn’t restart it, because if we survived, she’d kill me once we got on the ground.

Know your airplane, know yourself and know your passengers.

Marty