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  #1  
Old 12-28-2017, 03:58 PM
bsacks05's Avatar
bsacks05 bsacks05 is offline
 
Join Date: Jan 2005
Location: Warner Robins, GA
Posts: 1,187
Default My experience running a tank dry.

Due to my impatience and boneheaded fuel expectations I managed to run a tank dry on a recent long cross country.

I knew the left tank was getting close to being empty but I thought it would get me another 10-15 minutes along before I switched to the right tank. I was about 20 minutes from home with rapidly diminishing daylight at 3500 ft. "The fuel in the right tank would be enough to get me home with reserves", was my thinking before the left tank went dry.

I did not think it would happen but suddenly the engine quit with the prop windmilling at a good clip. I was pretty quick to switch tanks and after about 3 long seconds the engine restarted. I don't remember if I pushed in the mixture and turned on the boost pump but was very relieved that the power came back on.

So...do I fly on, confident that the right tank would carry me through a darkening sky to my destination? No. I finally made a wise decision and diverted 9 miles to an airport I knew had SS fuel. I made it home later than I planned and logged some night flying and and a landing. I would have gotten home sooner if I had just topped off the tanks before I left in the first place.

Lesson Learned: After 11 years and 1100 hrs with my RV9, overconfidence, impatience, and complacency are real dangers. I'm glad this happened. It needed to happen and I am a better pilot for it.
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Bruce Sacks
RV-9 N659DB - Flying since 7/1/06
Hatz CB-1 - Fabric covering with Polyfiber.
Warner Robins, GA
A&P
APRS KJ4EFS
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  #2  
Old 12-28-2017, 04:20 PM
Bevan Bevan is offline
 
Join Date: Sep 2007
Location: BC
Posts: 1,537
Default

Thanks for sharing. Carb or FI?

Bevan
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RV7A Flying
O-360-A1F6 (parallel valve) 180HP
Dual P-mags
Precision F.I. with AP purge valve
Vinyl Wrapped Exterior
Grand Rapids EFIS
Located in western Canada
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  #3  
Old 12-28-2017, 05:08 PM
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Ed_Wischmeyer Ed_Wischmeyer is offline
 
Join Date: May 2005
Location: Savannah, GA
Posts: 669
Default

Not sure that's necessarily a problem...

Suppose you're on a long flight burning a bunch of fuel from each tank. How do you know how much fuel you've got in each tank? And how do you know that you won't run one tank dry on short final or unport the tank if you slip the wrong way?

I've thought about this a bunch, but don't have a good answer. My "thoughts" are:
* Change fuel tanks five miles out, so you know that you're not about to run one dry on final. And that's still high enough that if there's a problem, you can go back to the other tanks;
* Or run one tank dry in flight, knowing then that the other tank has all the fuel reserves/

And let's face it, precise fuel management in an RV is more optimism than practice. Probably the best fuel burn numbers come from factory built airplanes with the same engine/prop combination, and that will give fuel burn per hour, but those numbers will need adjustment for climb, etc. And although RV tanks are relatively easy to fill completely, the wing ribs can act as air traps, so you may not get them exactly full.

And then there have been flights where the destination airport didn't have gas -- the credit card reader was inoperative, the fuel hose was stuck, or the gas vendor wasn't open on weekends. On long trips, I've gotten in the habit of planning to land with two hours of gas, and that means that if I have to go somewhere unplanned an hour away for gas, I can land there, still with an hour of reserves.

But there have been flights back to home base when the landing was planned with only an hour of reserves, night was falling, etc.

As they used to say on TV, be careful out there!
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RV-8 (steam gauges), RV-9A at KSAV (Savannah, GA; dual screen G3X with autopilot, GTN 650)
Previously RV-4, RV-8A, AirCam, Cessna 175
ATP CFII PhD, so I have no excuses when I screw up
2018 dues paid
Retired - "They used to pay me to be good, now I'm good for nothing."
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  #4  
Old 12-28-2017, 05:23 PM
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JohnInReno JohnInReno is offline
 
Join Date: Jun 2005
Location: Prescott Valley/Chandler AZ
Posts: 282
Default Grumman Trainer

While building my 9A, I purchased a Grumman AA1B with an O-320 and stock gas tanks. 11 gallons on each side and an 8 gal/hr motor flying around the middle of Nevada makes for critical fuel management. I got used to running a tank dry so that I knew how much time I had on the other tank. Like this:

Left 30 min - Right 30 min
Left 30 min - Run it dry (15-20 min more)

Right tank now has 30 min plus the run dry time.

One eye on the fuel pressure gauge when it is about to run out makes the swap without the engine stopping.

I have not used this technique in the 9A but I could.
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RV-9A N946PM 500+ hours since 2013
Nevada/Arizona
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  #5  
Old 12-28-2017, 05:29 PM
Kyle Boatright Kyle Boatright is offline
 
Join Date: Aug 2005
Location: Atlanta, GA
Posts: 3,218
Default

On long range flights, I'm a proponent of running a tank dry so you know you've got all of your remaining fuel in one tank. No sense running both of 'em down to the "is one gonna unport in the pattern?" level.
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Atlanta, GA
2001 RV-6 N46KB
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  #6  
Old 12-28-2017, 05:49 PM
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AZtailwind AZtailwind is offline
 
Join Date: Nov 2005
Location: Flagstaff, AZ
Posts: 428
Default

Quote:
Originally Posted by Ed_Wischmeyer View Post
Not sure that's necessarily a problem...

Suppose you're on a long flight burning a bunch of fuel from each tank. How do you know how much fuel you've got in each tank? And how do you know that you won't run one tank dry on short final or unport the tank if you slip the wrong way?

I've thought about this a bunch, but don't have a good answer. My "thoughts" are:
* Change fuel tanks five miles out, so you know that you're not about to run one dry on final. And that's still high enough that if there's a problem, you can go back to the other tanks;
* Or run one tank dry in flight, knowing then that the other tank has all the fuel reserves/
Agree- I've tried to run out a tank many times, doing the 5 miles out option then switch. Nice too see someone has ran a tank dry, I have not been able to yet. These RV's are fast and efficient!
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http://www.westcoastravens.com
RV-6A 180HP-purchased
Be V35
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  #7  
Old 12-28-2017, 06:04 PM
bsacks05's Avatar
bsacks05 bsacks05 is offline
 
Join Date: Jan 2005
Location: Warner Robins, GA
Posts: 1,187
Default

Quote:
Originally Posted by Bevan View Post
Thanks for sharing. Carb or FI?

Bevan
Carbed O320 160 hp, 1 mag, 1 EI
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Bruce Sacks
RV-9 N659DB - Flying since 7/1/06
Hatz CB-1 - Fabric covering with Polyfiber.
Warner Robins, GA
A&P
APRS KJ4EFS
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  #8  
Old 12-28-2017, 07:13 PM
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grubbat grubbat is offline
 
Join Date: May 2012
Location: Ga
Posts: 537
Default Me too

I always run the left tank dry when on cross country and left hand pattern airports in the plan. On our -9, six gallons is another hour of flying but I'm looking for a place to refuel around 8 gallons.
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RV-3 Sold
RV-6a Sold
RV-9 IO-360 CS, Flying
1946 Piper Cub - in process......
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  #9  
Old 12-28-2017, 08:21 PM
Ed_Wischmeyer's Avatar
Ed_Wischmeyer Ed_Wischmeyer is offline
 
Join Date: May 2005
Location: Savannah, GA
Posts: 669
Default

If the turn is coordinated, it makes no difference which tank is selected.
__________________
RV-8 (steam gauges), RV-9A at KSAV (Savannah, GA; dual screen G3X with autopilot, GTN 650)
Previously RV-4, RV-8A, AirCam, Cessna 175
ATP CFII PhD, so I have no excuses when I screw up
2018 dues paid
Retired - "They used to pay me to be good, now I'm good for nothing."
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  #10  
Old 12-28-2017, 08:30 PM
RV8JD's Avatar
RV8JD RV8JD is offline
 
Join Date: Jan 2005
Posts: 801
Default From AFP for FI Systems

From AFP:
"WARNING

Airflow Performance and Bendix/Precision fuel injection systems are non-returning systems. In the event that a tank is run dry in flight, an air lock will be formed on the out let of the pumps. It is possible that the auxiliary pump will not pick up fuel, as the auxiliary pump cannot create enough air pressure to over come the flow divider opening pressure, thus displacing the air and resume pumping fuel. It is not recommended to run a fuel tank dry in flight without adequate testing and proper documentation of the procedure for this operation."
So try it safely before you need it.
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Carl N.
Arlington, WA (KAWO)
RV-8, 340 Tach Hours
(Pic 1),(Pic 2)
- Out with the Old, In with the New
(Pic)
RV-8, 1938 Tach Hours (Pic 1),(Pic 2) - Sold

Glasflügel Standard Libelle 201B, N564NS - Sold
Rolladen-Schneider LS1-f, N61MP - No longer owned

Last edited by RV8JD : 12-28-2017 at 08:33 PM.
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