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Switch Tanks, Switch Tanks, Switch Tanks!


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I’ve only made one cross country flight in my E and I can already see the value in reaching your destination with one tank as full as you can manage and doing that by running the other nearly dry. 

During my training I’m using a stopwatch app on my phone (yoke mounted) to track my tank usage times because at some point I’m going to have to make some remaining fuel calculations with the JPI.  Which brings me to a question: when you guys set up your tank size in the JPI are you using the capacity of one or both of the tanks?  It seems to me that if I put in 52 gallons and take off...and don’t run one dry, then the JPI prediction of when I’m going to run out of fuel on this tank is wrong.  I’ll run out when it reports I have more left but it’s actually in the first tank. How are you all dealing with M20 split tanks and the JPI FF?

Absent if the JPI FF (not yet installed) my plan is to run an hour on right tank, then to left to run dry. Then back to the right. At this point if the cumulative time on the right timer ever matches the empty left tank timer...game over.  This is basically what the POH advises but modernized.  

Below is how much time I’ve spent on each tank as it sits in the hangar today...no I’m not going to trust it for another flight without checking the levels.  The timer feels useful though.  I have a routine and it seems to work.  I’ll get used to when I’m at risk of sputtering and be sure to be prepared for it at the proper altitude.  Gives me something to compare the crappy flappy fuel gages to as well.  
 

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You have two tanks...

Keep track of them separately...

Without FF...

Climb on one tank... until you really get a feeling for the FF at WOT... because it is about 2X of cruise while nicely leaned...

I typically changed tanks on the hour after that...

I didn’t have a wing leveler... so my fingers were a bit tired supplying the pressure on the yoke all the time...

The plane is pretty sensitive to a fuel imbalance... it can track the magenta line with precision when the fuel load is perfectly balanced with the people load... as long as there is no X-wind...

Keeping the climb separate from the cruise you can get a better feel for FF for each phase of flight...

But, if you lean differently the next time... or set power differently... you end up with large variations in fuel used...

Make sure the fuel level indicators are working properly...

Make sure you know how much useable is in each tank...

The Sooner you complete this knowledge assignment, the better off you will be...

Then get the practice of running a tank dry...

 

The first thing people do when able... get a calibrated FF gauge with a totalizer... to know how much fuel they burned... decent fuel level gauges make a great back-up to the totalizer...

Getting Cies Fuel level gauges is like a backup to your backup....

With your current fuel level system you have to be extra aware of its shortcomings and plan to carry extra fuel around...

When one tank runs out as a surprise... it is time to land, now... you can’t afford another surprise running the other tank dry... :)

PP thoughts only, not a CFI...

Best regards,

-a- 

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12 hours ago, Nukemzzz said:

I’ve only made one cross country flight in my E and I can already see the value in reaching your destination with one tank as full as you can manage and doing that by running the other nearly dry. 

During my training I’m using a stopwatch app on my phone (yoke mounted) to track my tank usage times because at some point I’m going to have to make some remaining fuel calculations with the JPI.  Which brings me to a question: when you guys set up your tank size in the JPI are you using the capacity of one or both of the tanks?  It seems to me that if I put in 52 gallons and take off...and don’t run one dry, then the JPI prediction of when I’m going to run out of fuel on this tank is wrong.  I’ll run out when it reports I have more left but it’s actually in the first tank. How are you all dealing with M20 split tanks and the JPI FF?

Absent if the JPI FF (not yet installed) my plan is to run an hour on right tank, then to left to run dry. Then back to the right. At this point if the cumulative time on the right timer ever matches the empty left tank timer...game over.  This is basically what the POH advises but modernized.  

Below is how much time I’ve spent on each tank as it sits in the hangar today...no I’m not going to trust it for another flight without checking the levels.  The timer feels useful though.  I have a routine and it seems to work.  I’ll get used to when I’m at risk of sputtering and be sure to be prepared for it at the proper altitude.  Gives me something to compare the crappy flappy fuel gages to as well.  
 

 

 

I have an EDM 830 which is accurate to about a tenth of a gallon. However, I still dip my tanks as part of pre-flight, every flight. Even if I just checked them, flew around the pattern a few times and locked the plane in the hangar, I will still dip the tanks before the next flight. It doesn't take long, and I know exactly how much fuel I have and I will add/subtract to what the JPI is showing.

I have a EDM 900 and CIES senders sitting on the shelf with a bunch of other things for a future upgrade later this year. Those will give even greater accuracy, but I will still dip my tanks before every flight. There's a few things that fall in what I call the "never should happen category" and one of those is running out of fuel because I thought I had more than I had.

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45 minutes ago, Skates97 said:

I have an EDM 830 which is accurate to about a tenth of a gallon. However, I still dip my tanks as part of pre-flight, every flight. Even if I just checked them, flew around the pattern a few times and locked the plane in the hangar, I will still dip the tanks before the next flight. It doesn't take long, and I know exactly how much fuel I have

THIS is exactly what I was about to recommend to @Nukemzzz. Use your dipstick, learn your fuel burn, check before and after every trip. That will calibrate your power & mixture to the JPI and clock. Since all I have are the factory gages and a clock, I am diligent about dipping my tanks before every flight.

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Regular dipping of tanks must be combined with the fuel used data from the JPI and fuel added data from the pump. Repeat that enough times and you'll have both your stick and JPI FF data, calibrated and confirmed.

Now that all that is done, add the other data point to the equation by running a tank dry at altitude. Then after landing and refueling that tank, repeat with the other tank. Now you'll know exactly how much useable fuel you have in each tank. The stick will tell you how much before you take off, and the JPI will tell you while in flight. 

There is nothing quite as comforting on a long cross country, as accurate fuel data.

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1) Fuel tanks are attitude sensitive...

2) Mooneys on the ground point towards the sky on level ground...

3) Filling the tanks part way takes knowledge of how to measure fuel level...

4) Low tech method... requires using a consistent method and a calibrated stick...

5) the process is called sticking the tank...  :)

6) the next step up uses mechanical float gauges that are often found mounted in the access panel near the fuel cap...

7) These devices are all designed to be accurate while on level ground...

8) Nobody has reported any accuracy while sticking a tank in flight...:)

9) panel mounted fuel level indicators are calibrated for level flight .

10) Old fuel level floats have a tendency to stick... cleaning them can work wonders...

11) old gauges can be replaced with near identical new ones... or OH’d by a known entity... in PA.

12) every flight can start with a known amount of fuel...

13) every flight can be executed with decent fuel usage knowledge...

14) Most MSers that have run out of fuel... knew the risk they were taking...  :)

15) One of the biggest challenge seems to come with no fuel available at the point of departure...

16) Running out of fuel, and VFR flight into IMC....continue to be the killer of otherwise good planes... (mild understatement)

17) Digital fuel level sensors have incredible accuracy built into them... both accuracy and precision...

18) computerized displays can also enable smooth indications in bumpy weather...

19) Cies has discussed methods of using the same float sensors calibrated for filling tanks while on the ground... 

20) Bottom line... Don’t run out of fuel... :)

PP thoughts off the top of my head... no research required... not a mechanic... or CFI 

Best regards,

-a-

 

 

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On 6/17/2018 at 1:58 AM, gsxrpilot said:

One of several reasons I like to regularly run a tank dry at altitude. Switching tanks becomes the default quick reaction. I can recognize the very early initial symptoms of fuel starvation and instinctively reach for the fuel selector to switch tanks. Just performing an action, will get one past the initial "startle effect" and on to productive troubleshooting.

Not to mention knowing where yoru fuel guage REALLY means empty... I can run my left ank down to the red... The right tank is empty at the white lien just before the red.

I always make sure I am at a low power setting when doing this.

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To clarify, my question above concerned how to set up the fuel flow settings in JPI EDM when you have two separate tanks. If I put 52 gallons it will report I’m fine when I run the first tank out (26 gal fine).  Which lead me to another reason to run one tank dry. If you program 52 and change tanks with 5 gallons left in the first the JPI will say you have an extra 5 gallons of time left before empty and you could accidentally run out while on the second tank. 
 

Do some of you set up left as main and right as Aux in the JPI?

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The knee board still reigns supreme!!! :)

Some people can probably memorize the details... when executed in a uniform way...

I just use the piece of paper on my lap to write down frequencies, ATC station, altitude, kolman’s number...

Add in notes like fuel change, time, gallons used...

With 100 gallons on board... I start running out of United States... before I run the tanks dry... :)

Best regards,

-a-

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I just have the total for both as one number in my JPI. I make a note on the pad on my knee pad as to how much is in each tank at the start of the flight. When I switch tanks I note the amount used and do the math and make another note as to what is left in that tank, along with the time I switched. 

Pretty easy to keep track of. I even made an excel sheet that's on my tablet that will do the math and keep track of it all if I put the starting amount and the amount used when I switch tanks, but usually just do it by hand on the note pad. 

I find that during cruise on a 3-4 hour cross country I have plenty of time to make notes and do math... 

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6 hours ago, Skates97 said:

I just have the total for both as one number in my JPI. I make a note on the pad on my knee pad as to how much is in each tank at the start of the flight. When I switch tanks I note the amount used and do the math and make another note as to what is left in that tank, along with the time I switched. 

Pretty easy to keep track of. I even made an excel sheet that's on my tablet that will do the math and keep track of it all if I put the starting amount and the amount used when I switch tanks, but usually just do it by hand on the note pad. 

I find that during cruise on a 3-4 hour cross country I have plenty of time to make notes and do math... 

I do it the old fashioned way [no fuel flow . . . ]--if full, one hour on each tank, then 1-1/2 on the first one, leaving me 1-1/2 to land and get to the pump. That will leave some reserve due to extra fuel burn during climbout; if I need range, I'll run the first tank dry, which can be an additional 10-15 minutes, but I really like to be descending for my destination by then, 4 hours in the cockpit is uncomfortable.

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