Fuel management

Rebel Lord

Rebel Lord

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Rebel Lord
So I'm trying to come up with a fuel management strategy for the cherokee 235 on long trips.
I threw this together and wanted to share it for critique. I'm going to add a totals column but wanted to see of anyone had any tips or tricks on what yall do for keeping track of fuel enroute.

fueltable.PNG
 
This is how I:m planning on filling it out with half hour tank changes





fuel in use.PNG
 
Cies digital fuel senders and one of these.

10-04432.jpg
 
I’ve got a 4 tank Cherokee 6. I tried a similar table to what you have and didn’t find it very helpful. Too much data; too much space. I’ve simplified since then. I do have a JPI 830 with fuel flow and rely on it.

On my knee board on the top right corner, I write the 4 numbers for the amount of fuel in each tank. When I switch tanks, I look at fuel used on the JPI, and write down that amount below the tank I used and then do the math for remaining fuel. I keep a separate fifth column for total fuel used.

So...
Filled to the tabs, my page has 17 20 20 17. Meaning 17 in the left tip, 20 in the left main, 20 in the right main and 17 in the right tip.

At TOC, I switch tanks from left main to right main. So, let’s say 5 gallons burned, below the left 20, goes a 5. I draw a line. Simple math and I now have 17 15 20 17. And I’ll put a 5 in the 5th column.

At 30 minutes, I switch to one of the tips. Let’s say a total of 12 gallons burned so far. A 7 goes below the right 20. Draw a line, simple math. I now have 17 15 12 17. The 5th column gets a 7 and totaled to 12.

Sometimes next to that 12 in the 5th column, I’ll put the fuel remaining. In this example a 62 as a cross check.

For hard IFR, as I join the approach, I’ll switch over to one of the mains. I’ll do my last fuel used calculation and circle my fuel remaining in each tank. With a quick glance, I know where my fuel is in case of a missed approach.

For most flights, I make 3 or 4 fuel tank switches and my little chart is simple and efficient. On a long trip, I know exactly how much fuel I have in each tank. And for an ifr approach, I know where my fuel is.

YMMV. If this doesn’t make sense, send me a PM and I’ll go over it better.


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drjcustis said:
I’ve got a 4 tank Cherokee 6. I tried a similar table to what you have and didn’t find it very helpful. Too much data; too much space. I’ve simplified since then. I do have a JPI 830 with fuel flow and rely on it.

On my knee board on the top right corner, I write the 4 numbers for the amount of fuel in each tank. When I switch tanks, I look at fuel used on the JPI, and write down that amount below the tank I used and then do the math for remaining fuel. I keep a separate fifth column for total fuel used.

So...
Filled to the tabs, my page has 17 20 20 17. Meaning 17 in the left tip, 20 in the left main, 20 in the right main and 17 in the right tip.

At TOC, I switch tanks from left main to right main. So, let’s say 5 gallons burned, below the left 20, goes a 5. I draw a line. Simple math and I now have 17 15 20 17. And I’ll put a 5 in the 5th column.

At 30 minutes, I switch to one of the tips. Let’s say a total of 12 gallons burned so far. A 7 goes below the right 20. Draw a line, simple math. I now have 17 15 12 17. The 5th column gets a 7 and totaled to 12.

Sometimes next to that 12 in the 5th column, I’ll put the fuel remaining. In this example a 62 as a cross check.

For hard IFR, as I join the approach, I’ll switch over to one of the mains. I’ll do my last fuel used calculation and circle my fuel remaining in each tank. With a quick glance, I know where my fuel is in case of a missed approach.

For most flights, I make 3 or 4 fuel tank switches and my little chart is simple and efficient. On a long trip, I know exactly how much fuel I have in each tank. And for an ifr approach, I know where my fuel is.

YMMV. If this doesn’t make sense, send me a PM and I’ll go over it better.


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Click to expand...

Yeah so basically this.


fuel1.PNG
 
I find 30min switches far too tedious.

I switch off my taxi/takeoff tank at 45 mins, over to the next for an hour, back to the prior for an hour, etc.

Sometimes I switch to the most full for landing, sometimes I don't mess with it. I depends on a few factors.
 
Rebel Lord said:
Yeah so basically this.


View attachment 75917
Click to expand...

Yes. And it fits on the right side of my knee board. No graph.

And after I get my fuel flow stable, I’ll calculate gallons per minute and my minutes per gallon rate. So, when you’re on the second half of the tip tanks, you can calculate when to switch.

So, at a fuel flow of 14 gph, you’ll burn 7 gallons in 30 minutes and then switch.

Left tip for 30 minutes, you’ve burned 7. Right tip for 30 minutes, you’ve burned 7. Now back to the left tip for 30 minutes and you’ve burned another 7 for a total of 14. You have 3 gallons left. 14gph is 0.23gpm or 1 gallon every 4.3 minutes. Again, simple math (I’m a big believer in simple math when flying so it’s a phrase that I use a lot). You can fly 12 more minutes on that tank.

So, for me, a long cross country is LM to TOC, RM, LT, RT, LT, RT, LT AND RT, LM, RM. With this, I’m confident down to an 8 gallon reserve. (But, I keep my personal reserve at 12 gallons).


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I don't think a table would be all that helpful for me -- if I'm going to forget a tank change I'm also going to forget to look at the table, so it won't help much.

I also don't switch every 30 minutes; I'll do the first switch after 30 minutes and then change every hour after that. When I move to the outboard tanks I will switch more often though, because I can feel the balance change more.

At some point I will probably replace the senders with Cies, but that'll wait until my next spending spree. I have to re-do all the wiring for them, I gather.
 
Simpler is better, especially single-pilot IFR. For two tanks, I keep two columns on my printed flight sheet, one for each tank. (The rest of the sheet contains pre-formatted areas for copying clearances.) At the top of each column is total time in tank, e.g. 2+15. The Z time off is noted at the head of the table. At each tank change, I record the Z time of change and the updated time in tank in the appropriate column. Time in tank depends on cruise setting, which is normally the same for most flights and results in a block fuel consumption of 8.0 gph. If I'm using an economy cruise, I'll adjust time in tank appropriately for the expected block fuel flow. This is normally sufficient to determine if there is going to be 1.0 hour of fuel left at the destination. If not, a precautionary refueling stop is planned immediately. This method normally results in refueling being within +0/-2 gallons of calculated, satisfactory enough. (The last 2.7 hour flight was 1 gallon less than estimated.) I don't have a fuel flow meter, so timer it is for me. A fuel flow meter would allow easier monitoring, but the "stopwatch" method is pretty darn accurate, compared to my fuel gauges, which have balky floats and non-linear displays that are nearly useless for fine fuel management. I've only used economy cruise once, on a trip to Waterville, Maine, which was right at or just beyond my range limit with 1.0 hours left in the tank. An economy cruise about 300 rpm less than normal as sufficient to stretch fuel to make it work without a stop, but GOD WAS IT SLOW GOING. (Or so it seemed.)
 
I regularly fly a Comanche with 15/30/30/15. Start, taxi, takeoff on either main tank. After 30 minutes switch to the opposite aux tank. After 60 minutes, switch to the other aux. Another 60 minutes, switch to the opposite side main. Continue switching mains hourly. Burning 14 gph, that means each aux is one hour of fuel, each main is two hours.

I don't like 30 minute switching. A. Unnecessary B. More possibility to forget C. Just more wear on the selector and more chance of breaking something.
 
In the Comanche it's both mains simultaneously till top of climb, both tip tanks simultaneously until empty. Then back to the mains. One always seems to draw faster than the other, and it's never the same one, so then I just figure out how much time I've got left and when the first one hits 12 gallons (there's actually a few more than 12 in it at the time) I shut that one off and burn the rest out of the other.
 
The top of the table says 3 gallons unusable but you don't account for it in the table.
 
EdFred said:
In the Comanche it's both mains simultaneously till top of climb, both tip tanks simultaneously until empty. Then back to the mains. One always seems to draw faster than the other, and it's never the same one, so then I just figure out how much time I've got left and when the first one hits 12 gallons (there's actually a few more than 12 in it at the time) I shut that one off and burn the rest out of the other.
Click to expand...

You have a both setting in a Comanche? Granted I've never been in one with tips.
 
midwestpa24 said:
You have a both setting in a Comanche? Granted I've never been in one with tips.
Click to expand...

Yeah, with the tip tanks, there's a left valve and a right valve.

. . . MAIN . . . . . . MAIN
TIP . .^. . . . . . . . . ^ . . TIP
. . . OFF . . . . . . . OFF
 
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