Fuel Management in GA Aircraft

[Flyin'Dutch']

Following on from the other thread.

1. How do people determine the fuel required for a flight.

2. How do you determine how much fuel there is and how much to take uplift before you go and en-route (if you have multifple stops)

3. How do you manage your fuel en-route.

Honest answers, not textbook ones; after all we can all read the textbooks ourselves.

FD

[B2N2]

Cessna 152 6 gallons/hr
Cessna 172 10g/hr
Pa28 10g/hr

Any other airplane I'm not familiar with:
Horsepower/2= gallons per hr.
So 310hp equals about 16 gallons an hr with proper leaning.
It basically exceeds book values by 25%.
I like to carry at least 1hr additional fuel above req. tripfuel.
Fuel gauges are for general indications, I keep track of time since engine start.
So eg 10 gallons/hr since engine start-time not since T/O.
Furthermore I have dipsticks for 152/172.
The fuel gauges in the new 172 SP's are reliable enough at least on the planes I fly.When flightplanning suppose we'll have a 10 knot wind 40 degrees cross,I'll count that as a 10knot headwind for trip time calc.
I haven't run out of fuel yet.
Just another thought, I've done a couple of 2000+mile trips in various airplanes, I always do a couple of what I call "check" legs,I fly at a fixed altitude & power setting, land well within fuel limits and check with the fuel bill so I can get an exact fuel burn.
Add 0.5 gallons/hr and that's the fuel burn for the rest of the trip
WHEN IN DOUBT FILL UP;) ;) ;):ok:

[FlyingForFun]

1. Fuel required for flight. I know the approximate range of the aircraft I regularly fly. If my flight is going to be at least 2 hours less than the fuel I'm carrying, I don't bother working anything out. Otherwise, get out a plog (the chances are it's a long enough trip that I've done a full plog anyway) and work it out more accurately.

2. In the Europa - the fuel guage is a capacitance-type guage, and so is pretty reliable. There is absolutely no other way of checking the fuel, so I have to rely on the guage. I have about an hour in the reserve tank in case the guage turns out to be faulty and it all goes quiet. In every other aircraft I've ever flown, I check the fuel visually before I fly.

When I uplift fuel, I always fill the tanks to the top - this avoids any doubt about how much fuel there is. Two exceptions are when weight+balance is an issue (I fill to my w+b limit, minus a bit in case I eat too many pies at my destination), and refuelling the Europa at the end of the flight (group policy is to re-fuel to the 3/4 mark on the fuel guage to ensure the next pilot doesn't have a w+b problem).

3. Check the guages regularly (every 15 mins or so). Check that they read roughly what I'd expect them to read at this stage during the flight. There's not much more you can do, is there? If I have multiple fuel tanks to choose between (a la PA28), I usually change tanks every 30 minutes or so. Most of the trips I've done in this type of aircraft, there's been enough fuel in either tank to last the entire journey, so if I screw up en-route it doesn't really matter. I've done a couple of longer trips - a 400nm trip in an Arrow where I had to change fuel tanks several times springs to mind - where I've noted down the time and which tank I've selected each time I changed tank, so that if there was any confusion about how much fuel was remaining later in the flight I'd be able to work it out. But it's rare for me to fly the kind of trip where this is necessary.

Very good thread subject - interesting to see how others' habits vary from mine.

FFF
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[Evo]

Very good thread subject - interesting to see how others' habits vary from mine.


Agreed. Mine's kind of the same as FFF... :ok:

In my case for (2), I always dip (in the Robins) or look at the fuel level relative to the tabs (PA-28). If it's less than tabs then i'll fill to that level (so I have 17 gals per side ... or is it 19..? :O ). The only issue with the Robins would be dual aerobatics in the 2160 which is quite W&B critical - for a 'normal' flight i'd always fill up to at least half tanks. With tabs/half tanks I'll always have much more than I need - unless it's an unusually (for me) long flight in which I'll have plogged the fuel requirements.

One thing my instructor taught me was to always, always visually check the fuel and oil before flying - and if you're a pax then you still check it unless you've seen the P1 do it. Might get the occasional odd look, but better that than a silent engine... :)

[Chilli Monster]

1. Fuel required:

Flight fuel + 45 minutes holding + div fuel + 10%

2. When to refuel:

Either when the aircraft has done 3 hours and you know it has done this from full or if it's not definite and the tanks can't be dipped (i.e Seneca) filling to a known datum and adding from there (i.e 'rib' fuel plus in the case of the Seneca)

3. Fuel management

PA28 - 'minute hand' method - Left hand tank half past to on the hour, Right hand tank on the hour to half past

PA34 - not a lot of management required - Left hand tank left engine etc.

PA27 - inboards for departure and landing, outboards for the cruise, back to inboards after 3 hours in the cruise (from full of course)

[bluskis]

Long flights.
Plan trip, note still air time, mark on flight plan in big letters fuel tank change over point. Select alternates, particularly en route alternates.Assess wind influence. Fill to the brim. Try to keep hand on tank change knobs 20 mins before empty time, and change tanks 10 minutes before theoretical dry time, earlier if course or frequency changes are coming up, or if weather is iffy.
Aim to land with a theoretical hour of fuel in the remaining tanks.

Short flights, one pair of tanks full, and at least 2.5 hours fuel for 1 hour flight.

[IO540]

1. How do people determine the fuel required for a flight.

I fly at a chosen power setting, e.g. 65% power, which at just slightly LOP is 11-12GPH, and with 86USG usable fuel this gives me about 7hrs endurance. So the longest leg I would ever do is 5 hours - end of story. I have a table of power settings versus range, flow rate, IAS, etc stuck in the cockpit.

2. How do you determine how much fuel there is and how much to take uplift before you go and en-route (if you have multifple stops)

I look in the tanks; if I can just see the fuel that is half a tank, and above that there is a scale inside the tank. I check this against the fuel gauges (which I know are very accurate). I also check it against the Shadin flowmeter FOB figure (which ... well .... is quite handy en-route but obviously may not be right to start with). I always fill right up when below half tank (when the fuel level cannot be seen anyway), unless I have a trip planned with 3 heavy passengers in which case I might underfill as far as 50USG (4hrs) total fuel and then the trip would be limited to 2 hrs airborne time.

3. How do you manage your fuel en-route.

At a given power setting there is nothing to "manage" as such because the flow rate is always about the same. Unless there is a leak in which case one is relying on the fuel gauges to spot it. I keep half an eye on them and whenever they are unbalanced by more than about 4mm (say 20% of tank capacity) I switch tanks.

So, always 2hrs+ fuel available for a diversion. I accept that many planes can't easily do this while remain useful but that's one of the countless tradeoffs in this business. If I was flying a PA28-181 for example I would do the same; only the useful range would be a lot less.

One problem is that most training operators don't actually know the flow rates versus power settings, and anyway if someone rents "wet" they have an incentive to fly full bore and then the GPH is likely to be some 50% higher than at say 65% power and optimally leaned. Given that almost nobody in that business will pay for a decent flowmeter, I really have no idea how to handle this problem, other than to work with figures so grossly conservative as as to make the aircraft useless for flights of more than an hour or so. All this makes a mockery of the "tech log" in which you famously write how much fuel there is left...

As to the question why we have crappy fuel gauges, I think the simple answer is that pilots have long ago learnt to simply accept what is served. This starts on the first flying lesson in a 1972 C150 and never really changes. Technologically, the solutions are trivial.

[paulo]

Robin 2160 - I only ever go for aeros so it's simple - half tanks means I've got loads of reserce and am in W&B, assuming no fatso friend, who besides which would be excused FO duty at the "controls full and free" check :-)

I do it by eye on the walk round and then see if the guage tallies.

Thankfully the 2160 guage seems to have some vague resemblence to reality, unlike the PA-28s I trained on which always seemed to be either momentarily full, but otherwise empty. There's a few other gizmos on the 2160 (warning light, fuel flow meter on the injected one that I fly) that all seem to agree with each other.

[Evo]

Fuel gauge on the 2160i does odd things while inverted - works very well the rest of the time though :ok:

(and don't ask why I was looking at the fuel gauge while inverted... foxmoth and his unusual attitude training... :) )

[Gertrude the Wombat]

Cessna 152 6 gallons/hr People I usually hire from require the sums to be done at 7 gallons/hr (USG, that is) (the book says around 5.5).

I check the log, and then check the fuel gauges (which aren't that bad), and then dip the tanks, and I refuel before departure if all three data sources don't agree that there is enough for the flying time + taxi and takeoff as per POH + 1 hour reserve (which is more than plenty given there's a runway every few minutes round here).

Then I check the gauges every few minutes during the flight, and would land if I saw anything unexpected. Hasn't happened. Yet.

[Structural Failure]

The best fuel system/guages are in the Yak 52

in it's original form it only carries 120 litres, the 2 wing tanks drain at the same time, so no fuel selector. Each tank has a row of lights. From memory they are at 5L intervals. They are very accurate and the best thing about the yak is that on average it burns 60L/hr so the guages tell to your remaining endurance

In other planes, i work out how many minutes of fuel in each tank, write the time i select each tank, and when i finish with that tank i write down the new endurance for it, always trying to keep 45 minutes reserve in one tank

[englishal]

fuel full or on tabs....flight <2.5hrs = plenty of fuel.

flight ~ 3hrs, full fuel, plenty.Tabs should be plenty but get the POH out and check.

Flight time of ~4hrs, full fuel should be no problem but carefully study weather for wind and alternate fuel stops if weather looks to be IFR.

fuel < tabs or full, fill to tabs or full. Every intermediate stop, fill to tabs or full. Better to have a bit extra than not enough....

In flight, switch tanks when I do a FREDA check,which is when I think about it really (don't have a set method as such, just switch when it feels about right)...

EA:D

[gasax]

pa22 - three tanks totaling 160 litres.

Average fuel burn 30 to 31 litres (160 hp), long flights as low as 26.

Burn from the right hand main until the reserve can be transfered to it. Switch tanks around every 30 minutes once the reserve is empty, but use the right tank twice as much as the left.

The right tank is placarded against takeoff and landing when less than 50%.

The gauges are useless - if they more there is some fuel in the tanks!

Calibrated wooden dipstick lives in the luggage. Visual checks only tell you if it's full or there is 'something' in it. We only use full tanks on long trips due to the effect the weight has on strip performance.

It's pretty easy so long as you know how much is in it and remember to use fuel in the correct order. Thankfully there are no c of g issues with fuel.

[strafer]

the best thing about the yak is that on average it burns 60L/hr
Do you light your cigars with a £50 note as well?:cool:

[Cusco]

For our group's Arrow 2:

1) Dip both tanks with a purpose made calibrated wooden dipstick (painstakingly made by measuring from empty to full tanks by a group member ) before every flight.

2) Take said dipstick in A/c and dip before takeoff at every stop and after every fill-up if only taking on part fill of tanks.

3) Right hand side of watch minute hand for right tank, left hand for left as mentioned by other listers.

4) Fill up at every opportunity.

5) Assume 10 Imp gall/hour and lean wherever possible.

6) Never fly a leg longer than 2 and a half hours (endurance is 4 hours)

7) Try to equate gauge readings with what the dipstick has just said to build up a mental picture of just how inaccurate the gauges are.

8) Dip tanks at end of every flight and post on Internet booking system for the benefit of next user's flight planning (We don't have the luxury of fuel at our airstrip.

Safe flying, and I'm glad the Seneca chap got off: The judge clearly had information we are not privy to, making a conviction unsafe:

So to all the barrack room lawyers on this forum: knock it off and discuss something else.

Ducks.


Cusco.:ok:

[Northern Highflyer]

On a PA28.

Check fuel to the tabs = 30 Imp Gallons

Burn @ 100kts = 8.5 gall/hr = 3.5 hours flight time

Fly for no more than 2.5 hours before refuel.

I believe they hold 40 gall to the top but would have to check.

This is what I was taught and how I plan my fuel management.