Fuel Log

[Mr Garrison]

Hi All,

Have been reviewing my fuel log taught to me by my flying school recently and don't think that its comprehensive enough. I have been taught to make a recording in the log every 30 mins, but this recording is the time, expected fuel (litres), actual fuel (litres from fuel gauge) and endurance (minutes).

Although this takes into account the total fuel on board, it doesn't make it clear at any stage exactly how much of the total fuel is allocated to things like:

Variable Reserve
Alt Fuel
Holding
Fixed Reserve

I know that there is a fuel plan on the back of flight plan submission forms that states the above, but when recording a fuel log isn't it important to know things like, how much fuel we have left for cruise, how much is allocated to the 15% variable reserve, how much fuel we can allocate to things like Point of No Return etc etc.

I'd like to know what other people out there are using for the recording of their fuel logs.


Thanks in advance......


Mr G

[InTransit]

What you should be doing is during flight planning, work out what fuel you SHOULD have on board at each stage, then you'll have something to compare your fuel log with.

[Chadzat]

You have a training aircraft that you can actually get an accurate figure from the fuel gauges?! Wow, some of us are lucky!

[Inbound On Descent]

Agree with InTransit. In addition, may I suggest the following:

Whilst planning, and having established how much fuel you will depart with, make the top line of your fuel log your Flight Fuel(Not total FOB) in minutes. You might want to divide the top line into columns representing different tanks depending on your aircraft type, and update your log as you change tanks.

Keep it simple. You don't plan to burn your reserves, so don't let them concern your in-flight calculations (unless of course it becomes a concern ! :}). Then, as you complete your log at regular intervals, you can compare your flight fuel remaining in minutes with your planned ETI's. If the fuel guage actually works, Gross Error Check by comparing the guage with your expected FOB per InTransits idea.

Probably many schools of thought. Chat to your instructor / CFI.

Cheers,
:ok:
Inbound

[rmcdonal]

Im with Chadzat on this one. The gauges are just a guide, not only are they not accurate (don't even start with that whole "but they have to be" crap), but in turbulence there usless. You should have a PNR worked out before you go flying, takes ages to figure one of them out on the ground let alone in the air.
If you subtract the reserve fuel at the start from your total available then when your fuel calcs reach 0 your burning whatever reserves you set aside.

[Chadzat]

or just go for a longish flight in said aircraft, dip tanks before and after, then take the difference and divide by tacho hours flown. If you do this over a number of "typical" flights you very quickly learn if the "book figure" of fuel burn is on the money or not. Then you can guesstimate fuel burnt based on how many tacho hours you have flown in that flight already and then do a gross error check against the gauges.

Works out pretty accurate at the end of a flight, if you are worried about being within tolerances at the end of a training flight for say CPL they just like you to have tanks within 30mins fuel of each other and also within 30mins of what you think should be left.

[Sunfish]

I use the four column approach. Two columns each tank. Left one in ten minute intervals right one is litres remaining at the arbitrary school planning fuel flow figure. (ie 36 l/h C172, PA28, 40 l/h Arrow). The last 60 minutes (30 either tank) are marked off with a double line to indicate we are into reserves. Just cross off left or right tank at ten minute intervals and you have an instant estimate of what should be in your tanks, that you can compare with gauges and fuel flow indicator.

[hoss]

Mr Garrison,

'Slap my ass and call me Charlie':) . I cant believe you haven't consulted Mr Hat before posting on PPRuNe, you know how fuel wise he is, don't you?

;) (sorry it's a south park thing)

[Mr Garrison]

Well sorry Mr Hoss!!

I asked Mr Slave and he couldn't give me an answer so I thought Pee Prune would.

Now go on children and be good liddle hetrosexuals!!

Love South Park!!


Mr G

:ok:

[Chimbu chuckles]

My aircraft is fitted with a EDM 700 + fuel computer....is most excellent:ok:

It is very interesting comparing what it says to the original fit rubbish fuel gauges...they are a useless waste of panel space...particularly at the E end of the scale:ugh:

On a recent long trip I decided to check the actual useable fuel in each tank against the book useable figure. Book useable is 140 liters/side, 155 lt total.

When checking the right side I climbed on the left tank...burning 20 liters out of it before changing tanks. I then ran on the right tank only calculating it would burn dry between 160 and 175 used. At 175 liters used fuel pressure started fluctuating so I changed tanks before scaring my daughter in the back with a faultering engine...I had pre warned her of course but she had since fallen asleep.

Interesting that in the time period after 160 liters used I was experiencing light/moderate turbulence causing significant yawing and roll excursions...and despite having my hand on the fuel selector expecting unporting of the fuel intake never experienced any problems until the fuel finally ran out at 175 used...during a period of smooth conditions.

So I have added 20 liters to my 'useable' figure, leaving 5 lt per side 'unuseable'...and Beechcraft can kiss my ass:ok:

Having 'recalibrated' my fuel tanks I was more than happy to depart my next port of call, where no avgas was available, with only 60 liters total (45 'useable') in the left tank and fly somewhere 35nm away for fuel...absolutely safe in the knowledge I would land with 45 minutes reserve....more like 55 minutes + actually because on that short low level leg i was operating LOP and only burning 49 liters/hr...making 45 minutes reserve 37 liters..I pulled up at the bowser with 42 liters total...mind you the low fuel warnings on takeoff, where I was burning best part of 100 lt/hr, were a little interesting...but soon alleviated while watching the endurance figure climbing steadily as I leaned:ok:

How anyone can fly with only the original fit fuel gauges in old SE or twin piston aircraft is beyond me...how owners can sleep at night while the available technology is available so cheap also bemuses me no end.

[Reverseflowkeroburna]

Chimbu has made a most important point for those wishing to increase the accuracy of their fuel logs............Use the newer technologies Luke!

On that note, I feel compelled to point people to affording due consideration toward the fuel page in their GPS (eg. In the case of the Bendix/King KLN series, OTH+5), as these GPS thingys are found in even some of the more modestly equipped machine these days. The Shadin air data computer is also something I've often found infinitely more usefull than Mr. Beechcraft's gauges.

So while we may be legally bound to use the manufacturers gauges, I know not of a wise man who chooses not to consider all available sources of information! :ok:

[THE CONTRACTOR]

Total A/C HP * %PWR SET = HP ACTUAL

HP * 0.2268 = Kg/Hr

Kg/Hr
_____= L/Hr

0.72


Ex

The ole 180 HP 172 RG.
I cruise at 75% Power

180 * 75% = 135 HP Actual

135 * 0.2268 = 30.618 Kg/Hr

30.618
______= 42.525 L/Hr
0.72


So when I get out at good ole Ibeenherebeforeimsure and it took 4.5 hours, I would expect to be missing 4.5 * 42.525L/Hr of fuel ie 191L.

If I am missing 225L guess what, the next leg plan at 225/4.5 = 50L/hr.


The 0.2268 only works for normally aspirated piston engines.

This little gem helps when the ole headwind kicks in and everyone told you to plan at x amount per hour. ie It gives a realistic fuel consumption based on power set.

0.72