Minimum Fuel Load - Cessna 152

[Nil Flaps]

Hi,

Can anyone tell me what is the minimum fuel load for a c152? I am aware consumption rate is 23 litres per hour (2300 rpm @ 2000ft) and when I fly we need 45 minutes of fuel in reserve. I can't for the life of me find out what the minimum fuel load should be at take-off.

Best I can come up with is this...

Fuel Capacity = 97.7 litres
Fuel Useable = 93.2 litres
Non useable fuel = 4.5 litres.

Therefore...

60 minutes flying = 23 litres
+
45 minutes reserve = 17.25 litres
+
Non-useable fuel in tanks = 4.5 litres
=
44.75 litres minimum?

I'll probably get told I should never be allowed to fly again but without the answers, this is the best guess I can come up with. Be gentle with me, I'm just a dumb student! Any helpers welcome. Thank you!

[djpil]

Interesting to also do the opposite calculation - student plus me plus 45 litres in a 150 Aerobat was about max take-off weight. Wasn't impressed when the fuel truck driver got mad for having to drive all that way just to put 5 litres in. He doesn't do that anymore as there's another fuel agent who understands that when I need more fuel I also cannot take more.

[Gertrude the Wombat]

Well, you could also add whatever the book says for take off and climb.

Then, especially for a 152, you could do a maximum fuel calculation, which for two normal-sized grown-ups is rather less than full tanks.

You won't need full tanks for a one hour lesson, so there won't be a problem as there will be a wide gap between the minimum and maximum, but when you've got your PPL and you want to go on a longer flight with a passenger, perhaps landing somewhere with no fuel supply on the way, you shouldn't be surprised if you find the minimum fuel you need is more than the maximum weight you can carry.

[Piltdown Man]

Nil Flaps - I think your maths is sound. You'll go far (but not in a 152).

PM

[Nil Flaps]

Eh? What are you getting at PM?!

Do I have it completely wrong then?

[dmjw01]

Originally Posted by Nil Flaps

I am aware consumption rate is 23 litres per hour (2300 rpm @ 2000ft)

It's been a while since I've looked at a 152 POH, but my suspicion is the 23 litres per hour figure is for a correctly leaned engine. If that's the case, then you will not achieve that figure if you're flying around at fully-rich and you should add at least 5 litres per hour to that figure. There's no point using the POH's fuel-burn figure unless you also use the technique required to achieve that figure.

I would urge you to get into the habit of dipping your tanks before and after every flight. That way, you'll get an accurate fuel-burn figure for that aircraft, and more importantly for your particular power setting and mixture setting. Soon you'll be able to predict to within half a gallon how much fuel is remaining at the end of your flight, and this gives you a great deal of confidence to plan longer flights knowing exactly how much fuel you'll need.

[Piltdown Man]

Nil Flaps - No you don't, your maths (and logic is good) is good! (providing you have plugged in the right figures). But a 152 is not exactly the quickest ship and if you don't fly very fast for one hour, you won't have flown very far!

PM.

[Nil Flaps]

All valuable information. Keep it coming!

The reason I ask this specific question is an FI asked me the MINIMUM fuel I should have at take-off (I guess being a student he means with 2 passengers) and he told me to work it out.

This question is something of a last resort as I couldn't find the info elsewhere. I wanted to at least make an attempt at an (educated?!) guess before lazily taking the easy route, passing the buck and just asking someone. That would seem like a bit of a cop-out.

Piltdown, thanks for your words of encouragement. I didn't follow your last comment [duh] but I do now! I intend to transfer to a faster ship one day. Incidentally, I did fly a brand-spanking Tecnam P2002 Sierra to try it out recently. Much better performance but seemed unnervingly light in a crosswind for me and I wasn't used to its better performance in the circuit. Much preferred the stick as opposed to a yoke though, and trimming correctly with buttons seemed easier. Liked the low-wing set-up more also... amazing views in 30 degree turns.

But saying all that, taxiing was weird with the (park) brake... no toe brakes on the pedals. And being much lighter, it soon gets away with you on downward slopes! Also found there were many new features that were alien and just a bit too strange to me after getting used to the 152.

So, much as I'd love to keep going in the Tecnam given it's pros, the tired-but-sturdy 152 (never thought I'd find myself describing one like that!) seems to suit me better right now. Slower yes but I do feel a little more 'at ease' with it and I don't want to exceed my limitations.

By the way, does anyone have any opinions about the Tecnam as a trainer, given it is not strictly seen as GA?

Thanks to everyone so far, and that sounds like great advice dmjw01. Your advice has been duly noted, given my leaning is not exactly fabulous at this point!

Keep minimums answers coming please, and many apologies to myself and others for shocking thread creep.

[Gertrude the Wombat]

Originally Posted by Nil Flaps

The reason I ask this specific question is an FI asked me the MINIMUM fuel I should have at take-off (I guess being a student he means with 2 passengers) and he told me to work it out.

Try "half full is enough, three quarters is probably ok, full is too heavy"?

I rented a 172 and instructor on holiday, for a joy ride with one of the kids in the back. The instructor treated it more as a check flight than a joy ride, and watched me check over the aircraft. So, I asked him for a dipstick to check the fuel. He said there wasn't one, and told me to estimate by eye whether we had enough fuel! - my estimate was lower than his, which I suppose is the right side to err on (the guages actually seemed to work on that aircraft btw).

[Flying Farmer]

Nil Flaps

The minimum fuel you should carry is your:
Taxi Fuel +
Trip fuel, worked out at the planning stage, time A to B x the fuel burn +
Alternate fuel, time to alternate x fuel burn +
Final Reserve Fuel, I would suggest using 45 minutes x fuel burn.This figure is what you MUST land with, if there is any doubt you will have less on arrival its a PAN call, if you KNOW you will land with less its a MAYDAY.

I think this is what your instructor was after.

Your flying order book should clarify what your school expects.

[J.A.F.O.]

Originally Posted by Flying Farmer

This figure is what you MUST land with, if there is any doubt you will have less on arrival its a PAN call, if you KNOW you will land with less its a MAYDAY.

Eh?

[Dude~]

Taxi fuel... sure it uses some fuel, but its hardly going to be worth worrying about. Its not a big jet... 5mins even at full throttle would only use 2 litres, so at idle power its going to be a lot less...

I'd be more than happy to land with less than 45 mins fuel without declaring the fact to all and sundry. I'd only ever call PAN or MAYDAY if I actually needed assistance.

[Flying Farmer]

If its good enough for JAR OPS its good enough for me even for a private flight. Its no wonder so many private pilots run in to fuel difficulties given the above posts

Dude where do you draw your line at a final reserve figure, 30 mins maybe even 15?The 45 minutes is a figure that sprung to mind, I didnt check it in JAR OPS, but I was under the impression that for pistion engine aircraft 45 minutes was the correct final reserve fuel?

When the odds stack againt you one day you will be glad of that 45 minutes worth.

I am fully aware the 150 will not use much in the way of taxi fuel but it shows some awareness on behalf of the guy doing the planning that his instructor might like.

[Confabulous]

Surely landing with less then 45 mins of fuel on board is technically illegal in it's own right? A lot of people have declared a 'fuel emergency', which ATC promptly ignored becuase it's not a defined emergency in CAP 413. If you find yourself below 45 mins at any reasonable distance from the field it's not good and a PAN should probably be declared. If the CAA finds out you've been flying below the 45min line (not that anyone here has) they'll be very interested in the excuse.

Those 45 mins are there for contingency only, and dipping into it is a contingency in itself. So a PAN makes sense to clear the way. Granted a PAN won't solve all the world's problems, but it will let someone know there could be trouble ahead.

[J.A.F.O.]

I only queried it as I'd never heard anything of the sort before:

"if there is any doubt you will have less on arrival its a PAN call"

So, if you think that you might land with 40 mins fuel you'd declare a PAN?

"if you KNOW you will land with less its a MAYDAY"

So, if you work out that you'll definitely land with 40 minutes of fuel it's a Mayday? Is that really grave and imminent danger that requires immediate assistance?

I thought declaring distress or urgency was up to the individual captain's discretion and didn't know these limits were laid down anywhere. I'm not taking the mick, I am a devout coward and always get back with far more fuel than I needed I'd just never heard of these limits before or the requirement to send a Mayday or Pan.

[Flying Farmer]

JAFO these limits are laid down somewhere, unfortunately I have to fly and not back untill Wednesday, so don't have time to look up the answer for you.

The final reserve fuel is there for a good reason.

Say you fly A to B, that uses your trip fuel. You get to B and the runways blocked, I have seen this so it happens, so off you toddle to C. Now you get to C and local weather which wasnt reported in the TAF or METAR precludes you landing!! do you see how this is all conspiring to make your day really bad. You have now used your alternate fuel, now you need help and quickly, do you see how it works now?