Cessna 172: fuel / center of gravity / gross weight?

Question

How does one drain fuel from Cessna 172 to get the cg and gross weight within the envelope? Certainly not the sump drain?

Let's say I have full fuel and wanted to carry myself and 2 passengers for a 30 minute joy ride (no baggage).

40 gallons is outside of envelope

30 gallons is just inside envelope

20 gallons would be more comfortable

How would one drain off this much fuel? Is this service provided by FBO? If so, any credit for drained fuel?

Answer 1

Often adding ballast can bring the CG within the envelope.

Otherwise drain from a wing tank.  Certainly.  Do it yourself if you want to re-use the fuel.

Answer 2

I'd find it hard to believe a 172 with full fuel could not carry you and two passengers.

Try this for a double check:

http://home.new.rr.com/trumpetb/alph/wb1...

Its for a 172N, but you should be able to plug in your numbers and see what it looks like..

Answer 3

Sometimes ya just need a bigger airplane.

Answer 4

Must be a messed up 172 'cause ours is well within the envelope with two people and full fuel.

Put some baggage in the back.

You can drain the fuel from the wing tanks.  You are not supposed to re use the fuel so no credit.  Should be about an hour's shop time.

Why not go bang off some circuits instead?

Answer 5

Why not drain from the sump? You can pay a fee to the fbo for a suck truck if you want I suppose. They may buy it back but a couple cheap 5 gal. jerry cans should do the trick to. This is a no brainer. I'm not looking at your calculations but I cannot imagine how fuel in a high wing cessna tank can shift the cg out of the envelope other than weight. Dosen't seem possible but it has been decades since I had to worry about it in a 172.

Answer 6

Since all the fuel and front seat passengers are over the CG, you need only be concerned with gross weight. Use the POH to find the proper numbers and see how much over gross you are. If you have standard fuel tanks, you can fly off the extra weight in about 2 hours.

If your figures show you can fly with 30 gallons, fly with 30. Never leave fuel behind that you might need.

Answer 7

Sounds like you would be over max gross weight with you and 2 passengers but with out weights for the passengers its impossible to calculate.

Draining fuel is not something the FBO wants to do so make sure you let them know ahead of time you don't want a full load of fuel then they will not fill it to the top. At my airport the FBO has only been keeping the planes filed to the tabs (17.5gal on a 172) on each side unless requested otherwise.