Fuel leak

fredh · #1 02-07-05, 03:55 PM

I have a 73p t337g. i have owned this a/c for 7 months or so. we had a bad rear engine and ended up overhauling it. we never had any fuel leaks since we purchased the airplane. we have about 5 hrs on the new engine and fueled it up, put it in the heated hanger,we live in michigan, under a tube type heater and the next morning it was leaking fuel. i thought it was expanding fuel under the heater so i shut the heat off, allowed the hanger to air out for 5-6hrs with the heat off turned the fuel back on an it still leaks. the leaks appear to be at or above the strainer but not just out tube. also we burned 1hr of fuel 12.5 gals out of the airplane before putting in the hanger. any ideas?

SkyKing · #2 02-07-05, 08:15 PM

Fred, have the strainers been serviced with new O-rings, especially the one in the top?

You're not too specific as to where the leak is originating from and some more details would help out here.

If you've got fuel leaking from the inboard wing and down the side of the fuselage, of course that would dictate opening up the top inboard cover between the fuselage and the boom and taking a look-see at the two (and perhaps three if later model) inspection cover plates and their cork gaskets up top side. Over time these gaskets will dry out -- especially of tanks are not routinely kept full -- and when you first top off the tanks, you'll have a real gusher down the side of the plane.

SkyKing

WebMaster · #3 02-07-05, 10:06 PM

Which would be especially likely if the plane sat for a while, like during an overhaul.

fredh · #4 02-07-05, 10:13 PM

the fuel is leaking from both the front and rear engines above the strainers. when i shut the fuel off inside the leaks stop. it acts as if the system is pressurized and weeping from the strainers or above them. some fuel comes from the strainer tube, but i'm not sure if it is following down the outside or inside. i am going to work on the airplane wednesday and thursday evenings so i can look deeper into the leaks origin. the airplane never leaked at all before and now from both engines at the same time. seems like there should be a common denominator? any idea's ?
thanks
fred

hharney · #5 02-07-05, 10:19 PM

ARE YOU REFERRING TO THE STRAINERS ON THE ENGINES? WHERE THE FUEL IS DRAINED FROM THE OIL CHECK ACCESS ON THE COWL?

WHERE ARE YOU IN MICHIGAN? WHERE DID THE PLANE COME FROM?

fredh · #6 02-07-05, 11:07 PM

yes the same place the fuel comes out of when you pull the knob. but also higher. Z98 Ottawa Exectutive, Zeeland, Michigan. Came from New Jersey.

stackj · #7 02-07-05, 11:34 PM

Fred

If you are getting fuel dripping from front and rear drain tubes, it has to be two seperate problems... Unless the whole fuselage is wet with fuel.

Might want to take a look at the top of the gascolators. If they are not wet up there, be sure you have pushed the drain knobs all the way back in.

If not that, it nearly has to be bad O-rings in both gascolators.

hharney · #8 02-07-05, 11:57 PM

HAD TO REPLACE MY O-RINGS ON THE FRONT 2 YEARS AGO
HAD FUEL ALL OVER THE TIRE AND ON THE FLOOR. SIMPLE TO DO AND HAS BEEN FINE SINCE.

FRED, I AM AT GRR AND TALKED WITH A GENTLEMAN ABOUT HANGER SPACE AT YOUR FIELD. HE TOLD ME ABOUT YOUR AIRPLANE AND THE NEW ENGINE. SURE LIKE THE IDEA OF THAT HANGER IN MY HOUSE..........................DREAMY

THERE ARE 3 OTHER SKYMASTER FLYERS AROUND YOU. WE TRY TO GET TOGETHER AS OFTEN AS POSSIBLE. MAYBE YOU CAN JOIN US.

SkyKing · #9 02-08-05, 12:23 AM

Hey Fred...

When this thread was started I thought it was Fred Emde in Oklahoma who IS a mechanic... so I guess we should call your attention to the line mechanic and the Cessna 340 a few weeks ago. The 340 had a fuel leak problem and when the mechanic turned on the master switch... KA-BOOM ... plane destroyed!

So, just a word of caution since you most likely have the plane inside the hangar troubleshooting the fuel leak during the cold weather: I would BE VERY CAREFUL not to turn the master switch on, or flick-on any other switch where a small spark could be generated. That's all it would take to turn a small problem into a disaster.

You just might want to park the plane OUTSIDE to make sure that no fuel vapors collect near the floor of the hangar.

SkyKing

WebMaster · #10 02-08-05, 10:28 AM

After my engine gets here, and Jerry's exhaust gets fixed, maybe we can get together some place.

rick bell · #11 02-08-05, 02:21 PM

had the outside o ring new fuel contriller
go bad and dumped lots of fuel in the hanger, it also dumps gas out the back when flying . it is a simple fix just rejplace the outside o ring, doen't even take an hour' anyway that where my fuel was leaking from

Jerry De Santis · #12 02-09-05, 12:10 AM

Hi Fred, This is Jerry De Santis. I have a 1975 P337G and I am based on Battle Creek, Mi (BTL). I came from New Jersey also in 1977.

last summer I had to remove the inboard tank on the left side of the plane due to leaks. Turned out to be a crack in the bottom of the tank. Hope you don't have to get involve doing that it is a real tight fit removing the tank and getting it back in. Problems are the interconnecting hoses from the middle tank being very short. However, what you describe does not sound like it.

On Marshall airport there is a real good mechanic that knows Skymasters in and out. His name is Eric Metzger and his phone number is 269-598-8497. At the present time there are two Skymasters there, Larry's which is getting a new engine and mine which is getting a new Turbocharger. Should get my plane back this week.

At the end of each wing on the trailing edge there is a vent for the fuel tanks. Check them out to see if they are clogged. If they are, there is no room for the gas to expand if the tanks are full. My hanger is also heated with a tube type gas heater that sits above the wing. Never found that to be a problem.

Call Eric, he can debug it quickly and you will still have money in you pocket.

BTW, I go to the flyin at your airport.

Jerry
N34EC

Mark Hislop · #13 02-10-05, 10:09 PM

Fred:

It might not be the strainer. It could be the aux fuel pump. I had this happen on my 73 P337. There is a little drain line that is connected to the aux pump. It's purpose is to make sure that if the seals between the electric motor and the pump fail, the fuel is drained away from the motor. These pumps have a TBO recommended by the manufacturer(Dukes). Carefully track down the fuel leak, and the drain lines.

Mark

fredh · #14 02-11-05, 10:36 AM

Rear engine appears to be bowl gasket and the stem/control for sumping , front engine appears to be a t- fitting on top of the strainer and are totally seperate issues. thanks for the input and i'll post anything unusual I find.
Fred h

bsbomber · #15 02-17-05, 12:51 AM

Don't be sad Fred..When I purchased my bird, (Only 3 months
after annual) I had 5 fuel leaks to fix...Both engine strainers,
heater pump, wing pepcock, and the good old Dukes aux pump
on the rear engine! Well my hangar now smells much better,
and my flying is somewhat improved as well!! jim T337b