201 with O&N bladders fuel leak in flight.

[johnbkeck]

Hello,

Maybe somebody has heard of almost a full right wing tank of fuel during a 1:20 flight. The bladders were installed in 2004. I never had any problems since acquiring the airplane in 2011. I took off with full fuel and climbed to 5000 feet IFR in the clouds. I started to pick up rime ice and requested and descended to 4000'. The temperature was about 38 degrees at 4000'. The ice didn't melt at 4000'. I did smell some avgas but didn't connect the dots. I requested and descended to 3000' and the ice went away.

About 20 minutes from landing I noticed that the right wing tank was way down to 1/4 tank left. I looked down at the fuel selector thinking it was selected to the right tank, but it was on the left tank. On approach I maintained a higher approach speed not knowing how the plane would handle with 2/3 in the left and 1/8 in the right tank. After an uneventful landing and taxi in, I checked the right tank and it was about dry. Under the wing about 3-4 feet outside of the landing gear doors, I saw blue fuel stains streaming back to the flaps. Not evidence of fuel stains near the quick drains or inboard of the landing gear.

My friend called O&N and said we had the leak and they said it is very rare that the bladder would leak. They suggested that the top wing panels be removed (not the bottom) and look for loose hose line clamps and especially a large plumbing type 2" attachment that might be leaking.

I know I will hear how stupid I am for flying in clouds with ice. The temperature on the ground was in the high 40's to the low 50's and I thought I would be OK at a low altitude. Maybe a few fuel tank vents iced up and I lost all of the fuel in the right wing and there is no fuel problem? Thanks in advance of any similar problems or suggestions.

[M016576]

I can't help you with the mystery of the leaking fuel: honestly- you're the first person with mooney O&N bladders that I've heard of with a potential leak (although ice heard of and seen plenty of brand C models with leaks in their bladders).

A few unsolicited comments though: some of which you've already mentioned: icing can occur when the OAT is within +5 degrees of freezing. I won't get deeper into decision making, but steering clear is prudent. The other thing you Optested yourself: one tank full, one tank empty is a non-issue... In fact, I think it has to be demonstrated for certification, else it would need a warning or restriction. Stay safe!

[Mooneymite]

_{I've had bladders for years (installed 1992, I think)....completely problem free.  However, about a year after I bought the airplane when the bladders were about seven years old, I did get some evidence of a fuel leak.  I did as suggested and removed the access panels and found that all the screws for the bladder access panels had become loose as the seals had compressed over the years.  About twenty minutes with a philips screw driver and the problem was gone.  Never had another issue.}

 

_{I've talked to other bladder owners who have had exactly this issue at about the same number of years.}

 

_{Simple cause, simple fix.}

 

_{I love those bladders.}

[N601RX]

My bladders are almost 20 years old and had some leaks about 3 years ago when I purchased it. They are connected with short aluminum pipes and heavy duty hose clamps. These may need snugging up a little. Each cell has a access plate in the top of it. The access plate has a cork gasket around it and several bolts that need to be torqued to a specific torque. There are also 2 cork gaskets around each fuel sender. O&N told me that sometimes tightening the bolts a little would normally stop the leaks, but In my case they had already been overtightened and squeezed the gaskets out a little. They sold me a complete gasket set for $110 and that stopped all my leakes. I have a copy of the install manual if you need it. It contains the correct torques. I took the oppertunity to drain them completely and get the stuff out that had accumulated over the years.

O&N also told me they had never had a bladder itself leak, it was always a interconnect pipe or gasket.

[johnbkeck]

Thanks for the great feedback! N601RX if you could send the install manual, I will give it to the mechanic who is looking at it on Monday. They are a King Air turbine shop but work on everything. Would be really nice to send these replies along to him to save us labor costs and the correct torques.

Thanks again everyone!

John

N201AJ

[N601RX]

Manuals

M20C,D,E,&G_Install_dwgs.pdf

M20F-J Install Instructions.pdf