Interesting Problem

I went out to do a bit of practice. A friend who is also a pilot, but
inactive at present due to sending three kids through college, went
along.

We practiced most of the maneuvers needed for the PPL and I let him
fly the Deb for a while. He is one of the few experienced pilots who
have done well. It didn't take him long at all to get used to the
different sight picture. (lower glare shield with a really good view).

At any rate the Deb does departure stalls in a very nose high attitude
with the CAS right off the scale. Who knows at what speed. I do know
it's less than book with the tip tanks.

When we parked on the ramp in front of the hanger he was first out. As
he walked around front he pointed under the plane on my side and said,
"Yah got a leak". So I got out and sure enough there was a 1/4 inch
stream coming out of a vent on the bottom of the fuselage near the
trailing edge of the wing on the pilot's side.

I knew it had to be a vent line. Switching between tanks and to off
made no change. When I opened the Aux tank on the passenger side
there was a whoosh and the leak stopped.

The gas was siphoning out the vent and the vacuum was pulling the
bladder right up off the bottom of the wing leaving the gauges showing
full. It had lost a bit over a third of a tank, most of which ended
up in my Cub Cadet (we caught the gas in a plastic waste basket...the
Cub has a good gas filter)

Either the break vent line is plugged or the check valve is stuck, or
the check valve is in backwards. Gotta get the mechanic over to take
a look.

Interesting,

**************************************************

Since then they found the "break vent", or "anti-siphon" vent line was
plugged. It wasn't mud dobbers, but it was some kind of insects that
had gotten up in there and died.

They used a 177 cal cleaning brush to clean the line. They couldn't
even blow it out before running that brush in there.

With bladder tanks that thing could have siphoned dry and the gauge
would have still read full.


Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com
Roger