My 360 at 8 years old and 300 TT developed a fuel leak in the left wing last
week so I brought home a nice 6mm borescope this weekend to take a look around
and I am not very#$%^&*()_happy with the results...I have the fuel bridged
between the BL99 & BL104 ribs for long tanks so some of the pics attached are
from each rib. The leak appeared to be coming from between these ribs as it
was leaking out the inspection panel for the aileron belcrank. Inside the wing
I found MUCH deterioration in the way of cracking and flaking of the hysol
joint "squeeze" between the bottom skin and ribs etc. It seems that hysol is
not to be used around "some" fuels. Yes that orange  - red stuff (that used to
be blue-green) is really the hysol ! Also note the amount of debris floating
around...yes that gives me a warm fuzzy how about you ? So yes my flying
season is over for ??? or till I can find some pygmies to put inside my wing.
I was thinking about selling my plane and moving up but suddenly ALL OUR
LANCAIRS might not be worth quite as much as we thought  ????????????????? I
have been mixing 100LL with premium auto fuel  50% / 50 % for its entire life.
  Does anyone have a plane this old that has NEVER had any auto fuel in it ? I
would sure like to look in the wings....

Lloyd,

 

Interesting problem.  Maybe an LMLer with a chemistry background could answer. 

 

Does your auto gas contain 10% ethanol?  Could ethanol/alcohol laced gas been picked up some at another airport?  How are you able to do this mix at re-fueling airports away from home?  Was the Hysol out-of-date when it was applied?  Was the mix ratio correct?

 

My plane does not have this problem after 10 years and almost 1000 hours.  There may be two reasons: Exclusive use of 100LL and the surfaces were bonded with the pre-cursor to Hysol, a 3M industrial cement available in the early 1990s.

 

No other Lancairs that I know of have had this problem so I think you are overstating it when you say "ALL OUR LANCAIRS might not be worth quite as much as we thought."

 

You may have to remove the bottom skins and re-bond them to the wings to be safe.