Greetings,

 

I flew my Legacy from northern California to the Portland, Oregon, area (McMinnville KMMV) and back the weekend before Thanksgiving.  On the way up, I flew through a lot of rain, including a very heavy rainstorm.  The airplane sat on the ground for 48 hours, exposed to rain most of the time.  On the way home, I again flew through heavy rain.  My total time flying in rain this trip could have been two hours.  My true airspeed was 210 knots or so.

 

The good news is that I haven't found any paint chips on the leading edge of the wing, although I found three tiny chips on the leading edge of the air intakes on the front of the cowling.  This success might be because I was careful not to use any micro on the wing leading edge and to keep the thickness of paint primer (WLS) on the leading edge thin.  My hypothesis is that paint chips caused by flying in rain are not a failure of the paint, but a failure of the underlying material.  I think that micro and primer are somewhat soft and more likely to fail under impact.  I used flox with some cabo-sil, on the wing leading edges, avoiding micro and avoiding a thick film of primer.  It was harder to sand, but possibly more resistant to chipping.

 

I extensively rebuilt the air intakes on the cowling and may have gotten a little lazy about avoiding micro there because of all the bodywork I was doing, which might explain the chips I received in that area.  I don't know.

 

The bad news is that a few days after returning home, while doing a normal post-trip inspection, I discovered some water on the floor behind the pilot's seat, in the baggage area.  The more I looked, the more water I found.  It was behind the aft wing spar in the baggage area, in the tunnel in the baggage area, at the aft baggage bulkhead, and at the autopilot pitch servo bulkhead.  I soaked up the water with a towel and wrung it out into a bucket.  I collected about a gallon of water! 

 

So where did all that water come from?  I think it came from the tail and moved forward.

 

I have heard that the cockpit and aft fuselage are at low pressure during flight, so it's possible that the water was sucked into the tail through openings in the aft spar for the vertical stabilizer and the elevator bellcrank.  (I don't understand how that could be, but it's a possibility.)  The water would have collected behind a bulkhead until the water level got higher than the lowest opening in the bulkhead.  At that point, additional water would flow downhill to the next bulkhead, where the process would be repeated.  That's certainly what it looked like when I was bailing it out.

 

It could also have entered through those same holes in the aft vertical stabilizer spar while the airplane was sitting on the ground in the rain for 48 hours.  If so, it would have traveled forwards in the same manner as described in the previous paragraph.  It's hard to imagine that a gallon of water could have dripped into the airplane, though. 

 

If the water is entering the tail while the plane is parked in the rain, then drilling a drain hole in the bottom of the fuselage, at the first place the water will collect, would be one solution.  If it's sucking in during flight, that's a harder problem to solve.  I suppose I could put a drain in the bottom of the fuselage, with an opening fabricated so that it would suck air and water out of the fuselage, but I'm not sure.

 

Anybody else had this problem?  Anybody else solved this problem?

 

Independently of finding the water puddles, I decided to avoid such wet trips in the future, although I'm sure I'll fly through rain from time to time.  But preflighting in the rain, opening the canopy in the rain, etc. isn't any fun.  Plus, even more important, my wife didn't like it.

 

Regards,

Dennis Johnson

Legacy, now over 100 hours tach time

 

PS

I understand that many pilots would have cancelled the trip, and avoided the risk of flying in bad weather.  Each of us makes his own decision in that regard, and I respect pilots who might have made a different decision.

 

I was comfortable with the risks.  I studied the weather and talked to pilots who had local knowledge.  There was no convective activity.  Ceilings were reasonably high throughout most of the flight.  Ice was a big concern.  I developed a plan to minimize that risk, which worked perfectly.  I had enough fuel to get to CAVU weather.  I'm comfortable flying an ILS to minimums.