I was at the Lancair factory a few years
back and happened to talk to one of the test pilots who was doing the “fly
off” on a Legacy. I asked him how it was going and he said great, except
for the canopy coming open in flight, apparently due to an improper adjustment of
the over center latch. Anyway, he handled the emergency well, but then again,
he was a test pilot …
Dana
From: lanny
[mailto:poprundell@bellsouth.net]
Sent: Friday, April 18, 2008 1:28
AM
To: lml@lancaironline.net
Subject: Legacy crash -
speculation
First I would like to extend my sincere
condolences to the family of the Legacy pilot. I was at Sun-N-Fun Friday and
Saturday and saw the airplane. I was a beautifully built aircraft and I was
hoping to meet the owner but never got the opportunity.
I don’t know how old the airplane
was or how long the engine had been hanging on the mount, but it usually
happens that the engine will sag in the mount over time. This is a normal
thing and causes only cosmetic problems. Sometimes in sever cases in a tightly
cowled engine the exhaust pipes or some of the baffling will begin to rub.
Lycoming engines with the alternator mounted on the front will sometimes wear a
hole in the lower cowling from the pulley rubbing. This doe’s not cause
loss of control nor doe’s a broken engine mount unless the engine comes
off. I have seen quite a few ag aircraft land with broken engine mounts from
hours of high stress turns and countless landings on rough runways. You
usually experience a new vibration.
What can cause loss control is a canopy
that is hinged at the front and comes open in flight. About 10 years ago my
son and I were test flying a Lancair 320 with a forward hinged canopy. The
latch looked overbuilt consisting of a ½” threaded bolt with a knob on it.
You closed the canopy and screwed the bolt that was mounted to the canopy
bulkhead into a receptacle in the rear of the canopy. The tighter you turned
it the tighter the canopy pulled down onto the canopy seal. Crude but
effective. We went out for about a half hour flight to get familiar with the
airplane. As we were descending to pattern altitude, the receptacle in the
canopy frame that the bolt screwed into, pulled out of the frame and the canopy
came open. It popped up about 4 to 6 inches at the rear. When it popped up,
the nose pitched up sharply. I countered by pushing forward on the stick. The
canopy dropped down in the rear and the nose now pitched down sharply. I now
had the power to idle trying to slow down. As the nose pitched down, I countered
by pulling back, the nose suddenly pitched up again. This was not a pilot
induced movement, it seemed that the canopy was flying straight and level and
the airplane was pitching up and down around the hinge point. My son was
finally able to get his hands on the rear of the frame and pull it down and the
pitching stopped. While flying the pattern to land, we tried moving the canopy
up and down and found that it controlled the pitch. Push the canopy up and the
nose pitched up, pull it down and the nose pitched down. If you did not hold
it stable in one position, it was almost impossible to control the pitch of the
airplane. Also, the higher the speed the worse the condition became. If my
son had not been with me and had the presence of mind to get hold of the
canopy, I am not sure I could have gotten it under control by myself.
Always make sure the canopy is locked
before takeoff. While the forward hinged canopy seems like the safest way to
go, it may not be. Some aircraft have forward hinged canopies and seem like
the least desirable, but these are usually designed to rip off in the event it
comes open. The Glasair uses a Gull wing that is designed to rip off if it
comes open.
The forward hinged canopy is not a bad
design. I just has to be locked in flight. I worry that some people
don’t worry about it coming open because they figure it will just ride
stable until you can close it. This can be a very dangerous attitude.
Happy Landings.