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Thanks Wayne,
I printed off the items you listed to be
concerned with in regard to the Alon / M-10 canopy. This I will
keep as a check list at inspection time.
I sometimes fly with the canopy only partly
closed. It's hooked in on both sides but not latched. This keeps the
air moving on a hot day. I wonder how safe this is compared to full
open?
I once lost part of the canopy on a 415-C.
it wasn't fun. I had just left the airport at Zanesville,
OH (ZZV) and as I got higher I started getting cold. The plane had
the three piece sliding windows and I had slid the green center piece over to
the right for easier entry and just left it there. I reached up to
center the green sun screen, pulled on it and the green plastic broke from the
front to the back. I had only the frame in my hands with a small piece
attached. The large piece flipped up into the rough air above the
windshield and before I was able to get a hold on it, it broke off. I now
had the left frame in one hand and grabbed the right frame just before it
left the ship. I looked down to see the green piece floating down to
a big plowed field. I bet the farmer wondered how it
got there. Although I wasn't in any real danger,it was
panic city for a few seconds. I sure wouldn't want to lose an Alon/ M-10
canopy.
Jim Palmer N9513V
M-10
Wayne
wrote:
Here are the things that I would be concerned with when inspecting the
security of the Alon canopy for flying the plane with the canopy open:
1. The diameter of the nylon canopy rollers should be checked to
make sure that they are significantly larger in diameter than the "slot" or
opening in the side canopy tracks that they roll in. This will prevent
the roller from popping out of the track. Also, when inspecting the
rollers, check that they have not worn round on the flat ends. The ends should
be square or nearly so in cross section. These rollers do wear over
the years.
2. Check the security and condition of the screw that the roller is
attached with. There should be a fiberlock nut on the inboard end of the
screw. Make sure that the nut is there, that it is tight, and that
the threads are sticking out of the nut by one or two threads. If this
nut falls off, the screw can work its way out, turning the roller loose,
and then the canopy will be free to separate from the fuselage on that
side.
3. Check the condition of the aluminum canopy frame where
the hole for the above screw is drilled. Make sure that there
are no cracks in the aluminum or any other signs of impending failure of
the aluminum itself. This aluminum can take a beating if people grab the
canopy frame to hoist themselves up on the wing, because when the canopy is
forced aft, the thing that stops it is the rollers stopping on the
phenolic blocks. This tends to impart a twisting or bending moment on
the aluminum frame around the screw. If a lot of force is applied, it
can bend the aluminum around the roller screw.
4. Make sure that the phenolic blocks inside the side canopy
tracks are there, and that they are in good shape, and that the screws and
nuts that hold them in place are tight and in good shape. These
blocks stop the canopy from traveling too far aft. As you know, the
slots in the side canopy tracks are cut out large enough for the rollers to
pass through them at the extreme aft end so that the canopy can be removed
after these phenolic blocks are removed. If you have one of these blocks
come loose, that side of the canopy may be able to move back to a position
where the roller can come out of the track. The two screws that
hold these blocks see a lot of stress because every time you latch the canopy
from the inside, these screws are "pulled forward" and every time the canopy
rollers hit the phenolic blocks, these screws are "pushed backward".
Adding to this problem is that fact that the screws pass through the plastic
arm rest material, so they probably are not maintaining much, if any, torque,
so the screws are probably able to move back and forth slightly in the holes
when the canopy is pushed back and when it is latched from the inside.
If the screws are moving in the holes, they are wearing in the holes.
5. Inspect the aft canopy track and slide block to make sure that
the nylon part of the slide block is in good shape and firmly attached.
The slide block should be large enough so that it can't come out of the aft
canopy track.
6. Inspect the condition of the tracks themselves for any wear that
would open the canopy track slots up more than they should be.
If all of these items are in good shape, the canopy should not come
off in flight. Like Ralph said, it was designed to be able to be
open in flight. If everything is as it should be, it should be safe
enough. Having said all that, I personally don't trust it and that is
one of the reasons that I don't like flying with the canopy open. But
that's just me, and I tend to be overly conservative about anything that might
prevent me from flying again tomorrow.
Best
Regards,
Wayne DelRossi
Alon N5618F
Hours logged since
restoration: 187.3
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