Sonex Down - Check That Canopy

[daleandee]

Thankfully the pilot only has minor injuries:

https://news.yahoo.com/plane-crashes-hi ... 55246.html

[Jester504]

I'm glad he's OK. This brings up a question I had looking at my own canopy and the stock latch design.

It seemed to me that a potential design flaw is that if something caused the canopy to be pushed backwards, and there's enough gap between the canopy and turtle deck or the canopy is slightly too large, then the left side of the canopy could be pushed back AND UP slightly which would pull the latch out of the canopy rail WITHOUT actuating the latch and rip the entire canopy off. The canopy latch pin only holds the latch in place relative to the canopy - it doesn't actually latch the canopy to the airplane.

Does anyone else see that as a potential problem? To avoid it, I figured there were a few things you could do without drastically changing the design.

1. A very tightly fitted canopy that can't move backwards OR slide even slightly over the turtle deck even with significant force applied.
2. Reverse the direction of the latch mechanism so that the "hooks" on the latch face the other way and the spring is on the back, so that even if the canopy is pulled backwards, the hooks remain fully inside the rail and the canopy can't be pulled upwards.
3. Modify the pin design so that it actually latches to the airplane, not the canopy.

Let me know if I'm off-base. I'm certainly no engineer or Sonex expert.

[Area 51%]

There is a pin that orients the canopy to the longeron. At least there is on a Legacy. If that pin is missing, the canopy can and will slide back just as you describe.
On my Waiex plans the pin is shown on page D-02. The part is -17.
I always carried a spare and it was the first item on my pre-flight checklist. They have a way of finding a path to the fuselage floor.

[Bryan Cotton]

Jester,
Pics of the alignment pin here:
viewtopic.php?f=33&t=7356&p=55546&hilit=Canopy+pin#p55546

[Jester504]

Oh dang, mine doesn't have that! I am not the builder and I haven't flown it yet. Still in the mechanical getting-to-know-her stage and fixing a few other small issues. Somehow I missed that so far. A pin is easier than the ideas I had! Good thing I asked about it!

[Area 51%]

If I were a betting man, I'd wager that pin (read that "missing pin") has brought down more planes than any other single cause.

[cliffrunkle]

The plans also call for a spring to be installed as to keep the latch creeping back In the event the key is accidentally omitted. This spring is integral to the design for max safety.

[Bryan Cotton]

The plans also call for a spring to be installed as to keep the latch creeping back In the event the key is accidentally omitted. This spring is integral to the design for max safety.

Agreed! I thought the earlier plans did not include it. Should be a mandatory addition.

[mike.smith]

This is what I've used successfully for 9 years:
http://www.mykitlog.com/users/display_l ... 6165&row=7

How to remove the pin and open the canopy is part of my passenger briefing.

[kmacht]

Mike,

I see on your build site that the pin is no longer available on Amazon. For those looking these pins are very common in the machining and tooling world. McMaster Carr has them in a number of different styles.

https://www.mcmaster.com/product/90985A100