Sonex Down - Check That Canopy
Posted: Fri Sep 29, 2023 11:55 pm
by daleandee
Thankfully the pilot only has minor injuries:
https://news.yahoo.com/plane-crashes-hi … 55246.html
Re: Sonex Down - Check That Canopy
Posted: Sat Sep 30, 2023 1:32 pm
by 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.
- A very tightly fitted canopy that can’t move backwards OR slide even slightly over the turtle deck even with significant force applied.
- 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.
- 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.
Re: Sonex Down - Check That Canopy
Posted: Sat Sep 30, 2023 3:12 pm
by 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.
Re: Sonex Down - Check That Canopy
Posted: Sat Sep 30, 2023 6:31 pm
by Bryan Cotton
Jester,
Pics of the alignment pin here:
viewtopic.php?f=33&t=7356&p=55546&hilit=Canopy+pin#p55546
Re: Sonex Down - Check That Canopy
Posted: Sat Sep 30, 2023 10:19 pm
by 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!
Re: Sonex Down - Check That Canopy
Posted: Sun Oct 01, 2023 6:50 am
by 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.
Re: Sonex Down - Check That Canopy
Posted: Sun Oct 01, 2023 5:26 pm
by 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.
Re: Sonex Down - Check That Canopy
Posted: Sun Oct 01, 2023 7:01 pm
by Bryan Cotton
cliffrunkle wrote: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.
Re: Sonex Down - Check That Canopy
Posted: Sun Oct 01, 2023 10:46 pm
by 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.
Re: Sonex Down - Check That Canopy
Posted: Mon Oct 02, 2023 12:39 am
by 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
Re: Sonex Down - Check That Canopy
Posted: Mon Oct 02, 2023 8:32 am
by pfhoeycfi
My canopy pin is on a keychain ring with a red embroidered “insert before flight” tag on it. When not inserted in the canopy rail performing its locking function, I insert the pin in a hole in the glareshield just above the Efis, with the tag hanging down in front of the Efis. Hard to miss.
Re: Sonex Down - Check That Canopy
Posted: Mon Oct 02, 2023 9:30 am
by Area 51%
mike.smith wrote:This is what I’ve used successfully for 9 years:
http://www.mykitlog.com/users/display_l … 6165&row=7How to remove the pin and open the canopy is part of my passenger briefing.
That pin and it’s location, along with the spring, is there to keep the LATCH from creeping aft on the canopy frame. It does nothing to guarantee the latch will stay engaged with the longeron.
Without the -17 alignment pin in place, the whole works can slide back far enough to alternately and inadvertently disengage the latch.
Re: Sonex Down - Check That Canopy
Posted: Mon Oct 02, 2023 10:03 am
by builderflyer
Bryan Cotton wrote:
cliffrunkle wrote: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.
Don’t know about the Waiex plans but the spring was shown on the Sonex plans since day 1. And, the hair on the back of my neck stands up when I think about those who would fly without the “pin” keeping the canopy latch closed. There have been far too many canopies coming open in flight when the pin has been intentionally omitted or simply forgotten.
Art,Sonex taildragger #95,Jabiru 3300 #261
Re: Sonex Down - Check That Canopy
Posted: Mon Oct 02, 2023 12:47 pm
by Jester504
Area 51% wrote:That pin and it’s location, along with the spring, is there to keep the LATCH from creeping aft on the canopy frame. It does nothing to guarantee the latch will stay engaged with the longeron.
Without the -17 alignment pin in place, the whole works can slide back far enough to alternately and inadvertently disengage the latch.
Seconded as this is an extremely important hair to split. Easy for newbies like me to confuse which pin people are talking about.
Re: Sonex Down - Check That Canopy
Posted: Tue Oct 03, 2023 7:18 am
by DCASonex
That spring my help but it is soft enough to be of limited value. I have a bracket around my master switch that allows fitting the canopy pin to lock the master in the off position. Aside from preventing the master from being be bumped on, that provides a place for the pin so it is rarely ever placed somewhere else. Also have a small bright bit of plastic attached to it. Still using the original 10+ years later.
David A.
Re: Sonex Down - Check That Canopy
Posted: Tue Oct 03, 2023 10:57 pm
by mike.smith
Area 51% wrote:
mike.smith wrote:This is what I’ve used successfully for 9 years:
http://www.mykitlog.com/users/display_l … 6165&row=7How to remove the pin and open the canopy is part of my passenger briefing.
That pin and it’s location, along with the spring, is there to keep the LATCH from creeping aft on the canopy frame. It does nothing to guarantee the latch will stay engaged with the longeron.
Without the -17 alignment pin in place, the whole works can slide back far enough to alternately and inadvertently disengage the latch.
The alignment pin IS there. This is just the pin I use for locking.
Re: Sonex Down - Check That Canopy
Posted: Mon Oct 09, 2023 8:35 am
by Tony4aro
I have a thought on the canopy issue… but I’m going to make a new post in the general section.
Re: Sonex Down - Check That Canopy
Posted: Mon Oct 09, 2023 12:03 pm
by daleandee
I’m familar with the video Tony posted on another thread. I don’t know all the details but the owner claimed the accident was caused by a worn out latch and a poor design.
How many Sonex aircraft have crashed due to canopy issues? I have eleven years on the same canopy and latching/locking system that mine was built with. The latch has to be correctly built and can’t have slop in it as it will lift if it has a poorly built latching system.
As for the canopy sliding back … there is a piano hinge on the right side to prevent that. There is an alignment pin on the left to prevent that. The only way it could move rearward would be on the left side and that would require either the alignment pin (NOT the locking pin as that is all together different) to be missing or very short along with a latching system so sloppy as to allow the canopy to lift enough for the alignment pin to clear the hole it is in. The design is not faulty if properly implemented.
Could the aligning/latching/locking system be improved? I have no doubt that there may be better ways to do this. The point of my post is to say that what Sonex gives in the original plans does work as proved by so many planes flying that have not had a problem.
I’m reminded of the U-Toob video of the guy that wanted to slam Sonex for, what he claimed, was a poor design of the OneX rudder system when if fact he had bought, not built, the plane. The orignal builder had not followed the plans and almost caused another plane to crash. This kinda stuff gives Sonex and us builders and pilots of Sonex aircraft a bad reputation. I don’t like it when that happens.
Dale
3.0 Corvair/Tailwheel
Re: Sonex Down - Check That Canopy
Posted: Tue Oct 10, 2023 7:28 am
by Tony4aro
daleandee wrote:Could the aligning/latching/locking system be improved? I have no doubt that there may be better ways to do this. The point of my post is to say that what Sonex gives in the original plans does work as proved by so many planes flying that have not had a problem.
I know it’s not a completely bad design. If built correctly, it works… as proven by thousands of flight hours on hundreds of planes. And maybe I’m just over thinking all of this. But, if there is a way for a simple rework… and it makes it idiot proof… then that just improves safety.
daleandee wrote:I’m reminded of the U-Toob video of the guy that wanted to slam Sonex for, what he claimed, was a poor design of the OneX rudder system when if fact he had bought, not built, the plane. The orignal builder had not followed the plans and almost caused another plane to crash. This kinda stuff gives Sonex and us builders and pilots of Sonex aircraft a bad reputation. I don’t like it when that happens.
Dale
3.0 Corvair/Tailwheel
I get it. These are home built, and people can blame them for anything, but the reality is… it was up to the builder to make it right.
Re: Sonex Down - Check That Canopy
Posted: Tue Oct 10, 2023 9:57 am
by builderflyer
daleandee wrote:
Could the aligning/latching/locking system be improved? I have no doubt that there may be better ways to do this. The point of my post is to say that what Sonex gives in the original plans does work as proved by so many planes flying that have not had a problem.Dale
3.0 Corvair/Tailwheel
Dale has it 100% correct here. Just build it per plans. Don’t omit the spring, check the alignment pin regularly, use the safety pin on every flight and you won’t have any likelihood of the canopy opening in flight. There are other things to worry about more than this.
Art,Sonex taildragger #95,Jabiru 3300 #261