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  #1  
Old 03-08-2017, 04:07 PM
Snoho3 Snoho3 is online now
 
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Default Dual Independent Latches on a Tip-Up

I've installed the Almost A -14 mod on my -9A tip-up. Now to the point where I need to modify some structure for the latching mechanism to accommodate the revised lateral support. I'm wondering if anyone has not bothered with the single latch design (per plans) and instead fabricated a dual independent latch set up? The question applies to tip-ups without the -14 mod as well.

It would mean an additional checklist item, but would save weight and avoid the ugly steel tube crossing behind the seats. Yes, when hangared/parked only the left side latch would be engaged, but would this be a problem?

Interested to hear what others may have done, or even just considered... Thanks.
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  #2  
Old 03-08-2017, 04:20 PM
rv7charlie rv7charlie is offline
 
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Inside only on the right? What about emergency external access?
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  #3  
Old 03-08-2017, 04:53 PM
Snoho3 Snoho3 is online now
 
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External access would be only on the left side - as it is now per plans. The right side latch would only be internal. Same as it is now. But it would not be connected to the left side, it would operate independently.

When you are in the aircraft and want to close and latch the canopy, you would have to operate BOTH latches. Hence the new checklist item. Opening the canopy from inside obviously would require two separate actions as well.

Just wondering if anyone has tried this. The trade off for avoiding the steel tube across the fuse seems reasonable but maybe I am missing something.

Appreciate your thoughts!
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  #4  
Old 03-08-2017, 07:32 PM
rv7charlie rv7charlie is offline
 
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Stock left access unlatches both sides. How does a rescuer unlatch the right side with your plan? Hatchet? ;-)
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  #5  
Old 03-08-2017, 07:36 PM
BillL BillL is offline
 
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Generally, this does not sound like a safety improvement. Just twice as likely to have a canopy pop up on take off. Each issue has it's challenges, so what is the typical design to restore the single latch point system with this mod?
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Old 03-09-2017, 04:20 AM
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N941WR N941WR is offline
 
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Quote:
Originally Posted by rv7charlie View Post
Stock left access unlatches both sides. How does a rescuer unlatch the right side with your plan? Hatchet? ;-)
That doesn't really matter because the tip-up has two latches, the one on the left side and the twist latch on the top of the canopy. The top one has no outside access. So, if you are right-side up and a "rescuer" needs to get the canopy open, they are going through the canopy anyway.

If the airplane is upside-down, the canopy is going to be toast anyway, so it won't matter.
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  #7  
Old 03-09-2017, 04:11 PM
jfogarty jfogarty is offline
 
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The latch systems that Van's has for the tip up canopy works very well. *For your own safety never forget to latch them both down. *
On your check list, per my transitional training, list the latching down twice. *If you ever forget to do this you will understand my meaning.
I slowed the plane down with just the right 20 degree turn to engage the left side latch. *It will
be noisy and you will consider landing at the next available airport. *

I never latch my plane in the hangar, I'm sure many do.

Jim Fogarty
RV-9A Flying
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  #8  
Old 03-09-2017, 06:33 PM
Snoho3 Snoho3 is online now
 
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Quote:
Originally Posted by BillL View Post
Generally, this does not sound like a safety improvement. Just twice as likely to have a canopy pop up on take off. Each issue has it's challenges, so what is the typical design to restore the single latch point system with this mod?
Agreed this isn't a safety improvement. And yes, just like in a C172, both latches would have to be checked every flight.

The 'Almost a -14' mod is designed for sliders, however an adjustment/fix for tip ups has been documented that moves the cross fuse steel tube aft a few inches by using some new linkage. I'll try to insert a link here...

https://nebula.wsimg.com/068b324554a...&alloworigin=1.

This tip up mod includes a penetration through the 705 bulkhead that has me raising my eyebrow. I think it would not be a bad idea to avoid the additional hole in the bulkhead, and also avoid the additional linkage and cross fuse steel tube altogether.

I appreciate the input, sincerely. And any additional thoughts as well! I guess I sound like I am trying to talk myself into this. I don't usually have too many original thoughts (!), but it seems like no one else has gone this route before. I am going to continue to think on this while I do some other work.
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