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Sheared rudder stop rivets

TJHeller

I'm New Here
My -10 is in the paint shop right now, and they were cool with me doing an inspection and double checking SB's while the control surfaces were removed. Anyways, we found 2 sheared rivets on one of the rudder stops. And since 2 were missing, it rotated inboard. I suspect this is more common than not since the rudder will flap in the wind on the ground without something preventing it. See attached pic.
 

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Yes typical. I used No. 6 screws in lieu of rivets, but that may prevent the stop from sheering but not the cracking. I inspect that area on every preflight. I have the parts to make the change. Maybe you have motivated me to go through the effort to remove the rudder. Here is a video from base leg aviation showing a failure of the stop. Around 3:00 https://www.youtube.com/watch?v=ZmETwYDRrw4
 
I believe this is a somewhat common failure, as the design is not strong enough for wind related slamming of the rudder, only to stop pilot induced pedal pressure and it is plenty strong for that. I believe the designers assumed the rudder would not be left, unlocked, to flap in the breeze. Maybe not a good assumption, given that the kit doesn't include any provisions for a rudder lock.

I build a solid, one piece stop that installs with the same dimensions as the two piece assembly. It is aluminum and much stronger, as any pressure is carried by 6 rivets, not 3. Pretty sure there are offerings out there in both Al and nylon for purchase.

Larry
 
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I believe the designers assumed the rudder would not be left, unlocked, to flap in the breeze. Maybe not a good assumption, given that the kit doesn't include any provisions for a rudder lock.

Larry

Interesting statement, as I've observed the Vans RV-10 demonstrator on display at various fly-ins with no gust lock installed....:eek:

-Marc
 
I build a solid, one piece stop that installs with the same dimensions as the two piece assembly. It is aluminum and much stronger, as any pressure is carried by 6 rivets, not 3. Pretty sure there are offerings out there in both Al and nylon for purchase.

Which just means you better be real diligent about inspecting for cracks per the SB referenced above.

I've expressed concerns in the past about similar "internal stop" installations on the 2-place models. Replacing the external stop with an internal really loads up the hinge brackets.
 
Bottom line with the 10 is, you can never walk away from the plane outdoors without installing a rudder gust lock. Given that the almost standard Bogart tow bar can be adapted to lock the rudder, and installs/uninstalls in 20 seconds, there’s really no excuse.
 
I’ve done the sizing for the rudder stops on a commercial aircraft. Somebody had the brilliant idea to propose eliminating the control gust lock system to save weight and cost. The dynamic loads on the stop generated by a rudder flapping in the breeze are enormous. A matter of when, not if, damage will result. Needless to say the gust lock system went into the plane.

Secure the flappy bits when not flying.
 
I use my rudder lock all the time as well, but this is one of the other reasons i always try to park with the nose into the wind, even if its inconvenient.
 
I use my rudder lock all the time as well, but this is one of the other reasons i always try to park with the nose into the wind, even if its inconvenient.

That works fine until some guy in a G-36 taxies in and does a power turn to park....

-Marc
 
Which just means you better be real diligent about inspecting for cracks per the SB referenced above.

I've expressed concerns in the past about similar "internal stop" installations on the 2-place models. Replacing the external stop with an internal really loads up the hinge brackets.

I didn't really change anything, design wise, from the plans. The plans have you make two internal stops on either side of the hinge bracket. I just made a one piece version of the same design. That said, I agree that this modification can transfer more load to that hinge bracket (though the load is now spread across the whole bracket, not just one side) and yes, I do check it. However, I am confident that the hinge bracket failures have been wind induced on the ramp and not from typical flying.

Maybe the two piece design is superior, as the rivets shear before the hinge develops cracks. I believe the key is not to let the rudder flap in the breeze.

Larry
 
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Maybe the two piece design is superior, as the rivets shear before the hinge develops cracks.

They are a structural fuse, limiting the maximum stress applied to the bracket. A one-piece stop increases the maximum.

Brackets still crack in some cases, likely because their operators didn't limit how often they are stressed.

The fatigue limit can be considered as how much x how often.

A fellow who wants one-piece stops would be well advised to complete the SB, installing the re-designed hinge bracket.
 
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