Crack in VS attach plate

[petehowell]

Inspected this last night and found no issues at 955 hrs. Added a special inspection to the annual checklist, too. Only takes 5 min to pull the emp fairing and give it a good once over.

Added hardwiring for the GDL39 as well - that was a bit more fun.....but worth it!

[mikehoover]

Originally Posted by ArVeeNiner

According to my directions (page 8-17 of the 12/13/04 Rev), paragraph 6 under Fitting the Vertical Stabilizer says:

"If the rear spar bends aft at the top when the front spar is clamped, the vertical spar may be mounted on the rear of the F-981 plate."

My F-981 plate is installed forward of the VS spar as well on my RV-9A. If I remember correctly, it just seemed to fit better that way. I can see putting a doubler on there, perhaps including the two upper bolts and several of the VS spar to F-981 plate rivets. I predict a service bulletin in the near future.

[dougweil]

I checked with the mechanic working on this airplane and it appears that this crack may have been there quite a while. The airplane is TruTraks "old" RV-9A that has 1200 total time on it. They have installed a new bracket and it will soon be back flying again.

[mtnclimber]

Agree with Mike. I'll definitely add reinforcement to this area on my 9A, and on my 8 under construction. Seems like good insurance, and easy and light.

I think this attach bracket can see significant bending stress in turbulence or hard aerobatics. Another possibility is cyclical stress from the propeller slipstream.

Roger Bloomfield
Colorado

[RV6AussieNick]

Looking at the photo it looks as if the crack is following the grain of the metal, if it is, the bracket should have been folded with the grain going the other direction for better strength. Just my thoughts..

[MarkW]

I am surprised at all the speculation. Other than Kelly Johnson.
I just finished this part last week and it is the factory part and is installed properly.
The directions clearly state on the RV-9(A) that the plate can be installed to the front or rear of the VS-702. Which ever gives you a better rudder hinge alignment.
However the multiple cracks we have seen are troublesome.

[Rupester]

..... to Kelly and Mark W. for checking the exact wording in the 9/9A plans. As I was reading this thread, I remembered being given the option of putting the attach plate on the front or rear of the VS spar ... then I quickly thought my memory must be wacko. As I was getting increasingly concerned - about both my VS attach and my memory - Kelly and Mark clarified it WAS in the plans after all. Whew! Feeling reprieved ....

[tc1234c]

After 1154 hrs and two twisted rudder locks (first a 1/8" ss rod, later two 3/16" ss rod) due to strong gusts my F-981 showed no cracks.
F-981 installed at the rear of spar.

[az_gila]

Originally Posted by Rupester

..... to Kelly and Mark W. for checking the exact wording in the 9/9A plans. As I was reading this thread, I remembered being given the option of putting the attach plate on the front or rear of the VS spar ... then I quickly thought my memory must be wacko. As I was getting increasingly concerned - about both my VS attach and my memory - Kelly and Mark clarified it WAS in the plans after all. Whew! Feeling reprieved ....

The fact that Vans usually accurate parts can fit either way says something about the tolerances in the area.

A careful inspection for all those who mounted it on the front of the fin spar to see that no part of the radius of the connector plate touches the bottom of the fin spar would be in order.

Then feel reprieved...

The two examples shown would appear to fit into this category.

[rockwoodrv9]

Gil, thanks for your insight on this. Im with Vlad - this is a good thread. Full of info and real concern for getting this right. The thread on the -12 window is the same way - not full of opinions, but everyone trying to find a solution to a problem. People are stepping up to test and to provide material for the test. It is appreciated by us first time builders.