Tip: Armrest Reinforcement

[RudiGreyling]

Some RV owners complain that people push too hard on their arm rest when getting in or out of the plane and then bend it.

I have seen how some people reinforce theirs with elaborate ideas and have come up with my own method that I think is simple and elegant.

Simply put a 1/2" 0.064 aluminium angle for the full length on the straight edge facing down and back. This have the following advantages:
- No additional holes in the main airframe
- The down force is distributed along the enitre arm rest
- Can be done before the armrest are fitted or retro fitted on existing installations
- Minimal weight addition (66 grams or 2.3 oz)
- Does not change the appearance of the arm rest, one would hardly notice the difference, only a row of rivits
- Create a nice smooth finished edge on the bottom of the arm rest compared the original thin edge, since the L bends backswards.
- Creates a lip to wrap upholstery around.
- 2 hours of work for piece of mind
- Since it is not structural you can use your home depot or hardware store variety alu angle here, so it is cheap.

Below are some photos, more on my website under Tips and Tricks

Here are the components with the 1/2" alu anlge cut to length:


Mark even spacing for the rivets aprox 30mm or 1"1/8:


Clamp the angle so that it aligns with the lip, and test that you can get a rivet squeezer in there:


Drill and clecko as you go, debur, dimple the armrest and countersink the alu angle:


Rivet it together using your rivet squeezer:


A picture of it being fitted to the airplane.


Kind Regards
Rudi

[RV7Guy]

Hi Rudi,

Hopefully you haven't riveted it in yet. The support you added is great but the real problem is the attachment point fore and aft. Mine cracked at the front.

The fix is simple by adding a piece of angle on the top or bottom. Since mine was installed I drilled a couple of rivets and installed the angle with pop rivets. If you haven't installed it will be much easier.

Most importantly, this is part of my pre flight briefing with passengers and again before they get out, to NOT use it to push out of the plane.

[RudiGreyling]

Hi RV7Guy,

thanks, it would be simple to use the same material flip it the other way and make 2 more smaller supports.

Regards
Rudi

[Paul Eastham]

Has anyone tried bonding a piece of wood or similar underneath the armrest with epoxy? Seems simpler, at least for retrofit installations, and might give more support. I think you'd want to try to get a close fit, so that you can engage the surrounding structure on all four edges.

That armrest is the only thing that jumped out at me as being sub-par during my demo flight at Van's. I can imagine it might give more nervous passengers a little concern -- not having something solid to hang on to!

[n2prise]

My process is fully described on my web site at this link:

http://www.n2prise.org/rv9a031.htm#Armrest_Mod

I used the heavy 3/4" x 3/4" x 0.125 6061-T6 aluminum angle. Photos and details are all on the page linked above.

Jerry K. Thorne
East Ridge, TN
RV-9A N2PZ 189.6 Hobbs Hours since June 6, 2005.

[Highflight]

Originally Posted by Paul Eastham

Has anyone tried bonding a piece of wood or similar underneath the armrest with epoxy? Seems simpler, at least for retrofit installations, and might give more support. I think you'd want to try to get a close fit, so that you can engage the surrounding structure on all four edges.

That armrest is the only thing that jumped out at me as being sub-par during my demo flight at Van's. I can imagine it might give more nervous passengers a little concern -- not having something solid to hang on to!

Be careful there Paul. A chuck of solid wood under each armrest could add 2 to 4 pounds easy. Before you know it, a couple of pounds here... a couple of pounds there...
I don't know how old you are, but if you're over 40, you probably know how weight can sneak up on you.

Adding the aluminum angle as noted, and even adding additional short angle pieces under each end of the rests would only add a few ounces. Of course before you know it, a couple of ounces here... a couple of ounces there...

[n2prise]

What really put the pounds on my RV-9A?

Hartzell Constant Speed Propeller
AM/FM CD/Tape Player
Modular Instrument Panel in front of Van's "hollowed out" panel
Full interior
Stereo Speakers (for ground ops)

Empty weight 1,184 pounds with paint, et al.

Jerry K. Thorne
East Ridge, TN
N2PZ www.n2prise.org

[zkvii]

Another thread with some ideas:

http://www.vansairforce.com/communit...ead.php?t=8131