X-brace modification

[dhillier]

Am planning the eventual strip down and re-build of 5240H - I just haven't had the guts to put a date on taking a perfectly serviceable aircraft out of the air.

I am considering a lot of modifications during the re-build. I came across this thread in the superb forums:

http://www.supercub.org/forum/showthread.php?40150-X-Brace

This considers the installation of a x-brace overhead. I have also read of the installation of a extra brace from the bottom of the instrument panel to the bottom of the firewall.

I see that Steve stated that he has installed this first mod previously on PA-16s.

The Atlee Dodge site indicates that it is on an STC for the PA-18 & 12.

Has anyone else had experience of installing these mods? By definition, these would be major modifications - would anyone have a copy of appropriate 337's please?
I take it however, that despite the obvious safety enhancements, the FAA would now not approve this type of 337?

A copy of a 337 would be useful though for reference.

Just had my prop re-pitched from a 52" cruise to a 48" climb - looking forward to the flight tomorrow to see what if any, difference it makes.

Regards

Dean

[ak49flyer]

Was just considering starting a thread asking the same thing. I’m just starting a -16 project I acquired. The top deck x-brace seems to be a forgone conclusion on cubs; how about shortwings?

[Steve Pierce]

I was in a midair at Sun & Fun in 2002 and went straight in from 100 feet. The right wing hit first and the impact transferred into the fuselage and collapsed the rear spar carry-thru tube behind my head. The right seat back was sitting out the door opening. The upper deck "X" brace will keep that from happening. The FAA would not approve the modification for a Clipper owner several years ago after I sent him a previously approved 337. I then sent him the pictures of my accident aircraft and asked him if he wanted to be responsible if something happened over adding two simple tubes. It got approved. If it didn't I would add them anyway. Atlee Dodge felt so strongly about the mod in the Super Cub that he gave it away.

[dhillier]

Thanks Steve - that has pretty much settled it in my mind. It it were to be approved, could you remind everyone of the dimensions of the tubing or post a copy of the 337 please.
Do you have a view on the other cub type modification that puts an extra tube from the firewall to the instrument panel?
Sounds a accident of nightmares. Glad you are ok.

[Steve Pierce]

I don't have the 337s in pdf but hopefully my Dad does. I believe this is the tube in the front section the Super Cub guys are talking about. It is for crash worthiness in case of a nose down impact. Not sure if it interferes with rudder cables on a Short Wing.
12961

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[Gilbert Pierce]

Picture of x brace and 337/

[dhillier]

Thanks very much.

Dean

[ak49flyer]

Thanks, Steve, and Gilbert; do you have any pics of the belly tail inspection panel mod and the center seat belt attach? Two more mods I’ve been planning to incorporate on our project. Thanks again...

[Gilbert Pierce]

Thanks, Steve, and Gilbert; do you have any pics of the belly tail inspection panel mod and the center seat belt attach? Two more mods I’ve been planning to incorporate on our project. Thanks again...

Belly panel and center seat belt attachment lug.1296912970129711297212973

[ak49flyer]

Thanks, Gilbert.

[wmvosburgh]

Looking this thread over as I continue puttering on the pacer project. The x-brace sounds like a no brainer on a pa 16, but would it be worth the effort on a pa 22? If you had a bare fuselage, what safety enhancements in regards to additional tubing would be worth considering?

[Steve Pierce]

The Pacer has a V structure which is actually better than the X. The X is a modification to rectify the crash worthiness of the Super Cub and Clipper. The Husky, Pacer and Tri-Pacer have that issue rectified in the V structure already.

[wmvosburgh]

Awesome, Thanks Steve!