The International Cessna^® 170 Association

So, I picked up a set of Rosen side mounts.
I don't have the nutplate in the forward face of the spar (1952) but I do have the single nutplate on the bottom of the spar (Both sides).

I'm not really crazy about knocking 4 new holes in my spar, even if Rosen says it's OK.
Has anyone tried using the single nutplate to mount the visors? It won't line up with any of the drilled holes on the Visor but, I could make an adaptor of sorts of of a piece of aluminum bar stock.

Thoughts?

Yes, but if you do that you will not be in compliance with the Rosen STC installation instructions.

The drilling of the front "spar" is not actually the spar....it's a hat-section, and the small holes for the rivnuts shouldn't be a problem. (and it's an approved installation versus any ad-hoc one which may later be questioned.)

I did notice that one of the reviewers of the product made the following comment:

"Cons
Installation of screws for the mounting bracket did not work as per instructions. Riv nuts provided were too short to extend through the carry through spar thickness and therefore did not form the riv nut properly when pulled. Had to use alternate method of installing the vertical screws for the brackets"

David,

The single nut plate you mentioned is for mounting the original Cessna (optional) sun visor kit. It is illustrated in the Parts Catolog Fig. 101 and takes an AN3-5A bolt. Also, see Fig. 21-8 (Attach sunvisor). As George says, follow the Rosen STC instructions.

I understand it's a hat section but everyone calls it a carry thru spar vs carry thru hat section.

Interesting note on the rivnuts. The ones provided in the kit appear slightly longer than other ones I've used. But I can measure the thickness of the material and make sure there is enough to properly set the nut.

Other things I noticed while fitting things yesterday.

1. You need to press in at least one headliner retainer tooth on the strip attached to the forward side of the hat section / spar. Be sure to get it very clean so the tooth goes flush or your bracket will never fit straight. Or, just break off the tooth and file it smooth.

2. You need to cut/trim the trim pieces that goes along the forward side of the hat section / spar as well as the upper door post trim piece in order to get the bracket over as far to the side as you can.

Yes, it is called a "carry thru", that is correct. But it only carries load in tension/compression and not any bending moments due to the wing struct attach to the gearbox/doorpost area, so a small hole or two drilled away from edges has virtually no effect on it's capability, was the point I was attempting to make.

gahorn wrote:Yes, it is called a "carry thru", that is correct. But it only carries load in tension/compression and not any bending moments due to the wing struct attach to the gearbox/doorpost area, so a small hole or two drilled away from edges has virtually no effect on it's capability, was the point I was attempting to make.

Where as a traditional 'spar' is carrying a bending load as well (at least outside the strut). Now I see why you were making the distinction.