170A Inner Cowling: Piano Hinge Mod

[spduffee]

Has anyone ever modified the inner cowling of a 170A by installing piano hinges in lieu of the two rolled edges that wear out? Has anyone ever seen it done, have pictures of it? The 170A has a top piece that is fastened in place. The two side panels slide or catch onto the top piece (or should) via rolled edges on each panel. If these start to fail, corrode or bend, they don't catch and slip out of place. I would think I would just have to cut a bit off each panel, weld or rivet a piano hinge onto the top and side panels and... If anyone has seen this or knows how to do it properly, please let me know. Thanks!

[Bruce Fenstermacher]

I'm not sure a piano hinge would work. On both my aircraft you had to lift then slide the door a bit to the rear to clear the front nose bowl. Yes this are gets worn but the most I've done is to add a PK screw or two along the overlap to help hold the lip together and the lid in place.

[kidalways]

I just replaced my whole inner cowling due to cracks and just overall appearance. I thought that I would also re-design this rolled latching of the cowl pieces - but after some thought I chose to stay with the way the original panels were done. However when I made my new panels I installed a small 6 inch long "L" bracket ,if you will, just inside of the rolled interlocking section of the center cowl panel. By doing this it does not allow the side cowls to not slip out of place. I made all the new pieces myself - granted I have the equipment - but if you want to see what i did - let me know and I will take some photos.

[spduffee]

Thanks Bruce, I hadn't thought of that. I'll have to look at it once again.
Kid always, if you don't mind posting some photos, I'd like to see what you did and see your homemade units. Thanks, Shawn.

[mekstrand]

Spduffee,

I've also got a 1950 A model that had worn out baffeling. I replaced it a few years ago and substituted piano hinges just as you suggested. It has proven to work very well and is easily removed without any tools. If you have any questions or want to have a look in person send me a PM, I'm just up the road at PAE.

Here's a couple photos from when I was putting it together.

[Bruce Fenstermacher]

I've also got a 1950 A model that had worn out baffeling. I replaced it a few years ago and substituted piano hinges just as you suggested. It has proven to work very well and is easily removed without any tools.

Can you pull the pins out through the front nose bowl or do you have to remove the cowl to do so? Can the inner baffle lid swing up open with the cowl on?

Another idea might be to use two shorter hinges so smaller pins can be pulled inside the cowl rather than one longer hinge. Like a normal 3 hinge door would be hung but you'd likely only need two hinges maybe 5" long.

[mekstrand]

Bruce,

Yes, the hinge pins can be pulled out through the front nose bowl. The hinge pins are first rotated and then pulled forward about an inch and a half then flexed slightly outboard (to clear the nosebowl) and pulled out. The inner baffle can swing up with the upper cowling in place but due to the shape of the rolled baffle it doesn't provide much access to anything before the inner baffle comes in contact with the upper cowling piano hinge. I should add that the the forward ends of the hinge pins are safety wired to the forward flange and must be rotated around the flange before they will come forward at all. This prevents the pins from wandering forward and coming in contact with the nose bowl. As I said before I'm very happy with the piano hinge arrangement as its very secure and only takes a few seconds to remove.

[spduffee]

Sweet! Yes, that's what I'm talking about! I will definitely make my way up to Everett to see that. Thank you for posting this.

[KS170A]

Here's a couple photos from when I was putting it together.

Incidentally, I'm also re-working my pressure box baffles. Do you have additional photos you'd be willing to share?

[mekstrand]

Josh,

Sure. I didnt take very many photos as I was working quickly to get the plane back in the air but here's what I took. I'll take some more photos next time I have the cowling off.

Here's the forward mounting bracket.


Here's my original and new rear section.


Here's the center portion before the piano hinge was installed.



Another view of the same part.



Another view of the front side before the horizontal ramps were installed.