Looking for Guidance on Cowl Attachment

[Jesse]

Originally Posted by Carl Froehlich

Reread my post. The 1/8? pins are filed down on the ends so they make the bend. They are full size along the top flat parts. This takes out the slop that exists between the 1/8? hinge eyes and the standard 0.90? pins along the top so under pressure the cowl does not bulge up.

Carl

Reread my post. I was responding to Scott.

[Mel]

The hinges work very well between the longitudinal seam. They work very well vertically on the sides of the bottom cowling. Many people have found them nice across the top.
Personally, most of the RVs I've worked on have screws or 1/4 turns across the top and bottom of the firewall.
Hinges across the top are difficult to install on many aircraft. Hinges across the bottom tend to break the hinge eyelets starting at the air outlet.
This is my experience working on RVs for over 30 years.

[Phil]

I noticed yesterday that I have .090?s on the top bends and on the sides (upper and lower attachment). The lower cowl at the firewall is .125?s.

No issues after 160 hrs despite the slightly smaller than suggested side pins. I do wish I had used extruded hinges though. I haven?t had any problems yet, but would like the longer-term confidence of having extruded pieces.

I have been considering dressing the pins with valve grinding compound and rotating them with a drill to help open up the travel-tunnel a bit. One of these days, I might try it.

[lr172]

Originally Posted by Carl Froehlich

Never liked the look of screws or camlock on the cowl (to each his own).

I used hinges with the following mods:
- On the top, instead of using the 3/32” pin in the 1/8” hinge, I used a 1/8” SS pin that I trimmed down to 3/32” on the last 10-12 “ or so. This allowed for the pin to still go in and make the bend, but it mitigates the cowl bulging up on air pressure at the top.
- On the bottom I used the MS20001P extruded hinge instead of the provided hinge. This hinge is far more robust and solves the typical issue of hinge eyes breaking off on the bottom hinges from vibration.

All is well after 500 hours.

If you don’t use the the extruded hinge on the bottom, use aluminum plate and nutplates.

Carl

The hinges that I have for cowl have .125" holes and may try your trick with the modified .125 pins. However, the extruded hinges that aircraft spruce sells all have .090 pins, even in the thicker versions, which I assume that I would want for the bottom. Is this what you used or did you find something with .125 pins?

Larry

[rvbuilder2002]

Originally Posted by Jesse

Page 47-7 specifies 0.090? pin material for this, not 1/8?.

The result of an apparent miscommunication, because both of the RV-10 prototypes have been flying with 1/8" pins (actually .115") at this location since they were built.

It works quite well since if built per plans, the pins insert at the top mid point of the firewall.

[lr172]

Thanks to all for the input. Much appreciated.

I can't wait to get past this top/doors!! Almost there though.

Larry