[N24YW]

I have 280 hours and my bottom hinge on the cowling is missing a couple of the hinge pieces next to the exhaust in the center. I have hear this being a on going problem. What is the best fix for this problem. I wish I could have used or found stainless hinge matereal for the original install.

Thanks
Jim Knight
Burlington Iowa
RV-6 FLying since July of 2005

 

[JonJay]

The cowling needs to be supported on the inboard edge. I followed Van's lead on their demo airplanes and installed an angle on the firewall with nut plates to accept #8 screws, one per inboard side.
Simple easy fix. Takes seconds to remove the screws to take the bottom cowl off. I did this before I broke any hinge segments.

 

[Steve]

Prob'ly something similar in function to that lash-up the "A" models use to support the sides of the nose leg slot.

Steve

 

[N941WR]

One other fix is to change to a SS hinge. At least that's what my Tech Counselor did on his -6A and never had a problem.

I used Skybolt fasteners on my -9 because I had heard this was a problem.

 

[rvbuilder2002]

The cowling needs to be supported on the inboard edge. I followed Van's lead on their demo airplanes and installed an angle on the firewall with nut plates to accept #8 screws, one per inboard side.
Simple easy fix. Takes seconds to remove the screws to take the bottom cowl off. I did this before I broke any hinge segments.

I don't think any of Van's demo planes have an angle with a screw.
They are built per plans with only hinge, but with a #6 screw at the inboard most rivet location on the cowl because this fastener is loaded in tension, and coupled with a lot of vibration will tend to fail if a rivet is used.

 

[JonJay]

Yep

I don't think any of Van's demo planes have an angle with a screw.
They are built per plans with only hinge, but with a #6 screw at the inboard most rivet location on the cowl because this fastener is loaded in tension, and coupled with a lot of vibration will tend to fail if a rivet is used.

Obviously, you would know, but that is where I got my inspiration to put a screw there. I used an angle riveted to the firewall with a nut plate for the screw to go into. Only viewed your demo planes from the outside, so not sure how you guys hold the screw in, but the angle worked for me.

 

[ncarmon]

Can you guys post some pictures?

 

[vlittle]

I don't think any of Van's demo planes have an angle with a screw.
They are built per plans with only hinge, but with a #6 screw at the inboard most rivet location on the cowl because this fastener is loaded in tension, and coupled with a lot of vibration will tend to fail if a rivet is used.

I had the inboard 2 rivets fail on both sides. I tried 1/8 pop rivets, still failed. Now I have #6 screws.

Hopefully this will fix it.

 

[Jim Harchanko]

bottom cowling hinge

I applied a couple layers of fiberglass/epoxy over the hinge rivets. After 4 and 1/2 years and 400 hours, there are no breaks/cracks.

 

[Snowflake]

I don't think any of Van's demo planes have an angle with a screw. They are built per plans with only hinge, but with a #6 screw at the inboard most rivet location on the cowl because this fastener is loaded in tension, and coupled with a lot of vibration will tend to fail if a rivet is used.

An old thread, but as I found this while dealing with a similar issue on my own cowl, thought i'd add this for future reference to others...

There are two failures being discussed here:

1. Piano hinge loops failing, in which you're left with a nice aluminum reinforcing strip on your cowl, but no loops through which to run a piano wire.

2. Rivets failing, in which the piano hinge is coming free from the cowling but staying attached to the firewall with the piano wire.

If you used aluminum piano hinge, and solve #2 with screws into the cowl, there's still a chance you'll see #1 some time down the road.

I currently have #1, and will be solving it by replacing the inboard portion of the hinge with a plate riveted to the firewall flange, and #8 screws/nutplates/countersunk washers to hold it to the cowling. I'm still evaluating whether it makes sense to remove the entire piano hinge along the bottom and put in a single long plate... I'm thinking it would be easier to remove 4 or 5 screws along the bottom than to dig past the innermost screw to try and find the piano hinge, as it would be recessed.

 

[JonJay]

I just have one screw and the hinge.

An old thread, but as I found this while dealing with a similar issue on my own cowl, thought i'd add this for future reference to others...

There are two failures being discussed here:

1. Piano hinge loops failing, in which you're left with a nice aluminum reinforcing strip on your cowl, but no loops through which to run a piano wire.

2. Rivets failing, in which the piano hinge is coming free from the cowling but staying attached to the firewall with the piano wire.

If you used aluminum piano hinge, and solve #2 with screws into the cowl, there's still a chance you'll see #1 some time down the road.

I currently have #1, and will be solving it by replacing the inboard portion of the hinge with a plate riveted to the firewall flange, and #8 screws/nutplates/countersunk washers to hold it to the cowling. I'm still evaluating whether it makes sense to remove the entire piano hinge along the bottom and put in a single long plate... I'm thinking it would be easier to remove 4 or 5 screws along the bottom than to dig past the innermost screw to try and find the piano hinge, as it would be recessed.

The angle I used to attach the nutplate for the screw rides over the top of the hinge. I used a round head #8 screw with a nylon washer and tighten it only to the point that it takes up some pressure, not all of the way down. You could use a spacer to take up the small amount of gap but I did not.
My theory is that the hinge and rivet problem is caused by the weight of the cowling and vibration working together.
My first rivet started smoking within a few hours. Now, over 300 hours and everything is as it was from day one with no signs of rivet or hinge issues.
I am sure there are better ways to do this, but this worked for me.

 

[BillSchlatterer]

Just a plate and screws,...

Just a piece of 041 with #8 nutplates. Very simple, allows just a little movement and seems very solid. I put a little bend in it to allow for the thickness of the cowl but would not do that if I did it again. Also using something like 41 allows you to "adjust" it a little bit after riveting.




Uploaded with ImageShack.us

Hope this helps.

Bill S
7a almost there

 

[Snowflake]

Further update, after taking a closer look this evening: My hinge is stainless, and the hinge on the cowling looks like this problem has been fixed once before. The innermost half of the hinge has been cut off, and a new piece spliced in. Sadly it's the new piece that's now failing.

I think i'll stick with the plan. Add a plate to the firewall flange that extends inside the cowling, and remove the broken end from the piano hinge in the cowling. I'm only going to make a plate about 3" long though, i'm going to leave the existing intact piano hinge in place and just reinforce the "free" end. I'll try to take photos tomorrow.

 

[Rick6a]

Documenting a Repair

Can you guys post some pictures?

I had the inboard 2 rivets fail on both sides. I tried 1/8 pop rivets, still failed. Now I have #6 screws.....

Built per plans, this is the logbook entry I made documenting the repair I made for a failure that seems to be very common. Since the time of the last repair, everything continues to appear normal.

 

[uk_figs]

Switch to extruded hinge

Had the same problem with the standard hinge, Vans sell an extruded (versus rolled) hinge that is stronger and I replaced the plans version with that. I also put two nutserts on the inside end of the hinge pins and used small hinge pieces to hold the hinge pins in place (similar to the cowl pin retainer approach) as I read that a big contributor to this problem is vibration caused by exhaust pulses in this area. Have 100 hours since with no problems.