Nose Cowl Fastners

[Charles Schefer]

[Charles Schefer]

So... today my IA and I started the process of replacing the SouthCo fasteners with the nut plates and stainless #8 screws and countersunk washer/trim-rings I obtained from Webco. When I ordered the hardware, Webco told me that the rivet holes in the nut plates have a slightly different distance apart than the factory holes for the old SouthCo fasteners but they are "close enough" to work. I recall them saying something about "angling it" and I thought they simply meant angle the rivets inwards through the factory holes to meet up with the narrower nut plate holes. My understanding (or misunderstanding as it turns out) was that the difference would be slight.

Attached here is a pic of how I thought the nut plate would be installed (except that the nut plate of course goes on the inside not the outside - I just put it on the outside to illustrate and make it easier to take the picture):

The problem is the difference in the distance of the holes between the nut plates and the factory holes in the airframe is between 0.05" and 0.06". That's the width of 1/2 or more of a rivet. They simply will not install this way it is not just a slight difference.

I called Webco back and they said it is not the rivets that need to be angled (they agree that won't work), they say it is the nut plates themselves that must be angled and 2 new holes drilled in the airframe. The factory holes used by the SouthCo fasteners will remain unused. Here is a picture of how they say to install the nut plates (again showing the nut plate on the outside instead of the inside simply for ease of picture taking and illustration):

I am not sure I want to drill new holes in the airframe for this purpose. According to Webco there are NO nut plates available that match the factory holes. They say that such hardware simply does not exist.

My question for the ICS forum and in particular, Pat and others who have made the nut plate conversion... are your nut plates installed as shown in the first picture or the second picture? If installed in the factory holes as shown in the first picture, can you tell me what kind of nut plates were used and where to get them. If as in the second - any advice on how much to angle and / or lessons learned would be appreciated. Overall before drilling new holes I thought it was worth asking more questions.

Many Thanks. While waiting to hear back from the forum we will get on with installing the new Bogurt Battery Box, copper cables, tubing, and Concorde AGM battery. Can't wait for the added cranking power!

Thanks,

- Charles

[N3322G]

Charles,

Sure do appreciate your frustration. The fine folks at Clifton made all of those hardware acquisitions and nut plate placements. My job was to start the conversation, fund the project and enjoy the outcome. There were 4 Southco's that were always hard to get in and since we used the same holes, there are now four screws that are hard to get it - a locator/aligner tool fixes it every time. Wish I could be of more help.

[Charles Schefer]

I just spoke to Tim at Clifton, what a great guy to chat with. Tim says that they do the nut plates exactly as described in my second picture of the previous post - the way Webco suggests at a 30-deg angle and drill 2 new holes. Hmmm I will have to think about that. I may just do new SouthCos.

- Charles

[William Flood]

Sorry to hear that the plan for the nut plates didnt work out. I was very close to calling webco and ordering the same. I think I may grin and bear the Southco's for another while so.

William

[JIMICS2452]

Not a big deal to drill new holes. Just make sure you can get a squeezer od a bucking bar behind them. In a couple of locations we ended up using Cherry pop rivets.

[md11flyer]

What I have done to ease the removal of the bonnet without installing screws, is removing the retainer rings on the fasteners.When I do the halve turn of the fastener
to remove them they just dangle loose in the hole and I simply feed them out of the hole.
This way you get the best of both worlds, fast removal of the halve turn fastners and no scratching of the paint.

Gary

[Charles Schefer]

Gary, that's a rather clever idea.... What I really would like about the nut plates and screws (or camlocks) is the nice stainless trim ring around the outside. I don't like the way the SouthCo screw heads are right up against the paint work.

- Charles

[Charles Schefer]

I haven't given up on the idea of nut plates and screws using the factory SouthCo rivet holes yet. I have spoken with someone at Aircraft Spruce and sent the attached diagram and they are going to see if they can source them. I'll let you know what I find out.

- Charles

[bernard nowlen]

I like gary's idea. I think one could selectively remove the retainer washers on the fasteners that cause problems. Perhaps just the bottom side corners ?
Ideas ?
bernie

[Charles Schefer]

Bernie - I agree with your thinking and Gary's idea. If the side retaining clips are removed that should solve 90% of the fussiness of the SouthCos. I'm also looking at CamLocks but I don't know that they will make it all that much better. If Spruce comes up with nutplates that are 3/4" on center (rivet holes) to match the factory holes than I will go that way but otherwise - new SouthCos with removed retaining clips. Brilliant!

- Charles