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Ah, but there is a way to stop it. It works, is inexpensive and has the added benefit of being the closest tolerance hinge tested to date. This has been discussed previously, but is worth going over again.
The key to preventing wear in the standard MS hinge is to distribute the load across sufficient area of the hinge material. The MS hinge pin doesn't do this. Its diameter is too small. Here is where the welding rod comes in. Because of its close tolerance fit, contact stresses are reduced to an insignificant level. This effectively translates into an infinite hinge life. I tried this on my plane ~11 years ago and there is still no sign of play.
The point of the original post was in regards to shaking doors and play in the hinge and rod end bearings. This is where the welding rod approach is better than anything we have seen to date. It has the least inherent play. I would caution against using any hinge with nylon bearing material in this application. In the gear door installation, the actuator is attached out in front of the hinge. This places a disproportionate load on the very first hinge element. Nylon is only good to ~2,000 psi and by its very nature will creep under load. Over time, this will only add to the play in the hinge and require continuous readjustment to the doors.
Chris Zavatson
N91CZ
360std
Lots of talk about hinges on the gear doors. Consider that aluminum by its nature wears with time, friction and the elements. Probably no way to stop it. That means the moment you put that aluminum hinge in service the fit between the pin and the hinge begins to wear and gradually become more and more sloppy.
Carbinge is designed with a nylon bearing that in our studies overcomes this quandary.
Shameless plug,
John Barrett
Leading Edge Composites
www.carbinge.com
From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Chris Zavatson
Sent: Friday, March 04, 2011 6:14 AM
To: lml@lancaironline.net
Subject: [LML] Re: Lancair 360 Inner Doors
If you extend the hinge line all the way forward to the leading edge of the door when you change out the hinge, it will stop the premature wear. The attached photo shows this mod with the original door installed. It will not stop all the 'shaking in the breeze' as seen in the video link, but will help save the hinge. The moment arm for the actuator is still too small for the size of the door.
Rod end bearings come in different flavors. This goes for all the spherical bearings as well, If you upgrade to a better alloy, it will prevent the play from developing. The load rating will seem excessive, but you will never have to replace the bearing for the life of the plane. Tolerances will remain much better. You can download the Aurora catalog, for example, and see how different series have different load ratings for the same dimensions. You'll need to go to a bearing place like Motion Industries to get these.
From: JON ADDISON <jraddison@msn.com>
To: lml@lancaironline.net
Sent: Thu, March 3, 2011 12:37:46 PM
Subject: [LML] Lancair 360 Inner Doors
Lancair 360 Inner Doors... again...
I have the larger inner doors and they vibrtate badly. (Someday I'll try to get the 3 piece carbon fiber doors)
But for now: I'm in the process of changing the worn hindge to an extruded aluminum hindge with an "over size" 3/32 " (.095 ") stainless steel welding rod.
Plus
replacing worn rod-end bearing. (New from Lancair this morning)
Considering remaking the attach channel that connects the rod end bearing and actuator to the door. ie making it twice as long as the origional.
Wondering if the attach point under the seat needs to be make tighter with possibly metal sleeves after drilling out the attach bracket on flloor.
Also, considering making a tiny spoiler 1/8 " or so high and temp mounting on aft / lower edge of door to stabalize it (and probably loose a knot).
Opinions and fixes that worked?? (Except the carbon doors which I can't afford yet.)
And also does anyone know if the inner door actrator can be rebuilt... both or mine leak a bit.
Jack Addison
N360JS Sisters, Oregon
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