Suspect F9 bracket

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Postby ozzie » Mon Jul 02, 2007 2:33 am

Hi everyone.
I read a recent post on lazair groups were Chappy mentioned a brocken F9 he experienced some time ago. I checked the one on mine with a magnifying glass and it looks ok considering the age. Then i went thru my spares box for a new F9.
it did not need to be viewed with magnification it has a visible score line running right across it just above the bend. It looks like it has been caused by the fingers of the folder. Good chance that it would fail if it had been fitted. This fitting will have to be rebuilt before use.
regards Ozzie
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Postby ozzie » Mon Jul 02, 2007 2:37 am

one more
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Postby xgary » Mon Jul 02, 2007 5:23 am

Ozzie ,

Excellent Heads UP !!


Thanks
Shorty .............
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Postby Shannon » Mon Jul 02, 2007 5:35 am

Because of the fact that the F9's were weak we always doubled them with a hand formed doubler that attaches to the boom. We even installed them on the Series 3's where normally you wouldn't expect the F-9 to get much abuse.
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Postby Shannon » Mon Jul 02, 2007 5:36 am

F9 Doubler
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Postby trimjim007 » Mon Jul 02, 2007 8:39 am

That is a great idea Shannon! Could you make me one? I would pay you for your time and expenses of course. :D

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Postby lazairiii » Mon Jul 02, 2007 10:53 am

When building my ship, I took Shannon's advise. I built and installed this bracket and I'm very pleased with the way it turned out. My F-9 bracket does NOT show any signs of a manufacturing score mark or cracking, BUT since I was under construction anyway, I wanted it on the plane as redundancy. These little things will really add piece of mind while in the air.

George
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Postby lazairiii » Mon Jul 02, 2007 10:54 am

Another view...
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Postby ozzie » Tue Jul 03, 2007 2:22 am

Shannon, if you are considering making one of these for Jim, could you can put me down for two. thanks

whilst on the subject of cracks i also noticed some time ago a crack developing on the other end at the tail attach bracket. a slight crack on one leg. this looked like it started at the edge where it was cut out. the edges are rough looks like a jigsaw or router was used. i have filed the crack out, it was very small. might pay to have a close look at yours.
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Postby Shannon » Tue Jul 03, 2007 9:37 am

Ozzie I took a close look at the only new factory F-9 I have on hand. After polishing I was able to get a good look at the bend line. On this particular part there is a minor score mark on one side that does not go completely across. I do believe you are correct in assuming that a score running all the way across weakens the part. If the part is stressed it's undoubtably going to break along a score mark. I'd like to point out that past failures of the F-9's here happened when planes (Series 2's) were either pranged, hit a chuck hole, or repeatedly flown from extremely rough ground. There was no mass failure of F-9's here on planes flown under "normal" circumstances. Despite this I still think it's a good idea to make the part redundant. This is especially true for the Series 2's where normal loads from the nosewheel will put the F-9 under repeated stress.
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