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Postby lazairiii » Fri Oct 14, 2005 11:37 am

Ray,

Yikes!!! I've read/heard that it's NEVER a good idea to rest the tips on the ground as when you do that the attach brackets on the wings bind in the brackets on the fuselage and have been known to shear the solid rivets in the front assembley brackets. Please inspect these rivets carefully and reconsider doing this moving forward. There has been discussion about this in the past year and a fatal case noted due to this "wing resting on the ground" prior to the accident.

I believe the manual even states not to do this.

Just a note of caution,
George Curtis
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Postby JPXman » Fri Oct 14, 2005 3:29 pm

i believe this article was 2 pages but i can only find this one page - i think its posted somewhere else on this site, but maybe good for here too.
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Postby rayjb60 » Fri Oct 14, 2005 6:03 pm

Wow.....Thanks for the heads up on this important factor, I will definately review my assembly process and check all the fittings carefully.

This is the advantage of having a great support group at this site....pointing out things people could easily miss.

Thanks,

Ray
<H5>Nothing is impossible...Even the word tells you Im-Possible!!!</ H5>
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Postby flyalaz » Sat Oct 22, 2005 4:32 pm

When I bought my second plane, this is what I inherited. Notice the cut out areas on the plate. The person had started to make a conversion for a bigger central engine installation. Not well done or thought out. Also, most of the solid rivets were dumped, meaning that they were more like bent nails as opposed to properly formed upset ends.
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Postby flyalaz » Sat Oct 22, 2005 4:37 pm

This is how I finished. Thicker plates all around, and the addition of two bolts on either side of centre to prevent the type of rotation that could happen if the rivets shear. This mod is what I have been told that the factory came up with after that accident shown in a previous post.

Karl
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Postby flyalaz » Sat Oct 22, 2005 5:22 pm

Finally got a little time to work on my L/H engine. As you can see, it sheared off right at the face of the counterbalance. At least I didn't lose the P-Tip!
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Postby flyalaz » Sat Oct 22, 2005 5:33 pm

This is how I separated the motor halves. A bolt of suitable length with a couple of nuts to fit inside of the extensions on the bottom side of the case. Unscrew the nuts a little at a time equally on both sides, and with a little bit of wiggling, they came apart very easily. No hammers needed. Maybe it's because The front output shaft was broken, because the aft side of the crank won't come out at all. Guess I'll have to put it in the oven after all and pound it out.

Karl
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Postby russell » Mon Oct 24, 2005 8:09 am

The article of the rotated front wing clevis and associated photos are quite disturbing especially considering that the ends of the sheared rivets (if sheared by rotataion how can two of the six shear and not shear the other four?) are still in place. This makes an inspection useless because all appears correct so it's like crossing your fingers and hopeing for the best. Is there any other instances like this?

Russell
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Postby flyalaz » Mon Oct 24, 2005 3:32 pm

Hi Russell,

The upper four remaining rivets are only common to the wing attachment plates and associated spacers. When the three rivets on each side of the centre bolt sheared, in allowed the entire clevis assembly (wing attachment plates) to rotate on the control support tube attachment bracket, which is attached to the fuselage tube end cap with the bottom six rivets as well as the six sheared rivets and centre bolt.
Maybe someone out there knows if there were any other incidents of this type. I only know of this one, and it was enough to make me do the mod. It was already apart, and two bolts for peace of mind was a cheap price to pay. My other Lazair does not have this mod done to it, and I still have full confidence in the design. I will never make that type of mod (third engine) to my plane, and am content to fly it in the envelope it came in!

Cheers,

Karl
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Postby russell » Mon Oct 24, 2005 4:12 pm

Karl,
I too fly with great respect for the integrity of the Lazair. I know that it was designed to be strong but I am aware that if flown outside of it's design envelope one is taking a risk of failure. I have never stressed my plane while flying. As everyone is aware the most stress can be applied while simply handling or assemblying. From the article it appears that this failure occured because of an error in assembly prior to flight. I do a thorough walkaround before each flight but this structural damage in the article is not apparent in any way. I like your modification with the extra bolts, however, Dale's words keep ringing in my ears. He has always stressed never to drill a hole in anything, anywhere unless you understand the structural engineering of the plane. So, because of my ignorance in this I could never bring myself to make any modifications.
Should you hear of any problems anyone else has had with this piece please post them.

Thanks,
Russell
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