Broken bracket

TJMay

Gold Supporter
Joined
Jun 12, 2006
Messages
485
Location
Santa Rosa Beach, FL
Aircraft
RAF 2000 GTX SE and Air Command Elite
Total Flight Time
175
I'm 99% sure this was not broken during my pre-flight. It damn near slapped me in the face during my post-flight. This is the bracket that penetrates the rear of the cabin and I assume anchors the fuel tank to the mast.

All of my 5 landings today were smooth, heard nothing pop and felt nothing unusual while flying or on the ground. Any ideas what could cause this break?

And, not having built his machine, not sure how to go about fixing it. Any ideas here?

Tommy
 

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Impossible tell anything from this single photo. Back away, get more surrounding superstructure in your photo frames. Take as many angles as you can. Next, what kind of gyro is it? How many hours on the AF? Fatigue is fatigue. If it is a part that mounts to anything that vibrates, if it was installed improperly in the first place, all that stuff could lead to failure. Example, was the part forced into position to bolt it in place?

Who built the gyro?
 
TJ,

That strap is L-shaped, and attaches to the back of your tank.

Unfortunately, you'll have to remove the seat tank to replace it. My guess is one or more of your seat bottom mounts is broken or loose, allowing the seat to rock side to side, or forward, enough to break that strap.

If you pull the bolt going thru the mast for the straps out, then you have to remove the four bolts under the seat. There are two on each side of the keel, which you can reach from the front of the seat, with difficulty. Remove the throttle assembly from the seat before you attempt to pull the seat out.

Removing and replacing the seat is a real pain, but is doable. I've probably had mine in and out 10 times over the last 5 years.

I would replace both straps when you get the seat out. You can make your own new straps to save yourself some money and time.

Good luck, and let us know what you discover when the seat is out.
 
NoWingsAttached said:
Impossible tell anything from this single photo. Back away, get more surrounding superstructure in your photo frames. Take as many angles as you can. Next, what kind of gyro is it? How many hours on the AF? Fatigue is fatigue. If it is a part that mounts to anything that vibrates, if it was installed improperly in the first place, all that stuff could lead to failure. Example, was the part forced into position to bolt it in place?

Who built the gyro?

Didn't think to take more pictures from different angles. I will but it may be a while before I can get back to the hanger.

It's an RAF with the higher seat tank. The TT is 278 hours.

It was built by Terrell Houtchens somewhere in Indiana, I think.
 
cgmg said:
TJ,

That strap is L-shaped, and attaches to the back of your tank.

Unfortunately, you'll have to remove the seat tank to replace it. My guess is one or more of your seat bottom mounts is broken or loose, allowing the seat to rock side to side, or forward, enough to break that strap.

If you pull the bolt going thru the mast for the straps out, then you have to remove the four bolts under the seat. There are two on each side of the keel, which you can reach from the front of the seat, with difficulty. Remove the throttle assembly from the seat before you attempt to pull the seat out.

Removing and replacing the seat is a real pain, but is doable. I've probably had mine in and out 10 times over the last 5 years.

I would replace both straps when you get the seat out. You can make your own new straps to save yourself some money and time.

Good luck, and let us know what you discover when the seat is out.

Thanks for all that.

How is the L-bracket attached to the tank?

Your comment prompted me to look more closely and found that there are two bolts that secure the cabin to the keel located immediately in front of the seat tank that are quite loose. They were obscured by the heater hoses that lie on top of the bolts and bracket. Are these the brackets you refer to?

Tommy
 
Tommy,

The upper straps attach to the back of the seat tank. If you're lucky, and the slot thru the back wall is tall enough, you can wiggle the tank out without loosening those back bolts. On mine, the slot is too low, and I have to loosen the back bolts to get the seat out.

Not sure what brackets you refer to holding the cabin to the keel, but those aren't what you're looking for. Under the seat, at the top edge of the keel, are two angle brackets that the seat sits on. There are two bolts at the front of those brackets, and two at the back. Those bolts are screwed into the underside of the seat. That's what carries the majority of the seat load, the upper straps are just reinforcements of the bottom mount.

If you use a flashlight, and bend down to the floor, you should be able to look into that keel chase under the seat, and see at least the front bolts. Failing that, slide your hand into the chase, and you will feel the bolts.

If the builder did it right, he mounted studs into the seat bottom, and used nuts under the bracket to fasten the seat. If he followed the manual, and used bolts into the seat, you're going to have a really tough time getting those bolts back into the seat.
 
The bracket I was talking about is several inches in front of where the seat tank meets the floor of the cabin. The picture shows the bracket with the heater hose moved to the side. I'll look for the brackets you are referring to next trip to the hanger.

How is the L bracket attached to the back of the seat tank? I assume with bolts thought the tank-back. And, if the slot is not tall enough, how do you get to the bolts to loosen them if the tank won't slide out due to the slot height?

Tommy
 
Here's the picture....
 

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I pulled out my construction manual that came with my machine and now see the two brackets and four bolts under the seat that need to be removed in order to remove the seat tank in order to replace the broken bracket.

But, while my mechanical skills and the tools available to me may be limited, my analytical skills suggest a more efficient way to attack this problem and would like some input.

Rather than struggle with the four bolts under the seat that anchor the seat tank to the keel, which I am told can be quite difficult, why couldn't I drill two holes through the rear of the cabin large enough for a socket that could reach the two bolts that secure the tank to the mast?

I realize that drilling through the cabin would require a great deal of care so that the drill would not penetrate the tank or catch in the carpet. I would likely have to start with a very small drill and slowly move up or, perhaps, file/grind the opening large enough to insert the socket.

Since there is a significant part of the broken bracket still protruding out of the slot, grabbing it and rotating it 90% to remove it through the slot after the bolt is removed should not be difficult. Inserting the new bracket and rotating 90% to reinsert the bolt should not be difficult either.

Once replaced, the two holes could be closed with a readily available plastic hole cover.

Any reasons why this approach should be reconsidered?

Tommy
 
Hi Tommy

Looking at the picture as best I can, it sure looks like a classic metal fatigue break, no distortion, twisting or tearing signs anywhere. If it is a fatigue break then it will have been caused most likely by high frequency vibes that you probably can't even feel.

Not being familiar with how "ridgid" this bracket is supposed to hold this bolt, I would suggest the following slight change. Enlarge the bracket in width so that a rubber grommet can be inserted into the hole and still have ample metal aroung it, then place a "fender washer on either side of the grommet. This will "kill" the high frequency at this point.

Just my 2 cents worth.

Tony
 
Hope you will be able to fix it without removing the set tank, those small bolts under the tank are almost impossible to remove and replace.
 
Tommy,

Your idea may work, but try this method first:

If you have enough room behind the seat, use a side ratchet wrench to remove the bolt in the back of the seat. If you have the room, it works, but it's a little tricky hanging onto the bolt and washer once it's loose. Try stuffing a rag underneath the bracket, so if you drop the parts, they don't fall to the cabin back floor.

That's what I do to loosen the bolts enough to flex the straps down enough to rock the straps out of the slot. In your case, though, the bolt has to come out, so you need the rag below it.
 
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