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Flap torque tube help

J

joew

Well Known Member
I installed my side bearing blocks and noticed the fit is really tight as far as moving the tube when it's inserted into the blocks. I lightly sanded the holes and the tube which helped a bit.

I put everything in place, including my center bearing block, installed my nut plates and tightened everything down. The motion of the torque tube feels tight...not sure what that means though. Almost too tight IMHO.

When I sight down the tube (side to side), I see a slight bend in the tubes at the side bearing blocks. Not a straight line across. Considering adding shims and longer bolts at the side bearing blocks to bring everything in line.

I must not of had the side blocks in the exact position when I drilled the holes for the center block. Any ideas?

Thanks,

Joe
 
Flap side blocks

Joe,

Hmmm, Although my plane has been flying for 2.5 years, I often get an initial 'clunk' when I deploy the flaps. This has been hounding me for quite some time. I've removed the side covers over the end blocks multiple times and all looks good. But just recently, I again removed the side covers and noticed that the blocks torque a small amount on initial deployment. I'm thinking the same that I may want to remove the two bolts holding the end blocks in place and see whether there is any shift of the block- a small shim may be the answer.
The flaps have worked without incident, but I now realize that a shim behind one (or both) blocks may relieve some of the tension.
Hope this helps.

Jim Diehl 7A
Lock Haven, Pa.
 
loosen the hold down bolts. If the tightness loosens up you have a geometry issue that needs to be fixed. keep playing with shims until it is not binding. If still tight, you'll need to keep sanding the blocks until it loosens up a bit. Don't sand the tube, just the blocks. I used white grease as well. Mine are a bit firm, but not tight.
 
Recheck

I went back and rechecked. I removed the the side bearing block bolts and kept the center block in place, to see how large the shims need to be. I measured about 3/16" to 1/4".

I guess I have two options. Make shims up to 1/4 inch thick and use those on both side bearings and use longer bolts.

Or

Order a new center bearing block from Vans, remove the aft nut plate I installed and make a flange doubler for the floor rib out of angle. Reinstall the center block, using the doubler and nut plate for the aft hole, and position the forward hole in the block to match the one already in place.

The shim option is easier. Any downside to using the shims?
 
I had the same problem and then noticed my center bearing block was not an exact match (dimensions) to the full scale picture in the drawings. I cut the bearing block down to match the dimensions in the drawing and now everything fits as it should. The block was labeled with the correct part number so I don't know if it was mislabeled and actually belongs to a different kit or not. Nothing in the instructions or drawings stated that it needed to be trimmed down in the manner that I had to.


joew said:
I went back and rechecked. I removed the the side bearing block bolts and kept the center block in place, to see how large the shims need to be. I measured about 3/16" to 1/4".

I guess I have two options. Make shims up to 1/4 inch thick and use those on both side bearings and use longer bolts.

Or

Order a new center bearing block from Vans, remove the aft nut plate I installed and make a flange doubler for the floor rib out of angle. Reinstall the center block, using the doubler and nut plate for the aft hole, and position the forward hole in the block to match the one already in place.

The shim option is easier. Any downside to using the shims?
Click to expand...
 
Torque Tube

I guess I'll redo the center block. I'll order a replacement from Vans, remove the aft nut plate, make a doubler from angle and install that underneath the flange. That will allow the center block to move forward and stay inline with the sides. The forward hole I will keep, and match the block to it since my edge distance is good.

I'm afraid to add shims to the sides which would be easier, but concerned over causing another misalignment later on.

Appreciate your inputs,

Joe
 
Reply

I did add a washer between the two halves. I saw that some of you all did just that. It wouldn't resolve the bowing of the torque tube sides though. Only thing to fix it are shims or redo the center block position
 
Resolution

After speaking to Vans, Ken opined that the idea to remove the nut plate and placing a doubler under the flange while working in the center tunnel would be too involved.

He agreed with the shim idea, saying it wouldn't affect anything. He then suggested the route i will go. Told me to make a new block from Derlin plastic stock. I found some 3/4" thick, 2" wide and a foot long at McMaster Carr. I will use the old one as a template, making it a bit longer and match the holes to the nut plates I already installed.

I'll let ya know how it goes.
 
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