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| The factory-supplied all components for the flap mechanism. |
Trial Assembly
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| Fig 1 |
Each bearing block was mounted using two [2] AN3 bolts, and after fitting the torque tube, the outer block was fitted, and the assembly was clamped lightly using the bolts.
The arms were located equally from the outside faces of the bearing blocks at a distance of 71.3 / 71.5 mm from both sides of the bearing block's external faces.
With the shaft located, the external faces of the bearings were transferred to the shaft with a felt tip pen.
All components were now removed for painting and finishing.
Painting
The torque tube is manufactured using two separate tubes, which are disassembled by removing the four [4] AN3 bolts securing the assembly. The orientation of the aluminium coupling was noted for reassembly.
The two bearing blocks are machined from an aluminium bar fitted with plastic shell bearings, these were removed, and the bearing were placed to one side.
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| Preparation Process |
The location of the bearing blocks on the tubes at both sides was offset by about 1 mm, and two layers of masking tape were applied. Next, the area was coated with an automotive paint stripper, and the areas were wiped clean to bare metal.
The masking tape was removed, and the bare area was covered with new tape painting for the final painting.
The bearing blocks were marked with a centre punch to allow matched reassembly.
The individual items were all cleaned, primed as required, painted with the cockpit colour, and set aside to dry.
Assembly Torque Arm
The torque arm is now reassembled, and the AN3 bolts were tightened lightly to avoid crushing the tube; both bearing blocks were reinstalled with the bearing shell, torque tube and the mounting bolts were lightly tightened. It was noted that the shells would spin in the housings with the tube, and it was decided to lock them into each bearing half.
Note: to assist in disassembly, the mounting holes were enlarged to 5 mm to provide additional clearance
Comment: doing this again, I would look at using floating nuts riveted to the inside face of the bulkhead at the elevator side.
The method chosen was to apply a bead of Loctite Black Max ACC, align, then fit the bearing cap onto the opposite bearing block, and the assembly clamped using a quick clamp to dry. Both bearings assemblies were fixed using this process.
The tube did not fit into the bearing on reassembly, so each bearing was sanded using 320 grit aluminium open cut wrapped around a rod the same diameter as the tube. After light sand, each bearing closed around the tube with 0.015'' aluminium shims fitted to prevent lockup at final assembly.
Note: The problem with the fit may have been caused by the application of the ACC closing the gap at the entrance, and we would most likely use the small tube as a spacer when clamped if doing it again.
The bearing was greased, and the long torque tube was installed with the final operation to fit the short tube, locking collars more than the last two retaining bolts.
The grub screws holding the collars were treated with Loctite Thread Lock on assembly. All bolts were carefully hand-tightened to ensure smooth operation when turned by hand.
Flap Drive Fuselage Mount
The actuator attachment arm was set at 78 mm, as shown in Fig 1.
When the cylinder was installed, the mounting bolts for the actuator appeared to land on a set of existing rivets.
After contacting the factory, it was decided to remove the existing rivets and replace them with counter-sunk rivets to allow the actuator brackets to be installed.
The method chosen was to apply a bead of Loctite Black Max ACC, align, then fit the bearing cap onto the opposite bearing block, and the assembly clamped using a quick clamp to dry. Both bearings assemblies were fixed using this process.
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| Locking Bearings |
The tube did not fit into the bearing on reassembly, so each bearing was sanded using 320 grit aluminium open cut wrapped around a rod the same diameter as the tube. After light sand, each bearing closed around the tube with 0.015'' aluminium shims fitted to prevent lockup at final assembly.
Note: The problem with the fit may have been caused by the application of the ACC closing the gap at the entrance, and we would most likely use the small tube as a spacer when clamped if doing it again.
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| Bearing block ready to accept torque tube The installation of floating nuts is recommended for maintenance |
The bearing was greased, and the long torque tube was installed with the final operation to fit the short tube, locking collars more than the last two retaining bolts.
The grub screws holding the collars were treated with Loctite Thread Lock on assembly. All bolts were carefully hand-tightened to ensure smooth operation when turned by hand.
Flap Drive Fuselage Mount
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| Remove & replaced with counter-sunk rivets. |
When the cylinder was installed, the mounting bolts for the actuator appeared to land on a set of existing rivets.
After contacting the factory, it was decided to remove the existing rivets and replace them with counter-sunk rivets to allow the actuator brackets to be installed.
The plans call for the brackets to be fixed with AN3 bolts, but an examination of the upper mounting showed that this would not be practical, and it was decided to mount the brackets using 5 mm pop rivets to secure the brackets.
The brackets provided suitable clearance to the existing counter-sunk pop rivets.
Drive Attachment
Examination of the mounting points showed that when the brass bushes and mounting bolts were assembled, there were no fixed relationships. It was decided to fix the mounting bolt's relationship relative to the other components.
An AN4 bolt was brazed to an S/S lug manufactured from 0.015'' stainless steel. The upper pin was pop riveted using a countersunk rivet located on the inside face of the outer bracket. In contrast, the lower pin's tab was extended to lock into the exiting slot located through the side of the arm.
At the assembly, 1/4'' fibre washers were fitted at each face of the brass bushes; finally, an AN4 nylock half nut was fitted and lightly tightened to secure the whole assembly. The fibre washers are to as a washer and prevent damage to the arm.
Comment: If the upper lug was fixed using a screw into a tapped hole, this would allow the removal of the spigot bolt like the lower mount.
The brackets provided suitable clearance to the existing counter-sunk pop rivets.
Drive Attachment
Examination of the mounting points showed that when the brass bushes and mounting bolts were assembled, there were no fixed relationships. It was decided to fix the mounting bolt's relationship relative to the other components.
An AN4 bolt was brazed to an S/S lug manufactured from 0.015'' stainless steel. The upper pin was pop riveted using a countersunk rivet located on the inside face of the outer bracket. In contrast, the lower pin's tab was extended to lock into the exiting slot located through the side of the arm.
At the assembly, 1/4'' fibre washers were fitted at each face of the brass bushes; finally, an AN4 nylock half nut was fitted and lightly tightened to secure the whole assembly. The fibre washers are to as a washer and prevent damage to the arm.
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| Upper lug |
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| Lower Lug Note: Fiber red washer typical on both sides |
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| Final installation |
Comment: If the upper lug was fixed using a screw into a tapped hole, this would allow the removal of the spigot bolt like the lower mount.
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