SECTION 40: FLAP SYSTEM

Check for more recent updates here

The bellcrank jig comes in the wing kit and at this point you may have possibly misplaced it. The measurement from the bottom of the jig to the 1/4 inch hole shown in Figure 2 is 1 & 31/32 inch if you want to make your own.

Step 2: You will need to re-assemble this in the airplane with much more difficult access. You will also need to twist pieces. Make sure that everything is deburred well so that the pieces can be re-assembled with minimal friction. An extra 15 minutes at this step may save you hours later.
Step 4: See this pdf with 4 templates for the cutout with rounding radiuses applied. Print at 100%. The outer corner dimensions on the printout should be 2.5" * 1.75".
Step 5: Grease may help get the bushings onto the tubes. In general, consider using grease on all unpainted portions and plastic bushings to minimize friction and protect the steel.

Step 1: Alternate way to install the torque tubes: instead of inserting the torque tubes like Figure 1 on page 40-5, instead slightly enlarge the holes in the skins on the wing roots so you can insert the torque tubes from the outside. Put both torque tubes in the freezer for about four hours. This makes it easy to slide the plastic bushings in place. The tolerances loosen up considerably between the plastic blocks and the steel tubes. Don't forget the central flap crank and make sure to position the UHMW plastic blocks before everything warms up.
Step 7: Be careful about how tightly you attach the AN3 bolts to the plastic bushings
- It's easy for the bolt head or washer to push into the bushing and cause a hole before getting fully tightened.
- Consider putting a washer (perhaps even an AN4 washer) to help prevent this.
- Fully torqueing these bolts can distort the plastic bushing and cause unnecessary tension on the rotation of the flap tubes.
- Test the rotation of the flap tube during this process so you will know if/when it stops rotating smoothly. Note that the rotation will likely end up being fairly stiff either way, but it may be a good idea not to make it any stiffer than necessary.
- Note that the newer RV-14 instructions specify that these do not need to be fully torqued.

Step 1: Consider skipping ahead to Page 40-8, Step 3 before bolting the flap crank in this step. Numerous builders have remarked that access is difficult when bolting the WD-1013 horns in the confined space along the fuselage sides. By not bolting the torque tubes to the central crank arm at this time, it allows you to spin/orient the outboard horns/torque tubes in any orientation thus making bolt installation easier. After this step, you can bolt the central crank arm to the torque tubes. Make sure everything is clocked correctly. This is highly recommended and there is no downside to bolting the two outside flap horns before bolting the inside crank.
Step 5: Use the F-1066A-1 bracket as a guide when tightening the castle nut -- if you tighten things too tightly, not only will the flap motor not rotate easily, but the assembly might not line up with the pre-drilled holes on the F-1066A-1 bracket.

Step 2: If you are having issues and you already bolted in the WD-1013A flap crank, consider unbolting it so that you can rotate the flap horn/tube more freely to get the four AN4 bolts installed. It may be impossible to get your torque wrench on all four of these AN4 bolts. At the very least, properly torque one bolt per side and then use the tightness of that nut to feel out the proper torque of the other nut.

The old flap motor (before mid 2022) has no built-in position sensor and needs an external POS-12 sensor. See section Flap_Position_Sensor

Some seem to be able to test their flap motor/actuator with a 9 volt battery, where others report you need a 12 volt battery to run the motor. This appears to be due to different generations of actuators.

Contents