AIR TRACTOR AT-502A, Maintenance Section

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Maintenance Page 16 Air Tractor, Inc.
March 14, 2018 AT502A/502B/504
AILERON AND FLAP RIGGING
With the flap actuator in the “Up” position, the flap push-rods are adjusted so that the lower side of the
flaps form a straight line with the lower side of the fuel tank at station 61.0. Flap travel from this point is then
set at 26
o
(+/- 1 1/2
o
). Flap markings on the flap are located opposite the wing flap bay upper skin so that the
pilot will view the markings at 10
o
, 20
o
, and at full travel.
The ailerons are rigged with the trailing edge 1/8" to 3/16" below the flap trailing edge so that flight
loads will bring the trailing edge up approximately even with the flap trailing edge. Aileron travel (with flaps
up) is 20
o
up (+/-1
o
) and 14
o
down (+/- 1
o
). Aileron control stops are located under the cockpit floor on each
side of the torque tube horn. The adjustment consists of tightening or loosening the bolts that compress a
stack of 6 to 7 neoprene washers (p/n 70067-1). The neoprene washers act as shock absorbers for the
control system, but sometimes split and fall out, so it is advisable to inspect the stops during annual
inspections.
The aileron and flap control system components under the cockpit floor are rigged as follows:
1. Set the control lock on the stick. Flaps full up.
2. Check the length of the push rod assembly (p/n 70014-2) that connects the flap torque tube to the
90
o
bellcrank. It should measure 6.65" from bearing hole to bearing hole.
3. Check the length of the push-rod assembly (p/n 70014-4) that connects the 90
o
bellcrank to the
rectangular welded support frame assembly (p/n 70072-1). It should measure 13.78".
4. Check the length of the push-rod assembly (p/n 70347-1) that connects the aileron control horn to
the 180
o
bellcrank. It should measure 19.88".
5. With all push-rods the correct length, the 70072-1 support frame assembly should clear the
fuselage vertical tube at the bottom approximately 1/4".
6. The push rod assembly (p/n 70014-1) that connects the wing bellcrank to the aileron will be
approximately 10.69" long but this is the push-rod that is adjusted to provide the necessary trailing
edge setting with respect to the flap.
AILERON AND FLAP BELLCRANKS AND SUPPORTS
The 180
o
bellcrank under the cockpit floor is p/n 70076-1 and is interchangeable right to left. The welding
operation on these bellcranks sometimes causes a slight warp which will reduce the clearance from the 70072-
1 support frame, so if the bellcranks are changed, be sure there is ample clearance and if necessary reverse
the direction of the AN24-19A clevis bolt that connects the push-rods to improve clearance. These bellcranks
have Fafnir KP6A bearings installed with a 70081-2 stainless spacer that allows the AN4-42A bolt that
connects the bellcrank to the support frame assembly to be fully torqued (100 inch-pounds at the nut).