AIR TRACTOR AT-502A, Maintenance Section

Page: 46 / 159

Air Tractor, Inc. Maintenance Page 27
AT-502A/502B/504 March 14, 2018
TRIM LEVER
The trim lever is p/n p/n 71362-2 for AT-502A/502B or p/n 71362-4 for AT-504. It has a p/n 70453-1
stop installed with slotted holes that allow movement up and down to adjust the tab travel. To position the
lever in neutral, install the control lock, position the lever in the green band, and adjust the forward push-rod
until the trim tabs are lined up with the elevator trailing edge. The stop can then be moved up or down to
provide a tab travel of 9
o
up, 7
o
down +/-1 1/2
o
.
If the trim lever creeps in flight, adjust the stops on each side of the trim lever so that a gap of .020" is
provided on each side of the lever.
FUSELAGE REMOVABLE SKINS
The side skins of the fuselage are attached to the fixed skins with Monadnock studs of various lengths. The
stud has a basic part number of 1142005 and the dash number designates the length. The most common stud
is a -3 with the next most common a -4. All studs have the dash numbers on the head. Stud lengths used are -
3 through - 15. Stud installation requires a 1142925-2 grommet and a 1142902 snap ring.
Installation pliers are needed for stud installation or removal. All Monadnock receptacles are p/n 1142715.
The side skins can be easily removed.
The side skins have a thin strip of neoprene to prevent chafing. This neoprene is 1/32" thick by 1.0"
wide, comes in 10 ft. rolls, has pressure sensitive adhesive backing and is p/n NS5565. A punch is made of a
piece of 3/4" OD tubing and one end sharpened on a grinder. At each Monadnock position, the neoprene is
marked and a 3/4" hole is punched.
The side skins are sheared to size, but the Monadnock holes will require drilling on installation. The old
skin may be used for a pattern, or if it is damaged, ask the factory to provide a hole finder. Use a Camloc
hole saw .471 diameter to drill the side skins to match the receptacles. These hole saws have a No. 30 pilot.
FUSELAGE FIXED SKINS
The fixed skins are attached with 832 machine screws and nuts. Nuts in the lower skins are stainless
MS21044-C08 and in the upper fuselage areas are AN365-832. The 100
o
countersunk machine screws are
p/n 90012-5 for the 832 x 1/2 size, 90012-7 for the 832x 5/8 size. The Truss head machine screws are
p/n 90013-3 for the 832 x 3/8 long, -5 for 1/2 long, -7 for 5/8 long, and -8 for the 3/4 long.
The long lower skin is attached to the skin under the cockpit floor with rivets, but if it is desired to
remove one skin but not the other, the rivets can be drilled out and replaced with 90013-3 or -5 screws and
stainless nuts. If the baggage floor is to be removed, it is necessary to remove the long lower skin, in order to
reach the nuts.
During annual inspections, all screws attaching the fixed skins should be checked to see if they are
tight.
The Monadnock receptacles are attached to all lower skins and stringers before these parts are
attached to the aircraft. If a skin or stringer is replaced, be sure to install the side skin and attach it to the part
being replaced so that it will be properly positioned for the side skins to fit after installation to the airframe.