2-38. FLIGHT CONTROLS LOCK.
Remove control locks before towing the aircraft or starting engines. Serious damage could result
in the steering linkage if towed by a tug with the rudder lock installed.
A removable lock assembly (Fig. 2-30) provides positive locking of the rudder, elevator, and aileron control sur-
faces, and engine controls (POWER levers, PROP levers, and CONDITION levers) consisting of two pins, and an
elongated U-shaped strap interconnected by a chain. Installation of the control locks is accomplished by inserting
the U-shaped strap around the aligned control levers from the copilot s side; then the aileron/elevator locking pin is
inserted through a guide hole in the pilot s control column assembly. If inserted from the top use extreme caution
to avoid scratching the PFD glass.. The rudder is held in a neutral position by an L-shaped pin which is installed
through a guide hole in the loor aft of the pilots rudder pedals. The rudder pedals must be centered to align the hole
in the rudder bell crank with the guide hole in the loor. Remove the locks in reverse order, i.e., rudder pin, control
column pin, and power control clamp.
2-39. TRIM TABS.
Trim tabs are provided for all light control surfaces. These tabs are manually activated, and mechanically controlled
by a cable-drum and jackscrew actuator system except the right aileron tab which is of the ixed, bendable type.
Elevator and aileron trim tabs incorporate neutral, non-servo action, i.e., as the elevators or ailerons are displaced
from the neutral position, the trim tab maintains an as-adjusted position. The rudder trim tab incorporates anti-servo
action, i.e., as the rudder is displaced from the neutral position the trim tab moves in the same direction as the control
surface. This action increases control pressure as rudder is delected from the neutral position.
a. Elevator Trim Tab Control. The elevator trim tab control wheel (Fig. 2-19) placarded ELEVATOR TAB -
DOWN , UP , is on the left side of the control pedestal and controls a trim tab on each elevator. A position arrow
indicates the amount of elevator tab delection, in units from a neutral setting.
b. Electric Elevator Trim. The electric elevator trim system is controlled by an ELEV TRIM OFF/RESET switch
located in the pedestal, dual element thumb switches on the control wheels, a trim disconnect switch on each control
wheel and a 5-amp circuit breaker placarded ELEV TRIM on the overhead circuit breaker panel (Fig. 2-12). The
ELEV TRIM OFF - RESET switch must be in the ELEV TRIM (on) position to operate the system. The dual element
thumb switch is moved forward for trimming nose down, aft for nose up, and when released returns to the center
(off) position. Any activation of the trim system through the copilot s trim switch can be over-ridden by activation
of the pilot s switch. Operating the pilot s and copilots switches in opposing directions simultaneously results in the
pilot having priority.