Wing Flap Controls (Calco System) - Piper Navajo Chieftain PA-31-350 Service Manual

NAVAJO CHIEFTAIN SERVICE MANUAL
NOTE
The only way that further right flap extension can occur after the
time delay switch shuts off the motor, is if the pilot would cycle the
master switch off and on. and again select flaps.
The time delay switch does not affect or shut off the flap motor if a
failure occurs when the left flap is between the up and down limit
switches.
The time delay switch is passive in the flap electrical system during
normal flap operation.
d.
Reinstall the access plates in the left wing false spar at wing stations 92.50 and 101.00.
5-72. DESCRIPTION
AND OPERATION.
The wing flap control system provides continuous control
and monitoring of flap position and condition over its full range. In addition to the limiting of both up and
down overtravel. the system will shut the driving mechanism off in the event of a 5
°
or more differential
between right and left flap position and it will self-monitor and automatically react appropriately in the event
of critical component failure in the control circuitry.
Preselection of any desired flap position from full up (0
°
) to full down (40
°
) is possible thru the posi-
tioning of the selector control which has an 80
°
stroke analog lever. (That is. 2
°
of lever movement represents
1° of wing flap movement.) The selector incorporates a friction type drag brake to hold the lever at any
desired intermediate position as well as ball lock detents at 0
°
15
°
. and 40
°
of flap extension. Flaps are
deployed mechanically by a single motor driven thru two flexible shafts connected to individual ball screw
actuators.
Selection of the desired flap position moves the control rheostat wiper relative to the left wing flap
rheostat wiper w ith a resultant amplifier output which will operate the flap motor through contactors K I and
K2 to mo e the left and right flaps to the desired position. If at any time the amplifier sees a differential voltage
in excess of 0.55 VDC between left wing flap rheostat wiper and the right wing flap rheostat wiper. the
amplifier will shut the system off. This condition corresponds to a maximum differential of 5
°
of flap position.
A flap fault test switch is provided to check the control circuitry for asymmetrical flap protection as well
as the operation of the fault lamp switching transistor. The activation of this switch while flaps are in motion
will give a false signal to the right side follower potentiometer, simulating an out-of-sync condition causing
the amplifier to shut the system off and illuminate the fault light. Release of the switch will clear the simulated
fault and allow the system to respond normally to selector position command.
All adjustments are made with the motor circuit breaker pulled (OFF) and the flaps in the down posi-
tion. Adjustment procedures will require some special equipment such as a digital voltmeter and flap trans-
mission tools.
Revised: 10/5/83
SURFACE CONTROLS
Effectivity
1J15
CALCO