Elevator Control System Friction Measurement - Piper Navajo PA-31 Service Manual

PIPER NAVAJO SERVICE MANUAL
4-91. ELEVATOR CONTROL SYSTEM FRICTION MEASUREMENT. The complete control system
including Autopilot, if installed, must be checked to determine the total friction. The system must be rigged to
its proper travels and cable tensions prior to determining the total friction.
The total friction must not be in excess of six pounds (seven pounds for PA-31-325) with the bungee
spring readjusted to 30 ± 1 (37 + I for PA-31-325) pounds. The actual frictional value of the system will
be determined by the following procedure:
a.
Attach a spring scale to the inboard trailing edge of the elevator as shown in Figure 4-20.
b.
With the spring scale attached, position the elevator trailing edge down approximately 2 inches
from the neutral position.
c.
Record the force (see Note 2) required to raise the elevator through the neutral position until the
trailing edge is approximately 2 inches above neutral.
d.
Record the restraining force lowering the elevator from the 2 inch up position through the
neutral position to the original 2 inch down position.
e. Repeat above raising and lowering processes until average forces are obtained.
f. The "Total Friction" is obtained by subtracting the two forces.
NOTES
1. Do not exceed 60 pound force for any measurement.
2.
The elevator shall be rotated with a steady movement and the
force reading taken when the elevator is passing through the
neutral position. Do not stop rotation when taking the
reading.
Revised: 3/11/81
STRUCTURES
1G13