Piper PA-24 Comanche, Service Manual

Page: 231 / 846

04/01/09 IV - STRUCTURES
1E23
PIPER COMANCHE SERVICE MANUAL
4-49.
Repair of Rudder.
WARNING: NO REPAIRS TO THE RUDDER ARE ALLOWED, OTHER THAN THOSE STATED
HEREIN. THE STRUCTURAL INTEGRITY OF THE ASSEMBLY MUST BE
MAINTAINED.
Repairs are limited to replacement of complete skin sections, ribs, hinges, spars, etc. and paint.
Precautions must be taken when performing any maintenance and or repairs to the rudder. Repairs must
be made in a manner that maintains the original configuration, strength, stiffness and weight distribution.
4-50.
Balancing Stabilator (Horizontal Tail Surface)
(Refer to Figure 4-7c.)
The importance of keeping the horizontal tail surface in proper balance cannot be over emphasized.
NOTE: Before balancing the horizontal tail surface, check the stabilator, stabilator trim tab and tab
mechanism for any free play. The following procedure is recommended :
A. Stabilator: Check the stabilator for any "free play" at its attachment points by grasping each halve
near the tip and gently trying to move it up and down, fore and aft, and in and out, on its torque
tube. NO play is allowed.
B. Stabilator Trim Tab: Set the stabilator trim tab in neutral position. This neutral position is
determined with the airplane properly rigged per instructions given in this section of the service
manual; the control wheel in its neural position per Table V-I, and the trim indicator at its neutral
position. Place a support under the stabilator spar to prevent movement. (Refer to Figure 4-7d.)
Obtain a straightedge long enough to extend from the ground up to a few inches above the trim tab
trailing edge. Place the straightedge next to the trim tab inboard (center) trailing edge and grasping
the tab, gently move it up and down, without moving the stabilator, mark the limits of the tab free
play on the straightedge. The overall travel (free play) must not exceed .076 of an inch. The use of a
dial indicator and fixed stand is recommended. (Refer to Figure 4-7d.)
C. Stabilator Trim Tab Mechanism: The complete trim tab mechanism should be checked for free play
at the various components such as trim control rod end bearing, trim bellcrank, trim screw, trim
drum and trim drum assembly. The bearing located between the stabilator tab horns should fit close
enough to eliminate play in the actuator system. However, it should not be so tight that the control
rod cannot easily be moved sideways or endwise on the bearing. Whenever any portion of the
horizontal tail surface has been repaired and/or repainted (refer to paragraphs 4-47 and 4-48) it must
be rebalanced before the airplane is flown. The following balancing procedure is recommended:
CAUTION: IT IS VERY IMPORTANT TO HAVE THE STABILATOR FREE TO ROTATE WITH
A MINIMUM OF FRICTIONAL RESISTANCE. TO INSURE THIS
REQUIREMENT, CHECK THE BEARINGS, TRIM TAB HINGES AND TAB
CONTROL ROD END BEARINGS FOR RUST, DIRT OR WORN PARTS. IF ANY
OF THESE CONDITIONS EXIST, REPAIR OR REPLACE BEFORE BALANCING.
1. The horizontal tail surface installation must be complete and ready for flight before balancing.
2. The control cables at the balance arm must be disconnected before balancing.
NOTE: The stabilator must be balanced without leading edge guards. If leading edge guards are
installed, remove them prior to balancing. Reinstall after balancing.
NOTE: There are several different stabilator balancing procedures; one for the PA-24-180, 250 and
260 aircraft without tip weights, another for the PA-24-400 aircraft, and one for the PA-24-
250 and 260 aircraft with stabilator tip balance weights installed.