Technical data

13773-001
55-20
Page 2 30 Nov 2000
(f) Verify proper installation of safety wire and for use of new cotter pins on all fasteners.
(g) Install access panels LE1 and RE1. (Refer to 6-00)
(h) Operate elevator controls and inspect for any abnormal resistance.
(4) Elevator Balancing
CAUTION: Before balancing, ensure no breeze or drafts are in balancing room.
Note: To balance the elevator, the assembly must be complete including composite ele-
vator tip and all attaching hardware.
(a) Remove elevator. (Refer to 55-20)
Note: The mass balance weight must be removed before balancing the elevator.
(b) Remove the bolts, washers, and nuts securing the mass balance weight to the elevator.
(c) Mark the chord line on the inboard rib shearweb.
Note: The chord line is defined as the line extending from the trailing edge
through the hinge line. It is perpendicular to the elevator spar.
(d) Place the complete assembly on knife-edge supports and determine if a static overbal-
ance (leading edge heavy) or static underbalance (trailing edge heavy) condition exists.
(e) To determine the amount of static underbalance (trailing edge heavy), attach a paper cup
to one end of a short, small diameter string. Secure the string with masking tape to the
leading edge of the elevator tip. The paper cup should hang vertical without contact. Add
the mounting hardware in the paper cup.
(f) Add weight in the cup until the elevator balances with the chord line level. Check this by
holding a spirit level aligned with the chord line.
(g) Remove the string, cup and its contents. Weigh them to the smallest calibration possible
(grams).
(h) Weigh the elevator mounting hardware and mass balance weight.
(i) Add or remove weight as necessary to achieve the total predetermined weight needed to
balance the elevator.
Note: Underbalanced (trailing edge heavy) conditions are corrected by adding
additional weight to the control surface. Typically, by placing additional
washers, lead or steel, under each nut or bolt head retaining the balance
mass, as required. A maximum of 4 per bolt and nut retaining the balance
masses and a maximum of 3 under any bolt head or nut.
Overbalance (leading edge heavy) conditions are corrected by removing
small amounts of material from the lead balance mass, typically by drilling
or other means. Correction may also be accomplished by reducing the num-
ber of washers, used in retention of the mass balance.
(j) Secure the total weight needed (to balance the elevator) to the elevator with bolts, flat
washers, and self-locking nuts. Tighten bolts to 50-70 inch pounds (5.6-7.9 N.m.).
(k) Install elevator. (Refer to 55-20)
(l) Operate the elevator and inspect for any abnormal resistance.