Technical data

13773-001
55-40
Page 4 30 Nov 2000
(5) Balancing - Rudder (See Figure 55-402)
CAUTION: When balancing the rudder, the rudder assembly must be complete including
mounting brackets, paint, stripes, rudder bottom, and rudder tip. The bench used
to support the knife edge supports must be level. Before balancing, ensure there
are no drafts in the balancing room, which can deflect the surface from its bal-
anced condition. Maximum mass balance weight is 2.5 pounds.
(a) Acquire necessary tools and equipment.
(b) Remove rudder. (Refer to 55-40)
(c) Using the reference holes in the rib, 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. This line runs perpendicular to the rudder spar.
(d) Place a straight edge directly on the center of each rivet head used to secure the rudder
skin to the rudder spar (not the hinge mount rivet heads).
(e) With straight edge in place, mark a reference line to indicate the rivet head centerline.
(f) Mark a reference line 4 inches aft (towards trailing edge of rudder) of the rivet head cen-
terline mark previously made. This line must run parallel to the centerline of all three
hinges.
(g) Using the rivet head centerline as a reference, mark a reference line ¾” forward (towards
the hinges). This reference line is referred to as the hinge centerline.
Note: The area between the hinge centerline mark and the line 4 inches aft of the
rivet head centerline is referred to as the balance zone.
(h) Place close tolerance balance pins into the upper and lower hinge mounts.
(i) Level the work bench (in all directions) using a spirit level.
(j) Using the rudder assembly as a temporary locator, place the balancing fixtures into posi-
tion on a level work bench.
(k) Ensure each knife edge support is parallel to the bench top by placing a spirit level on
each of the knife edge supports.
(l) If required, shim the base of the knife edge support fixtures to ensure that the knife edges
are parallel to the bench top.
(m) Ensure balance arm is parallel to bench top by placing a spirit level on the balance arm.
(n) If required, shim base of balance arm to ensure balance arm is parallel to the bench top.
Description P/N or Spec. Supplier Purpose
Close Tolerance Balance
Pins
- Any Source Support Rudder Assembly
Balance Fixture - Any Source Balance Rudder Assembly
Straight Edge - Any Source Mark Chord Line and Hinge
Centerline
Grease Pencil - Any Source Make Reference Marks