Weight & Balance for CESSNA 170B

WEIGHT FLAT SURFACE READ CONTROL SURFACE MOMENT AT CENTER OF WEIGHT BEAM ASSEMBLY - CHORD LINE Figure 3. Balancing of Control Surface (2) Position the sliding weight to allow the control surface to be balanced (control surface chord to be parallel to horizontal, flat surface). Read the number on the scale directly below the center mark on the sliding weight. The number read is the moment of the control surface in inch-pounds. The moment must be assigned a + or as follows: - A-5 A-6 FLIGHT CONTROL SURFACE BALANCING (a) Overbalance is defined as the condition that exists when surface is leading edge heavy and is defined by symbol (-). If the balance beam sliding weight must be on the trailing edge side of the hinge line (to balance the control sur- face), the control surface is considered to be overbalanced. (b) Underbalance is defined as the condition that exists when surface is trailing edge heavy and is defined by symbol (+). If the balance beam sliding weight must be on the leading edge side of the hinge line (to balance the control sur- face), the control surface is considered to be underbalanced. (3) Refer to the applicable Service or Maintenance Manual to deter- mine if the control surface is within allowable balance tolerance and whether or not the control surface balance weight needs adjustment to reduce or increase the amount of weight. *5180002-14 MANDRELS FLIGHT CONTROL SURFACE BALANCING *5180002-12 WEIGHT ASSEMBLY WASHER AND BOLT *5180002-5 SLIDING WEIGHT *5180002-2 BEAM ASSEMBLY *INCLUDED IN 5180002-1 FLIGHT CONTROL SURFACE BALANCING FIXTURE KIT. FLIGHT CONTROL SURFACE BALANCING FIXTURE KIT (PART NUMBER 5180002-1) GENERAL NOTES 1. 2. 3. 4. 5. 6. Balance control surfaces in a draft-free area. Place hinge bolts through control surface hinges and position on knife edge balancing mandrels. Be sure hinge bolt shank rests on knife edge. Make sure all control surfaces are in their approved flight configurations: painted (if applicable), trim tabs installed, all foreign matter removed from inside of control surface, elevator trim tab push-pull rod installed and all tips installed. Place balancing mandrels on a table or other suitable flat surface. Adjust trailing edge support to fit control surface being balanced while cen- ter of balancing beam is directly over hinge line. Remove balancing beam and balance the beam itself by moving the adjustable weight (fastened by bolt and washer). Fine balance may be accomplished by use of washers at long screw on end of beam. When positioning balancing beam on control surface, avoid rivets to provide a smooth surface for the beam and keep the beam 90° to the hinge line of the control surface. B-1 FLIGHT CONTROL SURFACE BALANCING 7. Paint is a considerable weight factor. In order to keep balance weight to a minimum, it is recommended that existing paint be removed before adding paint to a control surface. Increase in balance weight will also be limited by the amount of space available and clearance with adjacent parts. Good workmanship and standard repair practices should not result in unreasonable balance weight. 8. The approximate amount of weight needed may be determined by taping loose weight at the balance weight area. 9. Lighten balance weight by drilling off part of weight. 10. Make balance weight heavier by fusing bar stock solder to weight after removal from control surface. The ailerons should have balance weight increased by ordering additional weight and gang channel, listed in applicable Parts Catalog and installing next to existing inboard weight the minimum length necesary for correct balance, except that a length which contains at least two attaching screws must be used. If necessary, lighten new weight or existing weights for correct balance. CENTERLINE ON BEAM MUST BE ALIGNED WITH CONTROL SURFACE HINGE CENTERLINE HINGE BEAM ASSEMBLY HANGAR ASSEMBLY CENTERLINE CONTROL SURFACE CHORD ADD WASHERS AS NECESSARY TO FINE BALANCE THE BEAM ASSEMBLY ADJUSTABLE WEIGHT MANDREL B-2 HANGAR ASSEMBLY (TO BE IN PROPER POSITION) FLIGHT CONTROL SURFACE BALANCING SLIDING READ CONTROL SURFACE MOMENT WEIGHT AT CENTER OF WEIGHT BEAM ASSEMBLY MANDREL FLAT SURFACE CHORD LINE CONTROL SURFACE BALANCE REQUIREMENTS Balance limits for control surfaces are expressed for "Approved Flight" configuration. "Approved Flight" con- figuration is that condition of the control surface as prepared for flight of the airplane whether it be painted or unpainted. "Approved Flight" limits must never be exceeded when the surface is in its final configuration for flight. UNDERBALANCE is defined as the condition that exists when the control surface is trailing-edge heavy, and is symbolized by a plus (+). OVERBALANCE is defined as the condition that exists when the control surface is leading-edge heavy, and is symbolized by a minus (-). B-3 FLIGHT CONTROL SURFACE BALANCING A balance in this range is “underbalance". -A balance in this range is “overbalance”. BALANCING MANDREL 90° BALANCING MANDREL B-4 RUDDER TRAILING EDGE SUPPORT. SPIRIT-LEVEL PROTRACTOR SLIDING WEIGHT CENTER LINE CHORD LINE LEVELED SURFACE HINGE POINT ELEVATOR 1 1 * D FLIGHT CONTROL SURFACE BALANCING -HORIZONTAL PLANE -AILERON A. -ATTACH AILERON HINGE TO NOTCHED END OF MANDREL A -57°10' -AILERON CHORD LINE HINGE LINE -LEVELED SURFACE 1.80 INCHES View A-A NOTE This detail is applicable to ailerons which are attached to the wing with piano-type hinges. *D minus 1.80 inches equals chord line of aileron. Make sure trailing edge is straight in area where 1.80-inch measurement is taken. B-5 $ .85 FLIGHT CONTROL SURFACE BALANCING AILERON L View A-A A ·Balance aileron inverted, with trailing edge at point op- posite cut-out for middle hinge .85" below hinge line horizontal plane. B-6 A. HINGE LINE HORIZONTAL PLANE ) 1 CONTROL SURFACE BALANCE LIMITS FOR EARLY MODEL AIRPLANES AILERONS RUDDER MODEL SERIAL BALANCE WEIGHT (POUNDS) (IN. LBS) WEIGHT BALANCE BALANCE |(POUNDS) (IN. LBS) | (POUNDS) (IN. LBS) RH ELEVATOR WEIGHT LH ELEVATOR WEIGHT BALANCE (POUNDS) (IN. LBS) | 120/140 8000 3.50 0.0 THRU +.25 ΤΟ NONE SPECIFIED 15075 -.00 × 14.3 140A 15200 1.75 0.0 THRU +.06 ΤΟ NONE SPECIFIED 15724 -.00 +11.31 170 18000 3.50 0.0 4.00 +23.0 NONE 0.0 NONE 0.0 THRU +.25 ΤΟ +.12 ΤΟ SPECIFIED ΤΟ SPECIFIED ΤΟ 18729 -.00 +14.3 -.00 +27.0 +67.3 +44.0 170A 18730 *2.94 0.0 4.00 +23.0 NONE 0.0 NONE 0.0 THRU +.06 TO +.12 ΤΟ SPECIFIED ΤΟ SPECIFIED ΤΟ 20266 -.00 +11.31 -.00 +27.0 +67.3 +44.0 170B 20267 2.94 0.0 4.00 +23.0 .92 +22.0 .75 +19.44 THRU +.06 ΤΟ +.12 ΤΟ +.10 ΤΟ +.10 ΤΟ 27169 -.00 +11.31 -.00 +27.0 -.10 +26.0 -.10 +24.0 190/195 7001 RH -.94 5.70 -.94 11.00 -.94 6.12 -.94 THRU 7.93 ΤΟ +.13 ΤΟ +.13 ΤΟ +.13 ΤΟ 7999 LH +.94 -.00 +.94 -.00 +4.69 -.00 +4.69 & 6.56 16000 THRU 16083 190/195 16084 RH -.94 5.70 -.94 6.71 -.94 6.00 -.94 THRU 7.93 ΤΟ +.13 ΤΟ +.13 ΤΟ +.13 ΤΟ 16183 LH +.94 -.00 +.94 -.00 +4.69 -.00 +4.69 6.56 * Some Model 170A airplanes were delivered with 1.75-pound lead balance weight in ailerons. C-1