3805. Measuring Reaction Points during Aircraft Weighing using an Inexpensive Laser

Paper

Abstract

Maintaining an aircraft’s weight and balance within specified limits throughout all phases of its lifecycle is critical to its performance and the safety of its crew, passengers, and maintenance personnel. Measuring the weight and center of gravity (CG) of the aircraft in its Empty Weight configuration is typically the starting point for all subsequent weight and balance calculations. This procedure is often accomplished by placing load cells on jacks underneath the aircraft at three (or more) known locations relative to the aircraft coordinate system, raising and leveling the aircraft, measuring the weights on each cell, and calculating the moments and resultant CG. If the load cells are positioned at fixed reaction points on the airframe, the locations of the cells are easily known. If the load cells are positioned beneath the landing gear, the reaction points must be measured since the gear typically moves with an increase or decrease in load. Finding the true dimensions of these reaction points can be difficult, time consuming, and prone to error. This paper describes a method for quickly and accurately determining the reaction locations for the jacks under gear (JUG) method using an inexpensive laser distance meter. All aircraft designs are unique, so the process may not work exactly as described here, but the hope is that this paper will stimulate discussion and ideas for extending the concept as needed to fit your situation.