Gen II
User Manual
4-4 – Propeller Balance
Chapter 4
Revision 2.2, Apr 2020
Propeller Protractor
The propeller protractor is designed to measure angles in a typical propeller/spinner assembly.
The propeller protractor pictured below is a complete circle. It is divided into five-degree
increments. Every 15 degrees, the angle is identified by a tick mark. Every 45 degrees, the
angle is printed in a circular identifier. Place the propeller protractor over the spinner with the
proper direction of rotation side facing you as indicated by the text and an arrow. Since the
analyzer can be configured to calculate solution angles relative to the vibration sensor or
reflective tape, both methods are described in more detail below.
Using the Propeller Protractor
For correct use of the protractor when measuring relative to the vibration sensor, do the
following:
WARNING
Always ensure mag switches are off prior to any movement of the propeller
Rotate the propeller until the reflective tape is directly in front of the Phototach.
With the propeller in this position, place the protractor over the spinner with the Rotation
indicator pointing in the direction of rotation (forward looking aft) and the 360-degree
points aligned with the position of the vibration sensor.
Read the numbers in the circles, and then interpolate values of the unmarked incremental
lines to locate the desired angle.
For correct use of the protractor when measuring relative to the reflective tape: