This SAE Aerospace Recommended Practice (ARP) specifies the requirements of balancing machines that make them suitable forthe subject class of work. was developed for soft-bearing balancing machines but may also be used for hard-bearing machines until ARP4050 is issued forth at type of machine.

This Aerospace Recommended Practice (ARP) delineates the technical specifications for the rotating type of soft-bearing, single plane (i.e., static) balancing machine used for measuring the amount and angle of unbalance in gas turbine rotors.

This document also delineates performance tests to be used to ensure conformance with the requirements in this ARP.

This document was prepared to describe dimensional and performance requirements for machines capable of balancing most rotors either now in service or to be put in to service in the foreseeable future. This will enable both rotor and balancing machine manufacturers to standardize, avoiding the need for separate tooling to adapt a particular rotor to a variety of machines in one capacity range. It can also be used as a general specification by purchasers (users) in procuring suitable balancing machines from manufacturers (suppliers).

Particular note should be taken that this ARP only examines the capability of a balancing machine to indicate the correct amount of static unbalance in specified proving rotors. Such rotors are commonly used for testing balancing machines to provide precisely controlled and comparable test results. Further tests of a particular machine may be necessary to assess its capability to balance rotors of different weights and configurations and those with disturbance causing features, such as rotors subject to blade scatter, windage, etc.

This ARP specifies dimensional and performance requirements in the following areas:

a. Machine capacity relating to weight and physical dimensions of rotors that can be balanced

b. Accuracy of amount and angle indication

c. Sensitivity and linearity of amount indication

d. Ability to measure static unbalance unaffected by couple unbalance

e. Balancing speed and direction of rotation

f. Drive requirements

g. Standard drive adapter flange requirements

h. Proving rotors, test masses, and rotor safety enclosures