Gen II
User Manual
4-33 – Propeller Balance
Chapter 4
Revision 2.2, Apr 2020
The “Start Aircraft” banner screen indicates the upcoming run number and directs you to
“Perform FOD check and start engine(s) per flight manual”. Press [OK] to start prop balance.”
Then repeat the procedures described above starting with paragraph 4.1.5 until the level of
vibration is at or better than an acceptable level. See the
ACES Systems Guide to Propeller
Balancing
for details of vibration levels and weight installation procedures.
NOTE
If the engine/propeller assembly is mechanically sound, a normal balance job should take no more
than three runs to complete. The analyzer will only allow you to complete 6 runs in attempts to
balance. If the balance job is not completed by the sixth run you should suspect possible
problems with your technique or mechanical faults with the engine and/or propeller assembly.
Mechanical faults may also be indicated by drastic changes in suggested weight or angle from
one solution to the next.
4.1.9.
– Vibration Summary
The “Vibration Summary” screen will appear when the vibration measured during any run is
lower than:
Cobra II Viper II
Units
English
Metric
Velocity
0.07 IPS peak
1.78 mm/sec peak
0.178 cm/sec peak
N/A
Displacement 0.35 mils peak
8.0 microns peak
Acceleration
0.04 g’s peak
0.35 m/s/s peak
35.0 cm/s/s peak
These levels are approximately equivalent to 0.07 IPS at propeller balance speeds in the 2000-
2400 RPM range. It is recommended that you quit balancing when the vibration drops below
these levels.
