Specifications

Chapter 26. Troubleshooting Common Problems
26.1. Vibration problems
Heli vibration can be broadly categorized into two types:
• Main rotor vibration
The main symptoms of this are landing gear vibrating, and the vertical tail fin vibrating left/
right.
• Tail rotor vibration
The main symptom of this is the tail boom vibrating up/down at high speed.
If you follow these directions step-by-step, you should be able to solve most vibration prob-
lems.
The basic methodology is to keep removing parts from the helicopter until the vibration stops,
and when the vibration stops the last piece you removed was causing the vibration problem.
Note that some helicopter models are known to have problems. For example:
Many Hummingbird Elite CPs appear to have been shipped with warped plastic head blocks
(CNE205).
Early models of the Robbe Eolo were shipped with warped tail parts which caused tail vibra-
tion.
26.1.1. Excessive vibration (entire heli)
Checklist for main rotor vibration
• Check the obvious
Check if main gear mesh is too tight.
Check if the main gear is missing teeth.
Check if the tail belt is too loose or too tight.
• Check main blade tracking. Put a piece of marking tape on one blade and run up the motor.
Check if the blades are tracking properly. If the blades do not track properly, then see the
section on blade tracking.
• Check if the blade grip bolts are too loose or too tight. Hold the helicopter so the right side
or left side is facing down, and see if the main rotor blades will stay horizontal to the
ground. If they just barely stay horizontal then this is just right.
• Check main rotor blade CG and balance. Balance the main blades on a blade balancer and
ensure the CGs match and the blades balance. If the CG does not match or the blades do
not balance, then see the section on blade balancing.
• Check if the feathering shaft is bent. Disassemble the main rotor hub and remove the feath-
ering shaft. Check the feathering shaft using the directions given for the main shaft below.
142