The Marvel Manufacturing Company copyright 2017
2
Tail Rotor Balance
Eurocopter Models BO 105, BK 117, EC 145 Typical
Balance Equipment
1 ea 7HEL078N1
Kit – Tail Rotor Balance
Note: The 7HEL078N1 KitTail Rotor Balance supplies all balance
equipment items required for this rotor and includes Part Number
3165 Arbor AssemblyBalance Indicating.
The 7HEL077N1 KitTail Rotor Balance Adapter is recommended for
use by those already in possession of Part Number 3165 Arbor
Assembly.
Description
The subject Tail Rotor is balanced as a hub and blade assembly, excluding the
pitch control linkage and teeter bolt.
The 3165 Balance Indicator Arbor is used with accessory adaptering to mount the
rotor in a fixed position below its lower end. A backbalance weight and
supporting anchor ring are used to raise the center of gravity of the total
suspended load to a position on the arbor that will provide the desired balance
indication sensitivity.
The rotor hub is secured to the fork section of the adapter with pins inserted
through each fork, engaging the hub and blade interconnecting fitting bores.
Linkage attachment bolts of the pitch arms contact the outer end of the pins for
blade pitch positioning. A threaded pressure ring, located central in the adapter
fork removes rotor teeter and positions its span axis square with the normal axis
of rotation.
Balance Procedure
1. Depress indicator Collar of 3165 Balance Indicator Arbor, releasing oil seal,
and reposition to provide minimum free clearance with arbor end. Lightly
secure with set screw. Suspend from hoist or other support.
