18-72 Ground Checks
NOTE
Run-up and shutdown helicopter throughout procedure as
required per R66 Pilot's Operating Handbook (POH) Section 4.
NOTE
Use the following balancing procedures in conjunction with
approved equipment manufacturer’s balancing instructions.
WARNING
Fan shaft and engine shaft balancing equipment must be
removed for flight.
1. Prepare helicopter for fan shaft and engine shaft balance per § 18-71.
2. Configure balance equipment per manufacturer's instructions.
3. Ground run helicopter at 100% RPM (2114 fan shaft RPM and 6016 engine shaft
RPM). Verify cyclic stick and tail rotor pedals are in neutral position.
4. Determine vibration level per balance equipment manufacturer's instructions. Maximum
vibration allowance is 0.2 IPS (inches per second). If reading is over 0.2 IPS:
a. Fan Shaft: Adjust balance by selecting one or more NAS1149D0463J,
NAS1149F0432P, NAS1149F0463P, A214-3, or A141-14 washers as required
and install under one nut of intermediate flex plate (tail rotor driveline) fastener.
b. Engine Shaft: Adjust balance by selecting one or more NAS1149D0463J,
NAS1149F0432P, NAS1149F0463P, A214-3, or A141-14 washers as required
and install under one nut of aft flex plate (engine driveline) fastener.
NOTE
If a large diameter washer is installed at a shaft flange, also
install one NAS1149F0432P washer against flange to prevent
flange damage (not required for flat flange). Additionally, an
NAS6604-5, -6, -7, or -8 bolt may be substituted for a bolt at
a flex plate fastener; verify thread engagement meets torque
requirements per § 20-30.
5. Adjust as required until reading is 0.2 IPS or less.
Page 18.34 Chapter 18 Track and Balance MAY 2015
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