95-23 Engine (N
2
) and Rotor Dual Tachometer (continued)
D. Accuracy Check and Needle Synchronization (continued)
7. Verify dual tachometer’s % NR indication is within 1% of % N
2
indication. If
required, adjust % NR by turning screw on back of tachometer. Turning screw
clockwise increases % NR and turning screw counterclockwise decrease % NR;
one-half turn equals approximately 1% change. Adjusting screw is accessed by
removing instrument face perimeter screws and pulling face aft.
8. Shut down helicopter per R66 POH Section 4.
9. Install perimeter screws securing face to console. Verify security.
E. Scheduled Maintenance and Inspections
Refer to § 5-45 100-Hour/Annual Inspection.
Refer to § 4-22 for recommended replacement time between overhauls.
F. Special Maintenance and Inspections
1. Perform accuracy check and needle synchronization per Part D.
2. If tachometer cannot be adjusted, remove tachometer per Part B, and return to
RHC for inspection.
3. Install airworthy tachometer per Part C.
Page 95.10 Chapter 95 Instrument System APR 2019
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