TM 55-1520-240-T
8-15.3 ROTOR TACHOMETER OPERATIONAL CHECK (Continued)
8-15.3
TASK
RESULT
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
Check that ROTOR TACH circuit breaker
(1) is closed.
Check that ROTOR TACH circuit breaker
(2) is closed.
Have pilot start engines and stabilize rotor rpm
at 100 percent. Check pilot and copilot rotor ta-
chometers (3 and 4).
Open BATT CHGR circuit breaker (5).
Have pilot set BATT switch (6) to O F F .
Check pilot and copilot rotor tachometers
(3 and 4).
Have pilot set BATT switch (6) to ON.
Close BATT CHGR circuit breaker (5).
Open ROTOR TACH circuit breaker (1).
Check copilot’s rotor tachometer (4).
Close ROTOR TACH circuit breaker (1).
Open ROTOR TACH circuit breaker (2).
Check pilot’s rotor tachometer (3).
Close ROTOR TACH circuit breaker (2).
If circuit breaker (1) is open, close it. If it opens
again, go to task 8-15.4.
If circuit breaker (2) is open, close it. If it opens
again, go to task 8-14.4.
Both tachometers shall read 98 to 101 percent. If
copilot’s tachometer does not read 98 percent to
101 Percent, go to task. 8-15.5 If pilot’s tachometer
does not read 98 to 101 percent, go to task 8-15.6.
If copilot’s tachometer varies or oscillates, replace
capacitor 054C1. If pilot’s tachometer varies or os-
cillates, replace capacitor 054C2.
Both tachometers
either tachometer
task 8-15.7.
Tachometer (4)
shall read 98 to 101 percent. If
pointer drifts downscale, go to
shall read 98 to 101 percent. If
pointer on tachometer (4) drifts downscale, go to
task 8-15.8.
Tachometer (3) shall read 98 to 101 percent. If
pointer on tachometer (3) drifts downscale, go to
task 8-15.9.
FOLLOW-ON MAINTENANCE:
Have Pilot Shut Down Engines
TM 55-1520-240-23:
Hydraulics Off
Electrical Power Off
Battery Disconnected
r
END OF TASK
Change 2
8-336.1
