ENSTROM F-28F/280F SERIES MAINTENANCE MANUAL SUPPLEMENT
Rev.
4
MM-21-12
Jun
21/12
(2)
The signal conditioning unit has been adjusted at the factory to activate at rotor
speeds below 332 RPM or above 385 RPM. The unit should not need readjustment,
but if it does, the operator may adjust the LO or HI potentiometers located on the top
of the unit.
a.
Turn the LO adjustment counter clockwise to reduce the low-end (i.e. 332 RPM)
activating rpm and clockwise to increase the low-end (i.e. 332 RPM) activating
rpm.
b.
Turn the HI adjustment counter clockwise to reduce the high-end (i.e. 385 RPM)
activating rpm and clockwise to increase the high-end (i.e. 385 RPM) activating
rpm.
E.
Installation – Signal Conditioning Unit
(1)
Install the signal conditioning unit by securing the unit onto the bulkhead with four
screws, washers, and nuts.
(2)
Plug the electrical connector into the signal conditioning unit.
(3)
Replace the seatback access panel and back cushions.
F.
Functional Test – Hi/Lo Rotor Rpm Warning System
(1)
Apply electrical power to the aircraft. Check the CLUTCH ENGAGE light is
illuminated and the ROTOR RPM light is not illuminated.
(2)
Engage the belt clutch. Check the ROTOR RPM light is illuminated and the CLUTCH
ENGAGE light is not illuminated.
(3)
Push the TEST button adjacent to the annunciator panel. Check that the ROTOR
RPM and CLUTCH ENGAGE lights are illuminated. Release the button. (The
ROTOR RPM light will remain illuminated with the clutch engaged.)
(4)
Raise the collective controls off of the down stop. Check the ROTOR RPM horn and
tone activate.
(5)
Place the collective controls against the down stop. Check the ROTOR RPM horn
and tone deactivate.
(6)
Carefully disengage the belt clutch.
WARNING
The following checks are to be performed by authorized personnel.
UNCONTROLLED COPY WHEN DOWNLOADED OR PRINTED
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