ENSTROM F-28F/280F SERIES MAINTENANCE MANUAL SUPPLEMENT
Rev.
5
MM-21-1
Nov
5/13
SECTION 21
ELECTRICAL SYSTEMS AND COMPONENTS
21-1. General – Reference Section 6 for Other Information
The electrical system of the 280FX and F-28F is essentially the same as the system used
on the 280F except for the changes listed below:
Combined anticollision and navigation lights – F-28F and 280FX (para. 21-2)
Annunciator Panel 280FX and F-28F S/N 746 and subsequent (para. 21-3)
Graphic engine monitor 280FX and F-28F (Section 24)
NOTE
: Early F-28F aircraft do not have the annunciator panel but do have press-
to-test lights for required items in para. 21-3.
Refer to paragraph 21-8 for the F-28F and 280FX electrical schematics.
21-2. Combined Anticollision and Navigation Lights
The 280FX and F-28F S/N 744 and subsequent are equipped with combined anticollision-
navigation lights. These light assemblies are mounted on the outside of each vertical
stabilizer, and the anti-collision light power supplies are located under the floor on either
side of the cabin, as shown in Figure 21-1.
21-3. Annunciator
Panel
All of the warning and caution lights for 280FX helicopters are contained in an annunciator
panel, which is located at the top of the instrument panel. On early production helicopters,
the warning lights include LOW ROTOR RPM, CLUTCH ENGAGE, and LOW FUEL
PRESS; the caution lights include OVERBOOST, MRGB CHIP, and TRGB CHIP. On later
production helicopters, STARTER RELAY is added to the warning lights and LOW
VOLTAGE is added to the caution lights.
The annunciator panel for F-28F helicopters was optional equipment starting with S/N 746.
Later F-28F production helicopters incorporated the annunciator panel with all eight
segments as standard equipment.
For aircraft equipped with the Hi/Low Rotor RPM Warning System, ROTOR RPM replaces
LOW ROTOR RPM in the annunciator panel.
Pressing the “press-to-test” switch at the extreme left of the panel will illuminate all of the
indicator lights.
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