MD Helicopters CSP-900RMM-2 Servicing And Maintenance Download

Page: 2065 / 2144

CSP

−

900RMM

−

MD Helicopters, Inc.

Rotorcraft Maintenance Manual

Page 7

Revision 35

76-00-00

4. Permanent Magnet Alternator

(Ref. Figure 2)

The PMA is an engine-driven bearingless
alternator mounted on the reduction gearbox.
The PMA provides the primary power source
for the EEC. The PMA rotor and stator are
mounted internally in the reduction gearbox
and are removeable from the gearbox. The
PMA has a quick disconnect that provides an
attachment for the electrical harness.

5. Fuel Metering Units

(Ref. Figure 2)

The FMUs are tandem mounted on the
engine-driven fuel pumps, that are mounted
on the reduction gearbox. The FMUs govern
the fuel flow rate based on inputs from the
EECs or the FMU power lever angle (PLA).
The FMUs operate in automatic or manual
modes:

Automatic mode operation is controlled by
EEC inputs

Manual mode operation is controlled by
throttle inputs from the PLA

The FMUs are shrouded on

902 CONFIG

rotorcraft — a Category A requirement.

During manual or automatic mode operation,
the fuel flow to the engine is regulated by an
internal metering valve. During automatic
mode operation, the metering valve is driven
by a stepper motor that is activated by EEC
inputs. During manual mode operation, the
stepper motor is deactivated, and fuel flow is
controlled by the internal metering valve
activated by throttle inputs from the PLA.

6. Powerplant Controls

The powerplant controls provide the pilot with
control of the EEC system and mechanical
throttle override control. During normal EEC
system operation, the twist grip throttle
control for each engine is set in the NORMAL
detent position and engine operation is
controlled by the EEC.

The pilot can override EEC full-authority
operation by rotating each engine throttle
twist grip out of the NORMAL detent position.
The mechanical override provides the pilot

with full range control of each engine throttle
to maintain engine torque requirements, or to
manually shutdown the engines.

7. Collective Lever Position Transducers

The collective control stick position transduc
ers are located in collective friction unit (CFU).
The left transducer sends an electrical signal
to the left engine EEC. The right transducer
sends an electrical signal to the right engine
EEC.

Each collective stick position transducer sends
a variable voltage signal, dependent on
collective lever position (CLP). The CLP signal
from the transducer is sent to the EEC to
compute rate and position changes for EEC
system operation when the collective control
stick tandem twist grips are in the NORMAL
detent position.

8. Collective Control Stick Assembly

(Ref. Figure 2)

Two tandem twist grip throttle controls are
concentrically located on the collective control
stick assembly. Each twist grip provides a link
to the FMU to provide mechanical control fuel
flow to the engine. The forward grip controls
the left engine, and the aft controls the right
engine.

During EEC operation, the tandem twist grips
are positioned in the NORMAL detent. When
the pilot rotates the throttles out of the
NORMAL detent, the detent module assembly
is activated and the EEC authority is inter
rupted. Two pushbutton switches on the
collective stick grip relate to manual operation
of the power management system:

OFF GATE (

Early Config

) release electri

cally retracts the gate that prevents the
twist grips from being inadvertently turned
to the OFF position

EEC RESET re-engages the automatic EEC
functions after the pilot has had manual
control

More current configuration collective controls
have removed the OFF GATE function at the
grip position and accommodate for this action
in the detent module itself. This detent module
configuration

MD Helicopters CSP-900RMM-2, Servicing And Maintenance

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