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THIS IS AN UNCONTROLLED DOCUMENT.
THIS ELECTRONIC DOCUMENT MAY HAVE BEEN SUPERCEDED.
THE MOST CURRENT DOCUMENT INFORMATION IS AVAILABLE
FROM YOUR BELL HELICOPTER TEXTRON REPRESENTATIVE.
PRODUCT DATA
JANUARY 2003
ELECTRONIC CONTROL UNIT
The Series IV 250-C40B engine use a digital electronic control system, based upon a
single-channel, Full Authority Digital Electronic Control (FADEC). It is also referred to
as the Electronic Control Unit (ECU). The system controls, monitors and limits the engine
while maintaining helicopter rotor speed. The control connection between the helicopter
and the engine is both electrical and mechanical. This interface includes a combination
of Power Lever Angle (PLA) [twist-grip throttle] input, hard wired discretes, analog
signals, and a RS-423 data link for ground maintenance interrogation. An ARINC-429
digital data link is used to transmit information on engine and control status to the
aircraft.
The Hydromechanical Unit consists of the dual element fuel pump, fuel metering valve,
manual fuel control, three solenoid valves, two check valves, a fuel shutoff valve with
a pilot valve (windmill bypass valve), bypassing type pressure differential regulator
valve, power lever input shaft, and two feedback potentiometers.
During automatic operation of the FADEC, fuel metering by the HMU is controlled
electronically by the ECU.
In the manual mode the pilot’s throttle input is tied mechanically to the fuel flow metering
window in the HMU. The manual mode is engaged by deenergizing a solenoid in the
HMU via a cockpit switch. This allows the pilot to vary fuel flow to the engine by moving
the twist-grip throttle.
This manual mode fuel flow is altitude compensated to allow a consistent throttle /
horsepower relationship verses altitude. At 100% throttle travel, the manual mode will
provide at least maximum continuous power. Additionally, the fuel flow slew rate is
mechanically limited to avoid blowout and to provide proper responsiveness for aircraft
operation.
HYDROMECHANICAL CONTROL UNIT
Содержание BELL 430
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