108
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THIS ELECTRONIC DOCUMENT MAY HAVE BEEN SUPERCEDED.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
The FADEC accomplishes automatic
engine load sharing by comparing engine
torque and/or MGT signals of the two
engines via the ARINC 429 data link. Each
FADEC contains the control logic to raise
the lower powered engine’s power level to
match the higher engine’s power level.
Upon loss of the MGT signal, torque signal,
or ARINC 429 bus, the load sharing will
revert to NG data, which is shared as an
analog signal between the engines through
the electrical harnesses. The pilot may
select either MGT or torque as the primary
load sharing data with the FADEC TEMP
TRQ switch located on the collective control
box.
MANUAL MODE
In the manual mode the pilot’s PLA 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 PLA. This manual mode fuel flow is
altitude compensated to allow a consistent
PLA 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.
ARINC-429 DATA BUS
The ECU provides a transmit only ARINC-
429 data bus. This data bus contains engine
parameters such as NG speed, NP speed,
MGT, and torque.
ENGINE FAULT ANNUNCIATORS
There are eleven warning/caution
annunciations included in the IIDS that
AUTOMATIC ENGINE LOAD
SHARING SYSTEM
are controlled by each FADEC. They are :
ECU (FAIL)
ECU (DEGRADED)
OVSPD (OVERSPEED)
30 SEC OEI (IN USE)
2 MIN OEI (IN USE)
FL HT (FUEL HOT)
FL CD (FUEL COLD)
A/RLT (AUTO RELIGHT)
SRT ABT (START ABORT)
ECU (DEGRADED)
M/OEI (OEI USE RECORDED)
M/ECU (SOFT FAULT)
The FADEC/ECU continuously monitors the
FADEC system for faults and makes
appropriate accommodations to continue
operation. Fault codes have been
preassigned to those parameters being
monitored by the FADEC/ECU. When a
fault is detected by the ECU the fault code
is stored in the permanent memory of the
ECU. Depending on the nature of the fault
the ECU may immediately display the fault
to the pilot via the IIDS and horn, or the
fault may not be displayed until the throttle
is placed in the cutoff position. The
multiple fault codes potentially generated
by the ECU have been assigned to specific
annunciations and horn based on the affect
of the fault to the operation of the helicopter.
The flight manual provides the appropriate
action required by the pilot for each
annunciation/horn indication. For more
details see the IIDS section of this book.
To Next Page
Loading...
