Figure 2-3-7. DECU Panel 714A
percent N1 then release the ENG START switch. The
automatic start sequence has been energized and FA-
DEC will complete the start. When an engine start is
energized, FADEC turns on the engine start solenoid to
introduce fuel flow and energize the engine igniters. Suc-
cessful engine ignition is immediately indicated to FA-
DEC by an increase of PTIT or compressor speed (N1).
Engine temperature is monitored throughout the se-
quence and will result in a fuel flow reduction if the tem-
perature exceeds 650_C with a full cutback to minimum
flow limit at 760_C. The starter motor and igniter are
automatically turned off when N1 speed exceeds 48 per-
cent. Ground idle is 50 to 59 percent and is corrected for
temperature. The engine is allowed to take 45 seconds
to stabilize at ground idle.
2-3-36. Engine Start Abort. 714A
PTIT above 816_C will cause immediate fuel shutoff to
below minimum fuel flow. The ECL must be retarded to
STOP to achieve total fuel shutoff. A start abort results in
the ENG 1 (2) FAIL warning to be illuminated until the
abort is reset by moving the ECL to STOP.
2-3-37. Starting in Reversionary Mode. 714A
The initial start sequence in reversionary mode is the
same as in primary mode except, when N1 reaches 8
percent, the control system turns on the engine start fuel
solenoid to provide an initial altitude biased fuel flow and
activates the igniters and latches the starter motor. The
pilot can modulate fuel flow to the engine with ECL to
start the engine at a desired acceleration rate. Tempera-
ture and temperature rate limiters are the same as in
primary mode except that the over temperature start
abort facility is not provided.
Alternate Reversionary Starting. For most conditions, a
start is successfully completed with the ECL held at the
GND position. However, if the engine fails to start due to
either a rich or lean hung start condition, the pilot may use
the ECL to increase or decrease the start flow as required
to complete a successful start.
Reversionary Rich Hung Start. A rich hung start
is characterized by N1 holding at about 40 percent and
PTIT climbing above 600_C. If a rich hung start is experi-
Set the affected engine ECL to STOP.
Allow PTIT to decay to 260_C or below (mo-
tor engine as required).
Check N1 0 percent.
Advance ECL half the distance between
STOP and GND (15_).
Motor engine using ENG START switch until
10% N1 and then release switch.
After engine ignition (PTIT rising), slowly ad-
vance ECL to GND. Check that N1 is stabilized at ground
Reversionary Lean Hung Start. A lean hung start
is characterized by N1 hanging approximately 30 percent
and PTIT remaining below 500_C. If a lean hung start is
Slowly advance the hung engine ECL to
achieve acceleration (maximum of one-third travel from
GND to FLT).
Retard the ECL to GROUND as ground idle
speed is approached. Check that N1 is stabilized at
2-3-38. Starting Cycle, Aborting and Motoring.
A starting cycle can be aborted at any time by moving the
ECL to STOP.
2-3-39. Power Assurance Test Switch. 714A
The primary FADEC will perform a BIT whenever the
PWR ASSURANCE TEST switch has been place to the
desired engine position. The switch is located below the
maintenance panel at station 524. The switch is label
1/OFF/2 and spring loaded to OFF. The results of the test
are displayed in the DECU BIT window.
2-3-40. Engine Wash System. 714A
The helicopter is equipped with an engine wash system
for each engine. Air and water connections are externally
mounted inboard of each engine work platform. A series
of spray nozzles are installed at the engine inlet and air
lines are routed to the bleed band actuator.