I A P 2 0 2 3 . 0 0 1 - A F M / I R I S T E X A N I I P A G E | 31
FOR SIMULATION USE ONLY – NOT A TRAINING AID
The PMU will not reset until IOAT drops below 121 °C. Once the PMU is reset (PMU
switch cycled from NORM to OFF and back to NORM), IOAT and ITT returns to
normal and the EDM FAIL warning should be removed.
The EDM is functioning normally if the EDM fail was present, but does not appear
after the PMU is successfully reset.
Auto Start Operations
To begin an automatic start, advance PCL to auto start position until the green ST
READY advisory on the EICAS illuminates. Momentarily selecting the STARTER
switch to AUTO/RESET while ST READY remains illuminated, initiates the fully
automatic start sequence.
The PMU activates the starter, boost pump, and igniters, and adds fuel at the proper
N1 speed.
At approximately 50% N1, the starter and igniters are de-energized and the boost
pump is deactivated if fuel pressure is above 10 psi. The engine continues to
accelerate to idle speed (60% N1).
The propeller automatically unfeathers during the start as engine oil pressure
rises. The PCL may be advanced to IDLE any time N1 is at or above 60%.
During a normal (auto) start, the PMU continuously monitors N1, ITT, and fuel flow.
The PMU can automatically stop fuel flow and deactivate the igniters and starter at
any time to abort the start if necessary to avoid a hung or hot start or if any engine
start parameter is exceeded.
After the PCL has been advanced past the start ready position, the PMU will not cut
off fuel to terminate a start. The start must be manually aborted either by moving
the PCL back to OFF or, if the PCL has not been moved past the IDLE gate, by
reselecting the STARTER switch to AUTO/RESET.
Either action resets the PMU and aborts the auto start. If the PCL has been moved
past the IDLE gate, the PCL must be moved to OFF to abort the start.
The PMU also provides air start capability, but does not provide engine protection.
During an air start, automatic N1, ITT, and torque limit protection are unavailable,
therefore, the pilot must monitor all parameters and abort the start manually if
necessary.
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