Alpha Technologies ECM - Manual (Page 18)

18
TM 744-862-C0-003 Rev.C
Engine Control Module (ECM)
1.2 Theory of Operation, continued
1.2.4. Normal APU Shutdown
The ECM will initiate a normal APU shutdown when AC line is
qualified, DC bus alarm is not active, the 12 minute cool-down
period has elapsed, and the Engine Run command is not active.
Otherwise, the ECM will continue to run the APU until the above
conditions are met or a major alarm occurs. Also, the APU will
run for a minimum of 30 minutes if started due to low DC Bus
voltage.
1.2.5. Abnormal APU Shutdown
The ECM will immediately shutdown the APU under the following
conditions:
• Major alarm
• Activation of manual engine stop switch
• Receipt of software engine stop command
• General generator failure
Crank Cycle
Crank
Attempt
Cranking
Engine
Pause
(no crank)
15 Sec 15 Sec 15 Sec 15 Sec 15 Sec 15 Sec 15 Sec 15 Sec 15 Sec
Engine
Overcrank
Alarm
30 Sec 30 Sec 60 Sec 30 Sec 30 Sec 60 Sec 30 Sec 30 Sec
1 2 3 4 5 6 7 8 9
Table 1-1 Normal Mode Crank Cycle