P6-2D (left) P18-2A (right)
Transfer Bus 1 Sect 1/2 - 115v ac (left)
Standby Bus Sect 1/2 - 115v ac (right)
On GND
Left ignition is powered by Transfer Bus 1. As a result, left ignition is only available when APU, ground power or the generator of a running engine is connected. This also explains why during an engine battery start, the Ignition Select switch must be placed to RIGHT.
Right ignition INOP : MEL 74-01 [Ignition Systems]
NOGO(M) In the event of loss of thrust on both engines, only right ignition is available for in-flight engines relight. Therefore, right ignition is mandatory.
The (M) maintenance procedure from the MEL provides standby electrical power to the left igniter, as follows :
With the Right Igniter system (spark or exciter) inoperative, the left and right igniters are swapped to the opposite EEC socket in the engine cowl.
In fact, you will now leave with the Left Ignition system INOP. Hence dispatching the airplane with the “Right Ignition Systems inoperative”, the engine must still be started with the Ignition Select switch placed to IGN R.
(Optional) Some airplanes come with an automatic back-up standby power source for the left ignition system. These airplanes have an extralabeled “STBY” ignition.
NOGO - Dispatch is not permitted if the ignition failure is due to an EEC Right Ignition fault (swapping the igniters will not resolve the problem since not the igniter but the ignition control is inoperative).
In FLT
If Transfer Bus 1 or 2 loses power, the left ignition for respectively engine 1 or 2 fails. Place the Ignition Select switch to R or to BOTH
ENGINE START SWITCH
OFF : - Ignition is off, unless auto relight (*) is active
AUTO : - Ignition is off, unless auto relight (*) is active
- Arms automatically high energy ignition to the selected igniter(s)
as follows :
Engine N2% > 0 AND Engine A/I ON or Altitude < 18,000 feet AND TE Flaps Extended
Automatic ignition to selected Igniter(s)
GRD :
- To be used for enigne start on GND or in FLT with starter assist
- Arms high energy ignition to the selected igniter(s)
- Arms high energy ignition to both igniters in flight
CONT :
- To be used to minimize possible engine flameout due to sudden disrupted inlet airflow during critical stages of flight (takeoff and landing). Turblence, bird strike or icing conditions with Eng. Anti-Ice selected ON
- Arms high energy igntion to the selected igniter(s)
FLT :
- To be used for flight in severe turbulence and moderate to severe icing
To be used for engine start in flight - Arms high energy ignition to both igniters, regardless of position of the Ignition Select Switch
(*) An auto relight capability is proveded for flame-out protection whenever the EEC detects an engine flame-out as follows :
Uncommanded rapid decrease in N2%
(On GND) 50% < N2% < 57%
(In FLT) 5% < N2%< Idle
OR Automatic ignition to both igniters