Panel Switches Flashcards
What does number 1 do?
This switch allows the DC service bus to be powered by the APU BATTERY DIRECT BUS, and hence by the APU battery. This is not the correct procedure at Mesa Airlines as the switch is often forgotten and left on, draining the battery. Instead use the external power switch to power this bus.
What does number 2 do?
Number 2 is the battery master switch. Turning it on powers the APU BATTERY DIRECT BUS, the MAIN BATTERY DIRECT BUA, and DC battery bus which will turn on ED1 and ED2 among other things. It will allow your to power up the APU.
How long after flipping number 2 to on do you need to wait before perform the fire test?
30seconds
What does it mean if number 3 is illuminated AVAIL?
It means that ground power is connected and its the correct voltage, frequency, and phases.
If the AVAIL light is illuminated on number 3, what will happen if that switchlight is depressed (both with other sources of power in use and when external power is the only power in use)?
If no other source of electrical power is available the switchlight will illuminate the white IN USE portion of the switch. This indicates that the aircraft is using external power and all the instruments should boot up. If any of the onboard generators are in use, pressing the AC EXTERNAL power switchlight won’t turn white and the plane will not be using external power.
What is the number 4 switch?
The IDG1 disconnect switchlight
What does it indicate if the number 4 switch illuminates the yellow FAULT light?
It indicates that a high IDG oil temp or low IDG oil pressure was detected on the left IDG. It will be accompanied by an “IDG 1 (2)” warning on the EICAS primary page. The temperature at which the FAULT light illuminate so on the IDG DISC switchlight is 168ºC.
What happens if the IDG switchlight (number 4) is pushed?
It disconnects the IDG on the eft engine. It does this by activating the disconnect solenoid, releasing the spring loaded disconnect plunger, which engages the worm shaft. This will cause the worm shaft to unscrew from to N2 accessory gearbox.
What is indicated by the number 4 switch illuminating with a white DISC?
It means that the left hand IDG has been disconnected and is no longer generating power.
If number 4 or number 6 display an illuminated FAULT message, and you don’t manually disconnected the IDG, what is likely to happen?
The FAULT light illuminates at an IDG oil temperature of 168ºC or at a low IDG oil pressure indication. Thus if we don’t manually disconnect the IDG by pressing the correct IDG DISC switchlight, the IDG may further overheat. At 186ºC the Solder point on the IDG disconnect solenoid will melt which will automatically disconnect the IDG. But now the IDG will need maintenance.
What could happen to the IDG in an overtorque condition?
The shear point could break, causing a disconnect of the IDG but also serious damage to the IDG.
What does is mean if number 5 is illuminated?
It means that the AC ESSENTIAL BUS is not receiving power from AC BUS 1. This would likely happen in an IDG 1 failure when AC BUS 2 automatically begins to power the AC ESSENTIAL BUS.
What is number 5 called?
The AC ESSENTIAL BUS transfer switchlight
What happens if you press number 5?
It manually switches the AC essential bus from being power by its current AC BUS to the other AC bus, e.g. from AC BUS 1 to AC BUS 2. Pressing it a second time will cause the AC ESSENTIAL BUS to be powered by the original source.
What does number 7/11 do?
In the OFF/RESET position it electrically disconnects the left or right IDG from all electrical busses. It does not stop the IDG from spinning, so it is NOT mechanically disconnected from the N2 accessory gearbox.
In the AUTO position it will allow the IDG to power normal busses when the IDG is spinning (i.e. when the appropriate engine is operating).
