A318 thru A321 ENG Master switches?

[BigHitDH]

Hi all.

I have a question about the A318 thru A321 ENG Master switches, although I suppose this applies to Boeing aircraft as well.

The way I understand it, switching the engine master switch to "on" during an auto engine start opens the HP fuel valve, provided the ENG MODE selector is in the IGN/START, and starts the engine with bleed air from the APU or ground air unit.

Selecting "off" closes the HP and LP fuel valves, and resets bith channels of the FADEC. This will effectivly shut the engine down I presume?

Are these switches protected in any way? Do they have a "gate" to stop accidental activation, or is there some other method of failsafe in place?

Looking at the position of these switches (between the flap/spoiler selector handles, and immediately aft of the the throttles) this seem like the kind of position where one could easily get caught by a shirt cuff or accidentally knocked with a hand, shutting down the engine. (I'm presuming here that that's what it does).

If this is the case, it seems to me like this could only happen during takeoff (flaps up) a manual descent at TOD (thottles to flight idle) or when activating the spoilers in flight for a speed bleed.


I've seen on Boeing aircraft, the switches are "guarded" bu loops either side. Why doesn't Airbus do this?


Thanks in advance!

Edited to correct my poor typing...

[Carnage Matey!]

There's a kind of catch type thing that you have to lift the switch out of before it will move from the on or off positions. I think it would be quite difficult to inadvertently move the switches when moving the spoiler or flap selector levers as your arm is quite high above the position of the master switches and the spoiler and flap selectors are rearwards of the masters. If you were moving the thurst levers then I reckon you have a good eight inches between the levers in the climb detent and the master switches, and four inches with the levers in idle. Even if you did catch your enormous cuff on the masters, the forward position is ON so advancing the thrust levers would pull the engines to the on position. Still, I suppose stranger things have happened.

[BigHitDH]

Thanks Carnage for the comprehensive reply.

What you say makes sense, and I'm glad to hear there some form of "gate" provided.



Just out of interest, do aircraft manufacturers consult pilots on flightdeck ergonimics?

I've had the pleasure to spend some time in the cockpit of both the A320, B752 and B744, and some aspects seem strange.

For example, the CB board looks like it would be difficult for the F/O to reach in flight, and (on the B744 especially) the aft portion on the overhead panel must require long arms to reach!

Do any pilots have any remarks about awkwardly/plain badly placed controls?

[Max Angle]

As Carnage said it's not really possible to move them by accident although I have had a few pairs of "wandering hands" come quite close to them in the days when kiddies were allowed to visit the flightdeck. Some guys used to cover them up with an Aerad booklet before we opened the door, not a bad idea, it would have made a good incident report anyway!. The fire handles on the 737 were also temptingly placed for the same to happen.