Engine Start at Gate - Reason?
 

On a flight yesterday (A320), pilot indicated the need to start one of the engines at gate due to some minor mechanical reason, but did not provide any specific.

Anyone know the reason behind?

Thanks!

I've been on flights where the pilot used "powered backing" to back out of a gate. Don't know if that occurred in your case, but it would be unusual on a plane with wing-mounted engines.

https://en.m.wikipedia.org/wiki/Powerback

Seems likely that the plane was having a problem with the Auxiliary Power Unit (APU). I think in most cases, modern planes push back first, start the APU (which is a mini-jet engine in the tail), use air bleed form the APU to start one of the main engines, and then use air bleed from that engine to start the other engine. (or something like that).

I also think that in some cases an inoperative APU isn't an MEL (minimum equipment list) item. So they start one engine from a cart at the gate and then the second engine after push-back and don't have to take the plane out of service right away.

I'm not aware of any US airport that allows powerback, and haven't seen it done for decades. It's a noise and exhaust management problem for the terminal building and ground crew, and it has a very high risk of flinging foreign objects from the ramp area against the terminal building - or kicking up a dust storm that will then be sucked into the engines.

Without a specific announcement, we really can't tell why.

I was on a flight where the pilot announced that she had seen minor damage on one of the jet engine turbine blades, but the damage could be fixed (that will buff out!).
After the fix, that engine was not only started at the gate, but run up to what seemed like pretty high revs. I was sitting more or less inline with the front of the engine so I wasn't too happy about what might have happened if the fix hadn't worked. But apparently the fix worked so we took off and completely the flight without incident.

You start an engine at the gate with APU bleed air is unavailable. A ground air, or huffer, cart is used to provide the air pressure to start the engine. After pushback, and usually away from the gate area, the second engine is started using bleed air from the first.

Minor damage on fan blades is blended to smooth it out and remove any sharp angles that would lead to cracks. The same thing is done on metal propellers on prop planes. The engine run would have been to check for any excessive vibrations, not to see if the repair would hold. Such repairs are very common.

NW was doing power-backs at MSP and DTW with their DC-9s up until the merger. Unsure about after as I bailed and went to UA.

Inop APU, yes, most likely reason to do a gate start.

As others have said an inoperable APU. I have been on multiple flights where an engine was started at the gate because of an inoperable APU.