Airbus A320 Engine Problem
 

Hi

Was on a BA A320 (I think) on the way up to Edinburgh from Heathrow a couple of weekends ago and just before pushback the captain said he couldn't get the port engine to start, but that we would taxi out and an engineer would come and have a look at it.

Throughout the taxi and the engineer's fiddling there was a really strange, loud "thumping" sort of noise, which I think was the hydraulics. Really quite alarming but I wasn't overly concerned since it seemed obvious that this aircraft wasn't going anywhere soon. I was thus surprised when after 15 minutes the captain said everything was sorted and we'd be off in five minutes ... which we were!

My questions are:

1) What would cause an engine to simply not start (is it a safety cut-out measure or something, and was it anything to be even remotely concerned about)
2) What was the REALLY lound noise (I fly a lot but have never heard anything like it before, and it lasted for a good 15 minutes).

Thanks.

Helo

Bit confused how you could taxi out whilst an engineer is trying to fix an engine problem????

To clarify ...
 

Sorry, perhaps should have said ...."throughout the single engine taxi, and the subsequent engineering fiddling on the then stationary aircraft"

Helo

Worked on the ramp for Servisair at MAN for a summer in the 80s, and one day was despatching a Connectair Shorts 330. Everything went fine, so stood waiting for him to taxi off after the doors closed. However the Captain seemed to have trouble starting No1 engine, and after several attempts I saw him walking down the aisle, so wandered over to see what the problem was. I was a bit puzzled to see him clutching the ship's axe, but as he just wanted some engineering steps I assumed he hadn't flipped!

Imagine how far my jaw dropped when he climbed on the wing, and proceeded to belt the engine a couple of time with the blunt side of the axe (add 6 inches and that's how far the passengers' jaws dropped, looking through the window!). 'Should be fine now' said the Captain as he got back on board and shut the door - sure enough everything roared into life and he departed.

I'd heard of hitting a car's starter motor to free it, but this was a new one on me!! Could explain the thumping noise though!!!

Sounds like a stuck start valve ( allows air from the APU, auxillary engine in the tail) to turn the engine until it gets to a certain rpm before ignition then fuel is introduced so that the engine can self sustain. The valve can be actioned on the ground by the engineer via a door on the side of the engine.
The noise you heard was probablly the transfer pump between two of the three hydraulic systems, and can sound (or does to me), like a dog barking in the hold. The Power transfer unit works when both engine master swithes are put to on during the engine start (on the ground) till both hydraulic sytems reach the same pressure, so i'd guess that was the sound you'd heard.
All perfectly normal and nothing to be concerned about.
Hope that helps
FBW

Ahhhh!
 

Thanks FBW, all become clear now.

It was, indeed, like a barking dog in the hold... I was struggling to describe the noise in my earlier post. Interestingly, I've heard the "barking dog" a few times before on flights ... in the distance, as though it really was in the hold, but this definitely sounded like a bloody great doberman sitting right beside me (no jokes about my lovely wife, please!) ... VERY loud indeed (again, no wife jokes please)!

Thanks again.

Helo

Its actually Rod Eddingtons dog.

Helo

The airbus barking dog syndrome can normally be traced to the Power Transfer Unit. The PTU enables the yellow hydraulic system (normally pressurised by the hydraulic pump on #2 engine) to pressurise the green hydraulic system (#1 eng) and V V.

With both engines running, the dog curls up and goes to sleep!