Compressor Stall #2 engine A320

[pakeha-boy]

Was rudely interupted last evening on a flight with an ecam....#2 engine stall"....these sorts of happening actually get your attention and make you sit up and open both eyes.

In the climb passing FL330 for 360,managed speed,managed climb,....had the # 2 engine, compressor stall on us twice.......very noticeable,with good yaw .....disconnected the autopilot ,leveled off expecting to shut engine down.......noticed EGT AND N1 fluctuations....no red lights,no engine parameter,s exceded(that we could tell)just the ecam...#2 engine stall" as this happened very quickly.

After 30,s engine stabilized(even above the screaming of the 150 paxs in the back)..... Quickly referenced the QRH,complied with the inflight portion,numerous checks...CFDS,AIDS.....called MTX .....after 25 minute chinwaggle continued flight.... ops checks normal, flight continued with no other problems......

Had the same thing happen on T/O a while back and rejected the T/O.....

Come to find out it was the 7th stage thingymejig on the rear end of the tranmisonthing.....

Would be interested to hear from the techies how often these occur

The F/O reckons the PAX never bought the "High altitude wake turbulence" I spun......hey why ruin a good story with the facts....the dunny light on the overhead stayed on for 3 hours:} ....PB

[Gary Lager]

Have had the same thing on an A320 at top of descent, although recovery was a lot more rapid.

So rapid, in fact, that even though we felt a kick as the aircraft yawed and heard a bang, the engine instruments had just recovered before we were able to assimliate what they were telling us.

It was only when the purser came into the flight deck to tell us pax had seen flames coming out of the front of the RH engine that we had a clue which one it had been!

No reoccurence, and put down to a sticking Variable Stator Vane (VSV) or bleed valve.

VSVs are refinements of the compressor section which allow for very precise control of the compression schedule through the rotors and staors, by bleeding air off in appropriate places to allow efficient performance on the 'edge' of the operating envelope without the risk of stall. If one is a bit 'sticky' then the airflow, operating under an adverse pressure gradient whilst being compressed and thus prone to 'depart' with only minor persuasion, can break down and burp back out the front.

We in fact subsequently found out, after the engine suffered a non-recoverable stall with v. high vibration a week or so later, that it was due to the abradable lining around the rotors having deteriorated and starting to fall down the engine in chunks.

Whoops! :eek:

[pakeha-boy]

Gary...interesting....turns out it was a 7th stage bleed valve....and like you it happened very quickly and trying to make an educated decsion:} ....and she,s all over.... :{ ...more concerned about the VIB ,which all stayed low...

The two things we did do,was to roll the airspeed back with the A-thrust on,then speed up to .80 ...then do the same thing with the A-thust off...the idea being to give rapid changes and see if we could re-create the stall...

The reason....destination airport was close to mins,in the event of a go around...TOGA style....a compressor stall at that stage is not my idea of fun.....easier to shut her down at altitude,set it up for a SE landing and go somewhere tropical:D .....some cold tinnes and marvel at what fine aviators we are:yuk: ....PB

[Rainboe]

In the early days of fan engines, compressor stalls were a regular occurence. As far as i know, it is just caused by sticky or failed pressure relief valves in the engine- when the overpressure builds up in a section, it can 'cough' loudly. At night it is spectacular- you get instantaneous flames and 20' sparks coming out of the engine, accompanied by a canon shot sound. You can imagine the effect in the rear galley of a VC10 when the engine 5' away surged! It used to burst the knicker elastic of the girls working there! The 747-100 was a merry surger. As long as the parameters recover, you didn't have to shut down. Indeed, for a long period, it was permissable to try a re-start even if you had to shut down. Most surges happened when you made significant power changes, and the vast majority at altitude. Low altitude surges were virtually unknown.

They are not a structural problem with an engine and appear to cause no undue stress- just alarm. The CFM-56 seems to be a most stable and reliable engine, and I have never known it to surge, or even heard of it happening to others. I was once sitting next to B707-336 No. 3 engine at night when all hydraulics were lost in the flare. The only way to stop was holding full reverse on until stationary. It was repeatedly surging right next to me, banging and flashing and flaming. I really enjoyed the 'firework show'- it was excellent entertainment! Then they had to pull reverse on to stop rolling and hold it and it was surging away again. All quite harmless, but very noisy.

All that old fun has ended now- I never had a surge on a 747-400 in 8 years. People can't believe how harmless they can be, which is why the 747-400 ex LAX-LHR 'incident' raised so much concern about damage to the airframe- there was nothing wrong with it at all, just a sticky valve in the engine.