A320 engine stall In flight QRH procedure

[CMpilot1]

In case of engine stall In flight, the QRH procedure calls for bringing back the THRUST LEVER to idle, and if parameters are found normal, then slowly advance the lever. It doesn't say about disconnecting the autothrust to carry out the procedure. On one of my simulator training, my instructor was adamant that the autothrust should be disconnected. Any thoughts?

Also, the end note says, "continue engine operations if a stall does not recur". Does that mean, that one can continue to destination without diversion?

[fpuentegomez]

Moving your thrust levers to Idle position will disconnect the ATHR, maybe he wanted you to disconnect the ATHR a certain way, it happens everywhere that some instructors have their little fixations and habits.

[lomapaseo]

From a technical standpoint (no intent here to conflict with a QRH) the idea of slowly advancing the thrust is to confirm that the engine will operate normally through a range of thrusts. Once confirmed you at last have confirmation that the engine can safely operate at a lower thrust level if conditions warrant.

I'm not quite sure if the same validation will be achieved with autothrust if it simply drives the engine to the same condition where it stalled in the first place without a chance for it to stabilize at a slightly lower thrust setting.

other comments?

[763 jock]

Just done this in the sim right now for you. Idle the faulty engine as per the QRH and if you don't move the other one into MCT the ECAM tells you to move the lever. You also get the prompt "LEVER MCT" on the ADI.

The faulty engine power output is limited by the thrust lever position, so I can't see why you need to turn the A/T off. You are controlling the thrust on that engine manually.

[EcamSurprise]

I agree with the above.

The power output of the faulty engine is limited by the thrust lever position.
The "good" engines thrust is being controlled by the AutoThrust.

No need to disconnected the A/T.

[Good Business Sense]

CMPilot1

Does that mean, that one can continue to destination without diversion?

Have a chat with your company engineering people if you can - many companies have the ability to monitor your engine event data in great detail in real time.

If you can't contact your company and you know that you don't have extensive maintenance support at destination you might need to consider a diversion to an airport that can offer you support.

If all the engine parameters are ok you can continue normally although that doesn't mean that the engine doesn't need attention before the next flight.

It happens a lot more than you would imagine.

[tdracer]

Also, the end note says, "continue engine operations if a stall does not recur". Does that mean, that one can continue to destination without diversion?

There are a great deal of reasons why an engine can surge, and many have nothing to do with the health of the engine. Severe turbulence or wake encounter, lightning strike (inlet distortion due to the lightning), and momentary fuel interruption being just a few. Assuming the surge itself didn't cause damage, the engine is just fine. As GBS notes, if realtime monitoring is available, your engineering people can quickly tell you if your engine is healthy enough for continued operations.


Many years ago, I was SLF on a 727 when the center engine surged during the takeoff roll - it was felt as well as heard and it was LOUD (and I was seated near the front, well away from the engines). After my initial shock from the BANG, my immediate thought was 'I'm going to miss my connection'. Not only did they continue the TO, we flew on to the intended destination. As I was departing the aircraft, I asked the pilot about it. He started to explain what a surge was but I cut him off, telling him I was propulsion engineer at Boeing and knew about surges, I was just surprised he continued the TO. His response was it was 'no big deal and happens all the time' - so long as the engine behaved after they retarded and re-advance the throttle there was not reason to abort...

[misd-agin]

td - known issue with the 727 inlet duct in crosswinds. On stiff crosswinds we'd advance the center engine slightly with taxiing onto the runway. That way the crosswind effect was minimized. During initial acceleration #1 and #3 would be advanced and #2 would be advanced, slowly after a slight delay, as speed increased. I don't recall if that was technique or procedure.

In the cockpit the compressor stall was a blip on the EPR and perhaps a minor noise or shudder. In the back the f/a's thought the engine had exploded.

[mcdhu]

At risk of being slagged/flamed (A320 TRE 10+ years), allow me to run the scenario.
The No1 Eng has surged after TO, TL has been retarded, ac levelled off for Qrh procedure and trouble shooting. No 2 TL has been placed in the MCT gate. Speed selected to around 210KIAS A/Thr still ON
No1 Eng parameters normal so TL is advanced. In order to maintain the selected IAS, both N1s align around 55%. Parameters remain normal, but only up to 55%. In order to check the parameters over the full range, the A/Thr has to be disconnected and the TL exercised over the full range.

[RAT 5]

...THRUST LEVER to idle, and if parameters are found normal, then slowly advance the lever. It doesn't say about disconnecting the autothrust to carry out the procedure.

I'm surprised it doesn't say "slowly advance thrust to either full power or surge, which ever comes first."

IN ORDER to check the parameters over the full range, the A/Thr has to be disconnected and the TL exercised over the full range.

This seems to be common sense to determine just what power you have available. If it surges just above idle then you would consider an engine out approach with one left at idle.

To a Boeing guy I wonder why this advice is not in the QRH procedure. "Slowly advance the thrust lever." How far? In this day of QRH for dummies it really does need spoon feeding. Too many of today's pilots are so scared of doing anything that is not written down and in detail. Introducing common sense into a QRH is unthinkable. N'est ce pas?

So what is the correct answer for those who err on the side of the dummies?

[Lantirn]

My opinion is you dont have to disconnect. However bringing one lever idle means selecting MCT detent on the other.

Regarding the check pf the parameters, i dont think again you have to reach TOGA just to check. CLB detent is enough.

[tdracer]

td - known issue with the 727 inlet duct in crosswinds.

Yea misd-agin - my first job at Boeing was nacelle aerodynamics and we were quite familiar with the shortcomings of the 727 center S-duct. So I wasn't terribly surprised when it surged (although quite startled - it was the first time I'd ever heard an engine surge from inside the aircraft and as noted it was really loud). I was simply surprised they kept going.

In the cockpit the compressor stall was a blip on the EPR and perhaps a minor noise or shudder. In the back the f/a's thought the engine had exploded.

I've always found that phenomena interesting - in the 727 surge, after we were up and away the pilot came on the PA and said something like "you may have heard a little bang"
Years later we were doing some PW2000 flight testing where we expected the engine to surge (something called "Quick Windmill Relights"). I was in the flight deck for the first condition and didn't hear anything unusual although the people at the instrumentation racks in back confirmed an audible surge. For the second condition, I was back at the instrumentation rack talking to another engineer - off headset I didn't know we were on-conditions again. I nearly jumped out of my shoes when it banged

[Willie Nelson]

To add a little to what Lantirn said: specifically the conditions by which the FMGC will detect an engine out condition and therefore command you to select MCT (By flashing lever "LVR MCT" on the FMA) are:

- One engine master switch off, or
- N2 below idle, or
- One thrust lever angle is below 5 ° with the other above 22 ° (as you might have done in this case)or
- The FADEC shows an engine fault

In this case, the MCDU will then present you with engine out performance information on both the PROG page for EO LRC and the PERF page with EO service ceiling. This will then provide you with information to help you ascertain whether or not you can indeed proceed to your destination with adequate reserves (Notwithstanding company procedure and regulatory requirements)

Should you have to sustain a TLA below 5 percent because of a stall condition on one engine then you will need to disconnect the A/THR if you are in the Cruise (nominally above 20000) because this is the requirement in the FCTM to maintain an a EO drift down in OP DES with MCT on the remaining good engine.

If the lever remains above 5 TLA then a static LVR ASYM will be indicated on the FMA simply as a reminder of the reduced range on one engine.

I can see what mcdhu is saying in fact (having re read it) that would give you an opportunity to exercise the full range of the engine.

Regarding the diversion, even if you may not be 'required' to divert because it is still running, you are required to consider the likelihood of it failing, which, assuming you can't put it back in the CLB detent without stall/vibration recurring would suggest is better than fair. Notwithstanding getting your ducks in a row and finishing ECAM I would be landing at the nearest 'suitable' aerodrome taking in to account all safety factors.

Hope that helps.

[flying headbutt]

mcdhu, I see what you are saying. Sounds sensible.

[mcdhu]

Thanks gents. Taking it one step further....
Having returned the No 1 TL to the climb gate in level flight at around GD with both N1s now showing 55 to 57% in SPEED mode, we run the DM process (DODAR, GRADE etc) and decide a to carry on. When cleared to climb, OP CLB is selected and the N1s increase towards the climb value. If the fault was not diagnosed by exercising the TL through the (almost) full range (with A/Thr OFF), it might recur as the thrust increases.
So all the diagnostics/QRH Procedure was nugatory simply because the engine was not exercised through its full range (with A/Thr OFF).
I've seen this go wrong in the box as described so many times, all I'm trying to do is to promote thinking. I know Airbus don't want us to think, but here is a good example of when some logical thought can save embarrassment.

[763 jock]

I'm a TRE like you. One of the biggest problems of the sim is that it is simply not realistic. How often do we get beyond about 30 miles from our departure airfield? The "candidates" are not daft and know exactly what boxes have to be ticked. There are loads of items that need checking and a limited amount of time. They've probably been doing the same old thing for years. Ad nauseaum....

I'm also minded to think that modern FADEC engines don't complain unless there is a bloody good reason. By all means keep it running at whatever thrust it can give you, but are we seriously going to climb away from our departure airfield up to cruise altitude having suffered a surge/stall event? Unless I was being shot at, I would return and get it looked at. Take the rest of the day off.

In the real world, every event needs to be judged on its merits. ECAM and the QRH can only help with the basics.

Good discussion subject, no doubt lots of different ideas and opinions.

[mcdhu]

Absolutely, 763 jock!
We've probably done this one to its death now.

[Lantirn]

Good point mcdhu,

I have done the procedure in the sim a lot of times, its funny I can not remember if I disconected A/T. Its something that makes sense, as it makes sense to check all the required range of thrust by doing the appropriate steps to accomplish this task.

Also has to do with circuimstances, if during climb, you could check it with A/T on. If not, a disconnection is required!

But you pointed the threat.

[dream747]

Suppose engine 1 suffers a surge/stall, we get the ECAM and we level off to troubleshoot as per the QRH procedures without disconnecting the A/THR. FM detects an EO condition and LVR MCT flashes on the FMA and you move TL2 into MCT detent as requested. As you exercise TL1 through the full range, should the stall disappear say @ 40% N1, how does the FADEC/FM react to this?

The way I understand it would be the ECAM disappears, EO condition disappears, with TL2 at the MCT detent and A/THR still on, wouldn't engine 2 be commanded to MCT thrust immediately, creating a not so ideal situation?

[mcdhu]

Yes, you have to know what you are doing. In order to maintain the IAS, you would need to reduce the thrust on the "good" engine as you bring the "distressed" engine up.
The situation is much clearer with the A/Thr OFF - in my opinion.