Crash-Cork Airport

[mad_jock]

9% is nothing to be honest.

The simulated feathered torque is 10% so in an engine failure the plane can have 90% torque split between the engines.

At 9% imbalance they will be well away from V minimum control airborne issues, Vmca.

The roll is just a secondary effect of yaw which was obviously not controlled. And to be honest with the experience level of the FO I can understand the reasons why as well.

[captjns]

Sunnyjohn... You need to look at the root cause of the accident. Electing to continue an approach to an airport where the weather was below minimums.

The AAIU reported that the captain (31, CPL, 1800 hours total, 1600 hours on type, 25 hours in command on type) was pilot monitoring, the first officer (27, CPL, 539 hours total, 289 hours on type) was pilot flying. Both pilots were certified for CAT I, however, were not certified for CAT II.

Crew pairing clearly was an issue too.

[NigelOnDraft]

mad_jock

9% is nothing to be honest.

The simulated feathered torque is 10% so in an engine failure the plane can have 90% torque split between the engines.

At 9% imbalance they will be well away from V minimum control airborne issues, Vmca.

The roll is just a secondary effect of yaw which was obviously not controlled. And to be honest with the experience level of the FO I can understand the reasons why as well

From the report, #1 went to -9% torque (indicated), then feathered and up to 22% torque / down to 96% RPM.

Torque might normally relate to thrust, but (not being a TP pilot), I suspect not with a feathered prop? Therefore the P2 had to handle whatever the effect was of a quickly / without warning feathered prop on the left - and then 3s later, having corrected, having that feathered engine / asymmetry suddenly restored to full symmetric power.

I am open to education about the relationship of torque to thrust, especially when a prop is feathered in flight with a running engine.

Edit: might not the prop going to feather, but at 100% RPM, produce a significant increase in thrust on #1 engine? i.e. as prop went from beta (flat) to feather... from Link

Uncommanded feather
Uncommanded feather is very similar to the overtorque condition noted above. The propeller pitch will abruptly increase, causing a rapid rise in torque with a rapid drop in RPM because the engine is still providing power to the propeller. While the pitch is changing, the thrust may increase and then decrease rapidly. The airplane will have asymmetric thrust

[Sunnyjohn]

Sunnyjohn... You need to look at the root cause of the accident. Electing to continue an approach to an airport where the weather was below minimums.

I take your point. Because the crew were busy putting the seats back, as I previously mentioned, they left late. They made two attempts (below minimums, true) then held for twenty minutes while they looked at alternatives, all of which were also fogbound. However, ATC had suggested Kerry to them, which was above minimums and they were contemplating diverting when they heard another aircraft on approach told by ATC that the fog had lifted slightly. This may well have influenced them to try for the third time, instead of diverting to Kerry. Incidentally, for those of you who know the area, Kerry is literally just down the road from Cork but, being further west, was escaping most of the fog blanketing southern Ireland that morning. None of this, I agree, excuses their attempting to land below minimums, or their lack of experience, or their lack of CRM. I regret to say, being a resident of the country, that that all goes back to Spain, still, in many ways, a third world country. Those of you that have been party to the whole of this thread will remember that I did a bit of digging with regard to the dubiousness of the Spanish companies involved.

[mad_jock]

power is rpm times torque.

When the blade is feathered its zero torque. Its measured by the twisting moment applied against the mounting ring. But I don't think the blade can travel that fast to be honest and just from the torque values you can't really tell where the prop angle is you normally get negative torque when the props are disked as fine as they can get when shutting the power levers at Vmo and the flight idle is set to low. I can't see the blades going to fine then to feathered then back to fine again it would require a huge flow of oil and pressure.

The temperature torque limiting system is a fuel dump valve and it will drop your torque from 100% down to 40% in 0.5 of second. And its normal for the rpm to drop until the prop pitch controller sorts the blades out and restores the rpm.

I will see what diagrams I can find at work this afternoon for the engine prop combination.

[Bang Or West]

Sunnyjohn - your assertion that "Because the crew were busy putting the seats back, as I previously mentioned, they left late and did not obtain a Met report until they were airborne. Had they read it on the ground it might have turned out differently" is INCORRECT.

You have become absolutely hung up on the crew putting the seats back in at BFS/EGAA, they did have METAR and TAF information before they left BFS/EGAA first thing that morning.

The actual FACTS as reported by the AAIU (page 9) state that :

"The accident Flight Crew … commenced duty at EGAA at 06.15 hrs (and) downloaded flight documentation including meteorological information for Belfast City Airport (EGAC), Cork Airport (EICK) and Dublin (EIDW) in a handling agent's briefing office at 06.25 hrs.

The aircraft departed EGAA … at 06.40hrs on a short positioning sector to EGAC.."

A photo of the METAR and TAF they had in their possession is shown on page 31. The markings on the page (various circlings and underlinings) would indicate that time wasn't so short, as you seem to think, that they hadn't just printed it and put it in the FO's flightbag.

I'm going to make a suggestion, and there's no kind way to say this, but I suggest you put the kettle on, make a pot of coffee and sit down and actually READ the report from start to finish, wild fanciful speculation based on your own theories about what might have happened isn't really helping the flow of the debate here. IMHO.



[Trossie]

...I suggest you put the kettle on, make a pot of coffee and sit down and actually READ ... from start to finish...

Best advice for many, many, many who post on PPRuNe!!!

[JW411]

Another worthwhile aspiration is:

Engage brain before opening mouth.

[jumpseater]

SJ may have got confused with the seat refit, as the previous crew fitted them. On arrival at EGAC the accident crew held boarding and were both seen at the back of the aircraft with torches appearing to be doing something with the seats.

Neither crew were authorised to carry out the seat swap and no tech log entries made to reflect the changes in aircraft configuration. The seating on the accident flight was a non standard config.

[Sunnyjohn]

I'm going to make a suggestion, and there's no kind way to say this, but I suggest you put the kettle on, make a pot of coffee and sit down and actually READ the report from start to finish, wild fanciful speculation based on your own theories about what might have happened isn't really helping the flow of the debate here. IMHO.

Thanks, BangOrWest. I stand suitably chastised and have deleted the incorrect and wildly speculative part of my post.
I note that you have so far contributed three posts to this very long thread and so I look forward to reading more of your useful and informative contributions.

[blind pew]

It's ironic that around the same time the report was published yet another aircraft crashed after starting an approach when the airfield was below minimums.
Crash: Scat CRJ2 at Almaty on Jan 29th 2013, impacted ground near airport
There are a variety of reasons why crews break the rules or ignor simple airmanship...until the authorities get their act together the accidents will continue.
Like MANY airline pilots I have broken the rules...mostly as a copilot without any choice except get a job elsewhere...and I have only worked for flag carriers.
A sad industry that hasn't progressed in certain aspects over the last 40 odd years when my mate died in Britain's worst disaster...not properly trained...captains forced to take us along...cr@p maintanence ...and authorities not doing their jobs.

[Chronus]

CORK METROLINER CRASH

Have a look at my posts of 1st and 3rd September 2013. Thrust induced assymetry in one and assymetry previously reported on the accident aircraft the other. So all that was necessary for the ladies of fate to add an ill preprared crew who bust minima and for the PNF to compensate for the lack of automation and assume the role of an auto pilot and auto thrust system to bring about the fateful accident.
The question that we really need to debate is the lessons learned. In particular by operators which still appear to continue to allege that flight delays occasioned through technical problems are beyond their control and spend a fortune in the courts to defend claims for statutory compensation. Would it not be a lot better if they applied such resources to crew training and maintenance instead. Overworked, poor and inadequatly trained crews with ill maintained aircraft are a deadly combination.

[jetfour]

Co-incidence?

After three years in storage, Metroliner EC-GPS has left the IoM for Barcelona today.

[BARKINGMAD]

May I suggest that posters to this thread make an HONEST declaration, just as they would as professional flight crew signatories on public transport operations, as to how many pages they have read of the AAIU report?

I admit I'm only up to 145/244 and therefore NOT in a position to comment with enough knowledge and presumed authority on this awful tragedy.

Would the members of the lynching brigade like to 'fess up as to how much of the report they have digested before they spout about how allegedly wicked and evil and stupid they consider these unfortunate pilots were?

Dare they prefix their rantings with x/y pages read and considered, before they continue the outpouring of arrogant and complacent remarks implying their own professional perfection?

If the majority of posters are PROFESSIONAL pilots, I wonder have they lost the qualities of humility and awareness that we can ALL make mistakes under the incredible current commercial pressures.

Engage brain before opening mouth, as previously suggested!

[bookworm]

There is a theory/practise out there that some lift the gate before landing.

There's no explanation I can find in the report as to why the skipper might have selected reverse before touchdown, and MJ's is the only rationale I've seen. But is the 2100 m runway at Cork so limiting that the crew would feel it necessary to be so trigger-happy with reverse?

[BARKINGMAD]

"But is the 2100 m runway at Cork so limiting that the crew would feel it necessary to be so trigger-happy with reverse?"

If it's that sphincter cycling a length of runway, then the Ryr NG800s and Aerfungus 'buses would be having a sporting time?

The Capt's alleged enthusiasm for getting out of the detent should have been rectified during the inadequate preparation as per 2.17.2 of the report, for those too lazy to read it all.

[mad_jock]

Sorry no can do on diagrams the CAMO says there is copy right issues.

Anyway the NTS system on our versions as I thought is a completely separate system to the torque sensing system. Its a ring which slips and actuates a valve which opens a bypass valve which dumps the oil pressure from the beta tube which then the spring pushes the blades to feather.

The torque sensor is a strain gauge bridge on most aircraft with a rare old hydraulic system on one of them.

And as confirmed this very evening that negative torque can be obtained by disking the props and then it goes back to +2 again and then when you apply power again it goes to what ever you want without the NTS triggering and without the blades going to Feather and the power levers forward not in beta. The engineers are sorting the flight idle out as we speak up a couple of notches to +6 and I will do a flight idle check tomorrow to ensure it doesn't dip to zero or negative.

Negative torque is when the propeller is driving the engine not the engine driving the prop.

Its a single action prop BTW

I really don't think they were anywhere near feathered it could be that the negative was when the AOA of the blade was taken to negative value and the blade drove the engine then as fuel was increased to the engine it started driving the blades again. Even if you put the power levers forward again the spring isn't meant to be strong enough to rotate the blades back into a flight AoA. It could be that he put the lever forward again which increased the power but as the blade couldn't get into positive AoA it just gave more reverse which would been seen as a positive torque as the engine was driving the blades not the blades driving the engine. I can't really see how anyone can work out what angle the blades were in. You can't even look at them after the event because without the start locks engaged they will just go to feather as the oil pressure drops off.

If the spring isn't strong enough I can't see how the NTS system can even feather the props because all it does is dump the oil pressure out the beta tube. So even with zero pressure in the beta tube if the forces on the blade stopping it rotating back to flight AoA's are enough to defeat the spring it won't feather.

When we power back off stand the torques read positive in reverse then decrease to zero then increase again as you apply forward movement to the power levers bringing them out of the rev range.

[10Watt]

Beta range l think you meant.

mad - jock, l admire your fortitude.

[mad_jock]

The problem dealing with beta on the garette is that it means something different to the free turbine types.

Yes it means that reverse pitch on the blades is available but it also means there is a swap in shall we say dutys of various controllers.


So beta isn`t really a range its a engine prop control mode in which beta AoA of the prop blades can be used and is available. I think it also does something to the oil system supplying the beta tubes to increase the available pressure to protect against rev in the air with a prop pitch controller failure. But will check that tomorrow.

[10Watt]

l wouldn`t bother mate.

lf you`re happy that`ll do me.

Any news on the deaths ? l don`t check too often.