Air Asia Crash Report : Cracked Solder Joint on Rudder Limit Circuit Board

[Wytnucls]

Introducing new solutions is easy. The difficult part is to develop failsafe procedures for all kinds of failures, without overloading the flight crew and creating a new 'Gotcha' in the flight control system. The KISS principle comes to mind.

[Rupunzell]

“Active sidesticks significantly improve the level of safety, making evident control inputs of pilots to one another and allowing prompt recovery actions,” says Roman Taskaev, chief test pilot for the MC-21 programme.

Taskaev tested the failure modes of the active sidestick controllers in a series of recent trial runs in a ground-based simulator in Figeac, France, UTAS says.

Cockpits equipped with decoupled sidestick controllers that do not provide active feedback have been highlighted in several aviation incidents. A left-seat pilot on Air France flight 447, which crashed in the South Atlantic in 2009, did not appear to understand that the right-seat pilot was pulling back on his sidestick and causing the aircraft to stall.

https://www.flightglobal.com/news/articles/mc-21-ushers-active-sidesticks-into-commercial-aircr-411455/



Bernice

[Rupunzell]

http://aviationweek.com/defense/positioning-captain-s-personal-camera-caused-near-crash-uk-a330


Bernice

[Brumby]

I, too, am a supporter of the KISS principle which is why I like the idea of "I've got the stick, so I'm flying the aircraft."

I understand it's not as simple as that these days - and there are good reasons why - but the connection between the pilot and the control surfaces just seems to be getting more and more distant.

[Rupunzell]

2.3.2 Active side stick
"Contrary to passive side stick, the active side stick provides complete situational awareness by providing tactile forces calculated by the fly-by-wire computers during the flight (Hanke & Herbst 1999). Tactile feedback is obtained by electronic signals from aircraft system to the side stick through servo-motors.

Since the active side stick is coupled with the aircraft dynamics it provides tactile and visual cues allowing for better handling and reduced pilot workload (Hegg 1994).

The active side stick system is complex and requires more technical effort to assure its reliability (Hanke & Herbst 1999). For this reason, most commercial aircraft companies decide to implement a passive side stick as it is less expensive."

https://publications.polymtl.ca/872/1/2012_MarieEveCote.pdf


Bernice

[Brumby]

“Active sidesticks significantly improve the level of safety, making evident control inputs of pilots to one another and allowing prompt recovery actions,” says Roman Taskaev, chief test pilot for the MC-21 programme.

I am puzzled why this did not seem to be self-evident with the designers.

[Paul Moir]

I honestly don't know; airplanes are not my thing.  However preventing humans from making mistakes is, and going by my experience with that, picking training as a root cause is usually a cop-out.  Everyone forgets it, ignores it, or simply doesn't follow it sooner or later.  Like you said, we're human so failure is inevitable if we rely upon ourselves only.

The best solution in my experience is to design the process so the person isn't presented with the decision in the first place.  The second best is to prevent him from making the wrong choice.  That works really well:  you make it a hassle to make (what you think) is the wrong action.    Audible (primarily) and visual (very secondary) warnings are a distant third.  Far too easily ignored when you're busy with something more important then them.

To make a guess, the maintenance root looks like a real problem, as does design.  Why did maintenance think having all those failures with those two units was OK?  (I'm guessing this root really goes back to management with either budget or culture.)  Why did they think some incantations with the circuit breakers was an effective repair?  Why did the units, which Airbus thought so much of they put two in, both fall apart?

[Rupunzell]

Space Shuttle Discovery cockpit.





Bernice

[Rupunzell]

Gulfstream G500, G600


http://www.baesystems.com/en-us/feature/an-active-role


Bernice

[Wytnucls]

There should never be a 'push-me-pull-you situation' in any aircraft. The captain just shouts 'I have control' and the first officer has to sit on his hands.

While I have no quarrel with this - the fact is, it physically can happen.

My question is: WHEN conflicting inputs are being given HOW do the pilots find out?

The aural warning 'dual input' should sound, and both sides of the cockpit have a visual indicator as well.

Yes, but the system is not installed on all machines. it is unclear if the AirAsia plane was equipped with the upgrade, but anyhow the captain was aware of dual inputs, as he pressed his priority button.

The report seems to indicate that it was, however the alarm was suppressed by the stall warning. That is a flaw which needs rectifying.

Since the PIC has to take over controls in a stall situation, an easy solution would be to require a constant push on the priority button until the stall warning stops and upset recovery has been achieved.

[Monkeh]

Since the PIC has to take over controls in a stall situation, an easy solution would be to require a constant push on the priority button until the stall warning stops and upset recovery has been achieved.

Which is what should have occured, but I am unsure how that resolves the issue of a critical alarm being suppressed by another alarm.

[Esotech]

Hello all,

If the picture shown is the actual device it would seem it has been exposed to water at some stage - the right hand side upside downed pcb shows what appear to be area's of both corrosion and rust as does the dry joint shown. It doesn't look like very modern electronics as everyone else has noted either and if it is the actual item I am very surprised that a component in a critical system could be allowed to get into this condition.
 

[CatalinaWOW]

Haptic controllers are more safe, but more expensive and less reliable.  Maybe there is middle ground.  One that would require almost no additional hardware, and a small amount of software.  Just software that compares the controllers and activates a stick vibrator (on both sides) if there is significantly different input.  Potentially an issue in terms of flight crew sensory saturation, but at least gives a signal that something may be wrong.

[Monkeh]

Hello all,

If the picture shown is the actual device it would seem it has been exposed to water at some stage - the right hand side upside downed pcb shows what appear to be area's of both corrosion and rust as does the dry joint shown. It doesn't look like very modern electronics as everyone else has noted either and if it is the actual item I am very surprised that a component in a critical system could be allowed to get into this condition.
 

You are aware that this thing CRASHED INTO THE SEA, right?

[crispy_tofu]

http://aviationweek.com/defense/positioning-captain-s-personal-camera-caused-near-crash-uk-a330


Bernice

I know this post is from last year, but it reminded me of this:
https://www.washingtonpost.com/news/checkpoint/wp/2016/04/19/night-vision-goggle-case-cause-of-plane-crash-that-killed-14-air-force-says/