Are Airbus Sidestick Controls Causing Crashes?

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Member for

17 years 5 months

Posts: 9,738

Were the sidestick controls a major factor in the crash of the AirAsia A320:

http://www.bbc.co.uk/news/world-asia-34972263

This seems to be the second crash of an Airbus aircraft that involves the autopilot disconnecting, or being disconnected, and the pilot being unaware that the co-pilot was putting in contradictory commands via the sidestick; the crash of an Air France Airbus off Brazil in 2009 being the other:

http://www.bbc.co.uk/news/world-asia-34977543

Certainly crew training seems to be at fault too but would these two aircraft have been lost if they were fitted with old-fashioned control yokes that are physically linked so each pilot can see or feel what the other is trying to do?

Original post

Member for

15 years 9 months

Posts: 1,684

Has anyone seen the official report and is there is an accurate English translation?

I did not open a new thread yesterday on QZ8501 in case anyone thought I was trying to say I told you so as I did on this forum following AF447 2009.
My "plumb line" (luminous fishing line, a tiny maglight torch as weight and light, and "bluetack") in the flight crew pockets would have more than likely saved the day yet again in this case. See posts with comprehensive sketch diagrams.

If the report http://www.bbc.co.uk/news/world-asia-30632735 is factual then these are an alarming set of statements

" A crack in a tiny electronic module caused the system to send repeated warning alerts to the pilots, who responded by resetting the system.

This caused the autopilot to disengage and the plane rolled to the left. The pilots struggled to right the plane, which stalled and crashed.

The report found that maintenance crew had previously known about the problem, which occurred 23 times in 2014, and resetting the system had been one of several methods used to address it."

I would like to see Airbus comments on whether the above was "by their book"

Surely that aircraft should have been grounded until authorized maintenance was carried out instead of a "bodge" "supposedly 23 times".

Crew training (ie to fly the aircraft with failed instruments - by almost the seat of your pants) will help if maintenance advises "bodged workarounds".

As TomcatViP advocates on this forum "Bring Back the Stuntman"

My repeated heartfelt sympathies to the bereaved but sadly it is a different 'world' of safety standards in some areas of the globe.

Member for

14 years

Posts: 194

" A crack in a tiny electronic module caused the system to send repeated warning alerts to the pilots, who responded by resetting the system."

A fault like this could be due to bench testing showing NFF (No Fault Found) as the unit was probably not stressed by heat or cold on the bench as in the air.
Had lots of problems with Jindivik Transformer Rectifier Units until luckily found water across a couple of junctions. Normally this water would evaporate before being able to inspect item. This led to a change in design of the cooling air inlet!
Keith

Member for

12 years 3 months

Posts: 5,905

@nJayM:

No, I hadn't found a copy of the report so far and haven't read it yet. This is why I restricted myself from any comments.
You can find it here: NTSC final Report QZ8501 AirAsia Crash

Media reports are indeed troubling:

- the repetitive occurrence of the trim rudder failure
- the fact that the failure is an aggravating one instead of being tempered by a mechanical action (like the canards on the Gripen that switch to passive mode in case of damages - see also the rear CG of Airbus planes and the Pull down order of the Captain [?] ).
- The dual control stick with no linkage (again) and the fact that there are still no forced travel coordination b/w the two set in 2015! (a cheap upgrade)
- the Similar presence of a young Fr pilot behind the yoke that still point toward a lack of relevant screening process for trainee (add the Germanwings crash). Thank you for bringing up the apparent relevance of the Stuntman thread
- The fact that some major Media insisted on the pilot error when the mechanical fault and apparent weakness in SOP generated this disaster first (CNN)

Member for

12 years 3 months

Posts: 5,905

" A crack in a tiny electronic module caused the system to send repeated warning alerts to the pilots, who responded by resetting the system."

A fault like this could be due to bench testing showing NFF (No Fault Found) as the unit was probably not stressed by heat or cold on the bench as in the air.
Had lots of problems with Jindivik Transformer Rectifier Units until luckily found water across a couple of junctions. Normally this water would evaporate before being able to inspect item. This led to a change in design of the cooling air inlet!
Keith

Goof hypo but Airbus Engineers were way aware of the concerns. It's a problem of decision takers...

Extract from the NTSC:

According to the Airbus information, there were three Technical Follow-Ups (TFUs)
regarding the AUTO FLT RUD TRV LIM 1(2) (SYS) problems that were issued
since 1993. TFU No. 27.23.51.004 was opened in 1993 regarding the problem of
fatigue rupture of solder and closed on 1996. The problem found was “fatigue
rupture of soldering” and the improvement made was “new electronic module”.
Another TFU 27.23.00.004 was opened in 2000 with the same problem of “Rupture
of soldering” and closed in 2014 with the improvement of the “Electronic board
process” which was available since 2002. The third TFU (number 27.23.00.007)
“Mechanical stop failure” was opened in January 2015 following this accident.
Airbus informed that the installed RTLU on PK-AXC had been improved with both
Technical Follow-Ups (TFUs).

In other words: no conclusive actions were taken on that point since the problem was first discovered in... 1993.

Member for

12 years 3 months

Posts: 5,905

As a side note to the topic handle:

FCTM - Side-stick and takeover Priority Button

When the Pilot Flying (PF) makes an input on the sidestick, an order (an
electrical signal) is sent to the fly-by-wire computer. If the Pilot Not Flying (PNF)
also acts on the stick, then both signals/orders are added.
Therefore, as on any other aircraft type, PF and PNF must not act on their
sidesticks at the same time. If the PNF (or Instructor) needs to take over, the PNF
must press the sidestick takeover pushbutton, and announce: "I have control".
If a flight crewmember falls on a sidestick, or a mechanical failure leads to a
jammed stick (there is no associate ECAM caution), the "failed" sidestick order is
added to the "non-failed" sidestick order.
In this case, the other not affected flight crewmember must press the sidestick
takeover pushbutton for at least 40 s, in order to deactivate the "failed" sidestick.
A pilot can at any time reactivate a deactivated stick by momentarily pressing the
takeover pushbutton on either stick.
In case of a "SIDE STICK FAULT" ECAM warning, due to an electrical failure,
the affected sidestick order (sent to the computer) is forced to zero. This
automatically deactivates the affected sidestick. This explains why there is no
procedure associated with this warning

Source:
NTSC Final report QZ8501 p79