Air Asia crash caused by circuit board solder cracks

The crash of Air Asia QZ8501 was caused by cracks in the solder of a circuit board. Approximately 30 minutes after takeoff the first of three Master Caution lights for the rudder trim limiting system lit up. After the fourth, investigators heard sounds consistent with the Flight Augmentation Computer circuit breakers being pulled.

After the 6th master caution light the aircraft went into Alternate Law, which removed envelope protection systems. The rudder kicked over 2 degrees left, and the aircraft rolled to 54 degrees. It eventually rolled to 104 degrees before crashing. Over the previous year, the aircraft had 23 problems related to the rudder travel limiting unit. The investigation found that cracks in the solder led to a loss of electrical power to the RTLU.

www.flightglobal.com...

sounds like cheap solder or maybe overheating and rapidly cooling
"cracks" is vague enough it could have even been cold joints


could cheapskate management
an engineering oversight
or manufacturing

but somebody sucks at their job

a reply to: Zaphod58

Pretty much what you said .
www.9news.com.au...

a reply to: Zaphod58

The crash of Air Asia QZ8501 was caused by cracks in the solder of a circuit board.

In electronic, we call it cold solder. It is often associated with unleaded solder. Less toxic but less reliable.

a reply to: PeterMcFly

not necessarily
it happens even with lead solder and proper heating of the joint if it heats up and cools over and over
which would be more on the engineer not planning ahead or expecting as much heat as there is

(i would also be willing to bet atmospheric conditions play a role but i never really learned anything about that so eh)

In the early days of desktop PC's our computer labs used to have this problem due to heat stress. During the day they were roasting hot with 30+ CRT monitors and desktop units and that many students. At night they were freezing cold due to the lack of heat. During Winter months, some systems would fail because memory cards were pushed out of their sockets. Others would fail because soldered joints on the motherboards failed due to the difference in thermal expansion and contraction of the materials used to make the motherboard and the solder.

a reply to: fartlordsupreme

not necessarily it happens even with lead solder and proper heating of the joint if it heats up and cools over and over which would be more on the engineer not planning ahead or expecting as much heat as there is

Yes but according to my 30+ years of experience in electronics it append much more with unleaded solder, a lot more...

No need to patronize me as i know how to test electronic system using environmental (and shacking) chamber...

a reply to: PeterMcFly

dur hur hur ok
you know this is an open board and that information wasnt just for you though right?
you also know i would have no way of knowing what level of experience you have right?
you are also aware that time is not really a great indicator of how much you have learned right?

a reply to: fartlordsupreme

30+ years electronics experience and what like 45+ of being a dick?

Much better than being a cretin all my life...

a reply to: fartlordsupreme

you are also aware that time is not really a great indicator of how much you have learned right?

Yes but it was more than enough time to learn how to recognize cr.... when I see them.

a reply to: fartlordsupreme

"cracks" is vague enough it could have even been cold joints

Usually what they mean when discussing 'cracks' in solder 'joints'. The solder itself doesn't "crack" , rather the bond between the solder, device lead and circuit board trace or pad becomes broken. Not enough heat being applied to insure good flow and bond during the assembly process.

It might pass visual inspection and testing, even survive in flight vibration for some period of time, but over time the bond weakens and cracks develop, opening the circuit.

cold solder joints, images

So, I swear...if it's not Boeing, I'm not going...I swear it. If it's not the got tam tail getting ripped off , it's the solder...someone send me back to the good old days.....

originally posted by: Zaphod58
Over the previous year, the aircraft had 23 problems related to the rudder travel limiting unit.

Aw, it's fine. Recurring problems with flight control safety systems just fix themselves. Right?

The only thing that can go wrong is everything. I thought we would have learned our lesson about rudder issues when 737s were still dealing with the mysterious rudder hardovers. Apparently we need to relearn what a malfunctioning rudder can do all over again.

I wonder how the boards were soldered. A place I worked at had a failure on a bunch of boards. We found out that the wave soldering machine hadn't come up to temperature when the boards were run through it. The operator was screwing off and was afraid that he'd get caught so he ran a batch of boards through before the temperature light came on to make his quantity for the hour correct. The company tried to terminate him, but, the union covered for him. The result was that the Quality Control Engineer (me) had to certify that the temperature was correct before any boards were run.

a reply to: PeterMcFly

Having worked on circuit boards myself I wonder if the solder was tested after being applied. The places I worked would put boards in a heat room to check the solder and then we would retest the board. However I have also seen the quality of Chinese and Russian I.C. chips and boards, they were sub-par to say it kindly. Hence why they are so cheap.

I just can't believe how bad the basic pilot skills of these ATP certified guys is. A rudder induced roll is not fast. In order to roll 54 degrees by rudder would take several seconds (I'm guessing upwards of 10 secs). Yet the aircrew could not use basic flight control inputs to counter that. The aircraft had transmitted stall warnings and was having flight control warnings.

Most well-trained pilots learn what the heart of the maneuvering envelope is and move in that direction. For an Airbus, that's likely around the 250 - 300 KIAS range. Push the nose over, declare your emergency, counter the roll with lateral stick and coordinated rudder. Totally basic.

CNN reported that one of the aircrew was heard saying "Pull Down" Unless you're inverted, there is almost never a case of "Pulling Down" and if you're inverted in an Airbus (no matter what the movie "Flight" showed) you're already up the creek.

And don't they read the maintenance logs prior to taking possession of the aircraft? They should have seen the the previous gripes on the rudder trim system and been ready for that.

Sad. Just preventable and sad.

Im scared to think they had to repair the one part 23 times rather than just replace the board!!

With lead-free, I've seen perfect looking joints that had virtually no bond to the pad, despite it making a visually perfect fillet, caused by out-of-spec Entek. Even immersion tin will cause it at times.

The crash actually happened because of the mistakes made by the pilots , not the solder crack itself ...

a reply to: zoomer72

Without the solder crack the pilots wouldn't have been in position to make the mistakes they did. The bad solder was the first, and most major link in the accident chain.