Aer Lingus A-330 aileron castings
Or some loads were different from the ones expected. As this AD shows, there can be a problem with the two (or more) actuators attached to a control surface which can "fight" against each other, resulting in high loads between those leading to premature fatigue failure of the actuator attach fittings. For "traditional" aircraft this can result from misadjusted control linkages, stiff or seized spring rods, wrong wire tension etc. For "modern" FBW aircraft the actuators are electronically commanded, there could be a rare (and undetected) failure cases that result in two actuators fighting against each other. This could be a good explanation for such "one of" fatigue failure of an actuator fitting. The loads on an aileron of a long range aircraft (basically zero for most of the flight) compared to the loads actuators could produce against each other are extremely different. You do design such fittings for the static loads of such failure cases to "get home" and repair, but not for fatigue
i think its a wind up, those forgings are stronger than strong things but the broken area looks like its been deliberatley busted
put it another way, if there so much of an upset to snap the ends from these forgings there would be evidence of damage at the other end due to pivot action around the large centre bore
i await the abuse from experts
gs
put it another way, if there so much of an upset to snap the ends from these forgings there would be evidence of damage at the other end due to pivot action around the large centre bore
i await the abuse from experts
gs
i think its a wind up, those forgings are stronger than strong things but the broken area looks like its been deliberatley busted
put it another way, if there so much of an upset to snap the ends from these forgings there would be evidence of damage at the other end due to pivot action around the large centre bore
i await the abuse from experts
gs
put it another way, if there so much of an upset to snap the ends from these forgings there would be evidence of damage at the other end due to pivot action around the large centre bore
i await the abuse from experts
gs
Possible answer is that the overload was so minimal as to not visibly upset the metal (to a mark 5 eyeball of a low resolution photo) pure fatigue looks that way)
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AvHerald Report
A report into the incident has now been logged on the Aviation Herald.
Incident: Aer Lingus A332 over Iceland on May 11th 2010, broken aileron actuator castings
It would seem that the main turbulence encounter took place en route over Iceland:
I do, however, think that the pictures should not have been posted in the manner in which they were. Posting such images of broken components in the cabin of an aircraft, a cabin which is being littered by the maintenance staff as shown in the pictures, is less than professional to say the least, especially on behalf of the maintenance team.
I am sure that Aer Lingus will be aware of this.
Regards,
EI Premier
Incident: Aer Lingus A332 over Iceland on May 11th 2010, broken aileron actuator castings
It would seem that the main turbulence encounter took place en route over Iceland:
I do, however, think that the pictures should not have been posted in the manner in which they were. Posting such images of broken components in the cabin of an aircraft, a cabin which is being littered by the maintenance staff as shown in the pictures, is less than professional to say the least, especially on behalf of the maintenance team.
I am sure that Aer Lingus will be aware of this.
Regards,
EI Premier
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I was happy to see that the Aviation Hearld article agreed with me that one fitting failed due to fatigue and the other to to overload.
Not bad for a desk top failure analysis using only a picture if I do say so.
Not bad for a desk top failure analysis using only a picture if I do say so.
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The "castings" as they have been referred to in revious posts are more than likely parts machined from billet in -0 state, after machining they are then heat treated in an oven at set temps and times to achieve for example T3 or T6. Most machined parts like the ones in this topic are generally treated to T6.
The material in T6 state is usually to hard to obtain a smooth surface after machining and thus stress risers are induced during production process.
It is a possibility that damage has occured to the involved parts due to incorrect removal/fitting of the actuator where one or more gouges occured on the part(s) involved. If such gouges are/were present they will result in fracture.
To my knowledge the big Airbuses use the spoilers to effect roll at high(cruise) speed (combined with inboard aileron). Outboard ailerons were present deflect only at slow speeds.
The material in T6 state is usually to hard to obtain a smooth surface after machining and thus stress risers are induced during production process.
It is a possibility that damage has occured to the involved parts due to incorrect removal/fitting of the actuator where one or more gouges occured on the part(s) involved. If such gouges are/were present they will result in fracture.
To my knowledge the big Airbuses use the spoilers to effect roll at high(cruise) speed (combined with inboard aileron). Outboard ailerons were present deflect only at slow speeds.
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A colleague contacted the Irish accident investigators AAIU about this very incident. It is real, they are investigating, and a report will be published when they are finished.
PBL
PBL
