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SAS Q400 gear collaps CPH 27/10

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SAS Q400 gear collaps CPH 27/10

Old 31st Oct 2007, 15:43
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RatherBeFlying

So an O-ring got put into an invisible location -- worse, quality control did not catch it.

It looks like there was a rush put on to turn out 54 MLG assemblies, perhaps a bunch of overtime -- and one came out mis-assembled.
Much like SAS has rushed to blame the problems on the aircraft.

"This O-Ring did not come from the actuator and its source is unknown."

If the O-ring is not from the actuator then how did it get in there?

3 accidents in 1.5 months with the same carrier. There is a better chance statistically that this is a SAS maintenance issue rather then a systemic problem with the aircraft!

I'm curious as to how many of the other Q400's in service around the world were found to have the corrosion problems that SAS had with the earlier incidents?

Last edited by Troy_K; 31st Oct 2007 at 18:53.
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Old 31st Oct 2007, 16:16
  #182 (permalink)  
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Spoiler (de)activation on landing

Is it (or was it) SAS policy to deactivate the spoilers so that they do not deploy on landing?
You can see that on the 27/10 landing they did not pop up. If so how was this done By using the SPOILER PUSH OFF buttons or some other method pulling CB's for example. I presume the idea is to have 'softer' landing on to the remaining main wheel. However the down side, if the push off buttons are used then you have no in flight spoilers to aid the aileron. Not particularly nice when combining it with S/Eng and low speed & close to the ground
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Old 31st Oct 2007, 16:46
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If I remember correctly the DH8Q400 needs a WOW Signal from both MLG´s to deploy the spoilers.
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Old 31st Oct 2007, 16:57
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I'm curious as to how many of the other Q400's in service around the world were found to have the corrosion problems that SAS had with the earlier incidents?
ANA (Japan) found one with what they described as "mild" corrosion. AFAIK, that's it. Horizon declared all theirs to be free of problems as did flyBe (I think).
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Old 31st Oct 2007, 17:42
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Know that this really isn't related to the accident but with so many Q400 guys reading this would be interesting to get views. What is your view of the Dash's AFCS with regards to 'Alt Sel' and it's Function/Selection. No problem, User error or design flaw?



Q400 CA, here. When I upgraded into the Q from the CRJ, and was briefed on the operation of the AFCS regarding altitude capture, I believe my comment was, "You've GOT to be sh*tting me!" The airplane has many other features that are similarly behind the times. The only possible rationale, in my view, is the maintenance of a common type rating with the previous Qs, thus making the thing easier to pitch to the beancounters (although we don't fly more than one variant per pilot at QX).

Regarding landing the Q, I think it is actually easier to make consistently nice landings than it was in the jet. We carry a bit of power, flare to no more than about 5 degrees, and voila, no sweat!
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Old 31st Oct 2007, 17:44
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DrinkUp,

Flip-flopping could make it even more riveting! Presumably, indecision was precisely the opposite of the image they wished to project.
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Old 31st Oct 2007, 18:53
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Looks like a "float down the RWY and hit it accidentaly" technique. Not a good Idea if you have to land on 4000feet strips regulary.
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Old 31st Oct 2007, 19:22
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ALT SEL seems to catch quite a few people out. It's not a terrible system, just appears very different from the Boeings and Airbus systems. Young pilots with it as their first type seem to have fewer problems with it. The fact you can sometimes knock the ALT SEL out by moving the pitch wheel as it begins capturing an altitude is the biggest thing, but most operators SOPs are reducing the impact of this.

As for the common type rating, the Q400 should have been a fantastic aircraft, instead it has controls very similar to the previous models with wildly different systems behind them. The standard thing heard from 300 pilots converting onto the Q400 is "....but on the 300 it did this"

I understand it is related to beans and counting somehow, but a Dash 9 with autothrottles (it's a FADEC tubine so it's just a case of making the power levers move if you want to be fancy), 3 axis autopilot, heated leading edges instead of boots, a toilet at the back of the aircraft instead of the front (ok so on the plus side the F/O knows when the toilet needs dropping, but it still stinks), the ability to have red and white strobe lights on and perhaps a repeat of the engine torques on the Primary flying displays
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Old 31st Oct 2007, 20:11
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Originally Posted by Fokker28
The airplane has many other features that are similarly behind the times. The only possible rationale, in my view, is the maintenance of a common type rating with the previous Qs, thus making the thing easier to pitch to the beancounters (although we don't fly more than one variant per pilot at QX).
Or... (from Air Transport Intelligence October 13, 2000)
The airline (SAS) has ordered a total of 22 aircraft to replace its Fokker 50s, but when it entered service in February this year it was four months behind schedule because of unspecified development and manufacturing difficulties encountered by Bombardier.

SAS had been deeply involved in the specification of the aircraft, demanding and getting major changes to the cockpit layout after expressing considerable unhappiness over the original design.
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Old 31st Oct 2007, 21:31
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Is it not possible that the maintenance manual is ambiguous and perhaps SAS have mis-interpreted it?

I assume that mainenance manuals are all issued in English and it's down to the particular carriers to translate it as required? Or, do manufacturers issue translated manuals?

What other Scandinavian airlines operate the Dash 8?
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Old 31st Oct 2007, 22:05
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In Scandinavia the understanding of english is generally very good. I do believe that all manuals are written in english.
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Old 31st Oct 2007, 23:40
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Spoilers

It's something that we were talking about if it happened to us. Stop the spoilers coming up and deal with the slight lack of control (also on one eng). Not the best scenario but when it comes to keeping the wing up during roll out it would be worth it. The first dash to crash had it's spoilers deploy and the wing dropped very quickly. Compare it to the most recent where the pilot() kept the wing up til very late and the impact didn't carry nearly as much energy. Also keeping it on the runway til the very end.

Thanks for the response to the Alt Sel question. Keep them coming
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Old 1st Nov 2007, 00:23
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After watching the video of the first incident tried pressing spoiler push off in the sim. Quite possible that the sim doesn't actually simulate it very well but versus spoilers up it didn't make much difference. The wing can be held up effectively if it is well anticipated, rudder is also needed for this. What also made a fair bit of difference in the third incident, along with a well held wing, was the swift and prolonged use of full reverse once the wing went down which was probably the main reason it stayed on the runway for so long.

Just read from snowfalcon2:
In connection with the first incident in Aalborg, the captain in a press interview stated "he believed with 90% certainty the fault was an indication fault only". Evidently his experience of the "christmas tree" reputation of the Q400 (i.e. lots of more or less unfounded alarm indications) led him to believe the landing gear was most probably okay.
If this is the case it seems bizarre! Reports from the cabin state that the right MLG leg 'fell' from the nacelle with a loud bang (the actuator was no longer connected to it). The indication on the gear handle was 'not locked' and presumably the final check, the gear position indicator in the floor bay would have to have shown 2 out of 3 greens. That combination of events would lead most people to believe there was a 90% chance that the gear was unsafe. Far from a "christmas tree" reputation these are all sensible indications. Though hindsight is a wonderful 'skill' landing with a running engine on that side made a poor situation much worse, something which the unfortunate crews that followed did not repeat.

Last edited by Loop... Hole; 1st Nov 2007 at 00:42.
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Old 1st Nov 2007, 02:47
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Angry Reply to Bearcat

Before knocking the aircraft or crew in any situation, you should be aware of all the facts. It is very unprofessional to try to lay blame prior to the start of the investigation.

Last edited by Bluesteelfs; 1st Nov 2007 at 02:54. Reason: Need to direct it to individual not general
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Old 1st Nov 2007, 04:16
  #195 (permalink)  

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Another Q400 incident, this time prop related.
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Old 1st Nov 2007, 09:07
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A non incident more like.
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Old 1st Nov 2007, 09:55
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IP

This has reduced the number of inadvertant 'deselections' of ALT SEL, but it still drops out on movement of the pitch wheel in the final stages of capture. Still a bit of a gotcha, particularly at night. All the other knobs on the APFD panel are back lit EXCEPT the pitch wheel. It's easy to nudge as you reach for selections either side of it.
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Old 1st Nov 2007, 14:02
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What MLG Components where "swapped out"?

Professionally interested due to being a seals/rubber guy. When SAS swapped out the MLG actuators, did they replace the whole unit or just the rod, rod end and seals kit?
Second question, where did they "find" over 50 units/actuators in such a short time frame?
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Old 1st Nov 2007, 14:12
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Have a look here...

SAS is reported to have swaped out the entire rear actuator (main) on all of the aircraft. The parts were aquired from stores in England and even from machines on the production line in Downsview.... yes, even machines that were to be rolled out were canabalized to service the entire world wide fleet...
6to8
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Old 1st Nov 2007, 14:26
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It looks to me as though there was a design fault with the actuators allowing corrosion to occur, causing a main gear failure. This seems to be what happened with the first 2 identical accidents (and grounded a few Flybe aircraft too from what I hear).

Then in haste to change all the actuators, a maintenance error has crept in somewhere and allowed an O-ring to be mis-fitted meaning total non-deployment of RH main landing gear in the 3rd accident.

Of course this is pure speculation on my behalf.
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