Turkish airliner crashes at Schiphol
Joined: Dec 2007
Posts: 244
Likes: 0
From: Riga
Storminnorm
Rings a bell but I am not too sure why. Perhaps it was an issue on the Originals or the early Classics. There used to be an issue with the autopilot trimming the aircraft into an out of trim situation and then promptly giving up, but I think that was only an issue on the Originals.
The obvious one with the runaway situations were the ruder hard-overs. Doubt that was an issue here (but who can ever be 100% sure, except the investigators (sometimes)), but this aircraft was not fitted with a Spery autopilot from the Originals so the likelyhood of an out of trim is far removed from those early days when you had to disconnect the AP every once in a while during cruise just to see if the damn thing was still in trim. I am not sure if there is now a form of protection agains a runaway situation on the NGs (I have not done the differences - no one will let me anywhere near anything that new). Anyone shed any light?
RIX
Didn't the 737 have problems with stab trim motor run-aways
years ago?
years ago?
The obvious one with the runaway situations were the ruder hard-overs. Doubt that was an issue here (but who can ever be 100% sure, except the investigators (sometimes)), but this aircraft was not fitted with a Spery autopilot from the Originals so the likelyhood of an out of trim is far removed from those early days when you had to disconnect the AP every once in a while during cruise just to see if the damn thing was still in trim. I am not sure if there is now a form of protection agains a runaway situation on the NGs (I have not done the differences - no one will let me anywhere near anything that new). Anyone shed any light?
RIX
Joined: Jan 2009
Posts: 26
Likes: 0
From: kabul
Joined: Oct 1999
Aviation Qualifications: ATPL
Posts: 636
Likes: 327
From: LHR
There are some more good quality photos to look at now like these...
http://cdn-www.!!!!!!!!!!!!!!/aviatio.../2/1489234.jpg
Photos: Boeing 737-8F2 Aircraft Pictures | !!!!!!!!!!!!!!
With a view now of both engines it can be seen that neither first stage fan shows evidence of radial distortion indicating very low/no rotation at impact. In fact one of the fans looks in such good condition that it may actually have been at rest at impact.
Several hypotheses have been expounded about the probable cause.....
- Birdstrike ? Serious bird damage tends to come in two varieties, big flocks of small ones (Ryanair CIA) or small/medium flocks of large ones (those damn Canadians!). There is absolutely no evidence of mass bird impact on any of the forward surfaces, nor any isolated damage by larger birds to the first stage fans of either engine. Simultaneous engine loss caused by birdstrike would not seem to be on the agenda.
- Inadvertent stall by loss of SA (subtle A/T loss or whatever) ? The first reaction of any pilot to a stall warning, (stick shaker in the 737), is to apply TOGA power. Whilst the 737 is an absolute pig to recover in the approach config due to the trim change and drag, the initial reaction is always the same - apply TOGA power. These engines did not impact with TOGA power applied.
- Mishandling of SEF on finals? This is not an easy exercise on the 737 and involves continuing down the glide whilst increasing power and selecting a lower flap setting, when a safe speed is reached you decide whether to continue to land or go around. If this situation was mishandled the subsequent evidence would reveal TOGA power on the live engine at impact. It is also highly improbable that a mishandled SEF would result in a ground impact with the aircraft wings level.
I am at a loss to imagine a situation that the crew would not share with ATC, that evidences a stalled impact on short finals with both engines at very low/no N1. The crew clearly experienced a total power loss below 1000' which they were unable to translate into a successful off-field landing. I wonder whether both engines were running prior to 1000' or perhaps one had already been lost, the other failing around 600-800'.
Fuel exhaustion or starvation is now looking much more probable.
For the record.... I have an extreme distrust of any airline management that is capable of reporting 'No Casualties' from the comfort of their Turkish Office only minutes after an aircraft accident a thousand miles away. Furthermore, to then announce later that the technical records held at base bear witness to a perfectly serviceable accident aircraft takes a moron of extreme proportions.
Am I the only one to conclude that Turkish Airlines have an corporate safety culture that would be more at home in the depths of Africa?
http://cdn-www.!!!!!!!!!!!!!!/aviatio.../2/1489234.jpg
Photos: Boeing 737-8F2 Aircraft Pictures | !!!!!!!!!!!!!!
With a view now of both engines it can be seen that neither first stage fan shows evidence of radial distortion indicating very low/no rotation at impact. In fact one of the fans looks in such good condition that it may actually have been at rest at impact.
Several hypotheses have been expounded about the probable cause.....
- Birdstrike ? Serious bird damage tends to come in two varieties, big flocks of small ones (Ryanair CIA) or small/medium flocks of large ones (those damn Canadians!). There is absolutely no evidence of mass bird impact on any of the forward surfaces, nor any isolated damage by larger birds to the first stage fans of either engine. Simultaneous engine loss caused by birdstrike would not seem to be on the agenda.
- Inadvertent stall by loss of SA (subtle A/T loss or whatever) ? The first reaction of any pilot to a stall warning, (stick shaker in the 737), is to apply TOGA power. Whilst the 737 is an absolute pig to recover in the approach config due to the trim change and drag, the initial reaction is always the same - apply TOGA power. These engines did not impact with TOGA power applied.
- Mishandling of SEF on finals? This is not an easy exercise on the 737 and involves continuing down the glide whilst increasing power and selecting a lower flap setting, when a safe speed is reached you decide whether to continue to land or go around. If this situation was mishandled the subsequent evidence would reveal TOGA power on the live engine at impact. It is also highly improbable that a mishandled SEF would result in a ground impact with the aircraft wings level.
I am at a loss to imagine a situation that the crew would not share with ATC, that evidences a stalled impact on short finals with both engines at very low/no N1. The crew clearly experienced a total power loss below 1000' which they were unable to translate into a successful off-field landing. I wonder whether both engines were running prior to 1000' or perhaps one had already been lost, the other failing around 600-800'.
Fuel exhaustion or starvation is now looking much more probable.
For the record.... I have an extreme distrust of any airline management that is capable of reporting 'No Casualties' from the comfort of their Turkish Office only minutes after an aircraft accident a thousand miles away. Furthermore, to then announce later that the technical records held at base bear witness to a perfectly serviceable accident aircraft takes a moron of extreme proportions.
Am I the only one to conclude that Turkish Airlines have an corporate safety culture that would be more at home in the depths of Africa?
Last edited by Magplug; 26th February 2009 at 15:17.
Joined: Sep 1998
Posts: 1,615
Likes: 1
From: wherever
Magplug:
what about if the engines detached before the full weight of the aircraft structure hit them?
I'm thinking of tail strikes the ground causing rapid nose down pitching, then main gear hits causing high g load which detaches both engines before the fuse hits the ground.
If they came off their pylons with a high fan speed but bounced allong to a stop would the type of blade damage we see be possible?
I'm more inclined to go with mishandling the approach leading to a stall in the landing configuration than fuel starvation.
I'm thinking of tail strikes the ground causing rapid nose down pitching, then main gear hits causing high g load which detaches both engines before the fuse hits the ground.
If they came off their pylons with a high fan speed but bounced allong to a stop would the type of blade damage we see be possible?
I'm more inclined to go with mishandling the approach leading to a stall in the landing configuration than fuel starvation.
Joined: Mar 2002
Posts: 4,569
Likes: 1
From: Florida
magplug
What is meant by radial distortion?
Yes the two engines look different, but then again where are any pictures showing the same views of the fan blades outer airfoils?
Impact has two meanings. Most associate it with the aircraft which in this case seems to be the tail section before the engines.
However the damage to the fan blades has possible timings
1) in the air preceeding the initial ground impact?
2) at the time that the nose comes down hard?
3) One engine wing low takes the brunt of the impact?
4) an engine torn loose from the wing rolling along the ground?
Unless you are willing to connect the damage condition of the fan blades to one of the above then a conclusion is not possible.
Anyway, what does the turbine look like since it may have taken the brunt of the impact?
With a view now of both engines it can be seen that neither first stage fan shows evidence of radial distortion indicating very low/no rotation at impact. In fact one of the fans looks in such good condition that it may actually have been at rest at impact.
Yes the two engines look different, but then again where are any pictures showing the same views of the fan blades outer airfoils?
Impact has two meanings. Most associate it with the aircraft which in this case seems to be the tail section before the engines.
However the damage to the fan blades has possible timings
1) in the air preceeding the initial ground impact?
2) at the time that the nose comes down hard?
3) One engine wing low takes the brunt of the impact?
4) an engine torn loose from the wing rolling along the ground?
Unless you are willing to connect the damage condition of the fan blades to one of the above then a conclusion is not possible.
Anyway, what does the turbine look like since it may have taken the brunt of the impact?
Joined: Apr 2002
Posts: 3,349
Likes: 1
From: FUBAR
BlackWater01,
I think there exists a possibility yes. In this case the aircraft in a very draggy landing configuration is unlikely to make the Runway. The Ryanair accident is a little different as they had commenced a go-around which probably gave them a little extra height/energy before the second engine failed.
It would be a fairly difficult manouvere to convert a normal approach into a glide in landing configuration from say 200-300ft, and with landing flap the judgement of the flare/landing off a glide approach would not be so easy to do accurately, and could certainly be expected to result in a less than optimal "arrival" on a soft unprepared surface.
I think there exists a possibility yes. In this case the aircraft in a very draggy landing configuration is unlikely to make the Runway. The Ryanair accident is a little different as they had commenced a go-around which probably gave them a little extra height/energy before the second engine failed.
It would be a fairly difficult manouvere to convert a normal approach into a glide in landing configuration from say 200-300ft, and with landing flap the judgement of the flare/landing off a glide approach would not be so easy to do accurately, and could certainly be expected to result in a less than optimal "arrival" on a soft unprepared surface.
Joined: Jun 2002
Posts: 3
Likes: 0
From: Boston Mass
Not sure about runaway stab trim but there have been many issues with hard over rudder. Lots of corosion in A/P servo for rudder syst. I probably should not be speculating on this. leave that for the investigators etc..
Joined: Jan 2008
Posts: 287
Likes: 0
From: southwest
"Two pilots and an apprentice pilot"
I find this phrase, being used by the media, a bit unusual. I believe it came from the Dutch Safety Board.
Does anyone, especially a dutch speaker, know whether "apprentice" is intended to mean something different from "trainee".
Does anyone, especially a dutch speaker, know whether "apprentice" is intended to mean something different from "trainee".
Joined: Feb 2007
Posts: 4,598
Likes: 0
From: Amsterdam
Apprentice is not a Dutch word. Not even close to a Dutch word. So before putting this into context, consider that a Dutch word was first translated into English, leading to the word Apprentice. Trying to translate this back into Dutch and then attaching meaning to it, without context, isn't going to help a lot.
Where did you find this quote? We may be able to find the original Dutch text and put it into perspective for you.
But my guess is that they would indeed mean "trainee", or at least somebody who was not fully qualified yet.
Where did you find this quote? We may be able to find the original Dutch text and put it into perspective for you.
But my guess is that they would indeed mean "trainee", or at least somebody who was not fully qualified yet.
Joined: Aug 2005
Posts: 61
Likes: 0
From: Soesterberg (NL)
> [...] ...who was not fully qualified yet. => on that Aircraft type.
For the rest, I couldn't add anything to your precise linguistic explanation (& much else).
All the best,
vonbag
***edited after my Dutch wife returned at home:
"leerling op dat vliegtuig type" [?]
I did not have a chance and listen to that broadcast myself.
Het beste --
For the rest, I couldn't add anything to your precise linguistic explanation (& much else).
All the best,
vonbag
***edited after my Dutch wife returned at home:
"leerling op dat vliegtuig type" [?]
I did not have a chance and listen to that broadcast myself.
Het beste --
Last edited by vonbag; 26th February 2009 at 16:26.
Joined: Oct 1999
Aviation Qualifications: ATPL
Posts: 636
Likes: 327
From: LHR
What is meant by radial distortion?
www.flightglobal.com
As you can see from the first picture the first stage turbine blades are sheared off at around half of the length of their radius. This was because they were rotating at some speed when the impact occurred. The engine nacelle was forced onto the rotating blades causing almost identical damage to all the blades as they turned and they have all fractured at a similar radial length. The engine therefore must have been rotating and producing at least some thrust on impact.
Look now at the second image of the other engine and you will see that the turbine blades are all intact even though the nacelle has hit the ground quite hard and scooped in a lot of dirt in the process. This engine was not rotating at impact and therefore could not have been producing any thrust.
As is also witnessed by the BA incident, a total loss of thrust below 1000' can be brought so a safe outcome given favourable terrain.
