BREAKING NEWS: airliner missing within Egyptian FIR

[Prada]

RPB quetion

2. Rear pressure bulkhead still seem to sit at its installed position.

how do you reach that conclusion,, which images?

First of all, there is no visible damage around RPB. No peeling. I think you have seen plenty of images of tail section.

Then one HS was found broken off just outside of the fuselage. RPB explosion could not do that.


Also, if you try to peek into tail section there you can not see any gaping holes. Instead it looks like RPB sitting there.

[Prada]

seats

Looks like the seats are covered in dust not soot.

I don't mean soot. It could be darkening from heat. You could see that seats where passengers were seated are burned less.
If it was soot or dust you probably would see marks from touching these seats when passengers were taken away.

[Ian W]

While everyone is keen on the 'bomb theory' - remember that security services will immediately think was it a bomb - as that is what they do. Aircraft engineers will think break up and "where is the HS?" as even if the tail breaks off the HS and VS normally stay remarkably intact.

But politicians are advised by security services so will take action against security threats as that is a threat to their jobs and they need to take action to keep votes.

So - having said that - if the HS has a problem and departs the airframe, does that cause a fire? Well we have that answer on video already from earlier in the thread where an aircraft lost its HS while flying behind a tanking F-4. Guess what the aircraft went into a severe bunt, suffered structural failure and exploded in flames while airborne, then another large explosion on the ground. So a 'heat signature' from the airborne aircraft does not mean bomb any more than it means structural failure.

There has been no bomb residue found.

The HS parted company with the empenage in a most unlikely way not seen in any other aircraft bombing.

No answers - but before we start grilling low grade catering cart operatives and blame them and lax security, it would be better to get real evidence.

[auraflyer]

Are there any Explosives (Bomb materials) that don't naturally leave a chemical/forensic trace?

What's the trace of a lithium ion based explosive (mobile phone device) inside a compact non-security screened food container.

For chemical-based explosives, let's just say that there are fingerprints for everything if you know what to look for and have the cash to do so - noting that if there weren't, this would not be the place to say.

In common use, there are nitrates or peroxides, both of which can be picked up in various ways.

Lithium ion devices are not explosives in the true sense; they have thermal effects (thermal runaway).

[G0ULI]

Genuine questions, but just speculating on a what if scenario.

Given that the Airbus is a fly by wire, side stick controlled aircraft and probably climbing on autopilot at the time of the incident, what would be the effect of a full excursion rear or forward movement of one of the side stick controllers.

Could a pilot inadvertantly knock the sidestick control full travel? Very unlikely I know, but would the aircraft respond immediately to the sidestick input, dump the autopilot and move the elevators full travel or would the built in protections prevent that happening? My understanding is that the controllers remain in position and do not self centre, so it might take a couple of seconds to recentre the control. Would that be sufficient to damage the aircraft?

Given that the repaired tail section might be slightly weaker than on an undamaged aircraft, could a rapid control movement cause separation?

[A0283]

Major components still missing - update4

@Ian W - agree with you. If it was a bomb there is still no (clear) evidence of that in the videos and pictures i have found in the public domain till now. If a pprune would have found them, i think we would learn about that pretty fast.

Still "missing" (in my definition) the THS centerbox and the other half of the THS. And the rudder. Perhaps part of the (top of the) centerbox is pushed upward in the tailcone, but no explicit pictures of that. If so, it would suggest that both THS halves broke away flush with the skin.

Also still missing clear "evidence" (my definition) of a number of skin panels and the three cargo doors. When you talk about explosions, you would certainly like to know more about them. There are some other specific points that you would direct a person on site to, to look at... but alas, we are not in that position... expect the investigators to check these points.

We do not have the full set of pax doors. In my definition at least three missing.

There are a number of breaks in the fuselage wreckage that are along what i am used to call "production breaks" (discussed that on pprune during the AirAsia search). The breaks are quite 'clean'. If you are talking about intentional explosions, you would expect more 'ragged edges'.

+++

Would still be interesting to get some more close up photos of avionics boxes in the MEC.

[rubber stilts]

post # 511 made by Mitrosft included an image of what looked like schrapnel holes in a grey plastic slab from the interior of the rear galley; if I remember correctly.

[khorton]

Genuine questions, but just speculating on a what if scenario.

Given that the Airbus is a fly by wire, side stick controlled aircraft and probably climbing on autopilot at the time of the incident, what would be the effect of a full excursion rear or forward movement of one of the side stick controllers.

Could a pilot inadvertantly knock the sidestick control full travel? Very unlikely I know, but would the aircraft respond immediately to the sidestick input, dump the autopilot and move the elevators full travel or would the built in protections prevent that happening? My understanding is that the controllers remain in position and do not self centre, so it might take a couple of seconds to recentre the control. Would that be sufficient to damage the aircraft?

Given that the repaired tail section might be slightly weaker than on an undamaged aircraft, could a rapid control movement cause separation?

I work as a test pilot, and have flown flight tests on various Airbus aircraft (but not the A321, although its control laws are similar to models I have flown).

Assuming the FBW system was in Normal Law, as it would be if there were no previous failures, full aft stick movement would result in 2.5g (if at high speed), or an angle of attack short of the aerodynamic stall (if at low speed).

In Normal Law, full forward stick would give -1g, which while dangerous for anyone not wearing a seat belt, would not cause structural failure. If the stick was held forward, the pitch attitude would reach the lower limit allowed by the FBW system (-15 deg?), and the aircraft would accelerate to a speed somewhat faster than the maximum speed allowed in normal operations. The aircraft would have been designed to safely fly at this high speed with full forward stick, and it would have been done many times during flight testing.

There are additional non-relevant nuances in specific corners of the envelope, but the above is a reasonable top level description.

In summary, there is no risk to the structure from either full forward or full aft stick, no matter how sudden the movement, as long as the FBW is in Normal Law.

I won't speculate on the possible cause of the accident.

[PersonFromPorlock]

Just a general observation that the ground investigation effort seems a little less than professional: the investigators have driven rather casually all over the debris field - note the wheel tracks across that long cable attached to the tail section, for instance - and when I see that, I wonder what other poor handling the wreckage has undergone that we haven't seen.

Then too, there's a thundering herd of men in suits and ties in the photos. It's never good for productivity to have the big bosses on the factory floor.

Well, maybe I'm just being a worrier.

[G0ULI]

khorton
Thank you, I expected the protection mechanisms to limit the stress on the airframe, but I wasn't sure this would always be the case for a full control input.

[videoguy]

I work as a test pilot, and have flown flight tests on various Airbus aircraft (but not the A321, although its control laws are similar to models I have flown)

It is possible on Airbus aircraft error of uncommanded thrust reverser deployment as happen on Boeing 767 flight NG004, 26 May 1991 (Lauda Air)?

The aircraft also broke up in mid-air on the way down.

[Icarus2001]

Have a look at cold stream versus hot stream thrust reversers.

[oldoberon]

Originally Posted by Prada

First of all, there is no visible damage around RPB. No peeling. I think you have seen plenty of images of tail section.

Then one HS was found broken off just outside of the fuselage. RPB explosion could not do that.


Also, if you try to peek into tail section there you can not see any gaping holes. Instead it looks like RPB sitting there.

if thr RPB blew there would not be peeling around it but in the area behind it and lord knows there is enough damage there,

re the photo looking in the door, who knows what debris is there, and the light entering the door is only illuminating a couple of foot into the darkness at best, and at the aft end the light is from the wrong angle to throw much in there look at the image from the rear of the tail dense shadow.

no proof just yiur guess.opinion.

[oldoberon]

Break up or Bomb?

I personally can't decide but I always wonder about coincidences.

If this was abreak up due to earlier tail strike repair, there are a number of them that pop to mind.

A) How long since the repair and how many flights has this frame done since the repair, so what were the odds of it failing within about 14 days of Russia getting seriously involved in Syria

B) what were the odds of it failing whilst over flying potentially hostile territory or from departing a potential hostile airfield.

Had this happened within Russia these concerns would greatly diminish but not disappear entirely.

[DozyWannabe]

Originally Posted by dsc810

The French/German/USA will be desperate for it to be a bomb so it can be blamed on 'terrorism' (that's freedom-fighters if you are on the other side) and that the aircraft is 100% OK.

To be honest, I've never really understood why people tend to make this assumption. Airliner manufacturers are insured up the wazoo for circumstances like this one, and I suspect that if the problem was with the aircraft, both Airbus and Boeing (in the event it's one of theirs) would rather know of a problem so they can fix it rather than pretend one doesn't exist. This hasn't always been the case of course, but every time an airframer has tried to sweep things under the carpet it has tended to blow up in their face - to the extent that it would have been less damaging just to find and fix the problem.

Originally Posted by videoguy

It is possible on Airbus aircraft error of uncommanded thrust reverser deployment as happen on Boeing 767 flight NG004, 26 May 1991 (Lauda Air)?

Boeing had to redesign the reverser latching mechanism as a consequence of that accident, and I'm pretty certain that Airbus would have looked at theirs and fixed it where it needed to be.

Originally Posted by PersonFromPorlock

Just a general observation that the ground investigation effort seems a little less than professional: the investigators have driven rather casually all over the debris field - note the wheel tracks across that long cable attached to the tail section, for instance - and when I see that, I wonder what other poor handling the wreckage has undergone that we haven't seen.

As long as the original positions were noted before that happened, I don't see that to be much of a problem. In accident scenarios with survivors, the rescue services will disturb the airframe wreckage as much as they need to in order to pull people out - and that's never caused a significant issue...

Originally Posted by Ian W

While everyone is keen on the 'bomb theory' - remember that security services will immediately think was it a bomb - as that is what they do. Aircraft engineers will think break up and "where is the HS?" as even if the tail breaks off the HS and VS normally stay remarkably intact.

Sure, but as I alluded to earlier there has been a group of international accident investigators on scene for the best part of a week now - if it were simply a matter of security services exercising caution, then we'd have been hearing about the probability of a bomb being involved within hours of the crash. To my mind, enough time has certainly passed for the metallurgical specialists among the investigators to have found something troubling.

[PrivtPilotRadarTech]

Mirosft's Shrapnel Photo

Rubber Stilts said: "post # 511 made by Mitrosft included an image of what looked like schrapnel holes in a grey plastic slab from the interior of the rear galley; if I remember correctly."

Yes, it looked like it had been hit by a spray of shrapnel, and the authorities (who are privy to much more information than we are) seem to be leaning to the bomb scenario. Surely by now they have analyzed any chemical signature left behind, and bits of the shrapnel embedded in that plastic piece. Thanks Mitrosft. I just checked, and verified that it is post #511, if you missed it. Thanks Rubber Stilts.

[paulmoscow]

Assuming that the cabin crew started heating food as soon as possible after takeoff, 25 minutes into the flight could conceivably be the time it takes for the food heaters to reach high temperature. One (or more) of those food packages could have been a bomb - disguised as a meal (breakfast?) – detonated by being heated to a moderately high temperature.

According to passengers who flew with Metrojet in the past, no hot meals were served.

[josh96]

Rear galley ovens

http://s7.postimg.org/gg9p1dpzf/Clipboard01.jpg

[Prada]

RPB

re the photo looking in the door, who knows what debris is there, and the light entering the door is only illuminating a couple of foot into the darkness at best, and at the aft end the light is from the wrong angle to throw much in there look at the image from the rear of the tail dense shadow.

Well, this image shows no gaping hole either. This area should have been relatively clean of surrounding insulating material and small debris. But never mind this.

Most importantly HS would never have broken off the way it has broken by ruptured presure bulkhead.

[RatherBeFlying]

Only one panel on the rear door in the #511 photo shows the marks. Note also lack of distortion in this panel.

How would the adjacent panels escape similar damage?