National Air Cargo B744 at Bagram on Apr 29th 2013, lost height shortly after takeoff

[phoneman]

I don't know, 5 vehicles weighing 27000 pounds of steel each won't melt. Plane crashed relatively flat. just curious to their position.

[3WE]

...and positions of control surfaces...

I'm thinking that a pic might be not quite adequate for this.

[brianw999]

I'm thinking that a pic might be not quite adequate for this.

I'm thinking that the position of control surfaces can best be described as "a bit over there, another bit over there, more bits elsewhere.....etc......etc.

I'm also thinking that I smell someone who is after starting some kind of conspiracy theory....and I don't mean you 3WE !

[guamainiac]

Are you sure the cargo containers are made of steel? I would think a heavy gauge tempered aluminum.

In any fireball like that where it spins or drops straight in like it seemed to, the aluminum would melt then vaporize in the fire. Especially with the fire concentrated in a small area. You usually see a piece of fuselage when it breaks away from the aircraft.

They may get lucky and recover one of the tie down hooks or eyes and determine through metals analysis the direction that it tore off and if it was a load towards the rear (a shift during takeoff), or it forward during the final impact?

[Petertenthije]

Are you sure the cargo containers are made of steel? I would think a heavy gauge tempered aluminum.

The cargo was not containerized, they where (possibly palletized?) armoured vehicles.

[phoneman]

I'm thinking that the position of control surfaces can best be described as "a bit over there, another bit over there, more bits elsewhere.....etc......etc.

I'm also thinking that I smell someone who is after starting some kind of conspiracy theory....and I don't mean you 3WE !

Why would you think that? What do you think the NTSB is going to look at besides the Black Boxes?

[3WE]

So, it might be interesting to see what's left of an armored tank (sorry to say that).

...and you could SPECULATE if it's somewhere other than where it should be with respect to the rest of the aircraft, or all stacked at the back...but the plane probably still had a lot of forward speed probably scrambling the big chunks of steel to where we don't know.

Brian was very accurate on the position of the control surfaces, but I wanna know how he would identify most of them...from a photo.

[AVION1]

I used to work for DHL as A&P mechanic for their 727-200 and DC-8, and I remember the "cargo guys" used to fill any empty stations with empty cargo containers in order to prevent any cargo shift.
For example on the 727-200 if they take 12 cargo containers and today they only have 10 containers, those two empty stations have to be filled with two empty cargo containers, that was the rule.
And when the aircraft was full and there were many cargo containers left, we used to rent another aircraft from "Kitty Hawk". Usually a DC-9-10. Have you ever seen a DC-9-10 with cargo configuration?

[Gabriel]

On Jun 2nd 2013 accident investigators by the Ministry of Transport and Civil Aviation of Afghanistan reported in a press conference that quickly shifting cargo, consisting of three armored vehicles and two mine sweepers totalling at 80 tons of weight, caused the accident. The cargo slammed so hard at the back of the aircraft, that parts of the aircraft separated and wiring in the back was severed. As result of the shift and loss of aircraft parts the center of gravity moved so far back, that the attitude of the aircraft could no longer be controlled, the nose of the aircraft rose beyond the flying envelope of the aircraft and the aircraft stalled destroying the aircraft and killing all crew in the resulting impact. Parts of the aircraft, that separated as result of the initial load shift, were recovered from the runway. The straps used to tie down the cargo were recovered from the accident site, although charred they provided evidence of having fractured before final impact, it was unclear however, whether the fracture(s) had happened before or after takeoff.

http://avherald.com/h?article=46183bb4&opt=0

[Leftseat86]

http://avherald.com/h?article=46183bb4&opt=0

So whomever was responsible for the loading and securing of this cargo was pretty clearly at fault...

[TeeVee]

or maybe the angle of the climb out, dictated by the potential dangers of being shot down, strained the cargo retention straps beyond their design parameters...

[Gabriel]

or maybe the angle of the climb out, dictated by the potential dangers of being shot down, strained the cargo retention straps beyond their design parameters...

I really don't think so.
The acceleration and best angle of climb, for a given weight, depends only on how much thrust is applied. And I can't think of the straps being selected taking into account anything less than full rated take-off thrust.

I mean, many times when the runway is long, there are no obstacles in the initial climb, and there is no hand-held A-A missile potentially waiting for you, many times a "flex take-off" is carried out, where less than fully rated take-of thrust is used to reduce wear and tear of the engines. But the pilot is free to use full rated thrust at any time he sees fit (for example, a windshear during take-off roll), so nothing should be dimensioned thinking that he will not.

[Gabriel]

So whomever was responsible for the loading and securing of this cargo was pretty clearly at fault...

Well, maybe, but there is one thing that I don't like. In a related AVHerald article, the FAA said:

The FAA especially annotated after re-iterating procedures to tie down heavy loads properly: "Unsymmetrical tie-downs permit load distributions that may ultimately result in tie-down failure. Such a failure would result from the different load-deflection rates of dissimilar materials or of identical materials of different length. Any material subjected to a tension load will stretch. A longer length tie-down has more stretch potential than a shorter length tie-down. If two tie-downs of the same type and capacity are used to restrain a load in a given direction and one is longer than the other, the longer tie-down, with its greater stretch potential, will permit the shorter tie-down to assume the majority of any load that may develop. If the shorter tie-down becomes overstressed and fails, the longer tie-down would then be subjected to the full load and it, too, would likely fail. Therefore, symmetrical tie-downs should be as close to the same length as possible."

http://avherald.com/h?article=4628deb1&opt=0

Does this comes from the same FAA that says that no single failure at a component or system level shall lead to a catastrophic failure at the whole airplane level?

A failure of a tie-down, its attachment point, or the supporting structure can be caused for a number of reasons including errors during the manufacturing, maintenance and operation.

But no matter what, the failure of a single tie-down should not bring an airplane down. And that includes that it should not cause the other tie down to fail too.

That doesn't mean that it's not a good advice to use symmetric tie-down to distribute the load evenly. But even if by mistake or ignorance it was not done, one tie-down taking more load than the other should not make it fail (because each tie down should be ready to withstand the full load in case the other tie down fails), and if it fails, then the other tie down should be able to withstand the full load too exactly for the same reasons.

What I mean is: No single failure at a component or system level should cause a catastrophic failure at the whole-airplane level (i.e. down the plane).

The failure of one single strap should not have to "power" to down an airplane. Be it if the strap is part of the airplane design (as the FAA requires for any part) or an external accessory.

Here, the FAA says that it is ok to secure a load in such a way that all straps used are needed to bear the load because the failure of just one of them could cause the others to fail too, so do it carefully so one of them is not more loaded than the other. Good advice, but the penalty for failing at that shouldn't be a crash like this.

[Highkeas]

One thing I've observed is that textile straps can lose strength if exposed to adverse environments and not routinely tested. I saw a new 100,000-lb plus nylon strap break well under its limit load due to embedded sand particles on its second use.

Another failure mode for textile straps is using too small a dia anchor pin. As an anchor pin dia reduces in diameter the stress distribution across its thickness becomes more uneven. Somewher I have a great reference on this phoenominum.

[Schwartz]

What I mean is: No single failure at a component or system level should cause a catastrophic failure at the whole-airplane level (i.e. down the plane).

The failure of one single strap should not have to "power" to down an airplane. Be it if the strap is part of the airplane design (as the FAA requires for any part) or an external accessory.

Here, the FAA says that it is ok to secure a load in such a way that all straps used are needed to bear the load because the failure of just one of them could cause the others to fail too, so do it carefully so one of them is not more loaded than the other. Good advice, but the penalty for failing at that shouldn't be a crash like this.

Yes, they should have given an example using 3 different length tie downs in cascading failure to make their point assuming 2 tie downs could handle the load rating. That way it could handle any single failure assuming they were all symmetrically balanced.