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Air Transport for MRAP Vehicles

"The fiery plane crash at Afghanistan’s Bagram Air Base that killed a Madison native and six others was caused by heavy military vehicles breaking free, Afghan officials said Monday morning.

The country’s Ministry of Transport and Civil Aviation released the findings of its investigation into the Boeing 747 crash, during a press conference, Good Morning America reports.

Investigators believe armored vehicles weighing between 12 and 18 tons, slid to the back of the plane. In addition, to evidence from black boxes and voice recorders, they discovered broken buckles that were supposed to hold the MRAPs in place."

747 Crash in Bagram Caused by Shifted Weight: Afghan Officials [VIDEO]


Apparently the black boxes have been found, and given a preliminary review, with no other causative or contributing factors were found.


http://search.mywebsearch.com/myweb...&si=176484&pg=GGmain&pn=2&ss=sub&st=hp&tpr=sc



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This is a link to a discussion a few days after the crash, discussing ranges of possiblities.

Was the Bagram 747 Crash a Terrorist Drone/UAV Attack in the Runway Kill Zone (RKZ)?


The buckles might be subjected to more dynamic load on landing, so since the 747 had landed at Bagram, with the loaded MRAPS, the buckles may have been cracked on landing, and not checked sufficiently closely after landing, before the next take-off.

Also if the straps were 18,000 pound straps, and the straps were tightened from the front and the back, say 5000 pounds of tightness, then the strength of the strap would be reduced by 5000 Ponds to 13,000 pounds actual retaining strength.

Was there a sequence in the failure of the belts? Also, if some belts were a little looser than others, the tighter belts would fail first, then the looser belts would experience higher loading, as the tighter belts buckles broke.


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"DCA13RA081
On April 29, 2013, at about 1056 local time, a National Air Cargo B747-400, registration N949CA, crashed shortly after takeoff from Bagram Air Base (OAIX), Afghanistan. According to news reports, witnesses observed the airplane attain a very steep nose-up attitude shortly after takeoff before descending into the ground near the end of the runway. All seven crewmembers onboard were fatally injured and the airplane was destroyed from impact forces and post-crash fire. All seven crew members were American citizens. The 14 CFR Part 121 Supplemental cargo flight was destined for Dubai World Central - Al Maktoum International Airport, Dubai, United Arab Emirates.


The investigation is being conducted by the Ministry of Transportation and Civil Aviation of Afghanistan (MoTCA). The NTSB has appointed a U.S. Accredited Representative to assist the investigation under the provisions of ICAO Annex 13 as the State of the Operator, Manufacturer, and Registry of the airplane. All investigation information will be released by the MoTCA."


Untitled Page


So appparently the US NTSB will not be making a report of the accident.



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"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.

The FAA had released a Safety Alert for Operators on May 20th 2013 regarding securing heavy vehicles in aircraft, see News: FAA concerned about potential safety impact of carrying and restraining heavy vehicle special cargo loads."

Crash: National Air Cargo B744 at Bagram on Apr 29th 2013, lost height shortly after takeoff following load shift and stall



On 2 June 2013, investigators confirmed the load shift hypothesis; three armoured vehicles and two mine sweepers came loose and rolled backwards onto the rear bulkhead, damaging the aircraft and pushing the center of gravity outside its rear limit. Consequently, the aircraft became uncontrollable, rose up sharply and stalled, and crashed moments later.[4]

National Airlines Flight 102 - Wikipedia, the free encyclopedia




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Aerobat, P 33


"Another aspect affecting strap failure is the angle at which they are attached relative to the load-path.

I agree that this is an important consideration because the tension in the straps is a non-linear function of the attachment geometry. If I remember my physics correctly, for a restraint attached at three points, strap Tension = Force / (2 * cos (arctan (w/2*d)) where w = the distance between the floor attachment points and d = the perpendicular distance from the line between the floor attachment points and the cargo loop-back (tie-down) point.

So When "d" becomes very small with respect to "w", very small changes in Force (the force produced as acceleration acts on the restrained mass) can result in extremely large changes in the strap tension. Either the strap or the floor anchor points could fail and it might only take one to start a domino effect that causes a complete failure.


Cargo Crash at Bagram - Page 34 - PPRuNe Forums



"The plane, operated by National Air Cargo, a Michigan-based carrier, was loaded with three armored vehicles and two mine sweepers, almost 80 tons of equipment in all, for a flight from Afghanistan to Dubai, Mr. Qalatwal said. He said that the plane had been checked twice before takeoff, once two hours before departure and again just before it left, and that neither review had revealed any technical problems. Aviation experts had speculated earlier that there had been a problem with the plane’s pitch control, and that a part might have fallen off during takeoff.
The charred remains of the cargo straps were recovered from the site and appear to have been cut, but Mr. Qalatwal said it was unclear whether the damage had occurred before or after takeoff. The plane, consumed by fire from the crash, yielded little else in the wreckage, he said. "


http://www.nytimes.com/2013/06/04/w...oomed-plane-that-crashed-near-kabul.html?_r=1&





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Another factor for tied down vehicles in aiur planes, is the G force downward, on take-off and ascent. I have been on planes where the take-off and ascent are somooth, with almost no perceptible downward G forces. I have also been on flights, where I was pushed in the bottom of my seat, during lift-off or at some points during ascent. Other flights have been smooth as glass.

If a palne with MRAPS, or other vehicles, creates downward G's on take off, or ascent, then the suspension of the vehicle will be compressed. If there are enough downward G forces on take-off, then the tie down straps or chains may be loosened, if they are set at 30 or 60 Degrees, attached to the bumpers. Once the suspension is compressed, the chains and straps become loose, and allow movement of the vehicle, and creating more forward or backward G-forces.

Therefore, it may be important for cargo planes carrying vehicles to attempt to take off, and land, as smoothly as possible, to avoid compressing the suspension, thereby avoiding loosening the straps and chains with downward G forces.

The pictures on this thread show military vehicles tied down to the bumpers. Tow Truck drivers usually try to hook to the tires, or the suspension, close to the wheel, of a car or vehicle, not to the bumper.



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shlunka said:
I'm no aviation expert, but five MRAPs on a cargo plane flying in inclement weather sounds a bit excessive?
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I work for one of the companies that build the MRAP. loaded bumper to bumper its not an issue.
Remember the space shuttle was flown around on the back of a 747.
 
Gladiator said:
"A 747 U.S. cargo plane crashed on its ascent from Bagram, Afghanistan Monday, killing all 7 American crew members aboard. The exact cause of the crash is not known, but thunderstorms were in the area.
The plane, in route to Dubai (United Arab Emirates), was carrying 5 military vehicles according to the Aviation Herald."

Weather may have played role in horrifying Bagram Airfield Crash


Other sources ay the vehicles wer MRAP vehicles


MRAP - Wikipedia, the free encyclopedia


It may be important for the US to be able to tranport MRAP vehicles by air reliably, for deploying US forces, with a minimal risk of casualties from explosive devices.




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safety and military dont seem to go hand in hand.

ive been in a c130 where the takeoff announcement was if you hear a loud whistling your probably going die.then a speach about they couldnt do full mainetnance because of mission requirements.they basically flew an unsafe plane because mission dectated they had to fly it without proper checks and maintenance.

i can imagine even with civilian contractors the same applies,as mission dictates.of course i know for a fact the taliban and al quaeda have numerous antiaircraft artillery between mazer-i-sharif and bagram,and no matter how many they took out,they would always find more
 
longknife said:
Okay, here's a side of this nobody is reporting on -- we have no realistic land route available to move our military equipment out of Afghanistan!!!!!

When we moved out stuff out of Iraq we had TWO possible routes - west through Turkey or into the Persian Gulf.

Under this president/administration, we've lost access to neighboring countries to the north and Pakistan is in such a mess that we cannot take them through there. What does that leave? Costly and dangerous evacuation via air.
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In all fairness, we lost the routes through Uzbekistan when DoS decided to stick their noses in Uzbeki internal issues, most notably the handling of ethnic issues in the Ferghana Valley. We lost a major base at Karchi-Khanabad. That was under Bush.
 
Gladiator said:
Another factor for tied down vehicles in aiur planes, is the G force downward, on take-off and ascent. I have been on planes where the take-off and ascent are somooth, with almost no perceptible downward G forces. I have also been on flights, where I was pushed in the bottom of my seat, during lift-off or at some points during ascent. Other flights have been smooth as glass.

If a palne with MRAPS, or other vehicles, creates downward G's on take off, or ascent, then the suspension of the vehicle will be compressed. If there are enough downward G forces on take-off, then the tie down straps or chains may be loosened, if they are set at 30 or 60 Degrees, attached to the bumpers. Once the suspension is compressed, the chains and straps become loose, and allow movement of the vehicle, and creating more forward or backward G-forces.

Therefore, it may be important for cargo planes carrying vehicles to attempt to take off, and land, as smoothly as possible, to avoid compressing the suspension, thereby avoiding loosening the straps and chains with downward G forces.

The pictures on this thread show military vehicles tied down to the bumpers. Tow Truck drivers usually try to hook to the tires, or the suspension, close to the wheel, of a car or vehicle, not to the bumper.



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THAT is the most plausible explanation I have heard yet! :)
 
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