B-2 stealth bomber crashes - update with cause

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B-2 stealth bomber crashes - update with cause

This is an expensive accident.

A US B-2 stealth bomber - one of the world's most expensive planes - has crashed for the first time on the Pacific island of Guam.

The jet crashed shortly after taking off from the island's Andersen Air Force Base, but both pilots ejected and survived, the US Air Force (USAF) said.

Black smoke could be seen billowing from the site, witnesses said.

The B-2 bomber costs $1.2 bn and is capable of deploying both conventional and nuclear weapons.

Crowds gathered as emergency vehicles attended the scene after the crash, which happened around 1045 local time (0045 GMT).

More on the site

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By netchicken: posted on 23-2-2008

First pictures. Smoke billows from the runway at Andersen Air Force Base, Guam Saturday Feb. 23, 2008 after a B-2 stealth bomber crashed.

The two pilots aboard the bomber ejected before the crash and are safe the U.S. Air Force said. A board of Air Force officers will investigate what happened. Each B-2 bomber costs about $1.2 billion to build.

All 21 stealth bombers are based at Whiteman Air Force Base in Missouri, but the Air Force has been rotating several of them through Guam since 2004, along with B-1 and B-52 bombers.

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By netchicken: posted on 24-2-2008

The B-2 that crashed Feb. 23 in Guam “basically stalled” and is “absolutely a total write-off,” Gen. John Corley, head of Air Combat Command, told defense reporters at a meeting March 27 in Washington, D.C.

Corley said the pilots reported that the airplane “rotated early,” meaning the nose came up sooner and faster than the pilots commanded, and they could not get it to come down again. The airplane stalled—meaning the pitch was too high for airflow over the wings to create lift—and, when the left wing started dragging against the ground, the two-man crew ejected.

Corley made no mention of an onboard fire, which has been reported by some publications. He said there are two investigations underway: a safety and an accident probe. The former is due mid-April, the latter in mid-May.

The 20 remaining B-2s are not technically grounded, Corley said, but are not flying while the 509th Bomb Wing at the B-2’s home base of Whiteman AFB, Mo., reviews its training and inspection procedures. In the meantime, Corley said, crews are staying proficient by flying in the simulator and in the T-38 companion trainer.

By netchicken: posted on 29-3-2008

Video of the B2 accident. The B2 crashed because of dihydrogen monoxide screwing with the sensors. Ban dihydrogen monoxide now!

On takeoff from Andersen Air Force Base, the $1.4 billion plane abruptly "pitched up, rolled and yawed to the left before plunging to the ground," the AP describes.

The reason why:
... Quote:
Water distorted preflight readings in three of the plane's 24 sensors, making the aircraft's control computer force the B-2 to pitch up on takeoff, resulting in a stall and subsequent crash.

both pilots ejected safely just after the left wing made contact with the ground in the first crash since the maiden B-2 flights nearly 20 years ago.
In the video the accident starts at about 2:17. It must have been a scary episode for the pilots.


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By netchicken: posted on 7-6-2008

The spectacular crash of a B-2 stealth bomber in February could have been prevented by a simple, unofficial “bootleg” maintenance procedure that some ground crews have used for years.

Small errors, it now turns out, caused a large accident. A B-2 has four computers, called the flight control system (FCS), that translate the pilot’s cockpit inputs into movement of the plane’s control surfaces.

The $1.4 billion warplane was brought down by a few drops of water in three of the 24 air-pressure sensors that feed data to the FCS. The moisture distorted the plane’s air-pressure readings and confused the FCS badly enough to cause the crash, the first one of the B-2’s career.

February’s crash was caused by maintenance crews trying to do the right thing: They saw the wrong data and recalibrated the sensors. However, once the moisture evaporated, the sensors “fixed” by the crew were actually set incorrectly and were feeding the flight computer false data on airspeed and air pressure, which is used to measure altitude. “The pressure differences were miniscule, but they were enough to confuse the FCS, ” Maj. Gen. Floyd Carpenter, who headed the Air Force’s investigation, tells PM.

The FCS then took control; triggering a premature takeoff, automatically driving the airplane into a 30-degree, nose-up pitch and overruling the pilot’s efforts to regain control. Fortunately, the pilot and commander were able to eject safely just before the B-2, the Spirit of Kansas, crashed in flames.

The accident might have been avoided­ if the crew that readied the B-2 for?takeoff knew of an unofficial fix that had been used by maintenance personnel for at least two years. During the occasional, temporary B-2 deployments to rainy, humid Guam, where the planes were often stored outside, some B-2 ground crewmen noticed that air data calibration was required much more often.? In 2006, a Air Force engineer based in the United States suggested turning on the heat before the calibration to boil off any water in the system before adjusting the sensors.

The procedure worked, and some ground crewmen adopted it,? but it was never formalized into a technical order change or captured in any after-action reports. Unfortunately, the Spirit of Kansas’ pilots and ground crew were out of the loop.

Even those ground crewman who used the bootleg procedure had no inkling of the potential dangers of a slight miscalibration. Before the crash, air data calibrations were considered a benign way to double-check the altimeters.? Apparently no one made the connection that the air data sensors also fed info to the FCS computers about airspeed, angle of attack, and sideslip—and that the FCS flew the plane based largely on those numbers.

The B-2’s computerized fly-by-wire wizardry is a supreme technical achievement, but the Guam crash—the only one in the stealth bomber’s 19-year flying history—underlines the vulnerability of even sophisticated computer systems to mundane glitches. And it doesn’t matter how sophisticated a military system is if the people taking care of it can’t communicate.

By netchicken: posted on 5-7-2008

This photo shows the crashed B2 up close.

More pictures on the link http://www.popularmechanics...

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By netchicken: posted on 16-7-2008

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