LANGLEY AIR FORCE BASE, Valencia. US Air Force's Air Combat Command released its Accident Investigation Board report of Aug 19 201...
LANGLEY AIR FORCE BASE, Valencia.
US Air Force's Air Combat Command released its Accident Investigation Board report of Aug 19 2013 crash of B-1B Bomber aircraft near Broadus, Montana.
According to the report, a displaced fold-down baffle in the left overwing fairing of a B-1B Lancer during swing wing operation, punctured a hole in the fuel line, which led to a fuel leak and a series of detonations that disabled the aircraft prior to its crash.
The four crew members onboard ejected safely and sustained non-life-threatening injuries.
Both aircraft and crew were assigned to the 34th Bomb Squadron, 28th Bomb Wing, Ellsworth Air Force Base, South Dakota, one of the only two bases in the U.S. that have B-1Bs. Ellsworth had 28 of the planes, including the one that crashed.
When the accident occurred, the pilots were participating in a post-deployment training flight allowing them to become current on combat-mission readiness training items.
The wings of the B-1B move from a forward position to an aft position to increase the aircraft's performance at different speeds. During a training mission, the pilot leveled the aircraft off at an altitude of roughly 20,000 feet. While on a descent to 10,000 feet, he swept the wings from the forward to the aft position. During the sweep, the aircraft developed an undetectable fuel leak in the main fuel line. Unbeknownst to the crew, approximately 7,000 pounds of fuel leaked into the aircraft during the training mission.
Eventually, the fuel contacted exposed portions of the hot precooler duct, ignited, and caused an explosion that separated the left overwing fairing from the aircraft.
Ignited fuel streamed from the exposed left overwing fairing cavity, heated one of the aircraft's fuel tanks, and ignited the fuel vapors inside the tank. This detonation spread through the fuel venting system that connects the fuel tanks in the aircraft, and resulted in a cascade of detonations that caused a complete and permanent loss of power to the crew compartment.
According to the results of the investigation, at some time prior to pilot's initiation of the wing sweep, the left fold down baffle became detached at one or more points, preventing it from folding as the wing swept aft. The fold down baffle is supposed to fold flat when the wing moves to allow the wing to sweep over the top. Because the baffle was detached, the wing pushed the baffle into the overwing fairing cavity where the tapered edge of the baffle cut a v-shaped hole in the main fuel line.
Forward wing settings are used for takeoff, landings, air refueling and in some high-altitude weapons employment scenarios. Aft wing sweep settings - the main combat configuration -- are typically used during high subsonic and supersonic flight, enhancing the B-1B's maneuverability in the low- and high-altitude regimes.The loss was valued at approximately $317.7 million.
The multi-mission swing wing B-1 is the backbone of America's long-range bomber force. The B-1A was initially developed in the 1970s as a replacement for the B-52. The B-1B is an improved variant initiated by the Reagan administration in 1981. The B-1B's blended wing/body configuration, variable-geometry wings and turbofan afterburning engines, combine to provide long range, maneuverability and high speed while enhancing survivability.
Source: www.acc.af.mil
US Air Force's Air Combat Command released its Accident Investigation Board report of Aug 19 2013 crash of B-1B Bomber aircraft near Broadus, Montana.
According to the report, a displaced fold-down baffle in the left overwing fairing of a B-1B Lancer during swing wing operation, punctured a hole in the fuel line, which led to a fuel leak and a series of detonations that disabled the aircraft prior to its crash.
The four crew members onboard ejected safely and sustained non-life-threatening injuries.
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| Crash site |
When the accident occurred, the pilots were participating in a post-deployment training flight allowing them to become current on combat-mission readiness training items.
The wings of the B-1B move from a forward position to an aft position to increase the aircraft's performance at different speeds. During a training mission, the pilot leveled the aircraft off at an altitude of roughly 20,000 feet. While on a descent to 10,000 feet, he swept the wings from the forward to the aft position. During the sweep, the aircraft developed an undetectable fuel leak in the main fuel line. Unbeknownst to the crew, approximately 7,000 pounds of fuel leaked into the aircraft during the training mission.
Eventually, the fuel contacted exposed portions of the hot precooler duct, ignited, and caused an explosion that separated the left overwing fairing from the aircraft.
Ignited fuel streamed from the exposed left overwing fairing cavity, heated one of the aircraft's fuel tanks, and ignited the fuel vapors inside the tank. This detonation spread through the fuel venting system that connects the fuel tanks in the aircraft, and resulted in a cascade of detonations that caused a complete and permanent loss of power to the crew compartment.
According to the results of the investigation, at some time prior to pilot's initiation of the wing sweep, the left fold down baffle became detached at one or more points, preventing it from folding as the wing swept aft. The fold down baffle is supposed to fold flat when the wing moves to allow the wing to sweep over the top. Because the baffle was detached, the wing pushed the baffle into the overwing fairing cavity where the tapered edge of the baffle cut a v-shaped hole in the main fuel line.
Forward wing settings are used for takeoff, landings, air refueling and in some high-altitude weapons employment scenarios. Aft wing sweep settings - the main combat configuration -- are typically used during high subsonic and supersonic flight, enhancing the B-1B's maneuverability in the low- and high-altitude regimes.The loss was valued at approximately $317.7 million.
The multi-mission swing wing B-1 is the backbone of America's long-range bomber force. The B-1A was initially developed in the 1970s as a replacement for the B-52. The B-1B is an improved variant initiated by the Reagan administration in 1981. The B-1B's blended wing/body configuration, variable-geometry wings and turbofan afterburning engines, combine to provide long range, maneuverability and high speed while enhancing survivability.
Source: www.acc.af.mil
