Report: Small part failure doomed Ellsworth B-1 bomber - KOTA Territory News

Report: Small part failure doomed Ellsworth B-1 bomber that crashed


by Jack Siebold

The Air Force released the report on last August's B-1 bomber crash in Montana.  The cause was tracked down to a baffle used to restrain the flow of fuel.  It became "displaced," causing a leak, several explosions and the loss of the bomber.

What remains "baffling" is how that baffle became dislodged in the first place.  

The pilot had just swept the wings back to help increase speed as they dropped from 20,000 to 10,000 feet.  According to the report, the baffle was detached before the wings were swept back but the Air Force didn't explain how that happened.  

Sweeping the wings back pushed the loose baffle into the main fuel line, cutting it and causing thousands of gallons of fuel to leak into the aircraft.  This resulted in a chain reaction of several explosions.

Fortunately, the four-man crew was able to eject with non-life threatening injuries.

Here is the official release:

A displaced fold-down baffle in the left overwing fairing of a B-1B Lancer led to a fuel leak and a series of detonations that disabled the aircraft prior to it crashing Aug. 19, 2013, near Broadus, Montana, according to an Air Combat Command Accident Investigation Board report released today.

The four crew members ejected safely and sustained non-life-threatening injuries.
The aircraft was destroyed, with the government loss valued at approximately $317.7
million.  There were no injuries to civilians, and damage to private property consisted of
burnt pasture land.

Both aircraft and crew were assigned to the 34th Bomb Squadron, 28th Bomb
Wing, Ellsworth Air Force Base, South Dakota.  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. 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.


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