Engine Failure,
Aircrew Error Led to Fatal E-11A Crash in Afghanistan, Air Force Says
As an Air Force
E-11A battlefield communications aircraft conducted missions over Ghazni
Province, Afghanistan, on Jan. 27, 2020, a fan blade broke inside the left
engine. Efforts to address the problem led to a series of missteps that
caused the aircraft to crash, killing the two pilots, according to a new
Accident Investigation Board report.
The report, released
Thursday by Air Combat Command, concluded that the broken blade caused the
left engine to shut down automatically. But the pilots improperly assessed
"that the right engine had failed or been damaged" and initiated
right engine shutdown procedures, it adds.
With the right
engine shut down, the pilots were in a "dual engine out
emergency." They were unable to restart the right engine, though the
report does not explain why. It's possible they attempted to restart the
left instead, it states.
Lt. Col. Paul K.
Voss, 46, and Capt. Ryan S. Phaneuf, 30, were killed in the crash. They
were both assigned to the 430th Expeditionary Electronic Combat Squadron at
Kandahar Airfield, and were on a qualification flight while conducting a
combat sortie, the report states. The redacted investigation does not cite
names, but Air Force Magazine identified Voss as the flight commander, with
Phaneuf presumably the copilot.
The aircraft, tail
number 11-9358, was being used as a Battlefield Airborne Communications
Node, or BACN, acting as a "Wi-Fi in the sky" to boost other
pilots' situational awareness of beyond-line-of-sight activity.
BACN-equipped E-11 aircraft began operating in Afghanistan in 2011,
according to the Air Force.
The engine fan
malfunction occurred just before 1 p.m. local time, about an hour and 45
minutes into the flight, the report states.
The plane was in
range to glide to and land at either Kabul International Airport in eastern
Afghanistan, 17 nautical miles away, or Bagram Airfield, 38 nautical miles
away, it adds.
At one point, the
pilots could have glided to Forward Operating Base Shank -- 28 nautical
miles away -- but had only an eight-minute window to begin that maneuver,
the report states.
Instead, the crew,
flying at about 41,000 feet, decided to initiate an airstart on the right
engine and head toward Kandahar Airfield -- 230 nautical miles southwest
from their position. An airstart uses the aircraft's airspeed to turn the
engine turbines, a move that would require the aircraft to travel at 258
knots per hour. The aircraft, a modified Bombardier Global Express BD-700,
can reach a max speed of about 505 knots.
"... Mayday,
Mayday, Mayday … it looks like we have an engine failure on both motors. We
are proceeding direct to Kandahar at this time," one of the pilots is
heard radioing to Air Traffic Control, per the report.
However, the
aircraft was outside of the gliding distance to reach Kandahar; instead,
the pilots tried maneuvering toward Forward Operating Base Sharana, about
217 nautical miles to the east of Kandahar. But it crashed in a field 21
nautical miles short of Sharana.
There is limited
data on how the pilots reacted during the events, officials said. The harsh
vibrations caused by the left engine malfunction stopped the Cockpit Voice
Recorder, or CVR.
"Without the
CVR, it is difficult to fully assess the human factors and understand why
certain decisions were made," the report states.
Another key
instrument, the digital flight data recorder, stopped recording because of
the dual engine generator loss. While investigators could not confirm that
an engine airstart was attempted, there were signs that suggested the
pilots did try the reset, they said.
Because there was no
digital flight recorder data to make clear the pilots' steps, it is
possible they attempted to restart the left engine, thinking the right
engine was the one malfunctioning, the report states. The pilots
"may have concluded that the right engine suffered damage and
therefore only elected to airstart the left engine," it says.
Following the E-11A
single engine procedures checklist, the crew would have delayed starting
the Auxiliary Power Unit, or APU, which would have offered electrical power
to the engine.
But according to
photographs taken of the crash site wreckage, the APU intake door was open,
meaning that the crew "likely later used [it] in an attempted [auto
turbine]-assisted airstart."
On first approach,
search-and-rescue aircraft were unable to reach the crash site due to
weather. Crews that were able to reach the wreckage the next day and were
able to recover Voss and Phaneuf’s remains and some equipment, including
the CVR and flight data recorder. The remaining wreckage was ultimately
destroyed by U.S. forces, officials said at the time.
Ghazni Province has
been under majority Taliban control since 2015, shortly after U.S. combat
forces began drawing down in Afghanistan, but U.S. officials determined
early on that the crash was not the result of enemy action.
It was not
immediately clear how the crew misidentified the problem engine. In the
first few moments, the crew alert system "did not directly indicate
the left engine failure," the report states.
The Accident
Investigation Board president, Brig. Gen. Craig Baker, found that the
pilots had roughly a minute to deduce what was going on, but reacted just
24 seconds from the start of the violent vibrations to shut down the right
engine.
Based on the
information available, Baker concluded that the crew misidentified which
engine suffered the failure, resulting in them shutting down the wrong one.
"I also find,
by a preponderance of the evidence, that the [crew's] failure to airstart
the right engine and their decision to recover the [aircraft] to [Kandahar]
substantially contributed to the mishap," he said.
The aircraft, a Bombardier
Global Express, was maintained by Northrop Grumman, which developed the
BACN equipment. Northrop conducted the plane's last major inspection on
Jan. 13, just two weeks before the accident. A final inspection was
conducted one day prior to the flight, but "no aircraft discrepancies
[were] identified," the Accident Investigation Board report states.
The report did not
give a reason for the blade damage in the left engine, which was
manufactured by Rolls-Royce.
The loss of the
plane and its equipment was estimated at $120 million, the Air Force said
in an accompanying release.
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