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FLIGHTSAFETY.ORG | AEROSAFETYWORLD | MAY 2013
HELICOPTERS
Control Lost During Search
MD Helicopters MD902. Destroyed. Three serious injuries.
The pilot, flight engineer and forwardlooking
infrared radar (FLIR) operator
aboard the state police helicopter were
searching for a missing person near Engelsbrand,
Germany, in night VMC on May
10, 2011. The helicopter was circling about
600 ft above a hill when the radar operator
announced that the FLIR was showing an
unidentified heat source.
The pilot and flight engineer donned night
vision goggles (NVGs). The pilot then maneuvered
the MD902 close to the displayed heat
source and reduced speed to place the helicopter
in a hover. “Suddenly, the helicopter yawed to
the right,” said the report by the German Federal
Bureau of Aircraft Accident Investigation. “He
responded [by] actuating the left pedal up to the
mechanical stop.”
However, the helicopter continued to
yaw right and then descended out of control
into the forest. All three occupants sustained
serious injuries. The radar operator exited
the wreckage unaided; the pilot and flight
engineer were rescued by police ground
crewmembers.
The report concluded that visual restrictions
resulting from the use of the NVGs,
distractions caused by the search for the missing
person, and a “loss of spatial perception”
were among factors that likely contributed to
the accident.
“It is likely that while trying to position the
helicopter as close as possible to the identified
heat source, an unnoticed loss of altitude and
backward movement of the helicopter occurred,”
the report said. “It is highly likely that
the restricted spatial perception of the pilot due
to the NVGs contributed to the occurrence; the
same is true for crewmembers whose attention
was focused on the search.”
ONRECORD
Distracted by Radio Call
Eurocopter AS350 B2. Substantial damage. Three minor injuries.
The pilot, who had recently purchased the helicopter,
was receiving training by a certified
flight instructor (CFI) at Alliance Airport in
Fort Worth, Texas, U.S., the morning of May 29,
2011. “During practice traffic pattern work, the
helicopter’s hydraulic system was turned off to
simulate hydraulic failure on the flight control
system,” the NTSB report said.
During the subsequent approach, the CFI
and the pilot may have been distracted when
an airport traffic controller advised that they
were using an incorrect radio frequency, the
report said. While the instructor was setting
the correct frequency, the helicopter slowed and
entered an uncommanded left yaw.
“The CFI tried to regain control by adding
right pedal, trying to gain forward airspeed, and
reducing power,” the report said. “The helicopter
did not respond to the CFI’s control inputs,
descended and impacted terrain.” The pilot, CFI
and passenger sustained minor injuries.
Loose Nut Causes Power Loss
Bell 206B. Substantial damage. No injuries.
After the JetRanger’s engine lost power during
an aerial-application flight near Burbank,
Washington, U.S., on May 30, 2012, the pilot
conducted an autorotative landing in an apple
orchard. “During the landing, the rotor blades
impacted the trees and the tail boom separated
from the main fuselage,” the NTSB report said.
Maintenance records showed that the helicopter
had been flown six hours since the engine
bleed air valve was replaced. Investigators
determined that maintenance personnel had not
applied sufficient torque to secure a B-nut that
attaches the compressor discharge pressure air
tube to the engine. The B-nut had backed off the
stud during the accident flight, causing the air
tube to detach and the engine to lose power.
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