Bell 205A-1 Helicopter Part Fails
Bell Helicopter's Cracked Yoke Leads to Crash

This animation depicts the forces being exerted on the tail rotor blades, which weaken the tail rotor yoke and resulted in a crack in the tail rotor yoke. If large enough, these forces may result in "static overload" damage, which creates a loss of compressive residual stress and a resulting fatigue fracture. Static overloads occur when the tail rotor is stationary, not when a helicopter is in flight. Static overload can be caused by improper ground handling (such as using the tail rotor blade as a handhold to move the helicopter), collision with a vehicle, improper bearing removal while the yoke is off the helicopter, and wind gust or jet blast. The resulting crack eventually propagates throughout the yoke, causing it to separate and fail in flight.

Baum Hedlund had this animation prepared as one of several to be shown as evidence during their 2006 product liability trial at Los Angeles Superior Court against Bell Helicopter Textron, Inc., and Bell Technical Services, Inc.

History: A Bell Model 205A-1 helicopter, owned and operated by the LAFD crashed in Griffith Park during an airlift rescue operation in Los Angeles on March 23, 1998. The helicopter was airlifting an injured child from a car accident when the helicopter's tail rotor yoke failed and caused the aircraft to crash, destroying the helicopter and killing the child, two LAFD paramedics and an LAFD helicopter apparatus operator.

View Other Bell Helicopter Crash Animations

Griffith Part Bell Helicoptor crash simulation video: tail rotor loss
Griffith Part Bell Helicoptor crash simulation video: yoke breakdown
Griffith Part Bell Helicoptor crash simulation video: shot peening
Griffith Part Bell Helicoptor crash simulation video: flexure loss

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