aviation accident: McDonnell Douglas MD 900 near Mesa (2004-09-08)
Probable cause: fracture of a Tension-Torsion strap in the anti-torque fan due to progressive fiber failure of the composite strap material from compression and/or transverse shear stresses that occurred with repeated manipulation of the cockpit anti-torque control pedals without the fan operating at full rpm. A factor in the accident was the helicopter manufacturer's inadequate fatigue and load testing on the strap.