Helikopterulykke i USA skyldtes feil recovery fra Vortex Ring - AIN

 

Vortex Ring eller settling with power, inntreffer når helikopterets hovedrotor kommer inn i egen turbulens som kan skje ved 0 airspeed og en sakte nedstiging. Recovery er i hovedsak enkelt; ned med collective og frem med cyclic stick. Straks du får airspeed kan du dra på igjen. (Red.)

December 26, 2023

Tuesday

Vortex Ring Drill Triggered Bell 429 In-flight Break-up The NTSB is faulting the actions of both student and instructor practicing a vortex ring state (VRS) recovery maneuver in a Bell 429 that led to an in-flight breakup and their deaths. According to the NTSB, the probable cause of the April 26, 2022, accident in Elba, New York, was “the pilots’ inappropriate flight control inputs while in vortex ring state, which resulted in main rotor blade contact with the tail boom and a subsequent in-flight breakup. Also causal was the flight instructor’s inadequate monitoring of the flight.” A different student faulted the instructor for not reacting during an accelerated sink rate on a previous VRS exercise. Parametric data recovered from the accident flight revealed that the helicopter was operating within a VRS envelope with a descent rate between 800 to 1,300 fpm. The NTSB noted, “Shortly thereafter, multiple abrupt control inputs were recorded, which [included] a forward cyclic input, followed by a nearly full-aft cyclic input within one second, as well as a concurrent full-down collective input with an increasing left pedal input.” Contact signatures found on the tailboom and main rotor blades were indicative of an in-flight break-up. The NTSB found “no evidence of any mechanical malfunctions or failures.”