Cessna 402/402C/B379 Businessliner/Utiliner
Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 110; Flight Crew Total 11000; Flight Crew Type 1000
Training / Qualification
Ground Event / Encounter Ground Strike - Aircraft; Ground Event / Encounter Loss Of Aircraft Control; Ground Excursion Taxiway
Aircraft Aircraft Damaged
Human Factors; Aircraft
After landing; the pilot flying taxied off the runway and proceeded to taxi straight down to the departure end of the runway. Out of nowhere; the airplane suddenly started to turn to the right. The student commented to me that 'I can't straighten out the nose.' I said 'I have the controls.' The student released the controls and I tried to get the airplane back on the taxiway center line; but at this point the right rudder was deflected full right. The airplane was on the grass. Then; I felt the nose dip down and collapse. The prop struck the ground and that's when we shut down both engines before any further damage. We then proceeded to secure and exit the airplane.
During the taxi [with] both engines [at] idle; suddenly the plane started turning to the right. I pushed the left rudder but the plane kept turning. I told the instructor that I can't control the plane. He took the control and also didn't manage to stop the turn. The plane turned to the grass and then the nose gear collapsed and the propellers struck the ground. We shut down both engines; secured the plane; and exited.
C402B instructor and student pilot reported a loss of directional control during taxi that resulted in nose gear collapse and a prop strike.