MD-11
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Less Severe
Flight Crew Rejected Takeoff
Aircraft; Weather
During takeoff I rejected the takeoff at 90kts due to a violent vibration during the takeoff roll. We noticed a small vibration during taxi out; but it smoothed out at the end of taxi and before takeoff roll. My thought process was that we were light weight and the tires were cold soaked. We decided to continue and initiate the takeoff. I briefed the takeoff to include if we got a vibration during takeoff that I would reject. The vibration started around 40 kts and continued to get worse as we increased speed. The result was a rejected takeoff. Taxied back to ramp with no assistance required. Maintenance changed both front tires. Maintenance suspected that due to below freezing temps and extended period on the ground the tires developed flat spots. On preflight I noticed some wear on the nose tires but nothing out of the ordinary. I also mentioned to maintenance that we were loaded with an aft CG; light weight and didn't have a lot of weight on the nose which could have contributed to the vibration. Being so light weight and cold temps; the AC accelerates rapidly. After the first officer called 80 kts and the vibration continued; I decided to reject the takeoff. Next takeoff was successful.
During taxi from ramp to Runway XX; the Captain; PF (Pilot Flying); and I noticed a vibration in the airframe. We talked about it and decided it was probably a combination of flat spotted wheels (airplane had been sitting for a few days in below-freezing temps); being lightweight and being loaded with an aft CG. As we continued to taxi the vibration stopped; which we contributed to the flat spots on the tires working themselves out. Captain did a standard takeoff brief and at the end of his brief discussed that if the vibration came back that we would reject the takeoff. Accelerating through approximately 40 knots; the vibration began to come back and progressively got worse as we accelerated to the point of being violent at 80 knots. Just after I called the '80 knots' check; the Captain called for the reject. I believe the maximum speed we reached was 90 knots. Being so lightweight (350;000 lbs); the aircraft accelerates very fast; so all of that happened in a very short time frame. He slowed the aircraft and vacated [the runway]. After discussing with [Operations] Control; we continued back to [the] ramp with no assistance needed. After shutdown the situation was discussed with maintenance personnel and both front tires were replaced. Next attempted takeoff and remainder of the flight were normal.
MD-11 flight crew reported a rejected takeoff following a violent vibration on takeoff.