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MD-11 PCA Flight Accomplishments

  • Two PCA landings completed, in one of these there was absolutely no use of any flight control surfaces during the approach, landing, and rollout on the runway, thus validating the PCA concept for total hydraulic failure.
  • PCA operation was evaluated at 10,000 ft, 20,000 ft, and 30,000 ft and for Mach numbers to 0.83 and airspeeds from 160 to 360 kts. Although simulation had indicated otherwise, the flight tests showed very good PCA operation, showing that a PCA system would be able to function over the full flight envelope without additional control complexity.
  • PCA operation was checked with 2 of the 3 hydraulic systems on the MD-11 turned off. PCA was able to maintain level flight with a large aileron offset.
  • The PCA system was engaged with the airplane in an upset situation such as might occur in a real failure. PCA successfully recovered the MD-11 for a combined 45 deg. bank and 7 deg. dive.
  • PCA was evaluated for the Sioux City scenario (center engine failed, yaw asymmetry, no flight controls, no flaps) and a successful approach down to 100 ft. was accomplished by a pilot flying PCA for the first time.
  • PCA control was used for climbs and descents and during instrument flight rules operation under FAA airspace control. The PCA operation was easily adequate to maintain the required control precision for this typical airline operation.
  • Although not planned until later, 3 engine PCA operation was tested and found to work very well. Speed was controlled within a few knots of the selected speed. Again, this was better than expected.
  • PCA control was evaluated over a range of center-of-gravity positions for 23 to 32 percent, and was found to perform well.
  • PCA used for navigation on a flight from Edwards AFB to NAS Yuma without any flight controls being used.
  • NASA, MDA MD-11, and MDA C-17 pilots have observed PCA flight operation and all have been very impressed with the outstanding performance of the system.