LAX97LA021

A certified flight instructor (CFI) was administering dual instruction to a certificated pilot. A recently seeded and irrigated grass landing area was selected for practice (touchdown) autorotations. The grass surface was wet and uneven. The helicopter's right skid caught in the sod during the landing ground run, and the helicopter rolled onto it's right side. Both pilot's attempted to prevent the rollover by applying full left cyclic without success. There was a left 5-knot crosswind reported by the air traffic control tower at the time.

On October 17, 1996, at 1250 hours mountain standard time, a McDonnell Douglas helicopter 369E, N842LA, rolled over after a loss of control during the landing ground run. The pilot had completed a practice autorotation at the McDonnell Douglas Training Systems leased facility on Falcon Field, Mesa, Arizona. The helicopter sustained substantial damage. The certified flight instructor (CFI) received minor injuries and the commercial rated student pilot was not injured. The helicopter was being operated by McDonnell Douglas Training Systems as a training flight under 14 CFR Part 91 when the accident occurred. The local flight originated at 1145. Visual meteorological conditions prevailed.

The CFI indicated during a practice autorotation with turn, the helicopter's right skid dug into the turf surface during the landing ground run. The helicopter "lurched" right and rolled onto to its right side.

The commercial rated student pilot indicated the helicopter was sliding on the ground about 25 knots. After traveling 20 feet, the helicopter "suddenly and without warning " pitched forward and started to roll to the right. The pilot stated he and the CFI attempted to stop the roll with full left cyclic. The pilot also indicated there was a left quartering head wind at approximately 10 knots at the time.

The sod touchdown area is oriented parallel to runway 22/04 at Falcon Field. The long axis is about 900 feet long with a width approximately 180 feet. The area had been recently seeded and was being irrigated with sprinkler systems. Photographs of the touchdown area were reviewed and showed new grass growth forming uneven surface conditions. The photographs also showed impressions from vehicle tracks as well as the track of the helicopter's right skid. The impression from the helicopter's right skid crosses an area of greener grass and displaces the sod. The impression continues straight for about two helicopter lengths, then in about one helicopter length the impression arcs to the left and stops at the helicopter's point of rest.

The winds at the time of the accident were recorded by the air traffic control tower at Falcon Field and were reported to be from 140 degrees at 5 knots.