MIA00LA135 · Hughes OH-6A

Three helicopters departed in the following order, UH-1, AH-1, and the OH-6A, en route for a static display at an airshow. When the three helicopters neared the destination airport, the pilot of the UH-1 contacted the tower about 6 to 7 miles out and received landing instructions for the group. About 1 mile south of the field on a downwind for runway 09-27, the tower instructed all three helicopters to turn left [north] for an approach to the grass infield south of runway 09-27 then to cross and land in the area north of runway 09-27 and adjacent to the aircraft parking area. Each aircraft turned to a northerly heading for the approach. The pilots reported that they maintained approximately 150-250 feet separation from the aircraft in front. The UH-1 followed by the AH-1 landed uneventfully ahead of the OH-6A. The pilot of the OH-6A slowed the helicopter to 30 knots and reduced the pitch. He stated that when he '...increased the collective to maintain a normal approach profile...the increased collective had no apparent effect. He increased the collective again to arrest the increasing rate of decent. Again, the increased collective had no effect.' As he passed through about 50 feet agl, he noted that the Engine/Rotor RPM had 'dropped below 100 percent.' He announced, 'I have a loss of power,' and rotated the throttle to flight idle and initiated collective pitch pulled at 5 feet prior to touchdown. The pilot/passenger in the left seat stated, '...as we approached for landing, the AH-1 abruptly slowed. We closed within 75-100 feet behind...the AH-1, and [the pilot] raised the aircraft nose to maintain separation...and off set to its' right [east] 75 to 100 feet...[the pilot] called out that the aircraft was settling and he had no power response. He increased collective pitch but the aircraft did not respond and settled vertically...I noticed no warning lights but, as the aircraft hit the ground, I saw the transmission oil pressure light come on. No other warning light came on.' The helicopter slid about 50 feet before it came to a rest upright, and the pilot announced over the intercom that 'he could not shut the engine down' so the pilot/passenger pulled the fuel shut off valve, turned off the switches, and turned the battery off. According to the FAA inspector's statement, '...based on the relatively low time and experience of the pilot and crew member who were in control of this aircraft at the time of the accident...the accident occurred as the result of the pilot's loss of control of the aircraft when he inadvertently flew it into the wake turbulence of the two larger helicopters which landed in front of him...the pilot was unable to maneuver the aircraft out of trouble and consequently, the aircraft settled under power to a very hard landing.' The engine was test run and no discrepancies were found. No discrepancies were found with the airframe or controls. The reported wind conditions at the airport at 1053 were from 270 degrees at 7 knots. This wind condition had set up a crosswind condition from west to east, or from the landing helicopter's left to right. The pilot's flight times on the NTSB 6120.1/2, showed he had a total flight time in all aircraft of 5,100 plus hours, 3,253 hour in helicopters, and a total of 13.9 hour in this make and model helicopter.

Verbatim NTSB analysis and probable cause from the NTSB dataset