Accident Overview
On July 24, 2017, at about 1316 eastern daylight time, a Robinson R44 helicopter, registration N828RD, operated by Helicopter Solutions, Inc., doing business as Helicopter Adventures, sustained substantial damage during a hard landing near Myrtle Beach, South Carolina. The commercial pilot and two passengers were not injured. The flight was conducted under 14 Code of Federal Regulations Part 91 as a commercial air tour, on a company visual flight rules flight plan. Visual meteorological conditions prevailed at the time.
Flight Sequence
The flight originated at about 1310 from the operator's facility. During the Boardwalk Adventure tour, while near the Sky Wheel, the pilot felt a shaking described as a "minor kick," which he initially attributed to a stuck valve. He radioed the company to request a mechanic to meet the flight but continued the tour, attempting to maintain about 70 knots with 25 inches of manifold pressure, resulting in a 300 feet-per-minute descent. Near the departure helipad, company personnel observed white smoke trailing the helicopter, and the pilot noticed the alternator light illuminated. As he pulled power to slow the descent, the low rotor rpm horn activated and engine rpm spiked. Unable to reach the intended helipad, the pilot turned toward an adjacent field and applied full collective to cushion the landing, but the helicopter landed hard.
Engine Examination
Postaccident examination revealed oil on the V-belts in the engine compartment. The oil sump contained about 4.5 quarts, below the minimum takeoff capacity of 7 quarts. The No. 5 cylinder pushrod and shroud were fractured into two pieces. The engine was removed and disassembled under FAA oversight. The pushrod showed contact damage and bending consistent with overstress. The No. 5 cylinder exhaust valve exhibited impact marks from contact with the rotator cap; the rocker arm showed fretting damage. The governor passed operational tests. Damage to the tailboom skin was noted.
Maintenance History
The engine had been last overhauled on June 21, 2016, and installed in the helicopter on January 15, 2017, accruing 358.2 hours since major overhaul. Oil and filter changes were performed every 50 hours in accordance with Lycoming Service Bulletin 480F. Lycoming Service Bulletin 388C, a repetitive inspection for exhaust valve and guide condition every 300 hours, was last accomplished at 298.3 hours since overhaul. The operator reported prior stuck exhaust valves but no previous pushrod fractures.