Accident Overview
On August 3, 2015, at about 1600 central daylight time, a Bell 47G-3B-1 helicopter, registration N4002G, operated by Ewing Flying Services LLC, was substantially damaged during a loss of control on landing near Camden, Alabama. Visual meteorological conditions prevailed, and no flight plan was filed. The flight originated in Thomaston, Alabama, and was destined for Oak Hill, Alabama, operating under 14 CFR Part 91 as a positioning flight.
Flight and Pilot Information
The pilot was repositioning the helicopter for spraying operations scheduled the following day. He had been airborne for approximately 20 minutes and had used 10 gallons of fuel out of the 42 gallons he reported carrying. The pilot held commercial and airline transport pilot certificates with ratings for airplane single-engine land, airplane multi-engine land, and rotorcraft helicopter. His last flight review was on July 5, 2015, in the same make and model, and his most recent second-class medical was issued on May 14, 2015. He reported over 20,000 hours of total flight time, including 15,000 hours in helicopters and 1,080 hours in the same make and model.
Aircraft Information
According to FAA airworthiness and maintenance records, the helicopter was equipped with a supplemental type certificate for the Soloy Allison 250-CID turbine engine conversion. It was also equipped with an agricultural spray boom mounted under the forward fuselage above the skid and aft of the skid toe, approximately 30 feet in length, extending about 12 feet from both sides of the cockpit. The most recent 100-hour inspection was performed on February 19, 2015, at which time the airframe had accumulated 13,719.2 hours total time and the engine total time was 2,906.7 hours. Mast, bearing, hub, and swashplate maintenance was performed on July 9, 2015, at 13,764.2 hours total time and engine total time of 2,951.7 hours.
Accident Sequence
While at 300 feet altitude and about half a mile out on approach to the off-airport landing zone, the hydraulic system augmenting the controls failed, and the cyclic controls became stiff. The pilot braced his left leg under the collective pitch control and grabbed the cyclic with his left hand but was unable to cycle the hydraulic system switch with his right hand because the collective control had drifted down, increasing his descent rate. He then grabbed the collective and cyclic controls, leaving the hydraulic switch in the on position. He continued the approach into a large clearing in a forest. Just prior to touchdown, the agricultural spray boom made contact with trees and brush, causing the helicopter to yaw left. During touchdown, the heel of the left skid struck a dirt mound, rocking the helicopter forward. Subsequently, the toe of the right skid struck the ground, the helicopter began to oscillate, and it rolled to the left. The pilot attempted to correct, but the helicopter continued to rollover until it impacted the ground, coming to rest on its left side. After impact, the pilot evacuated as fuel poured out of the right tank directly into the engine and cockpit area. The fuel ignited, and the fire consumed the fuselage and caused significant damage to the transmission, engine, and components. The hydraulic pump was extensively damaged by the fire and could not be inspected.
Post-Accident Examination
An FAA inspector examined the helicopter at the accident site. The fuselage, main rotor blades, and tail boom were substantially damaged during the accident sequence, and fire consumed the fuselage and damaged the engine and components. The accident site was a forested clearing. The ground in the immediate vicinity was burned, but remnants under the helicopter and in the area contained brush, 1-inch diameter branches, and immature saplings. Several larger diameter fallen pine trees were near the helicopter. A dirt mound approximately 14 to 18 inches tall and several feet long was located 3 feet to the left of the helicopter near the main rotor head.
According to the Bell Helicopter Flight Manual Model 47, Section 2 Operating Procedures: "Hydraulic boost failure will be evident by feedback forces being transmitted to the cyclic stick when a control motion is made... When hydraulic boost power loss is detected, reduce cyclic control motions to the minimum required to complete the flight… If jamming of the controls or a condition of the controls tending to override the pilot is experienced, the HYD (hydraulic) SYSTEM switch, located on the instrument panel, should be immediately moved to OFF to relieve hydraulic pressure…"
According to the FAA Helicopter Flying Handbook (FAA-H-8083-21A), under System Malfunctions & Hydraulic Failure: "If hydraulic power is not restored, make a shallow approach to a running or roll-on landing. This technique is used because it requires less control force and pilot workload."