N138HAHiller UH-12E · 1976

On May 27, 2015 about 0815 Pacific daylight time, a Hiller UH-12E, N138HA, impacted an onion field during agricultural application operations near Wasco, California. The pilot was fatally injured, and the helicopter was destroyed. The helicopter was registered to and operated by Slikker Flying Service, Inc., under the provisions of 14 Code of Federal Regulations Part 137 as an agricultural flight. Visual meteorological conditions prevailed in the area, and no flight plan was filed. The flight originated from a refueling truck about 0813.

The truck operator reported that the pilot had just finished spraying a small field. The helicopter was filled with fuel and about 30-40 gallons of water to clean out the spray system. The pilot took off and departed the immediate area about 15 ft above the field. The truck operator cleaned the fuel/spray truck and was getting into the truck when he observed a plume of black smoke about ¼ mile away over a field crest. He drove toward the fire and observed the helicopter engulfed in flames.

The pilot held a commercial pilot certificate with ratings for rotorcraft-helicopter and instrument helicopter, and a Federal Aviation Administration second-class medical certificate dated February 18, 2015, with no limitations. The pilot's logbook was not recovered. During the pilot's last medical examination, he reported 1,136.2 total hours of flight experience, 277 of which were accrued in the previous 6 months. The pilot was hired by the operator in February 2014.

The pilot initially survived the accident but succumbed to his injuries about one week later. No autopsy or toxicology testing was performed.

The 0754, automated weather observation at Bakersfield Kern County Airport (BFL), located about 25 nautical miles southeast of the accident site, included wind from 290° at 3 knots, visibility 10 statute miles, clear skies, temperature 18°C, dew point 8°C, and an altimeter setting of 29.97 inches of mercury.

The helicopter impacted the onion field in a right-skid-low attitude. The field was disturbed between the first point of impact and the main wreckage. Throughout this area were bearings and portions of the tail boom and windscreen. The helicopter came to rest on its right side. The cabin area was destroyed and sustained heavy thermal damage. The tail boom was fracture-separated about mid-span and was found partially underneath the main wreckage.

The helicopter's main cabin was mostly consumed by the postcrash fire; however, the majority of the airframe remained intact. The cyclic, collective, and pedals were all found loose within the main wreckage; all exhibited signs of heat distress. The left side of the spray boom was fracture-separated in an aft direction. The tail boom was fracture-separated about mid-span, consistent with main rotor blade contact.

Control continuity from the cabin controls to the main rotor system was established. There was no evidence of binding or restrictions on the intact portions of the control linkages. The control linkages located underneath the seats and behind the cabin firewall exhibited breaks and evidence of heat distress. The observed fracture surfaces that were not consumed by the postcrash fire exhibited signatures consistent with overload.

Both main rotor blades remained attached to the main rotor hub. Both blades were deformed opposite the direction of rotation. The tips of both blades were fracture-separated and were not located.

The angled tail rotor drive shaft remained connected to the main transmission tail output flange, but it was separated at the aft end. The shaft and shaft housing were deformed about 90° to the left. Separated, deformed, and heavily fragmented pieces of the tail rotor drive shaft exhibited signatures consistent with overload. The aft portion of the tail rotor drive shaft remained attached to the severed aft tail boom structure and was connected to the tail rotor gearbox; when rotated, the tail rotor blades rotated normally.

The tail rotor blades remained installed at the tail rotor hub. The first blade exhibited a fracture at its leading edge near the root end of the blade and was deformed in the opposite direction of normal rotation. The second blade exhibited downward, chordwise bending near its inboard end.

The main transmission and engine remained mounted to the airframe. The main rotor mast exhibited evidence of contact with the main rotor hub.

The spark plugs were removed from the engine and exhibited normal operating signatures and evidence of sooting. The rocker covers were removed and there was no evidence of heat distress. The dual carburetor was removed from the engine and disassembled. There was no evidence of blockage. The interior of the right carburetor was dry, and the floats exhibited cracks. The interior of the left carburetor was wet with possible corrosion byproducts. Both magnetos were removed from the engine and rotated freely. The fuel tank was ruptured and contained no fuel. The fuel screen did not exhibit evidence of blockage or contamination.

On June 19, 2011, about 0720 Pacific daylight time, a piston engine-powered Hiller UH-12E helicopter, N138HA, experienced a hard landing in an agricultural field near Lost Hills, California. The commercial pilot, who was the sole occupant, received minor injuries, and the helicopter, which was owned and operated by the pilot, sustained substantial damage. The 14 Code of Federal Regulations Part 137 aerial application flight, which departed a local refueling site about 15 minutes prior to the accident, was being conducted in visual meteorological conditions. No flight plan had been filed.

According to the pilot, after making a spray pass during which he applied chemicals to an agricultural field, he ascended to about 100 feet above ground level (agl) in order to make a downwind turn. At that time the helicopter's engine suddenly stopped producing power. Because of his height above the ground, the pilot immediately entered an autorotational descent in order to attempt a forced landing. According to the pilot, during the landing sequence, he applied up collective in order to slow the descent rate and initiate the landing flare, but the main rotor blades ran out of energy to produce lift while the helicopter was still about 10 feet above the ground. It therefore landed hard in an alfalfa field, and the impact resulted in substantial damage to both the main rotor blades and the airframe.

A postaccident teardown inspection of the helicopter's fuel system determined that the engine driven fuel pump could not be turned by hand, that its internal metallic surfaces were galled, and that it was contaminated with loose metal particles. The inspection also determined that the 24 volt-powered auxiliary fuel pump had failed and could not be turned by hand.