LOWERLAKE, CA, USA
N801EH
Robinson R-22
After completing a refueling stop at a nearby airport, the helicopter was next seen flying on a southeasterly heading at low altitude. Gusting winds at the accident site were opposite the direction of flight. The aircraft began a deceleration, the tailboom struck the ground and was severed by the main rotor blades as the aircraft pitched forward. As the nose pitched down, the main rotor blades struck the ground in front of the aircraft and the rotor head separated from the mast. The aircraft then rolled onto its right side with the engine running. A few seconds after impact, the aircraft burst into flames. The throttle was at idle and carburetor heat was applied. The stinger was broken from the empennage. Neither occupant wore fire-retardant apparel. The area of the accident site is commonly used for simulated emergency landings. Insufficient evidence existed to determine which pilot was manipulating the flight controls.
HISTORY OF FLIGHT On October 5, 1998, at 1405 hours Pacific daylight time, a Robinson R-22, N801EH, collided with terrain while maneuvering over an open meadow southeast of Lower Lake, California. The aircraft was destroyed during the impact sequence and postcrash fire. The flight instructor and his student both received fatal injuries, although the student succumbed on November 24, 1998. The aircraft was being operated as an instructional flight under 14 CFR Part 91 by Sacramento Executive Helicopters, Inc., when the accident occurred. The flight originated from Sacramento Executive Airport earlier in the day, and had last departed Lampson Field, Lakeport, California, after a refueling stop about 1350, en route back to Sacramento. Visual meteorological conditions prevailed at the time and a VFR flight plan was filed. One witness near the accident site reported that he saw the aircraft fly over his home on a southeasterly heading. As he watched, the aircraft began a left turn toward a more easterly heading. He stated that the aircraft suddenly dove into the ground. He saw debris fly from the aircraft on impact. About 10 seconds after seeing and hearing the impact, he heard an explosion as he saw the aircraft burst into an orange and black fireball. He described the aircraft as having been flying "low" prior to the impact. He also reported that at the time of the accident the sky was clear with strong, gusting winds. Another witness stated that the aircraft was southbound at about 200 feet above the trees. He said that it entered a steep, right-banked turn and then hit the ground. He described the winds at the time as very gusty. The two persons who were the first to reach the aircraft after the crash reported that they heard the engine running. They also observed some mechanical movement in the burning wreckage. After walking around the aircraft they found that one of the occupants had climbed out of the wreckage. Another pilot at Lampson Field said that he told the instructor that there was a lot turbulence to the east of the airport. At a 10-foot hover he said that winds were from the southeast at between 15 and 30 knots. The operator reported that the Lower Lakes area is commonly used as a simulated emergency landing site by instructors en route to, or coming from, Lampson Field. PERSONNEL INFORMATION The instructor was a full-time employee of Petroleum Helicopters, Inc. (PHI). He worked a 7-day schedule with PHI and then worked Monday, Tuesday and Wednesday every other week as an instructor at Sacramento Executive Helicopters, Inc., and had worked this schedule since June 1998. A 14 CFR Part 141 standardization check was completed at the school in September 1998. He had obtained a private pilot certificate for airplane single-engine land on August 3, 1997. His pilot's logbook was not located after the accident and the flight time appearing on page 3 of this report, 500 total hours, was obtained from the pilot's declaration of flight time on his most recent Federal Aviation Administration (FAA) airman medical application. According to the operator's flight and payroll records, the pilot had flown the Robinson R-22 for 34 hours as a flight instructor during the preceding 90 days. The student pilot received his private pilot certificate with a rotorcraft helicopter rating on May 18, 1998, with 73.4 flight hours. He returned to his home in Japan after getting his certificate and returned to the same flight school on September 6, 1998, to continue training for his commercial certificate. His recent flight training records reflected better than average grades on autorotations and forced landings. The only negative comment was that he was slow in picking up visual cues. The chief instructor at the school attributed this to a lack of currency after he had not flown for nearly 4 months. He was currently flying 3 times a week and had accumulated 19.5 hours since he resumed training on September 6, 1998. According to the instructor, he had always been prompt in relinquishing the controls during previous progress checks. AIRCRAFT INFORMATION The operator reported that the aircraft was on a 14 CFR Part 135 certificate at the time of the accident and had accrued a total of 6,672 total hours of operation. The most recent 100-hour inspection was completed 1 month prior to the accident. The engine underwent the unscheduled replacement of the front crankshaft seal on July 7, 1998, and a crankshaft plug on October 2, 1998. The aircraft had a supplemental type certificate (STC) for auto fuel. The aircraft was last serviced with 14.1 gallons of 100-octane low lead aviation fuel at Lampson Field prior to its last departure. The aircraft gross weight at the time of last departure was estimated as 1,372.45. The manufacturer's gross weight limitation is 1,370. The center of gravity (CG) was estimated as 96.8. The CG range is 96.5 to 100 at maximum authorized gross weight. A review of the aircraft and engine logbooks by Safety Board investigators and FAA inspectors failed to disclose any discrepancies. A witness at Lampson Field reported that he saw a trace of oil on the starboard side at the forward end of the cooling fan shroud. WRECKAGE AND IMPACT INFORMATION The accident site was located at 38 degrees 50.460 minutes north longitude and 122 degrees 32.750 minutes west latitude across from 4794 Spruce Grove Road. The site was in an area of flat grassy terrain. Safety Board investigators estimated the elevation to be approximately 1,400 feet msl. The aircraft was found oriented on a bearing of 135 degrees. The median long axis of the debris field was also along the same bearing and extended about 500 feet. The aircraft was burned from the nose aft to the attachment point for the tailboom. The landing lights were found in their normal position and were not broken. The remains of both doors locking bolts were found within the area of the cabin. There was no deformation visible on the skids or cross tubes. Control continuity could not be established from the cockpit to the main and tail rotors due excessive thermal damage to the control components. The carburetor heat was found pulled open 2.7 inches (hot). The mixture was pulled 2 inches into idle cutoff. The throttle was at low idle. All were in their described positions both in the cockpit as well as on the air box and carburetor. The carburetor and induction system were examined and were found to be free of any obstructions. The fuel inlet screen was examined and was found to be free of contamination. The carburetor bowl contained no fuel. The metal floats were in place and exhibited no evidence of chaffing or binding. The airframe gascolator filter was destroyed. The engine was found attached to the engine mounts. The entire engine compartment had been exposed to fire. The cooling fan and flywheel were removed in order to be able to examine the crankcase seal. The STD-1211 crankshaft expansion plug was in position and was partially coated with silicon sealant. The LW13792 crankshaft oil seal was in position. The oil cooler had ruptured in an area where it had contacted the ring gear. This was evidenced by rotational scoring signatures at the rupture site. The crankshaft was hand rotated through the cooling fan mounted on the crankshaft flange. Thumb compression was established in the proper order at all cylinders. The complete valve train was observed to operate in the proper order as well. Lift action was observed at each rocker assembly. Uncontaminated oil was visible within each rocker box. Mechanical continuity was visually established throughout the rotating group, valve train assembly, and accessory section. The cylinders were observed through the spark plug holes and appeared to be free of any internal damage. The gas path and combustion chamber were free of any debris or contamination. Both magnetos were removed prior to hand rotation of the crankshaft to preserve any internal mechanical signatures. The left magneto was found clamped securely to the mounting flange with the cap and wires in place. Timing could not be established due to fire and heat damage. The drive was in place and it was properly saftied. The right magneto was found securely clamped to its mounting flange. Timing could not be established due to fire and heat damage. The drive was in place and it was properly saftied. The top and bottom spark plugs were removed and examined. It was noted that each spark plug was secure in its position and that their respective lead wires were attached. The electrodes were visually inspected, and, according to the Champion Spark Plug Check-A-Plug chart (AV-27), all showed normal wear patterns and coloration. The oil soaked condition of the top and bottom plugs in the No. 2 and No. 4 cylinders was attributed to the engine's final resting position by the manufacturer's representative. The main rotor system remained attached to the mast assembly and was found on the ground along side the skids. The mast was fractured above the mast tube cast attachment fitting. Both main rotor blades were bowed in a downward direction. One main rotor blade was broken off about 12 inches inboard from the tip. The blade tip was found 474 feet from the main wreckage on a bearing of 168 degrees. The separated blade tip exhibited leading edge damage. The main rotor hub up coning stops exhibited contact marks from the spindles. The spindle tusks appeared visually undamaged. The teeter stop bumper and droop stops were in place. The bumpers exhibited contact marks from the spindles. The swashplate assembly was in place. The slider tube exhibited contact marks from the swashplate ball. The forward left mounting lug was broken on the main rotor gearbox. The entire assembly had been involved in fire. The sprag clutch alternately freewheeled and locked when rotated in the appropriate direction by hand. The clutch actuator (belt tensioner) was extended 1.4 inches. According to the manufacturer, this is within the normal range of applied belt tension. The tail rotor drive shaft was broken into four sections. The forward section remained attached to the intermediate flex coupling. The aft section was attached to the aft flex coupling connecting the drive shaft to the input section of the tail rotor gearbox. It exhibited black transfers at the break point and was found 41 feet from the main wreckage on a bearing of 216 degrees. The interior of the tailboom and forward drive shaft exhibited evidence of rotational scoring. Wires were found wrapped around the forward drive shaft section in the direction of rotation. The tail rotor gearbox exhibited impact damage. The output section, gear case, and input section were separated and exhibited fractures and distortion. The output shaft remained attached to the tail rotor hub. The tail rotor hub plates were bent and fragments of the roots of both tail rotor blades were still attached to the hub. The first tail rotor blade was broken into three sections while the second was broken into two sections. There were red transfers on the surface on the outboard section of the second blade. The stinger was broken from its position in the empennage. Bending, which was visible at the attachment point, showed an upward deformation. MEDICAL AND PATHOLOGICAL INFORMATION The instructor sustained fatal injuries in the accident sequence and an autopsy was conducted on October 6, 1998, by the Lake County Coroner's Office, with specimens retained for toxicological examination. The toxicological tests were negative for alcohol and all screened drug substances. The student pilot sustained serious burn injuries in the accident sequence and was admitted to the hospital for treatment. He succumbed to his injuries on November 24, 1998. A medical records review of the student pilot was conducted on November 25, 1998, by the Sacramento County Coroner's Office. No toxicological specimens were retained. FIRE A postimpact fire encompassed the aircraft from the nose, aft to the tailboom attachment point. Known conflagration accelerants present were aviation fuel and oil. The fire spread from the aircraft to the surrounding dry grass. Gusty winds were reported by the California Department of Forestry (CDF) to be from 315 degrees at 30 mph and exacerbated initial efforts to prevent the fire from spreading. According to CDF estimates, the fire ultimately covered an area of about 6 acres before being extinguished. The aircraft came to rest on its right side. The auxiliary fuel tank is located on the right side above the engine compartment. The auxiliary tank showed evidence of crushing in the area of the main rotor mast and had ruptured along a forward inboard seam. The main tank is located on the left side of the aircraft above the engine compartment. The main tank had been partially consumed by fire. Fuel caps were found secured on both tanks' filler ports. The engine exhaust was found in line with molten aluminum that showed evidence of being distorted by a localized airflow prior to cooling. SURVIVAL ASPECTS Neither occupant wore a flight helmet, leather flight boots, a Nomex flight suit or Nomex flight gloves. ADDITIONAL INFORMATION The aircraft was recovered by Dennis James of Plain Parts on October 6, 1998, and transported to his storage facility in Pleasant Grove, California. The wreckage was released on April 4, 2000, to Robert Martellotti, a representative of the registered owner. There was no emergency locator transmitter (ELT) aboard the aircraft.
The flight instructor's failure to adequately supervise the conduct of the flight and the failure of the flying pilot to ensure that adequate ground clearance existed between the stinger/tail rotor and the ground during a deceleration while the aircraft was maneuvering for a practice forced landing. The identity of the flying pilot could not be determined. The instructor's decision to perform the maneuver with a gusty, surface tailwind was a factor in this accident.
Source: NTSB Aviation Accident Database
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