LAX06FA156

a loss of control and the divergence of the main rotor blade system from its normal rotational path for undetermined reasons.

The Canadian certificated commercial helicopter pilot was conducting a cross-country delivery flight with a non-rated passenger occupying the copilot seat. The passenger and pilot together had previously made delivery flights from the Robinson factory to Canada. Two witnesses saw the helicopter just before it impacted the ground and reported that the tail boom had separated from the fuselage. No witnesses were identified who saw the initial breakup sequence. Both main rotor blades were bent downward at significant angles, with one blade having penetrated the cabin on the right side with a downward slicing front to rear arc. The primary wreckage debris field was approximately 500 feet long on an easterly heading. The helicopter sustained damage consistent with a high-energy, fuselage level, vertical ground impact. Detailed post accident investigation of the engine, the airframe, and the control systems disclosed no evidence of any preimpact anomalies. The removable cyclic was installed on the left side copilot's position, contrary to manufacturer's recommendations when a non-rated passenger is seated in the left seat. The removable pedals and collective for the left side were not installed. The cyclic controls for both the pilot's and copilot's positions were broken from their respective mounting points. The copilot's cyclic grip exhibited inward crushing. The Safety Board adopted a Special Investigation Report on April 2, 1996, following the investigation into R22 and R44 accidents involving loss of main rotor control and divergence of the main rotor disk, which included a finding that the cause of the loss of main rotor control in many of the accidents "most likely stems from a large, abrupt pilot control input to a helicopter that is highly responsive to cyclic control inputs."

HISTORY OF FLIGHT On May 1, 2006, about 1430 Pacific daylight time, a Robinson R44 Raven II, Canadian registration C-FICL, experienced an in-flight breakup and impacted desert terrain near Desert Center, California. Zimmer Air Service, Inc., was operating the helicopter under the provisions of 14 CFR Part 91. The Canadian certificated commercial pilot and the non-rated passenger sustained fatal injuries. The helicopter was destroyed. The cross-country delivery flight departed Zamperini Field Airport (TOA), Torrance, California, at 1305, with a planned refueling stop at Blythe Airport (BLH), Blythe, California. Visual meteorological conditions prevailed, and no flight plan had been filed. The approximate global positioning system (GPS) coordinates of the primary wreckage were 33 degrees 38.016 minutes north latitude and 115 degrees 05.224 minutes west longitude. The pilot had taken delivery of the new helicopter from the Robinson Helicopter Company factory in Torrance on the day of the accident. The pilot and passenger, who were employed by Zimmer Air Service, Inc., departed from TOA with an intended final destination of Blenheim, Ontario, Canada. Riverside County Sheriff's Department personnel responded to the accident site and interviewed two ground witnesses. The witnesses related that they saw the helicopter just before it impacted the ground. They reported that the tail boom had separated from the fuselage; they did not see the separation sequence. PERSONNEL INFORMATION The operator reported that the pilot held a Canadian issued commercial pilot certificate with ratings for airplane single engine land and helicopter, with the following type ratings: BH06; BH47; BH47T; HL12; RH44; S350; SK55; and SK58. The pilot held a first-class medical certificate issued on December 5, 2005. It had the limitation that the pilot must wear glasses. The operator reported that the pilot had a total rotorcraft flight time of 7,615 hours. He logged 25 hours in the last 90 days, and 12 hours in the last 30 days. He had an estimated 1,041 hours in this make and model, and had completed a biennial flight review on March 31, 2006. The operator reported that the passenger did not hold any pilot certificates nor was he attempting to obtain any ratings. The passenger was related to the pilot by marriage and had flown with the accident pilot on previous delivery flights. AIRCRAFT INFORMATION The helicopter was a Robinson R44 Raven II, serial number 11209. A review of the helicopter's logbooks revealed that the helicopter had a total airframe time of 4.0 hours when it left the factory. The tachometer read 5.2 hours at the accident scene. The engine was a Textron Lycoming IO-540-AE1A5, serial number L-31092-48A. Total time recorded on the engine was 5.2 hours. Fueling records at TOA established that the helicopter was fueled to capacity (48.9 gallons) on May 1, 2006. Examination of the maintenance and flight department records revealed no unresolved maintenance discrepancies against the helicopter prior to departure. METEOROLOGICAL INFORMATION The closest official weather observation station was Blythe airport, which was 18 nm east of the accident site. The elevation of the weather observation station was 397 feet mean sea level (msl). A METAR for BLH was issued at 1453. It reported winds from 170 degrees at 8 knots; visibility 10 miles; skies clear; temperature 38 degrees Celsius; dew point 01 degrees Celsius; altimeter 29.74 inHg. COMMUNICATIONS The helicopter was not in contact with any ATC facility. WRECKAGE AND IMPACT INFORMATION Investigators from the National Transportation Safety Board, the Federal Aviation Administration (FAA), and Robinson Helicopter Company examined the wreckage at the accident scene. The on-scene examination of the accident site and wreckage revealed that the helicopter and separated components came to rest about 200 yards south of Interstate 10 (I-10) at mile marker 124. The accident site was 16 nm east of Desert Center, and 25 miles west of the city of Blythe. The area was open and flat with low shrubs, typical of desert terrain. The main wreckage, consisting of the fuselage, engine, transmission, cockpit, most of the right skid tube, a portion of the left skid tube, and the majority of both main rotor blades, came to rest on an orientation of 280 degrees magnetic. The tail boom was 100 feet west of the main wreckage. The tail boom separated just aft of the main fuselage attach point. The tail rotor blades and tail rotor transmission were attached to the tail boom, with minor ground impact damage noted. The primary wreckage debris field was about 500 feet long. The primary wreckage debris field consisted of the right side pilot's door, which was in two pieces, and pieces of fiberglass and Plexiglass. A secondary debris field, consisting of papers and light cockpit materials, was another 400 feet downwind from the accident site. The debris path was along a magnetic bearing of 090 degrees. Cockpit and Cabin The removable cyclic was installed on the left side, which is the normal position for a copilot or passenger. The removable anti torque pedals and collective had not been installed on the left side. The removable pedals were in the baggage compartment. Both the pilot and copilot cyclic grips were detached from their respective mounting positions. The copilot cyclic grip was also crushed inward. The pilot's collective was in a position close to full down, and the friction slider was fractured below the slot. The pilot's pedals were in a position close to full left. The ignition key was in the OFF position, while the throttle twist grip was in a full on position. The cockpit mixture control was in the full rich position; however, the arm at the fuel servo was in the full lean position. Miscellaneous personal items were recovered, which included luggage, clothing, toiletries, a digital camera, a P.D.A., a handheld GPS, quart bottles of oil, a cabin cover, airport guidebooks, notes, and aircraft charts. Fuel System Both fuel caps were in place. Both fuel tanks ruptured with hydraulic bulging in the lower corners. There was a strong odor of fuel in the sand beneath the helicopter and evidence of fluid flow. The finger strainer in the auxiliary tank was free of debris. The fuel line between the auxiliary tank and the main tank separated, and fractured in several places. The gascolator bowl was dislodged, but remained in place. Investigators removed the gascolator bowl. It was clean inside, but the screen was partially crumpled and inside the bowl. The fitting between the gascolator and the electric fuel pump was broken. The top of the electric fuel pump separated from the lower portion. The fuel return line between the return pressure valve and the auxiliary tank was kinked, but it was still intact. Investigators were able to blow air through all the components of the vent lines. Lubrication Systems The main rotor and tail rotor systems are lubricated using Swepco 90 weight gear oil, which is normally blue in color. The engine is lubricated using 20-50-weight mineral oil, which is normally a transparent golden color. The hydraulic system operates using Robinson hydraulic fluid, Part number A257-15, which is normally red in color. Powerplant The powerplant was severely damaged. Most of the accessory case fractured. The alternator drive pulley was in contact with the starter ring gear. The pulley exhibited a row of scores on its aft surface. The space of the scoring was approximately in size and dimension (spacing) to the ring gear teeth. The upper sheave's rear surface was in contact with the starter ring gear. There was some scoring at the contact area, with the scores spaced at the approximate size and dimension of the ring gear teeth. The engine oil filler cap was found secured to the filler