N700TH

HISTORY OF FLIGHT

On September 19, 1995, about 2238 hours Pacific daylight time, a Bell 206L-1, N700TH, was destroyed after colliding with a ridge line near Irvine, California. The helicopter was operated by Helistream, Inc., of Costa Mesa, California, under the provisions of 14 CFR Part 91 of the Federal Aviation Regulations. Instrument meteorological conditions were reported in the area of the accident. The ATP rated pilot, the sole occupant, was fatally injured. The flight originated at San Diego, California, at 2130 hours as a positioning flight.

The accident helicopter was the prototype for an FAA supplemental type certificate installation of two engines. The modification, known as a TwinRanger, replaces the single Allison powerplant with two Allison 250-C20R engines through a combining gearbox. The pilot departed the operator's base at the John Wayne Airport in the late afternoon for a series of demonstration flights with helicopter operators in the San Diego area.

According to the operator, the pilot obtained a "GTE DUATS" preflight weather briefing prior to the first departure and a telephone preflight weather briefing prior to the last departure. The "GTE DUATS" system was contacted in Chantilly, Virginia. The pilot's name was shown as a user; however, no record was found of system access subsequent to March, 1993. The "DUATS" system was also checked for records of access under the operator's name on the date of the accident, with no record found. Review of FAA Flight Service Station system records disclosed no record of a weather briefing provided to either the pilot's name or helicopter registration number prior to 2130 hours.

While en route back to Orange County, the pilot contacted the San Diego FAA Flight Service Station (FSS) while over Escondido at 2,500 feet msl. The pilot requested a surface observation for the Orange County John Wayne Airport. The briefer stated that the last reported Orange County weather was: sky partially obscured 800 feet scattered; visibility 6 miles in fog/haze; temperature 67 degrees Fahrenheit; dew point 64 degrees Fahrenheit. After acknowledgment from the pilot, the briefer gave the Orange County forecast as: clear occasional sky partially obscured 5 miles haze until 2300 PDT; then, 800 feet overcast, visibility 3 miles in fog.

The pilot contacted the El Toro MCAS military air traffic control tower (ATCT) at 2229:22 hours when 10 miles east at 3,000 feet. The pilot stated that he was inbound to John Wayne and requested El Toro's weather. The local controller stated that the weather observation 30 minutes before was 500 feet scattered, measured 700 feet broken and 1,000 feet broken. About 41 seconds after the initial contact with the ATCT, the pilot reported that he was 10 miles east at 2,000 feet, and he reported that it looks pretty solid here and "I need to look for a hole."

The local controller advised the pilot to stay north of El Toro and he may be able to get down under the overcast. The pilot was assigned a transponder code of 0164. Radar contact was confirmed 6 miles east of El Toro.

The pilot requested confirmation that he was headed towards Lake Irvine and the local controller confirmed that he was. At 2234:14, the controller asked the pilot "If you'd like to uh remain this frequency I can, uh, hopefully, uh help you into John Wayne, if you'd like." The controller asked the pilot several times if he could see El Toro, and each time the pilot reported negative.

At 2235:39, the pilot asked the local controller "whereabouts from Lake Irvine are w- am i?". The local controller stated " you're probably bout uh mile to mile and a half now sir southeast of Lake Irvine."

The local controller advised the pilot that he was "coming up on Lake Irvine now sir." The pilot requested a left turn to lower Peter's (a reservoir). The local controller responded "Uh, I believe so sir. I could tell you what... turn left suggested heading of about 170." About 49 seconds later the pilot asked, "Is it okay to descend here." The local controller responded "Just fine. Descend right there sir." At 2237:57, the pilot asked the local controller "What's my minimum altitude here?" The local controller stated, "Stand by." That was the last transmission received from the pilot. The last recorded radar position was at 2238:02 at an altitude of 1,300 feet msl.

PERSONNEL INFORMATION

According to the operator, the ATP rated pilot had been employed by the company since December 16, 1991. The pilot had accumulated 3,200 total flight hours, with 3,000 hours in helicopters and 700 hours listed in the Bell 206 model.

On the day of the accident the pilot's work day started at 1500 hours. The day before the accident his work day started at 0700 and concluded at 1730 hours.

AIRCRAFT INFORMATION

According to the operator, the pilot added 40 gallons of Jet-A fuel in San Diego. Calculating the fuel usage from Santa Ana to San Diego, the demonstration flight and the return to Orange County should have provided the pilot with approximately 32 gallons of fuel remaining at the time of the accident. The fuel consumption for the Gemini ST conversion is 30 gallons per hour single engine, and 44 gallons per hour in the twin engine mode. The helicopter may be flown as a single or twin engine at the pilot's discretion. The operator's policy is to fly twin engine with a heavy load, at night, or over water.

The helicopter was equipped with one Narco Escort Two, vhf navigation/communication radio. The radio will provide one function at a time, either navigation or communication. The aircraft was not equipped with the instruments and equipment required by 14 CFR 91.205 for flight into IFR conditions.

The helicopter was equipped with an Apollo Two, model 612B, Loran. The Loran is placarded for VFR use only and does not have a moving map display. The Loran was removed and sent to the manufacturer through the FAA Flight Standards District Office at Hillsboro, Oregon. The request was for the recovery of non-volatile memory. See the Testing and Research section of this report.

ATCT INFORMATION

The air traffic control tower (ATCT) at MCAS El Toro is a military installation operated by military personnel. It is responsible for controlling the air traffic in and out of El Toro MCAS. Normal hours of operation for the accident day was 0800 until 2200 hours. On the day of the accident there were aircraft carrier operations in progress off of the coast. El Toro is used as an alternate landing field in case of emergencies while the operations are in progress.

According to the FAA Airman's Information Manual 3-61, AIRPORT TRAFFIC AREAS; (a) Unless otherwise specifically designated (FAR 93), airport traffic areas consist of the airspace within a horizontal radius of 5 statue miles from the geographical center of any airport at which a control tower is operating, extending from the surface up to, but not including, an altitude of 3,000 feet above the elevation of the airport.

METEOROLOGICAL INFORMATION

The nearest weather reporting facility to the accident site is El Toro MCAS. At the 2155 scheduled weather observation, El Toro was reporting: 500 feet scattered, measured 700 feet broken, 1,000 feet overcast, 6 miles visibility in fog and haze; temperature 64 degrees Fahrenheit; dew point 59 degrees Fahrenheit; wind 220 degrees at 3 knots; and the altimeter was 29.96 inches of mercury.

At the pilot's destination, Orange County John Wayne Airport, the last scheduled weather observation by the ATCT for the evening was at 2147 hours and they were reporting: partial obscuration measured 800 feet broken; 5 miles visibility in fog and haze; temperature 65 degrees Fahrenheit; dew point 63 degrees Fahrenheit; wind 170 degrees at 5 knots; and the altimeter was 29.96 inches of mercury. The ATCT closes at 2300 hours.

A flight of two military CH-46E helicopters inbound to MCAS Tustin was returning from night operations at Twentynine Palms, California, on the night of the accident. About 2230 hours the flight was in the vicinity of Lake Irvine. The flight commander stated that there was a small hole in the overcast over Lake Irvine that allowed the pilots to see car lights and a couple of residences. The flight altitude was 2,400 to 2,600 feet msl, and was being conducted with Night Vision Goggles. The pilot reported the cloud cover was south of highway 91 to over the ocean and southwest of highway 55.

The pilot stated that at 2230 hours, the MCAS Tustin's automated terminal information service (ATIS) was reporting 700 feet scattered with 7 miles visibility. He stated that there was a solid layer of clouds below their flight. Upon arrival at MCAS Tustin at 2,400 feet, it was determined that an instrument approach would be required to descend and land. The pilot stated that they entered the clouds about 1,700 to 1,800 feet msl, and broke out at 900 feet msl.

WRECKAGE AND IMPACT INFORMATION

Accident site investigation revealed that the helicopter collided with the top of a ridge line of the Loma Ridge hills at an elevation of 1,250 feet msl. Parallel imprints matching the dimensional geometry of the helicopter's landing skids were found in the soil at the very top of the ridge. After the initial contact with the ridge line the helicopter became airborne for about 350 feet as the hillside dropped away. After the second downhill contact with the terrain, the helicopter continued down the hillside for several hundred feet along a 210-degree heading. The hillside slope was measured to be about 70 degrees down slope. After the second identified terrain contact the helicopter broke into multiple sections. After the entire helicopter structure and components were located and documented at the accident site they were recovered to a storage area for a detailed examination.

A postaccident examination of the helicopter drive train, control system...