NTSB Factual Report

HISTORY OF THE FLIGHT

On May 10, 1994, at 2142 hours Pacific daylight time, a Robinson R-22 Beta, N8047Y, collided with the upper static cable of power transmission lines in Hacienda Heights, California, while on a night cross-country flight. The helicopter was rented to the pilot by Skyline Aviation, Inc., Chino, California, and was being operated as a personal flight. The helicopter was destroyed by impact forces and postimpact fire. The certificated private pilot and certificated private pilot passenger received fatal injuries. The flight originated in Chino, California, at 2000 hours, destined for the Whiteman Airpark, Pacoima, California, and then was scheduled to return to Chino. The accident occurred during the return leg of the flight. Night visual meteorological conditions prevailed with visibility restricted to 4 to 6 miles due to fog and haze. The pilot left a visual flight rules flight plan with the helicopter's operator.

After the collision with the cable, the helicopter came to rest on the westbound lanes of Interstate 60. Witnesses traveling eastbound on the interstate indicated they saw the helicopter about 6 miles west of the accident site flying southeast along the interstate at a low altitude. The eastbound witnesses indicated they followed the low-flying helicopter's flight progress until they saw a flash followed by the helicopter descending uncontrolled and exploding.

Witnesses who were traveling westbound on the interstate indicated they saw the helicopter momentarily tethered by the cable before it started to descend. According to the westbound witnesses, there was electrical arcing and the helicopter exploded above their automobiles as they traveled under the helicopter. The westbound witnesses stated the helicopter exploded again when it struck the surface of the interstate, and the fire spread across several lanes as a flammable liquid spilled from the helicopter.

OTHER DAMAGE

Three automobiles were damaged when the helicopter struck the ground. One automobile stopped in the westbound lanes when the helicopter struck the ground in front of it. Another automobile struck the rear of the stopped vehicle. Another automobile in the eastbound lanes struck the helicopter's mast and was damaged as it dragged the mast down the interstate. All reported injuries on the ground were a result of automobiles colliding in the westbound lanes.

PILOT INFORMATION

The first pilot held a private pilot certificate with ratings for airplane single-engine land and Rotorcraft-Helicopter, which was issued on March 29, 1994. The most recent second-class medical certificate was issued to the pilot on October 29, 1993, and contained the limitation that correcting lenses be worn while exercising the privileges of his airman certificate.

No personal flight records were located for the pilot and the aeronautical experience listed in the factual report was obtained from a review of the pilot training records maintain by the helicopter operator, airmen Federal Aviation Administration (FAA) records on file in the Airman and Medical Records Center located in Oklahoma City, and investigator's estimate.

The second pilot held private pilot certificate with ratings for airplane single-engine land and Instrument-Airplane, which was issued on February 10, 1994. The second pilot was a passenger and his duties are listed none.

METEOROLOGICAL INFORMATION

The closest official weather observation station is the Ontario International Airport, which is located 16 nautical miles east- northeast of the accident site. At 2146 hours, a record surface observation was reporting in part: Sky condition and ceiling, partial obscuration; visibility, 6 statute miles with haze and fog; temperature, 61 degrees Fahrenheit; dewpoint, 57 degrees Fahrenheit; and winds, 280 degrees at 5 knots.

WRECKAGE AND IMPACT INFORMATION

The helicopter hit the top span of a 1,169-foot-long static cable. The cable was oriented in a north-south direction and crossed perpendicular to the interstate highway. The static cable was broken about 371 feet south of the north tower corresponding to a point over the westbound lanes of the highway. The height of the static cable above the surface of the highway was calculated from Southern California Edison drawings to be about 180 feet. The wires are depicted on the Los Angeles Helicopter Route Chart and the Los Angeles VFR Terminal Area Chart. The cable support towers are lighted and the lights were operating on the night of the accident.

Most of the helicopter's wreckage was found in the westbound lanes. The helicopter's mast assembly remained attached to the upper housing of the transmission which was found 481 feet east of the cable crossing.

Debris from the helicopter's plastic canopy extended east about 250 feet from a point under the wires. The helicopter fuselage came to rest about 308 feet east of the cable crossing about 19 feet north of the center divider in the number one and number two westbound lanes. A postimpact fire erupted destroying the cockpit and helicopter fuel system.

Examination of the helicopter's flight control system and rotor drive system did not reveal any evidence of malfunction or failure before the collision with the wires. The helicopter's powerplant exhibited scoring around the circumference of the engine-driven pulley. According to the engine manufacturer, this indicated the powerplant was turning until impact with the ground.

The red, main rotor blade was not located on the night of the accident. It was found during daylight hours the following day by the Los Angeles County Sheriff Aero Bureau about 286 feet south of the highway and 40 feet east of the wires.

The helicopter was recovered and the canopy was reconstructed looking for evidence of wire strikes. There were cable marks found on the center post at the level of the magnetic compass, both the right and left door posts, and the upholstered headliner in the cockpit. The areas of cable strikes were marked on an exemplar helicopter at the manufacturer's facilities. Photographs were taken to document the positions.

MEDICAL AND PATHOLOGICAL INFORMATION

Post mortem examinations on both pilots were conducted by the Los Angeles County Coroner Office on May 12, 1994, with specimens retained for toxicological examination.

The toxicological specimens for both pilots were sent to the Federal Aviation Administration Civil Aeromedical Institute for analysis. The results of the toxicological analysis for both pilots revealed positive results for nicotine and negative for test for carbon monoxide, cyanide, and other routine drug and alcohol screens. The concentrations of nicotine were not listed in the toxicological report.

ADDITIONAL INFORMATION

WRECKAGE RELEASE

The wreckage was released to the representatives of the owner on May 25, 1994.

NTSB Probable Cause

The pilot's selection of an en route cruise altitude which provided insufficient obstruction clearance, and his inadequate visual lookout. Factors in the night time accident were the reduced visibility as a result of the fog and haze.