NTSB Factual Report

On July 7, 1993, about 1559 hours Hawaii standard time, a Robinson R22B, N501R, crashed on a taxiway at Honolulu International Airport, Honolulu, Hawaii, following a loss of control during hover. Visual meteorological conditions prevailed at the time and no flight plan was filed for the operation. The helicopter was destroyed in the ground collision sequence. The student pilot, the sole occupant, sustained fatal injuries. The flight originated at the Honolulu International Airport on the day of the mishap about 1502 hours as a local area dual instructional flight.

According to the flight instructor's verbal statement, the 21- hour helicopter student had completed a solo phase check on the morning of the accident. After completing a period of dual instruction, the flight instructor said he felt the student was ready for his first supervised solo flight and he exited the helicopter after instructing the student to complete three takeoff, approach to a hover, and landing maneuvers. He said the student was on his third landing pattern and completed an approach to a 10-foot hover. The instructor said the helicopter was aligned with the taxiway nose toward the east when the helicopter began rotating to the right and climbing. The instructor reported that the helicopter reached an estimated height of 50 feet as the rotation rate increased, then it descended rapidly in a slight right nose down attitude to impact on the Reef Hotel taxiway.

A helicopter pilot stated that he departed the south ramp for a local maintenance test flight to the Keehi Lagoon and back to the south ramp. According to the air traffic control tower (ATCT) transcript, the accident helicopter was advised by the tower of the maintenance test flight helicopters route at 1557:30. The pilot stated that upon lift off from the ramp the ATCT advised him of the Robinson helicopter performing practice approaches on the Reef Alpha taxiway. The pilot made visual contact with the Robinson at that time. He further stated that he completed his test flight and, upon returning to the ramp at 1559:09, he observed the Robinson rolling inverted on the runway or taxiway surface.

PILOT INFORMATION

According to records obtained during the course of the investigation, the pilot was an Australian National who held an Australian unrestricted private pilot license for single and multi-engine fixed wing aircraft. He was type endorsed for piston engine, turbine engine, and jet engine aircraft. He was instrument rated. The pilot's reported total flight time in all fixed wing aircraft is 1904.6 hours. The pilot's total helicopter flight time was 21 hours of dual instruction prior to the accident flight.

The pilot flew with three different flight instructors employed by the operator for a total of 15 lessons. The pilot received a total of 21 hours of helicopter dual instruction prior to solo flight. All three flight instructors were graduates of the Robinson Helicopter Company R22 Flight Instructor Safety and Refresher Clinic.

The instructors ranged in experience from a high of 1295 hours to a low of 330 hours of instruction given. The instructors were utilizing the Robinson Flight Training Guide as a syllabus.

AIRCRAFT PERFORMANCE INFORMATION

The performance section of the pilot operator handbook for the R22 states that: Controllability has been demonstrated for crosswinds and tailwinds up to 17 knots.

METEOROLOGICAL INFORMATION

The Honolulu Air Traffic Control Tower (ATCT) was reporting at the time of the accident: 2500 feet scattered; 4300 feet scattered; 25000 feet scattered; visibility 25 miles; temperature 85 fahrenheit; dewpoint 65; wind 020 degrees at 14 knots; altimeter 29.93; moderate build-ups west; rain showers unknown intensity northeast.

The Honolulu International Airport encompasses 4220 acres and four major runways. The airport has a Low Level Wind Shear Alert System (LLWAS). There are five wind sensors located around the periphery of the airport to determine wind speed and direction to advise pilots of possible wind shear. The sensors average the wind speed every two minutes. The ATCT controller provides actual wind speed and gust information through an analog function of the number one wind sensor to landing and takeoff traffic.

The wind sensor nearest the accident site and time was the southeast sensor which was reporting a direction of 030 degrees magnetic with an average speed of 16 knots. During the time frame of the accident, the wind direction remained at 030 degrees with a low of 15 knots to a high of 18 knots average.

Periodic wind gusts to 25 knots were reported by the ATCT controller during the flight of N501R.

AIRPORT INFORMATION

The Honolulu International Airport (HNL) has four runways. The most southerly runway is known as the Reef Runway, 26L and 8R. The Reef Runway was built out into the Keehi Lagoon.

WRECKAGE AND IMPACT INFORMATION

FAA personnel on scene stated that the helicopter had impacted the taxiway with the tail rotor in a near inverted attitude followed by the top side of the main rotor blades and aft right side of the cabin. The top side of the rotor blades revealed chordwise striations and leading edge damage.

The impact location was near the centerline of the Reef Hotel taxiway. The main wreckage path was measured to be 243 degrees for a distance of about 70 feet. The main wreckage came to rest near the taxiway edge with the tail boom 20 feet further. Tail rotor parts were found about 150 feet from the initial impact point on the same path.

The entire helicopter was accounted for at the accident site. Post crash examination of the helicopter, control systems, and the engine failed to reveal any evidence of failure or malfunction prior to the collision with the ground.

MEDICAL AND PATHOLOGICAL INFORMATION

On July 8, 1993, the Honolulu County Medical Examiner performed an autopsy on the pilot. According to the autopsy report, the cause of death was attributed to extensive severe injuries. No preexisting conditions were noted that would have affected the decedent's abilities to pilot an aircraft.

The medical examiner obtained samples for toxicological examination by the FAA Civil Aeromedical Institute (CAMI) in Oklahoma City, Oklahoma. The results of the toxicological analysis were negative for alcohol and all screened drug substances.

ADDITIONAL INFORMATION

According to the operator, the company uses the Robinson Helicopter Company R22 Flight Training guide as a course syllabus. Under the School Safety Procedures section for weather minimums it states that: "Under no circumstances are students permitted to fly solo in winds in excess of 15 knots."

According to information published by the Transportation Safety Institute, unanticipated yaw occurs when the helicopter is placed in a flight situation where a series of factors, including weathervaning and main rotor vortex ring, can combine to produce an uncommanded yaw in the direction of the main rotor torque reaction. Information regarding this phenomenon is attached to this report.

NTSB Probable Cause

THE INSTRUCTOR ALLOWING THE STUDENT FLY SOLO IN WIND CONDITIONS EXCEEDING THE MAXIMUM ALLOWABLE WINDS IN THE TRAINING SYLLABUS, AND ALSO NEAR THE MAXIMUM DEMONSTRATED CONTROLLABILITY ENVELOPE FOR THE HELICOPTER. FACTORS WHICH CONTRIBUTED TO THE ACCIDENT WERE THE UNFAVORABLE WIND CONDITIONS.