TUSAYAN, AZ, USA
N444CR
BELL 206L1
N38903
BELL 206L3
THE PILOT OF N444CR HAD RETURNED TO THE COMPANY HELIPORT AFTER A TOUR FLIGHT, AND WAS CLEARED BY THE COMPANY CONTROL TOWER TO HOVER TAXI PAST A COMPANY HELICOPTER, N38903. N38903 HAD BEEN ADVISED TO HOLD FOR INBOUND N444CR, AND WAS LOADED WITH ROTORS AT MAXIMUM RPM AND FLAT PITCH. THE PILOT OF N444CR STATED THAT WHEN HE WAS ABEAM OF N38903, A GUST OF WIND CAUGHT HIM AND HE MESHED ROTORS WITH THE STANDING N38903. NO UNUSUAL WEATHER PHENOMENA WAS REPORTED BY EITHER THE CLOSEST OFFICIAL WEATHER STATION OR OTHER TOUR PILOTS AT THE HELIPORT. THE HELIPORT WAS OPERATING 5 HELIPADS, EACH WITH LESS THAN THE FAA RECOMMENDED MINIMUM SAFE DIMENSIONS BETWEEN NEIGHBORING PADS. THE TAXI ROUTE THAT N444CR HAD TO TAKE WAS BETWEEN A CHAIN LINK FENCE AND THE PAD WHERE N38903 WAS HOLDING. MEASUREMENTS SHOWED THAT N444CR HAD A 7-FT CLEARANCE BETWEEN ITS MAIN ROTOR AND BOTH THE FENCE AND N38903.
On August 7, 1993, about 1703 hours mountain standard time, a Bell 206L1, N444CR, collided with a second Bell 206L3, N38903, while hover taxiing to a parking pad at the Papillon company heliport, Tusayan, Arizona. Both helicopters were operated by Papillon Airways, Inc., Kirkland, Washington, under the provisions of 14 CFR Part 135 of the Federal Aviation Regulations as on demand air taxi sightseeing flights over the Grand Canyon National Park. Visual meteorological conditions prevailed at the time and both flights were on company VFR flight plans. Both helicopters were destroyed in the collision sequence. Each helicopter had seven occupants for a total of 14 persons involved. The pilot of N444CR was not injured, however, three passengers sustained serious injuries and three passengers incurred minor injuries. The pilot of N38903 was not injured, however, the six passengers on board incurred minor injuries. The flight of N444CR, using company call sign "Copter Four," originated from the Papillon heliport on the day of the mishap at 1633 hours and was returning to the heliport after completing a sight seeing tour of the park. N38903, using company call sign "Copter Eight," was awaiting a takeoff clearance from the company ramp controller to begin an aerial sight seeing tour of the Grand Canyon National Park. The Papillon company heliport in Tusayan has six parking pads, numbered from zero to five, which are oriented on a north to south crescent shaped line with pad zero at the north end. A common approach zone for all of the parking pads is located behind pads two and three. Company helicopters make approaches to a hover in the approach area, then must hover taxi to their assigned parking pads. The movement area is controlled by a company ramp controller stationed in a tower near the north end of the parking pads. Papillon Helicopters employs 16 helicopters in their Grand Canyon sightseeing operations from the heliport. At the time that Copter Four made an approach to a hover in the common approach area, pads one through five were occupied by other helicopters. Copter Eight was on pad one ready to liftoff. The ramp controller instructed Copter Eight to hold in position then cleared Copter Four to proceed to pad zero for parking. Copter Four then hover taxied from the approach area behind the helicopters on pads two and one toward pad zero on the north end of the line. The taxi lane along the pads is between the helicopters on the pads and a chain link fence. Initial measurements indicate that the taxiing helicopter had about seven feet of clearance between its main rotor and both the fence and the rotor of N38903 on pad 0. As Copter Four approached pad zero, and was nearly abeam Copter Eight, the main rotors of the two helicopters meshed and the aircraft came together. The pilot of N444CR stated that he was hovering onto pad O at a torque setting of about 80 to 85% in close proximity of copter number 8 (N38903), at the speed of about a walk. "I experienced a gust of wind and the very next thing I remember I was sitting on the ground with wreckage all around me." According to the pilot of N38903, he was holding position as per instructions from the company control tower. He stated that he was at 100 % RPM with no collective input at the time of the collision. PERSONNEL INFORMATION Examination of company flight department crew training and flight time records revealed that both pilots met the applicable requirements of 14 CFR 135. AIRCRAFT INFORMATION N444CR is a Bell 206L1 helicopter which is equipped with a low profile skid configuration. N38903 is a Bell 206L3 helicopter, which is equipped with a high profile skid configuration. According to Bell Helicopters, the difference in height between the low and high skid configurations is about 10 inches. The main rotor diameter of both helicopters is 37 feet. METEOROLOGICAL INFORMATION At the time of the accident the Grand Canyon Airport, which is about two miles from the heliport, was reporting: 5000 thousand feet scattered, 18000 feet broken, visibility 20 miles, temperature 79 degrees fahrenheit, dewpoint 51 degrees fahrenheit, wind 170 degrees at 7 knots and the altimeter was 30.16 inches of mercury. No unusual meteorological phenomena was reported by either the weather observer at the Grand Canyon airport, or, other company pilots at Papillion. HELIPAD INFORMATION The Tusayan Heliport in 1967 was listed by the FAA in the FAA Airport Facilities Record as a private Heliport with two based helicopters. According to the FAA site inspection performed on May 28, 1993, to update the airport master record (form 5010-1), 16 helicopters are now based at the heliport, which occupies about two acres. The FAA Advisory Circular 150/5390-2 provides a guideline to helipad layout and recommends a minimum clearance between helipads for hover taxi operations. In part, the advisory circular specifies that a taxi route width "shall be at least twice the rotor diameter of the largest helicopter which is expected to hover taxi." A drawing of the heliport is attached to this report which shows the measured dimensions between the parking pads, and, the taxi route flown by N444CR. As noted in the drawing, the widest point between the fence and edge of pad 1 along the taxi route to pad 0 was measured at 56 feet. The specifications contained in AC 150/5390-2 call for a minimum width of 74 feet. WRECKAGE AND IMPACT INFORMATION The wreckage of both helicopters was distributed principally on the northern end of the helipad in the vicinity of pads 0 and 1. Both helicopters sustained similar damage patterns, involving their respective main rotor systems, engine compartments, cabin roof structures and tail booms. ADDITIONAL INFORMATION The wreckages of both helicopters were verbally released to the Papillion operations manager at the Tusayan heliport on August 8, 1993.
FAILURE OF THE PILOT OF N444CR TO MAINTAIN ADEQUATE MAIN ROTOR CLEARANCE FROM N38903, AND THE OPERATOR'S FAILURE TO PROVIDE ADEQUATE OR RECOMMENDED SAFE HELIPAD DIMENSIONS. A FACTOR IN THE ACCIDENT WAS THE LACK OF VISUAL REFERENCE TO THE ROTATING BLADES OF THE PARKED HELICOPTER, N38903.
Source: NTSB Aviation Accident Database
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