ST. PETERSBURG, FL, USA
N72Z
BELL 206B
The pilot was on initial takeoff climb at about 60 knots and 200 feet agl when he heard a loud noise from the vicinity of the tail section, followed by an immediate nose heavy condition. A right turn was initiated away from mangrove trees and the collective pitch was lowered. The helicopter started to turn to the right and collided with water and terrain in a nose down, right skid low attitude. Examination of the helicopter by an FAA inspector revealed the number five bearing, thomas coupling, and about 2 feet of the tail rotor driveshaft had separated and were not recovered.
On May 19, 1994, about 1542 eastern standard time, a Bell 206B, N72Z, registered to Helicopter Inc., operating as a 14 CFR Part 91 aerial observation flight, crashed on initial takeoff climb into the bay near St. Petersburg, Florida. The helicopter sustained substantial damage. The commercial pilot and one passenger received minor injuries. Visual meteorological conditions prevailed and no flight plan was filed. The flight originated from the Channel 10 television helipad about 2 minutes before the accident. The pilot-in-command stated he was in a climb at 60 knots and 200 feet agl when he heard a loud noise from the tail section, and experienced an immediate nose-heavy condition. He initiated a right turn away from the mangrove trees and lowered the collective pitch. The helicopter started to turn to the right and collided with the water. The on-scene investigation was conducted by the FAA. The helicopter was located in Tampa Bay, sitting upright on the skids, adjacent to the 12200 block of Gandy Boulevard. According to the FAA, the helicopter collided with the water and terrain in a nose-down right skid low attitude. A main rotor blade slapped the top of the tail rotor driveshaft cover. The main rotor system separated from the helicopter. The tailboom was bent down aft of the intermediate section of the fuselage. The fuel system was not ruptured. The landing gear was attached with evidence of lateral shift. Examination of the airframe revealed evidence to indicate a mechanical failure of the tail rotor drive system. The No. 5 bearing, thomas coupling, and about 2 feet of the driveshaft had separated, and were not located. Examination of the flight control system, engine assembly and accessories revealed no evidence of a precrash failure or malfunction. Continuity of the flight control system was confirmed for pitch, roll, and yaw with the fracture in the tail rotor pitch tube exhibiting failures consistent with overload. Selected parts were shipped to the Bell Helicopter Textron Field Investigations Laboratory for examination. The laboratory concluded, all of the fractures and damage that occurred on the cover assembly, 90-degree gearbox upper and lower fairings, driveshaft hanger assembly, driveshaft segment, tail rotor pitch change tube, tailboom, and the main rotor blades resulted in overload. The 90-degree tail rotor gearbox was operational. The tailboom was fractured forward of the 90-degree gearbox, and the aft end of the tailboom was bent upward, and forward indicating it had received loads from below. The tail rotor driveshaft bearing hanger had fractured due to overload. Rubbing was present on the tailboom adjacent to the hanger where the Thomas coupling had been spinning, and the driveshaft hanger bracket where the bearing hanger and the Thomas coupling were mounted showed evidence of rubbing. (For additional information see, Bell Helicopter Report No. 20694R-006). The Bell Long Ranger Rotorcraft Flight Manual, Section 3, EMERGENCY AND MALFUNCTION PROCEDURES, PAGE 3-10, 3-14. COMPLETE LOSS OF TAIL ROTOR THRUST states, "IN-FLIGHT reduce throttle to idle, immediately enter autorotation, and maintain a minimum AIRSPEED of 52 KIAS (60 MPH) during descent." The helicopter parts were returned to Mr. William E. Roach Jr., Oldsmar, Florida, by Bell Helicopter on October 12, 1994. The parts were signed for by Mr. Joel Robinson, Oldsmar, Florida, on October 13, 1994.
THE FAILURE OF THE NUMBER FIVE BEARING, SHAFT, OR THOMAS COUPLING FOR UNDETERMINED REASONS. CONTRIBUTING TO THE ACCIDENT WAS THE PILOT-IN-COMMAND'S DELAYED RESPONSE IN CONDUCTING THE EMERGENCY PROCEDURE BY NOT REDUCING THE THROTTLE TO IDLE POSITION, AND IMMEDIATELY ENTERING AUTOROTATION.
Source: NTSB Aviation Accident Database
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