Fort Lauderdale, FL, USA
N80PH
Bell 206L-1
According to the pilot, while en route at an altitude of 400 feet, he heard a big bang and felt a "strong" left and right yaw. He performed an emergency shutdown of the engine, and did an autorotation landing on a beach. The investigation revealed fracture failure of the no.4 engine bearing. At the time of the accident, the roller bearings had approximately 5,487 hours since being installed in the engine on June 12, 1992, which was subsequently installed on the helicopter on September 3, 1992.
HISTORY OF FLIGHT On May 24, 2002, about 1315 eastern daylight time, a Bell 206L-1, N80PH, registered to and operated by Pompano Helicopters, Inc., experienced a loss of engine power and was substantially damaged during an autorotative landing on Fort Lauderdale Beach, Fort Lauderdale, Florida. Visual meteorological conditions prevailed at the time and company VFR flight following was being provided for the 14 CFR Part 135 on-demand, passenger flight from the Fort Lauderdale Executive Airport, Fort Lauderdale, Florida, to the Fisher Island Heliport, Miami, Florida. The commercial-rated pilot and one passenger were not injured. The flight originated about 1250 from the Pompano Beach Airpark, Pompano Beach, Florida. The pilot stated that after takeoff from the Pompano Beach Airpark, the flight proceeded to the Fort Lauderdale Executive Airport where after landing, he kept the engine running and picked up a passenger. The flight departed with the passenger on-board for the flight to the Fisher Island Heliport. While flying southbound over the shoreline at 400 feet mean sea level and 100 knots indicated airspeed, and 70 percent torque, N1 engine speed of 92 percent, oil pressure and oil temp 129 psi and 80 degrees Celsius, respectively, he heard a big bank and felt a "strong" left and right yaw. He applied anti-torque pedal to arrest the initial yaw with no effect from the pedals and began to descend maintaining 60-65 mph. He performed an emergency shutdown of the engine, and observed a clear area on the beach. When the flight was 50-60 feet above ground level, he initiated a progressive deceleration, and due to the sloping terrain, he "chose to go more vertical slowing down to approximately 20 miles-per-hour. He leveled the helicopter and pulled collective just prior to touchdown; however, the helicopter landed hard collapsing the skids. After coming to rest he completed the shut down, applied the rotor brake to stop the main rotor which was not effective, and while the main rotor was turning slowly, he ordered the evacuation of the helicopter. He further stated that he touched down downwind with forward airspeed, he did not experience engine overspeed during the flight, and he did not loose directional control of the helicopter when decelerating during the flare. PERSONNEL INFORMATION The pilot-in-command was the holder of a commercial pilot certificate with rotorcraft helicopter rating that was issued on June 29, 1993. He was issued a 2nd class medical certificate with no limitations on May 22, 2001. He was hired by the operator on May 2, 2002, and received his initial training in the accident make and model helicopter on May 3, 2002. He received basic indoctrination with the company that began on May 3, 2002, and he was signed off as pilot-in-command on May 10, 2002. His initial training consisted of .6 hour flight, and .5 hour ground time. Review of records provided by Pompano Helicopters, Inc., indicate that he scored 80 percent on the examination for that training. His last airman competency/proficiency flight check in accordance with 14 CFR Part 135.293 and 297 occurred on May 11, 2001; the result of the check was listed as "approved." The pilot was employed by another 135 operator at the time of this flight check. AIRCRAFT INFORMATION The helicopter was manufactured on March 3, 1980, as a model 206L-1, assigned serial number (S/N) 45401,and was equipped with an Allison 250-C28B turboshaft engine rated at 500 horsepower. The engine was manufactured as model 250-C28B, assigned S/N 860259, and originally installed in a Bell 206L-1 helicopter with a different registration, then installed in the accident helicopter on March 4, 1994. Review of the aircraft maintenance records revealed the helicopter was last inspected in accordance with a 100-Hour/300-Hour/Annual inspection on October 29, 2001. At that time the helicopter total time was 18, 977.1 hours and the engine total time was 16,674.1 hours. The helicopter had accumulated 89.1 hours since the inspection at the time of the accident. The maintenance records further reflect that the engine has not been overhauled since being manufactured on October 27, 1979. METEOROLOGICAL INFORMATION A METAR weather observation taken from the Fort Lauderdale/Hollywood International Airport at 1253 (approximately 22 minutes before the accident), indicates the wind was from 060 degrees at 12 knots, the visibility was 10 statute miles, broken clouds existed at 3,600 feet, the temperature and dewpoint were 27 and 18 degrees Celsius, respectively, and the altimeter setting was 30.07 inHg. WRECKAGE AND IMPACT INFORMATION The NTSB did not examine the helicopter at the accident site. The NTSB did however examine the helicopter following recovery of it to the operator's facility. Examination of the helicopter revealed the turbine and exhaust collector support assembly exhibited case penetration. Fire damage was noted on the right engine cowling that traveled up and forward to station 99.20, and on the left side of the helicopter between stations 155.00 and 167.33, above water level 51.67. The engine was removed and retained for further examination. The tailboom was displaced down approximately 14 inches aft of tailboom station 31.87. Tailrotor continuity was confirmed during rotation of the main rotor. Examination of the engine at the manufacturer's facility with NTSB oversight revealed several of the rollers of the No. 4 bearing were found during engine disassembly. Both inner race rails of the No. 4 bearing were fractured near the roller path/rail radius, and the forward rail was fractured into multiple pieces. The roller path of the inner bearing race was not recovered. Spalling and imbedded debris was found along the No.4 bearing outer race; a cross section through the outer race showed signs of localized heat distress on the aft shoulder. Both ends of the No.4 bearing rollers exhibited evidence of rubbing contact in the area of the inner and/or outer bearing races; however, the wear on one end was more pronounced. Examination of one of the rollers of the No. 4 main bearing indicated signs of cracks and a thermally altered microstructure, while the separator exhibited slight wear on the roller pockets and cross sections through the separator assembly. The separator also exhibited a thermally altered microstructure near the inner diameter. The rollers and separator met material specification for hardness and material and plating, respectively. No obstructions were noted of the pinion bearing oil nozzle, bench testing of the unit revealed it flowed as specified for the part number of the nozzle. No evidence of oil starvation was noted to the other bearings and other damage to the engine was considered as secondary. MEDICAL AND PATHOLOGICAL The operator did not have toxicology testing performed on the pilot as a result of the accident. TESTS AND RESEARCH Review of the engine maintenance records revealed roller bearings were installed in the Nos. 3 and 4 bearing positions of the gearbox assembly on June 12, 1992, in accordance with revision 3 of Allison Commercial Engine Bulletin (CEB) 72-2145. The gearbox was installed on the accident engine on September 3, 1992, at an engine total time of approximately 11,376 hours, and the engine was installed in the accident helicopter on March 4, 1994. There was no record that the gearbox had been removed from the engine following the roller bearing installation. A labyrinth seal was installed in the No. 5 bearing position of the turbine assembly on January 3, 1996, in accordance with revision 3 of Allison (CEB) 72-2146. The turbine assembly was installed on a different engine on January 23, 1996, then removed from the engine, reinstalled on a different engine, then removed from that engine on March 27, 1998, for overhaul. The overhauled turbine assembly was installed on the accident engine on December 17, 1999, by the director of maintenance for Pompano Helicopters, Inc. At the time of the accident, the turbine assembly had accumulated approximately 2,968 hours since the last labyrinth seal was installed, and 1,494.3 hours since the overhauled turbine assembly was installed. Additionally, the gearbox had accumulated approximately 5,487 hours since the Nos. 3 and 4 roller bearings were installed. The engine was originally manufactured with a No. 5 carbon seal installed in the turbine assembly; however, as previously discussed, a labyrinth seal was last installed in the turbine assembly on January 3, 1996. The accomplishment instructions listed in CEB 72-2146 Revision 3 indicates to install oil-pinion bearing nozzle part number (P/N) 23035174, or to modify the oil-pinion bearing nozzle P/N 23034601, then reidentify it as P/N 23035174. A warning in the CEB indicates that the oil-pinion bearing nozzle part number (P/N) 23035174 is to be used only in engines with Nos. 3 and 4 roller bearings and a No. 5 labyrinth seal installed in the turbine assembly. As noted during the engine disassembly, oil-pinion bearing nozzle P/N 23034601B was installed and was not modified. According to personnel from the engine manufacturer, there was no difference in the oil flow rates to the No. 4 bearing when comparing the oil-pinion bearing nozzle found in the accident engine (incorrect) and the specified oil-pinion bearing nozzle. ADDITIONAL INFORMATION The helicopter minus the retained engine was released to Mr. Pedro Turmero, Director of Maintenance for Pompano Helicopters, Inc., on May 29, 2002. The retained engine was released to Mr. Jim Howard, President of Pompano Helicopters, Inc., on August 25, 2004.
The excessive rate of descent by the pilot-in-command during the autorotative landing resulting in a hard landing, following a total loss of engine power caused by failure of the No. 4 bearing.
Source: NTSB Aviation Accident Database
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