Tasmania helo crash, no one injured
PPRuNe Time
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Tasmania helo crash, no one injured - now with ATSB Final Report (later post)
Three unhurt in helicopter crash
A tourist helicopter has crashed on Tasmania's west coast, but no-one has been injured.
A spokesman for Australian Search and Rescue in Canberra says an emergency beacon went off just after 1:30am AEST.
He says the helicopter was just above the water about 11 kilometres east of Strahan when it experienced mechanical problems and came down heavily in the water.
The spokesman says the pilot and two passengers on board all escaped injury although an ambulance crew is being sent to assess one person complaining of back pain.
He says the three were picked up by another helicopter in the area and have been taken back to Strahan.
A tourist helicopter has crashed on Tasmania's west coast, but no-one has been injured.
A spokesman for Australian Search and Rescue in Canberra says an emergency beacon went off just after 1:30am AEST.
He says the helicopter was just above the water about 11 kilometres east of Strahan when it experienced mechanical problems and came down heavily in the water.
The spokesman says the pilot and two passengers on board all escaped injury although an ambulance crew is being sent to assess one person complaining of back pain.
He says the three were picked up by another helicopter in the area and have been taken back to Strahan.
also
Three escape as helicopter crash-lands
By PHIL EDWARDS , Tuesday, 28 September 2004
A pilot and two passengers escaped serious injury when a helicopter crash-landed on Tasmania's West Coast yesterday.
The helicopter was operated by Seair Adventure Charters, of Wynyard.
Australian Search and Rescue spokesman Ben Mitchell said the accident happened 11km east of Strahan about 1pm.
"The helicopter was about 1m off the ground when it experienced some mechanical problems," he said.
The chopper, believed to be on a sightseeing flight, then landed heavily.
Mr Mitchell said there were no serious injuries but one person complained of back pain.
The three people were flown back to Strahan in another helicopter from the same company, where they were met by an ambulance.
Seair Adventure Charters owner Dale Triffett said the helicopter had been coming in to land at Teepookhana when it developed a tail rotor problem as it was hovering.
"This caused the helicopter to go into a 360-degree spin. The pilot had to try to put it down while it was spinning and ended up doing quite a bit of damage to the helicopter," he said.
Seair operates three helicopters around Tasmania.
By PHIL EDWARDS , Tuesday, 28 September 2004
A pilot and two passengers escaped serious injury when a helicopter crash-landed on Tasmania's West Coast yesterday.
The helicopter was operated by Seair Adventure Charters, of Wynyard.
Australian Search and Rescue spokesman Ben Mitchell said the accident happened 11km east of Strahan about 1pm.
"The helicopter was about 1m off the ground when it experienced some mechanical problems," he said.
The chopper, believed to be on a sightseeing flight, then landed heavily.
Mr Mitchell said there were no serious injuries but one person complained of back pain.
The three people were flown back to Strahan in another helicopter from the same company, where they were met by an ambulance.
Seair Adventure Charters owner Dale Triffett said the helicopter had been coming in to land at Teepookhana when it developed a tail rotor problem as it was hovering.
"This caused the helicopter to go into a 360-degree spin. The pilot had to try to put it down while it was spinning and ended up doing quite a bit of damage to the helicopter," he said.
Seair operates three helicopters around Tasmania.
Last edited by Time Out; 28th Jun 2006 at 11:57. Reason: I edited to add "now with ATSB Report" to the thread heading so the thread wouldn't be misunderstood as a new accident, but only the post title was able to be amended. (Maybe a Mod could hel
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ATSB FINAL REPORT
At 1215 Eastern Standard Time on 27 September 2004, the pilot of a Kawasaki Heavy Industries, 47G3B-KH4 helicopter, registered VH-MTF, was being operated on a tourist flight with two passengers in north-west Tasmania. The pilot reported that as he brought the helicopter to a 1 m hover above the raised landing platform, the helicopter began to rotate slowly to the right. The pilot unsuccessfully attempted to counter the rotation by applying left tail rotor control input. The pilot then increased engine power, however, that action had the effect of rapidly increasing the rotation of the helicopter to the right and the helicopter climbed to about 5 m above the ground. After the pilot lowered the collective control the helicopter impacted the ground heavily on its right side. The pilot and passengers received minor injuries.
The helicopter’s tail rotor drive shaft had failed during the occurrence. ATSB specialist examination of the failed drive shaft, attributed the failure to damage from a significant torsional overload event, leading to the shear fracture of the shaft. The examination was unable to determine when the torsional overload occurred, however, examination of the wreckage indicated that it was likely that it had occurred prior to this accident
Information received from the operator and from the maintenance organisation indicated that there had been no known tail rotor strike or sudden rotor stoppage since the helicopter was placed on the Australian aircraft register in 1992. The helicopter’s history prior to that time was not examined.
The action of the pilot in increasing engine power when faced with the loss of tail rotor thrust was also examined.
FACTUAL INFORMATION
At 1215 Eastern Standard Time1 on 27 September 2004, a Kawasaki Heavy Industries, 47G3B-KH42 helicopter, registered VH-MTF, was being operated on a tourist flight with one adult and a young boy as passengers. The flight included landing on a 1 m high wooden platform in the Teepookana Forest in north-west Tasmania.
The pilot reported that as he brought the helicopter to a 1 m hover above the platform, the helicopter began to rotate slowly to the right. He unsuccessfully attempted to counter the rotation by applying left tail rotor control input. The pilot then increased engine power in an attempt to regain tail rotor control and to move the helicopter clear of the landing platform. That action had the effect of rapidly increasing the rotation of the helicopter to the right and it began to ascend, reaching about 5 m above ground level. The pilot then lowered the collective control and the helicopter impacted the ground heavily on its right side, several metres from the landing platform. The pilot and adult passenger released their seatbelts and then both assisted the young boy to exit the wreckage. The pilot and passengers received minor injuries.
The pilot described the wind conditions at the time of the accident as a headwind with an approximate strength of 8 kts. That assessment was consistent with the wind data for the Strahan area provided by the Bureau of Meteorology3. The pilot also reported that the main rotor RPM indications were normal and that the helicopter had sufficient power to complete the approach4. At the time of the accident, the weight and balance of the helicopter were within prescribed limits. There was no evidence that the helicopter had collided with anything during the approach.
The pilot was appropriately qualified and endorsed to operate the helicopter type and held a valid medical certificate. He was a very experienced agricultural aeroplane pilot and had obtained a commercial pilot (helicopter) licence 14 months before the accident. He had accrued at total of 292 hours in helicopters since that time; 286.4 hours of which had been in the Bell 47 helicopter type. The pilot was experienced with operations into and out of the Teepookana Forest landing platform.
The landing platform was located within a dense forest in an area that was cleared of trees but covered by 1 m high scrub. The trees closest to the clearing had been trimmed to a height of about 5 m to allow a ‘fly-in, fly-out’ approach. There was no requirement to conduct a vertical approach to the platform.
The helicopter’s fuselage structure was deformed by the impact and the tail boom was bent in a downward direction at approximately station 1005. There was corresponding bending damage to the tail rotor drive shaft assembly long shaft at the same point. The operator reported that examination of the damaged tail rotor pitch control system revealed that the controls were intact and would have been capable of normal operation. All parts of the helicopter were accounted for by the operator at the accident site.
The two-blade tail rotor assembly, mounted on the right side of the tail boom, was intact and correctly attached to the helicopter. There was no evidence of rotational damage to the leading edges or tips of either blade (Figure 1). During the ground impact one blade had been bent outward at the tip and the other was bent in toward the tail rotor gearbox.
The helicopter’s tail rotor drive shaft assembly consisted of a series of two short shafts and one long shaft that were situated on the top of the tail boom assembly. The long shaft was supported in eight hangar bearing assemblies and was secured at its front and rear by drive coupling assemblies. The operator inspected the tail rotor drive system and found that the long shaft assembly tubing was fractured and the pin situated through the front drive coupling assembly was sheared. There was also significant distortion of the corresponding pin in the shaft’s rear coupling.
Inspection of the tail rotor drive system, including the drive shaft bearings, tail rotor extension housing and tail rotor gearbox, with the exception of the long drive shaft, revealed nothing that would have prevented normal operation.
ATSB specialist examination of the failed components (Appendix A) attributed the tail rotor drive shaft failure to a significant torsional overload event, leading to a loss of coupling security and the subsequent slippage, frictional heating and shear fracture of the shaft. That examination was unable to determine when the torsional overload occurred or what specific events may have contributed to it.
At the time of the accident, the helicopter had logged 72 flight hours since the issue of the current maintenance release. The last recorded maintenance carried out on the helicopter was a spark plug change on 21 September 2004, 1.0 flight hour prior to the accident. On 31 August 2004, 5.7 flight hours prior to the accident, one tail rotor blade was replaced because of delamination of the leading edge wear strip.
Information received from the operator and from the maintenance organisation indicated that there had been no known tail rotor strike or sudden rotor stoppage since the helicopter was placed on the Australian aircraft register in 1992. The helicopter’s prior history was not examined.
The company operations manual contained the published normal and emergency procedures affecting aircraft operations. An appendix to the manual contained the flight check systems and operating procedures specific to each aircraft type operated by the company, with the exception of the Kawasaki-Bell 47G3B-KH4 helicopter. The company did however, make available to pilots a copy of the Civil Aviation Safety Authority approved Kawasaki-Bell 47G3B-KH4 helicopter flight manual.
With reference to tail rotor failures, that flight manual stipulated:
Immediately execute an autorotative descent and maintain an airspeed of 34 KIAS at least.
Execute a normal autorotative descent and landing.
The flight manual did not contain any specific advice for pilots in response to a tail rotor drive failure when hovering.
Information in the company operations manual regarding pilot response to a tail rotor drive failure in another piston-engine helicopter (Robinson R44) included:
LOSS OF TAIL ROTOR THRUST DURING HOVER
Failure is usually indicated by right yaw which cannot be stopped by applying left pedal.
Immediately roll throttle off into detent spring and allow aircraft to settle.
Raise collective just before touchdown to cushion landing
The generally accepted procedure for pilot actions in the event of a tail rotor failure is to quickly roll off the throttle or snap close the throttle and perform a hovering autorotation6,7,8,9 For example:
The likely worst place for loss of tail rotor thrust to happen is in the hover, and the reaction is quite simple - get rid of the engine power and land the helicopter from a hovering engine failure condition. Easy to do on those machines that have throttle(s) on the collective10.
--------------------------------------------------------------------------------
The 24-hour clock is used in this report to describe the local time of day, Eastern Standard Time (EST), as particular events occurred. Eastern Standard Time was Coordinated Universal Time (UTC) + 10 hours.
The Kawasaki Heavy Industries, 47G3B-KH4 helicopter is a single pilot/single flight control helicopter manufactured under licence from Bell Helicopters. It is commonly known as the KH4 helicopter and is a derivative of the Bell 47.
Given that the pilot positioned the helicopter into wind during the approach and landing, the risk of loss of tail rotor effectiveness (LTE) was negligible.
There were no external conditions that would have placed the pilot at risk of overpitching or drooping the main rotor.
Positioned 100 inches aft of the datum. The datum was located 2 inches forward of the rotor mast centre-line.
Coyle, S. (2003). Cyclic & collective - More art and science of flying helicopters. Mojave, CA: Helobooks, pages 341and 342.
Federal Aviation Administration. (2000). Rotorcraft flying handbook (FAA-H-8083-21). Washington, DC: FAA.
Newman, R. (1999). Helicopters will take you anywhere: A manual for helicopter pilots. Mentone, Vic: The Helicopter Book Company.
Becker, M. (1997). Mike Becker’s helicopter handbook. Noosaville, QLD: Becker Helicopters Australia.
The Kawasaki-Bell 47G3B-KH4 helicopter had a throttle of this design.
ANALYSIS
The circumstances of the accident were consistent with a loss of tail rotor thrust following the failure of the tail rotor drive shaft as the helicopter entered the hover.
The time at which the damage to the drive shaft occurred was not able to be determined. However, given the absence of rotational damage to the tail rotor blades, it is unlikely that it occurred during the accident flight.
The action of the pilot in increasing engine power when faced with the loss of tail rotor thrust was inappropriate and exacerbated the situation.
At 1215 Eastern Standard Time1 on 27 September 2004, a Kawasaki Heavy Industries, 47G3B-KH42 helicopter, registered VH-MTF, was being operated on a tourist flight with one adult and a young boy as passengers. The flight included landing on a 1 m high wooden platform in the Teepookana Forest in north-west Tasmania.
The pilot reported that as he brought the helicopter to a 1 m hover above the platform, the helicopter began to rotate slowly to the right. He unsuccessfully attempted to counter the rotation by applying left tail rotor control input. The pilot then increased engine power in an attempt to regain tail rotor control and to move the helicopter clear of the landing platform. That action had the effect of rapidly increasing the rotation of the helicopter to the right and it began to ascend, reaching about 5 m above ground level. The pilot then lowered the collective control and the helicopter impacted the ground heavily on its right side, several metres from the landing platform. The pilot and adult passenger released their seatbelts and then both assisted the young boy to exit the wreckage. The pilot and passengers received minor injuries.
The pilot described the wind conditions at the time of the accident as a headwind with an approximate strength of 8 kts. That assessment was consistent with the wind data for the Strahan area provided by the Bureau of Meteorology3. The pilot also reported that the main rotor RPM indications were normal and that the helicopter had sufficient power to complete the approach4. At the time of the accident, the weight and balance of the helicopter were within prescribed limits. There was no evidence that the helicopter had collided with anything during the approach.
The pilot was appropriately qualified and endorsed to operate the helicopter type and held a valid medical certificate. He was a very experienced agricultural aeroplane pilot and had obtained a commercial pilot (helicopter) licence 14 months before the accident. He had accrued at total of 292 hours in helicopters since that time; 286.4 hours of which had been in the Bell 47 helicopter type. The pilot was experienced with operations into and out of the Teepookana Forest landing platform.
The landing platform was located within a dense forest in an area that was cleared of trees but covered by 1 m high scrub. The trees closest to the clearing had been trimmed to a height of about 5 m to allow a ‘fly-in, fly-out’ approach. There was no requirement to conduct a vertical approach to the platform.
The helicopter’s fuselage structure was deformed by the impact and the tail boom was bent in a downward direction at approximately station 1005. There was corresponding bending damage to the tail rotor drive shaft assembly long shaft at the same point. The operator reported that examination of the damaged tail rotor pitch control system revealed that the controls were intact and would have been capable of normal operation. All parts of the helicopter were accounted for by the operator at the accident site.
The two-blade tail rotor assembly, mounted on the right side of the tail boom, was intact and correctly attached to the helicopter. There was no evidence of rotational damage to the leading edges or tips of either blade (Figure 1). During the ground impact one blade had been bent outward at the tip and the other was bent in toward the tail rotor gearbox.
The helicopter’s tail rotor drive shaft assembly consisted of a series of two short shafts and one long shaft that were situated on the top of the tail boom assembly. The long shaft was supported in eight hangar bearing assemblies and was secured at its front and rear by drive coupling assemblies. The operator inspected the tail rotor drive system and found that the long shaft assembly tubing was fractured and the pin situated through the front drive coupling assembly was sheared. There was also significant distortion of the corresponding pin in the shaft’s rear coupling.
Inspection of the tail rotor drive system, including the drive shaft bearings, tail rotor extension housing and tail rotor gearbox, with the exception of the long drive shaft, revealed nothing that would have prevented normal operation.
ATSB specialist examination of the failed components (Appendix A) attributed the tail rotor drive shaft failure to a significant torsional overload event, leading to a loss of coupling security and the subsequent slippage, frictional heating and shear fracture of the shaft. That examination was unable to determine when the torsional overload occurred or what specific events may have contributed to it.
At the time of the accident, the helicopter had logged 72 flight hours since the issue of the current maintenance release. The last recorded maintenance carried out on the helicopter was a spark plug change on 21 September 2004, 1.0 flight hour prior to the accident. On 31 August 2004, 5.7 flight hours prior to the accident, one tail rotor blade was replaced because of delamination of the leading edge wear strip.
Information received from the operator and from the maintenance organisation indicated that there had been no known tail rotor strike or sudden rotor stoppage since the helicopter was placed on the Australian aircraft register in 1992. The helicopter’s prior history was not examined.
The company operations manual contained the published normal and emergency procedures affecting aircraft operations. An appendix to the manual contained the flight check systems and operating procedures specific to each aircraft type operated by the company, with the exception of the Kawasaki-Bell 47G3B-KH4 helicopter. The company did however, make available to pilots a copy of the Civil Aviation Safety Authority approved Kawasaki-Bell 47G3B-KH4 helicopter flight manual.
With reference to tail rotor failures, that flight manual stipulated:
Immediately execute an autorotative descent and maintain an airspeed of 34 KIAS at least.
Execute a normal autorotative descent and landing.
The flight manual did not contain any specific advice for pilots in response to a tail rotor drive failure when hovering.
Information in the company operations manual regarding pilot response to a tail rotor drive failure in another piston-engine helicopter (Robinson R44) included:
LOSS OF TAIL ROTOR THRUST DURING HOVER
Failure is usually indicated by right yaw which cannot be stopped by applying left pedal.
Immediately roll throttle off into detent spring and allow aircraft to settle.
Raise collective just before touchdown to cushion landing
The generally accepted procedure for pilot actions in the event of a tail rotor failure is to quickly roll off the throttle or snap close the throttle and perform a hovering autorotation6,7,8,9 For example:
The likely worst place for loss of tail rotor thrust to happen is in the hover, and the reaction is quite simple - get rid of the engine power and land the helicopter from a hovering engine failure condition. Easy to do on those machines that have throttle(s) on the collective10.
--------------------------------------------------------------------------------
The 24-hour clock is used in this report to describe the local time of day, Eastern Standard Time (EST), as particular events occurred. Eastern Standard Time was Coordinated Universal Time (UTC) + 10 hours.
The Kawasaki Heavy Industries, 47G3B-KH4 helicopter is a single pilot/single flight control helicopter manufactured under licence from Bell Helicopters. It is commonly known as the KH4 helicopter and is a derivative of the Bell 47.
Given that the pilot positioned the helicopter into wind during the approach and landing, the risk of loss of tail rotor effectiveness (LTE) was negligible.
There were no external conditions that would have placed the pilot at risk of overpitching or drooping the main rotor.
Positioned 100 inches aft of the datum. The datum was located 2 inches forward of the rotor mast centre-line.
Coyle, S. (2003). Cyclic & collective - More art and science of flying helicopters. Mojave, CA: Helobooks, pages 341and 342.
Federal Aviation Administration. (2000). Rotorcraft flying handbook (FAA-H-8083-21). Washington, DC: FAA.
Newman, R. (1999). Helicopters will take you anywhere: A manual for helicopter pilots. Mentone, Vic: The Helicopter Book Company.
Becker, M. (1997). Mike Becker’s helicopter handbook. Noosaville, QLD: Becker Helicopters Australia.
The Kawasaki-Bell 47G3B-KH4 helicopter had a throttle of this design.
ANALYSIS
The circumstances of the accident were consistent with a loss of tail rotor thrust following the failure of the tail rotor drive shaft as the helicopter entered the hover.
The time at which the damage to the drive shaft occurred was not able to be determined. However, given the absence of rotational damage to the tail rotor blades, it is unlikely that it occurred during the accident flight.
The action of the pilot in increasing engine power when faced with the loss of tail rotor thrust was inappropriate and exacerbated the situation.
------------------------------------------------------------------
The circumstances of the accident were consistent with a loss of tail rotor thrust following the failure of the tail rotor drive shaft as the helicopter entered the hover.
The time at which the damage to the drive shaft occurred was not able to be determined. However, given the absence of rotational damage to the tail rotor blades, it is unlikely that it occurred during the accident flight.
The action of the pilot in increasing engine power when faced with the loss of tail rotor thrust was inappropriate and exacerbated the situation.
The helicopter’s tail rotor drive shaft had failed during the occurrence. ATSB specialist examination of the failed drive shaft, attributed the failure to damage from a significant torsional overload event, leading to the shear fracture of the shaft. The examination was unable to determine when the torsional overload occurred, however, examination of the wreckage indicated that it was likely that it had occurred prior to this accident
Information received from the operator and from the maintenance organisation indicated that there had been no known tail rotor strike or sudden rotor stoppage since the helicopter was placed on the Australian aircraft register in 1992. The helicopter’s history prior to that time was not examined.
The action of the pilot in increasing engine power when faced with the loss of tail rotor thrust was also examined.
FACTUAL INFORMATION
At 1215 Eastern Standard Time1 on 27 September 2004, a Kawasaki Heavy Industries, 47G3B-KH42 helicopter, registered VH-MTF, was being operated on a tourist flight with one adult and a young boy as passengers. The flight included landing on a 1 m high wooden platform in the Teepookana Forest in north-west Tasmania.
The pilot reported that as he brought the helicopter to a 1 m hover above the platform, the helicopter began to rotate slowly to the right. He unsuccessfully attempted to counter the rotation by applying left tail rotor control input. The pilot then increased engine power in an attempt to regain tail rotor control and to move the helicopter clear of the landing platform. That action had the effect of rapidly increasing the rotation of the helicopter to the right and it began to ascend, reaching about 5 m above ground level. The pilot then lowered the collective control and the helicopter impacted the ground heavily on its right side, several metres from the landing platform. The pilot and adult passenger released their seatbelts and then both assisted the young boy to exit the wreckage. The pilot and passengers received minor injuries.
The pilot described the wind conditions at the time of the accident as a headwind with an approximate strength of 8 kts. That assessment was consistent with the wind data for the Strahan area provided by the Bureau of Meteorology3. The pilot also reported that the main rotor RPM indications were normal and that the helicopter had sufficient power to complete the approach4. At the time of the accident, the weight and balance of the helicopter were within prescribed limits. There was no evidence that the helicopter had collided with anything during the approach.
The pilot was appropriately qualified and endorsed to operate the helicopter type and held a valid medical certificate. He was a very experienced agricultural aeroplane pilot and had obtained a commercial pilot (helicopter) licence 14 months before the accident. He had accrued at total of 292 hours in helicopters since that time; 286.4 hours of which had been in the Bell 47 helicopter type. The pilot was experienced with operations into and out of the Teepookana Forest landing platform.
The landing platform was located within a dense forest in an area that was cleared of trees but covered by 1 m high scrub. The trees closest to the clearing had been trimmed to a height of about 5 m to allow a ‘fly-in, fly-out’ approach. There was no requirement to conduct a vertical approach to the platform.
The helicopter’s fuselage structure was deformed by the impact and the tail boom was bent in a downward direction at approximately station 1005. There was corresponding bending damage to the tail rotor drive shaft assembly long shaft at the same point. The operator reported that examination of the damaged tail rotor pitch control system revealed that the controls were intact and would have been capable of normal operation. All parts of the helicopter were accounted for by the operator at the accident site.
The two-blade tail rotor assembly, mounted on the right side of the tail boom, was intact and correctly attached to the helicopter. There was no evidence of rotational damage to the leading edges or tips of either blade (Figure 1). During the ground impact one blade had been bent outward at the tip and the other was bent in toward the tail rotor gearbox.
The helicopter’s tail rotor drive shaft assembly consisted of a series of two short shafts and one long shaft that were situated on the top of the tail boom assembly. The long shaft was supported in eight hangar bearing assemblies and was secured at its front and rear by drive coupling assemblies. The operator inspected the tail rotor drive system and found that the long shaft assembly tubing was fractured and the pin situated through the front drive coupling assembly was sheared. There was also significant distortion of the corresponding pin in the shaft’s rear coupling.
Inspection of the tail rotor drive system, including the drive shaft bearings, tail rotor extension housing and tail rotor gearbox, with the exception of the long drive shaft, revealed nothing that would have prevented normal operation.
ATSB specialist examination of the failed components (Appendix A) attributed the tail rotor drive shaft failure to a significant torsional overload event, leading to a loss of coupling security and the subsequent slippage, frictional heating and shear fracture of the shaft. That examination was unable to determine when the torsional overload occurred or what specific events may have contributed to it.
At the time of the accident, the helicopter had logged 72 flight hours since the issue of the current maintenance release. The last recorded maintenance carried out on the helicopter was a spark plug change on 21 September 2004, 1.0 flight hour prior to the accident. On 31 August 2004, 5.7 flight hours prior to the accident, one tail rotor blade was replaced because of delamination of the leading edge wear strip.
Information received from the operator and from the maintenance organisation indicated that there had been no known tail rotor strike or sudden rotor stoppage since the helicopter was placed on the Australian aircraft register in 1992. The helicopter’s prior history was not examined.
The company operations manual contained the published normal and emergency procedures affecting aircraft operations. An appendix to the manual contained the flight check systems and operating procedures specific to each aircraft type operated by the company, with the exception of the Kawasaki-Bell 47G3B-KH4 helicopter. The company did however, make available to pilots a copy of the Civil Aviation Safety Authority approved Kawasaki-Bell 47G3B-KH4 helicopter flight manual.
With reference to tail rotor failures, that flight manual stipulated:
Immediately execute an autorotative descent and maintain an airspeed of 34 KIAS at least.
Execute a normal autorotative descent and landing.
The flight manual did not contain any specific advice for pilots in response to a tail rotor drive failure when hovering.
Information in the company operations manual regarding pilot response to a tail rotor drive failure in another piston-engine helicopter (Robinson R44) included:
LOSS OF TAIL ROTOR THRUST DURING HOVER
Failure is usually indicated by right yaw which cannot be stopped by applying left pedal.
Immediately roll throttle off into detent spring and allow aircraft to settle.
Raise collective just before touchdown to cushion landing
The generally accepted procedure for pilot actions in the event of a tail rotor failure is to quickly roll off the throttle or snap close the throttle and perform a hovering autorotation6,7,8,9 For example:
The likely worst place for loss of tail rotor thrust to happen is in the hover, and the reaction is quite simple - get rid of the engine power and land the helicopter from a hovering engine failure condition. Easy to do on those machines that have throttle(s) on the collective10.
--------------------------------------------------------------------------------
The 24-hour clock is used in this report to describe the local time of day, Eastern Standard Time (EST), as particular events occurred. Eastern Standard Time was Coordinated Universal Time (UTC) + 10 hours.
The Kawasaki Heavy Industries, 47G3B-KH4 helicopter is a single pilot/single flight control helicopter manufactured under licence from Bell Helicopters. It is commonly known as the KH4 helicopter and is a derivative of the Bell 47.
Given that the pilot positioned the helicopter into wind during the approach and landing, the risk of loss of tail rotor effectiveness (LTE) was negligible.
There were no external conditions that would have placed the pilot at risk of overpitching or drooping the main rotor.
Positioned 100 inches aft of the datum. The datum was located 2 inches forward of the rotor mast centre-line.
Coyle, S. (2003). Cyclic & collective - More art and science of flying helicopters. Mojave, CA: Helobooks, pages 341and 342.
Federal Aviation Administration. (2000). Rotorcraft flying handbook (FAA-H-8083-21). Washington, DC: FAA.
Newman, R. (1999). Helicopters will take you anywhere: A manual for helicopter pilots. Mentone, Vic: The Helicopter Book Company.
Becker, M. (1997). Mike Becker’s helicopter handbook. Noosaville, QLD: Becker Helicopters Australia.
The Kawasaki-Bell 47G3B-KH4 helicopter had a throttle of this design.
ANALYSIS
The circumstances of the accident were consistent with a loss of tail rotor thrust following the failure of the tail rotor drive shaft as the helicopter entered the hover.
The time at which the damage to the drive shaft occurred was not able to be determined. However, given the absence of rotational damage to the tail rotor blades, it is unlikely that it occurred during the accident flight.
The action of the pilot in increasing engine power when faced with the loss of tail rotor thrust was inappropriate and exacerbated the situation.
At 1215 Eastern Standard Time1 on 27 September 2004, a Kawasaki Heavy Industries, 47G3B-KH42 helicopter, registered VH-MTF, was being operated on a tourist flight with one adult and a young boy as passengers. The flight included landing on a 1 m high wooden platform in the Teepookana Forest in north-west Tasmania.
The pilot reported that as he brought the helicopter to a 1 m hover above the platform, the helicopter began to rotate slowly to the right. He unsuccessfully attempted to counter the rotation by applying left tail rotor control input. The pilot then increased engine power in an attempt to regain tail rotor control and to move the helicopter clear of the landing platform. That action had the effect of rapidly increasing the rotation of the helicopter to the right and it began to ascend, reaching about 5 m above ground level. The pilot then lowered the collective control and the helicopter impacted the ground heavily on its right side, several metres from the landing platform. The pilot and adult passenger released their seatbelts and then both assisted the young boy to exit the wreckage. The pilot and passengers received minor injuries.
The pilot described the wind conditions at the time of the accident as a headwind with an approximate strength of 8 kts. That assessment was consistent with the wind data for the Strahan area provided by the Bureau of Meteorology3. The pilot also reported that the main rotor RPM indications were normal and that the helicopter had sufficient power to complete the approach4. At the time of the accident, the weight and balance of the helicopter were within prescribed limits. There was no evidence that the helicopter had collided with anything during the approach.
The pilot was appropriately qualified and endorsed to operate the helicopter type and held a valid medical certificate. He was a very experienced agricultural aeroplane pilot and had obtained a commercial pilot (helicopter) licence 14 months before the accident. He had accrued at total of 292 hours in helicopters since that time; 286.4 hours of which had been in the Bell 47 helicopter type. The pilot was experienced with operations into and out of the Teepookana Forest landing platform.
The landing platform was located within a dense forest in an area that was cleared of trees but covered by 1 m high scrub. The trees closest to the clearing had been trimmed to a height of about 5 m to allow a ‘fly-in, fly-out’ approach. There was no requirement to conduct a vertical approach to the platform.
The helicopter’s fuselage structure was deformed by the impact and the tail boom was bent in a downward direction at approximately station 1005. There was corresponding bending damage to the tail rotor drive shaft assembly long shaft at the same point. The operator reported that examination of the damaged tail rotor pitch control system revealed that the controls were intact and would have been capable of normal operation. All parts of the helicopter were accounted for by the operator at the accident site.
The two-blade tail rotor assembly, mounted on the right side of the tail boom, was intact and correctly attached to the helicopter. There was no evidence of rotational damage to the leading edges or tips of either blade (Figure 1). During the ground impact one blade had been bent outward at the tip and the other was bent in toward the tail rotor gearbox.
The helicopter’s tail rotor drive shaft assembly consisted of a series of two short shafts and one long shaft that were situated on the top of the tail boom assembly. The long shaft was supported in eight hangar bearing assemblies and was secured at its front and rear by drive coupling assemblies. The operator inspected the tail rotor drive system and found that the long shaft assembly tubing was fractured and the pin situated through the front drive coupling assembly was sheared. There was also significant distortion of the corresponding pin in the shaft’s rear coupling.
Inspection of the tail rotor drive system, including the drive shaft bearings, tail rotor extension housing and tail rotor gearbox, with the exception of the long drive shaft, revealed nothing that would have prevented normal operation.
ATSB specialist examination of the failed components (Appendix A) attributed the tail rotor drive shaft failure to a significant torsional overload event, leading to a loss of coupling security and the subsequent slippage, frictional heating and shear fracture of the shaft. That examination was unable to determine when the torsional overload occurred or what specific events may have contributed to it.
At the time of the accident, the helicopter had logged 72 flight hours since the issue of the current maintenance release. The last recorded maintenance carried out on the helicopter was a spark plug change on 21 September 2004, 1.0 flight hour prior to the accident. On 31 August 2004, 5.7 flight hours prior to the accident, one tail rotor blade was replaced because of delamination of the leading edge wear strip.
Information received from the operator and from the maintenance organisation indicated that there had been no known tail rotor strike or sudden rotor stoppage since the helicopter was placed on the Australian aircraft register in 1992. The helicopter’s prior history was not examined.
The company operations manual contained the published normal and emergency procedures affecting aircraft operations. An appendix to the manual contained the flight check systems and operating procedures specific to each aircraft type operated by the company, with the exception of the Kawasaki-Bell 47G3B-KH4 helicopter. The company did however, make available to pilots a copy of the Civil Aviation Safety Authority approved Kawasaki-Bell 47G3B-KH4 helicopter flight manual.
With reference to tail rotor failures, that flight manual stipulated:
Immediately execute an autorotative descent and maintain an airspeed of 34 KIAS at least.
Execute a normal autorotative descent and landing.
The flight manual did not contain any specific advice for pilots in response to a tail rotor drive failure when hovering.
Information in the company operations manual regarding pilot response to a tail rotor drive failure in another piston-engine helicopter (Robinson R44) included:
LOSS OF TAIL ROTOR THRUST DURING HOVER
Failure is usually indicated by right yaw which cannot be stopped by applying left pedal.
Immediately roll throttle off into detent spring and allow aircraft to settle.
Raise collective just before touchdown to cushion landing
The generally accepted procedure for pilot actions in the event of a tail rotor failure is to quickly roll off the throttle or snap close the throttle and perform a hovering autorotation6,7,8,9 For example:
The likely worst place for loss of tail rotor thrust to happen is in the hover, and the reaction is quite simple - get rid of the engine power and land the helicopter from a hovering engine failure condition. Easy to do on those machines that have throttle(s) on the collective10.
--------------------------------------------------------------------------------
The 24-hour clock is used in this report to describe the local time of day, Eastern Standard Time (EST), as particular events occurred. Eastern Standard Time was Coordinated Universal Time (UTC) + 10 hours.
The Kawasaki Heavy Industries, 47G3B-KH4 helicopter is a single pilot/single flight control helicopter manufactured under licence from Bell Helicopters. It is commonly known as the KH4 helicopter and is a derivative of the Bell 47.
Given that the pilot positioned the helicopter into wind during the approach and landing, the risk of loss of tail rotor effectiveness (LTE) was negligible.
There were no external conditions that would have placed the pilot at risk of overpitching or drooping the main rotor.
Positioned 100 inches aft of the datum. The datum was located 2 inches forward of the rotor mast centre-line.
Coyle, S. (2003). Cyclic & collective - More art and science of flying helicopters. Mojave, CA: Helobooks, pages 341and 342.
Federal Aviation Administration. (2000). Rotorcraft flying handbook (FAA-H-8083-21). Washington, DC: FAA.
Newman, R. (1999). Helicopters will take you anywhere: A manual for helicopter pilots. Mentone, Vic: The Helicopter Book Company.
Becker, M. (1997). Mike Becker’s helicopter handbook. Noosaville, QLD: Becker Helicopters Australia.
The Kawasaki-Bell 47G3B-KH4 helicopter had a throttle of this design.
ANALYSIS
The circumstances of the accident were consistent with a loss of tail rotor thrust following the failure of the tail rotor drive shaft as the helicopter entered the hover.
The time at which the damage to the drive shaft occurred was not able to be determined. However, given the absence of rotational damage to the tail rotor blades, it is unlikely that it occurred during the accident flight.
The action of the pilot in increasing engine power when faced with the loss of tail rotor thrust was inappropriate and exacerbated the situation.
------------------------------------------------------------------
The circumstances of the accident were consistent with a loss of tail rotor thrust following the failure of the tail rotor drive shaft as the helicopter entered the hover.
The time at which the damage to the drive shaft occurred was not able to be determined. However, given the absence of rotational damage to the tail rotor blades, it is unlikely that it occurred during the accident flight.
The action of the pilot in increasing engine power when faced with the loss of tail rotor thrust was inappropriate and exacerbated the situation.
http://www.atsb.gov.au/publications/...200403651.aspx
The report says the pilot's action in increasing power was inappropriate - maybe so over a nice grassy spot or something, but it also says he was trying to move clear of the platform. Not a bad idea under the circumstances, I would have thought - hovering auto onto a platform doesn't sound so great.
Maybe, but still not real great - not straight, moving as well, probably hook a skid on the platform, trip it over and end up upside down. I'd want to get clear, I think.
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"The likely worst place for loss of tail rotor thrust to happen is in the hover, and the reaction is quite simple - get rid of the engine power and land the helicopter from a hovering engine failure condition. Easy to do on those machines that have throttle(s) on the collective10."
I guess you can not but agree with this comment HOWEVER as it says it happened in the worst possible place, as these things do, the "quite simple" and "easy" comments though seem quite out of place here in an objective (??) report. Should it not simply state what the corrective action is without the expanding on the ease and simplicity of it.
ERGO if you have the left pedal on the floor during the landing at hover and it starts to yaw right then the "simplist" and "easiest" thing to do is to chop the throttle (not massage it CUT IT).... I aint the expert
but is there not a number of other maladies that could cause this effect with such corrective action not necessarily being what is required... which brings me to my point. Assesing why you are continuing to yaw right and deciding what the problem is before taking corrective action does not leave a lot of time to actually do it in this scenario.
I certainly hope something "quite simple" and "easy" like this never happens to me
I guess you can not but agree with this comment HOWEVER as it says it happened in the worst possible place, as these things do, the "quite simple" and "easy" comments though seem quite out of place here in an objective (??) report. Should it not simply state what the corrective action is without the expanding on the ease and simplicity of it.
ERGO if you have the left pedal on the floor during the landing at hover and it starts to yaw right then the "simplist" and "easiest" thing to do is to chop the throttle (not massage it CUT IT).... I aint the expert
but is there not a number of other maladies that could cause this effect with such corrective action not necessarily being what is required... which brings me to my point. Assesing why you are continuing to yaw right and deciding what the problem is before taking corrective action does not leave a lot of time to actually do it in this scenario.I certainly hope something "quite simple" and "easy" like this never happens to me
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Better to fall 1M than muck around and crash from higher and/or at a faster rotational speed. Hard to think of at the time I admit, especially when all you would be thinking of is 'What the ****', but has to be automatic.
I am raising this point of view to stimulate disussion on CAAP issues as this relates to a current controvesy about this in another eunrelated topic. I do not comment on the pilot's actions as I have not been there myself, and I have a lot of sympathy for AOTW's point.
One of the motivators qouted for the pilot to climb instead of roll the throttle off was the platform size and position. Did it comply to CAAP 92-2? Is that a requirement for charter ops as "best practice", and do you need a sound reason for deviating from these standards: for example....like you do for fuel reserves in another CAAP.
Would a CAAP 92-2 standard HLS allowed the pilot sufficient room to carry out the throttle chop? Should we have to justify divergence from a published professional advice of best practice?
One of the motivators qouted for the pilot to climb instead of roll the throttle off was the platform size and position. Did it comply to CAAP 92-2? Is that a requirement for charter ops as "best practice", and do you need a sound reason for deviating from these standards: for example....like you do for fuel reserves in another CAAP.
Would a CAAP 92-2 standard HLS allowed the pilot sufficient room to carry out the throttle chop? Should we have to justify divergence from a published professional advice of best practice?
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G, day Helmet Fire.
Unfortunately I have binthere, dunthat; I would briefly say that what was not said in the report speaks volumes. Mine was not a strike but a failure because the front S/S couplings were located too far apart and with manoeuvring it eventually just plucked the front short shaft out of one coupling. This was at about 35’ or so going up with power very much on. There was a jolt followed by a rapidly speeding rotation rate.
On the second turn I realised that next turn I would lose visual orientation and I reckoned, effective RPM, by now at about fifty feet, I says chop- boy-, I chopped. They only slow down a little, still no forward speed; I was able to steer toward a spot below, held off until a full pull, at ten feet, bumped on as it slowed rotating to a stop with the help of a prickly bush against the T/R guard tube. The T/R guard tube had bent right across the rotation plane of the T/R. The U/C cross tubes bent but were still within limits. I was in a 47 3B1 solo with about 90 minutes of fuel.
The point of that bit is that very quickly and well before I got to the ground the T/R had stopped rotating, I suggest the same happened here which is why there is no evidence of T/R strike damage during the crash sequence.
Your CAAP 92 discussion is irrelevant until you are satisfied with the level of operational training that the pilot should have had to that pad. It seems you have highlighted another area which ATSB should have, but did not, report on. Funny that, in the report they spent half an hour talking about the bloody time of day but nothing about the landing spot????
Your CAAP 92 discussion is not irrelevant if the regular tourist operation (RTO almost rhymes with RPT) is not organised in such a fashion so as to maximise at all times Emerg Landing Area availability, prior to certification for the operation.
I think you might be in a position to sway some better procedures, go tuit.
I suggest that what was omitted was that the pilot entered his third loss of T/R control turn at least, didn’t have a shmick what he was doing, lost vis and effective lift/RPM and as a last gasp lowered collective. At that time the A/C was falling and by the grace of God encountered some flora to absorb at least some of the energy and downward momentum so that they lived to get out. It would have been still rotating quite rapidly at impact; I suggest impact occurred after the T/R had just gone past the lowest point.
Before you posted I had prepared the following; here is.
Just to run a bit of a cut on the lengthy ATSB diatribe here is a shortened version.
Pilot had 292 hours in helicopters; brought the helicopter to a 1 m hover above the raised landing platform, the helicopter began to rotate slowly to the right. The pilot unsuccessfully attempted to counter the rotation by applying left tail rotor control input, then increased engine power, however, that action had the effect of rapidly increasing the rotation of the helicopter to the right (really?) and the helicopter climbed to about 5 m above the ground. After the pilot lowered the collective control the helicopter impacted the ground heavily on its right side.
The likely worst place for loss of tail rotor thrust to happen is in the hover, and the reaction is quite simple - get rid of the engine power, snap close the throttle and perform a hovering autorotation Easy to do on those machines that have a throttle on the collective.
The action of the pilot in increasing engine power when faced with the loss of tail rotor thrust was inappropriate and exacerbated the situation
OK no arguments the driver totally stuffed up, finger trouble or no training or both?
But The T/R strike?
The operator inspected the tail rotor drive system and found that the long shaft assembly tubing was fractured and the pin situated through the front drive coupling assembly was sheared. There was also significant distortion of the corresponding pin in the shaft’s rear coupling. (A water strike perhaps????))
In the absence of rotational damage to the tail rotor blades, (water again???) it is unlikely that it occurred during the accident flight ??? ahem!
On 31 August 2004, 5.7 flight hours prior to the accident, one tail rotor blade was replaced because of delamination of the leading edge wear strip. (?????)
There was no evidence of rotational damage to the leading edges or tips of either blade (Figure 1). During the ground impact one blade had been bent outward???? At the tip and the other was bent in toward the tail rotor gearbox which is on the stbd side.
1) Now let me get this straight the A/C fell on its stbd side and bent one blade outward toward the way it was falling by doing so??
2) If the blades are not equipped with strike tabs then they can easily have strong water strikes with no visible damage.
3) For sure the torsional T/R shaft damage did occur because of a strike.
{The amount of torsional damage would indicate that the next high power demand (I.E. left pedal at the hover) would precipitate a failure. Remember that the KH4 need only be equipped with L/W T/R shafting}
4) A damaged blade was replaced after the last 100 hrly at when the T/R drive shaft couplings are supposed to be disconnected and inspected. Let’s assume that they were, then the blades strike or strikes has occurred since the last 100hrly.
5) The pictures are lousy photos but from what can be seen there appears a god awful lot of paint that has been worn off the second (right side of picture) blade after only 5.7 hours. It also appears to have damage consistent with impacting the end of blade on a hard flat surface whilst still rotating under power. (Which is not water?) Of course an examination of the end of the blade would be needed.
6) The other (left hand photo) blade looks like it has been around for a while as the leading edge paint has been well worn and it also appears to have tip damage consistent with a leading edge strike at the tip.
Now I did try to copy and paste the pics here from the report but this is one thing that I am hopeless at. anyone can do this for me thankyou.
The only conclusion that can be gleaned on the presented data is that insufficient evidence was gathered. Evidence which might well be there upon a PROPER examination of both T/R blades.
One thing is for certain and which I have witnessed, is that major torsional damage to the drive shaft assy’s does not happen without a strong outside force.
There are no reports of the condition of the T/R guard tube condition?
ATSB need to be sent back to the job! ++++plus some++++
Unfortunately I have binthere, dunthat; I would briefly say that what was not said in the report speaks volumes. Mine was not a strike but a failure because the front S/S couplings were located too far apart and with manoeuvring it eventually just plucked the front short shaft out of one coupling. This was at about 35’ or so going up with power very much on. There was a jolt followed by a rapidly speeding rotation rate.
On the second turn I realised that next turn I would lose visual orientation and I reckoned, effective RPM, by now at about fifty feet, I says chop- boy-, I chopped. They only slow down a little, still no forward speed; I was able to steer toward a spot below, held off until a full pull, at ten feet, bumped on as it slowed rotating to a stop with the help of a prickly bush against the T/R guard tube. The T/R guard tube had bent right across the rotation plane of the T/R. The U/C cross tubes bent but were still within limits. I was in a 47 3B1 solo with about 90 minutes of fuel.
The point of that bit is that very quickly and well before I got to the ground the T/R had stopped rotating, I suggest the same happened here which is why there is no evidence of T/R strike damage during the crash sequence.
Your CAAP 92 discussion is irrelevant until you are satisfied with the level of operational training that the pilot should have had to that pad. It seems you have highlighted another area which ATSB should have, but did not, report on. Funny that, in the report they spent half an hour talking about the bloody time of day but nothing about the landing spot????
Your CAAP 92 discussion is not irrelevant if the regular tourist operation (RTO almost rhymes with RPT) is not organised in such a fashion so as to maximise at all times Emerg Landing Area availability, prior to certification for the operation.
I think you might be in a position to sway some better procedures, go tuit.
I suggest that what was omitted was that the pilot entered his third loss of T/R control turn at least, didn’t have a shmick what he was doing, lost vis and effective lift/RPM and as a last gasp lowered collective. At that time the A/C was falling and by the grace of God encountered some flora to absorb at least some of the energy and downward momentum so that they lived to get out. It would have been still rotating quite rapidly at impact; I suggest impact occurred after the T/R had just gone past the lowest point.
Before you posted I had prepared the following; here is.
Just to run a bit of a cut on the lengthy ATSB diatribe here is a shortened version.
Pilot had 292 hours in helicopters; brought the helicopter to a 1 m hover above the raised landing platform, the helicopter began to rotate slowly to the right. The pilot unsuccessfully attempted to counter the rotation by applying left tail rotor control input, then increased engine power, however, that action had the effect of rapidly increasing the rotation of the helicopter to the right (really?) and the helicopter climbed to about 5 m above the ground. After the pilot lowered the collective control the helicopter impacted the ground heavily on its right side.
The likely worst place for loss of tail rotor thrust to happen is in the hover, and the reaction is quite simple - get rid of the engine power, snap close the throttle and perform a hovering autorotation Easy to do on those machines that have a throttle on the collective.
The action of the pilot in increasing engine power when faced with the loss of tail rotor thrust was inappropriate and exacerbated the situation
OK no arguments the driver totally stuffed up, finger trouble or no training or both?
But The T/R strike?
The operator inspected the tail rotor drive system and found that the long shaft assembly tubing was fractured and the pin situated through the front drive coupling assembly was sheared. There was also significant distortion of the corresponding pin in the shaft’s rear coupling. (A water strike perhaps????))
In the absence of rotational damage to the tail rotor blades, (water again???) it is unlikely that it occurred during the accident flight ??? ahem!
On 31 August 2004, 5.7 flight hours prior to the accident, one tail rotor blade was replaced because of delamination of the leading edge wear strip. (?????)
There was no evidence of rotational damage to the leading edges or tips of either blade (Figure 1). During the ground impact one blade had been bent outward???? At the tip and the other was bent in toward the tail rotor gearbox which is on the stbd side.
1) Now let me get this straight the A/C fell on its stbd side and bent one blade outward toward the way it was falling by doing so??
2) If the blades are not equipped with strike tabs then they can easily have strong water strikes with no visible damage.
3) For sure the torsional T/R shaft damage did occur because of a strike.
{The amount of torsional damage would indicate that the next high power demand (I.E. left pedal at the hover) would precipitate a failure. Remember that the KH4 need only be equipped with L/W T/R shafting}
4) A damaged blade was replaced after the last 100 hrly at when the T/R drive shaft couplings are supposed to be disconnected and inspected. Let’s assume that they were, then the blades strike or strikes has occurred since the last 100hrly.
5) The pictures are lousy photos but from what can be seen there appears a god awful lot of paint that has been worn off the second (right side of picture) blade after only 5.7 hours. It also appears to have damage consistent with impacting the end of blade on a hard flat surface whilst still rotating under power. (Which is not water?) Of course an examination of the end of the blade would be needed.
6) The other (left hand photo) blade looks like it has been around for a while as the leading edge paint has been well worn and it also appears to have tip damage consistent with a leading edge strike at the tip.
Now I did try to copy and paste the pics here from the report but this is one thing that I am hopeless at. anyone can do this for me thankyou.
The only conclusion that can be gleaned on the presented data is that insufficient evidence was gathered. Evidence which might well be there upon a PROPER examination of both T/R blades.
One thing is for certain and which I have witnessed, is that major torsional damage to the drive shaft assy’s does not happen without a strong outside force.
There are no reports of the condition of the T/R guard tube condition?
ATSB need to be sent back to the job! ++++plus some++++
