Aviation Accident Summaries

Aviation Accident Summary FTW02LA217

Aircraft #1

N3174Y

Bell 206L-3

Analysis

While in cruise flight over open ocean water, the pilot of the air taxi helicopter heard a "bang," and the helicopter yawed. The pilot was unable to control the yaw, so he initiated an autorotation. Prior to water entry, the skid mounted floats were successfully deployed. After touchdown on the water, the helicopter rolled over inverted, and the pilot and passenger exited the helicopter and were rescued by a recovery boat. Examination of the wreckage revealed a main rotor blade contact mark just aft of the exhaust stack on a downward angle of approximately 45 degrees. Cyclic, collective, and tail rotor control continuity was established throughout the flight control system. Removal. of the tail rotor drive shaft cowling revealed that the #6 drive shaft (s/n VNMK-47448) twisted apart into two sections, with respective adjacent disc pack couplings deformed. The #8 drive shaft (s/n VNMKH-48083) was found twisted, but not separated, no deformity was noted on the adjacent disc pack couplings. One tail rotor blade (s/n CS-9003) showed damage to its leading edge, and was fractured along the chord in perpendicular to the leading edge. A "bluish", plastic appearing material was found smeared onto the damaged leading edge. The opposite tail rotor blade displayed no visible damage, however, some of the "bluish" coloration was found on its blade tip weight rivets. The tail boom showed evidence of scrapping along its left side, corresponding to the tip path plane of the tail rotor disc. Additional "bluish" coloration was present in the area of the scrapes, and on the tail rotor gearbox output shaft. All damage found was within the rotational arc of the tail rotor disc, with the exception of the exception the main rotor blade and the twisted #6 section of the tail rotor drive shaft. The baggage compartment door and latches were inspected for integrity. The door interior was not deformed and did not show visible evidence of impact marks and the latches were in good condition with no looseness when the door was in the closed & latched position. An electrical continuity check of the baggage door open warning system found no anomalies, and the caution panel bulbs were not damaged or burned. Additionally, neither the pilot or passenger reported noticing any warning lights being illuminated during the accident. All four passenger and crew doors were closed and latched, and would not open by normal means from inside the cabin. During recovery, examination, and interviews, some of the aircraft's standard on-board equipment and internal cargo that was loaded prior to take off were not found. Unoccupied Rear Cabin (5 seating positions): 3 personal flotation devices; 1 newspaper; 1 manila folder with contents. Baggage Compartment: 2 cardboard boxes, measuring 12 inches by 12 inches; 1 envelope; 1 plastic hard hat; 1 ice water cooler. Material analysis of the "bluish" marks on the tail rotor were not conclusive as to what type of object or material could have come into contact with the tail rotor during flight. No mechanical anomalies were discovered that could have contributed to the accident.

Factual Information

On July 25, 2002, approximately 1255 central daylight time, a Bell 206L-3 helicopter, N3174Y, was substantially damaged during a forced landing to the water following a loss of tail rotor control near an off shore platform, Eugene Island (EI) 192, Gulf of Mexico. The helicopter was owned and operated by Air Logistics LLC of New Iberia, Louisiana. The commercial pilot and 1 passenger sustained minor injuries. Visual meteorological conditions prevailed, and a company visual flight rules (VFR) flight plan was filed for the 14 Code of Federal Regulations Part 135 non-scheduled air taxi flight. The flight originated from an offshore platform, Ship Shoal (SS) 149, Gulf of Mexico, approximately 1248, and was en route to offshore platform, Eugene Island (EI) 206. According to information provided by the operator, the pilot heard a "bang," and the helicopter yawed. The pilot was unable to control the yaw, so he initiated an autorotation. Prior to water entry, the skid mounted floats were successfully deployed. After touchdown on the water, the helicopter rolled over inverted, and the pilot and passenger exited the helicopter and were rescued by a recovery boat. The helicopter was towed (still inverted) by a recovery vessel to an offshore platform whereby it was lifted onto a barge and transported to shore. Via truck, the helicopter was then transported to the operators maintenance base located in New Iberia, Louisiana, for examination of the wreckage. Examination of the wreckage revealed a main rotor blade contact mark just aft of the exhaust stack on a downward angle of approximately 45 degrees. The aft engine mounts were displaced down and to the right. The fuel control linkages were found in the "full open" positions and the governor set at 60 degrees. The left forward chin window was missing as was the left aft passenger window. The left overhead "green house" window was broken in an upward direction. Cyclic, collective, and tail rotor control continuity was established throughout the flight control system. Removal. of the tail rotor drive shaft cowling revealed that the #6 drive shaft (s/n VNMK-47448) twisted apart into two sections, with respective adjacent disc pack couplings deformed. The #8 drive shaft (s/n VNMKH-48083) was found twisted, but not separated, no deformity was noted on the adjacent disc pack couplings. One tail rotor blade (s/n CS-9003) showed damage to its leading edge, and was fractured along the chord in perpendicular to the leading edge. A "bluish", plastic appearing material was found smeared onto the damaged leading edge. The opposite tail rotor blade displayed no visible damage, however, some of the "bluish" coloration was found on its blade tip weight rivets. The tail boom showed evidence of scrapping along its left side, corresponding to the tip path plane of the tail rotor disc. Additional "bluish" coloration was present in the area of the scrapes, and on the tail rotor gearbox output shaft. All damage found was within the rotational arc of the tail rotor disc, with the exception of the exception the main rotor blade and the twisted #6 section of the tail rotor drive shaft. The baggage compartment door and latches were inspected for integrity. The door interior was not deformed and did not show visible evidence of impact marks and the latches were in good. condition with no looseness when the door was in the closed & latched position. An electrical continuity check of the baggage door open warning system found no anomalies, and the caution panel bulbs were not damaged or burned. Additionally, neither the pilot or passenger reported noticing any warning lights being illuminated during the accident. All four passenger and crew doors were closed and latched, and would not open by normal means from inside the cabin. The doors could be worked open with some degree of hand force. During recovery, examination, and interviews, some of the aircraft's standard on-board equipment and internal cago that was loaded prior to take off were not found. Unoccupied Rear Cabin (5 seating positions): 3 personal flotation devices; 1 newspaper; 1 manila folder with contents. Baggage Compartment: 2 cardboard boxes, measuring 12 inches by 12 inches; 1 envelope; 1 plastic hard hat; 1 ice water cooler. Material analysis of the "bluish" marks on the tail rotor were not conclusive as to what type of object or material could have come into contact with the tail rotor during flight. No mechanical anamalies were discovered that could have contributed to the accident.

Probable Cause and Findings

The loss of tail rotor control due to an in-flight collision with an object.

 

Source: NTSB Aviation Accident Database

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