Hughes 369 N500TN

Summary

On 9 September 2016 at about 18:00 local time, a Hughes 369 registered N500TN, operated by AIR2 LLC., was involved in an accident near Peach Orchard, Missouri, United States. 2 people were on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

9 September 2016 at 18:00

Classification

Accident

Location

Peach Orchard, Missouri, United States

Coordinates

36.3289, -89.9389

Aircraft

Hughes 369

Registration

N500TN

Category

Helicopter

Year built

1979

Engines

1

Operator

AIR2 LLC.

Operating rule

Part 133: Rotorcraft Ext. Load

Purpose of flight

External Load

Phase of flight

Not recorded

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

GAA16CA480

Nobody was injured.

The helicopter pilot’s failure to maintain sufficient separation between the main rotor blade and a power line during line guard installation, which resulted in an electrical arc to the main rotor.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

The helicopter pilot reported that he was flying in support of a utility company crew that was installing line guards for a conductor damper on an energized 161 kilovolts (Kv) electrical transmission line. The transmission line had three phases (power lines) that were separated vertically and staggered horizontally from one another and ran parallel to the ground. The lower phase power line was about 9.5 ft (horizontally) further out from the middle phase power line. While the helicopter was approaching the lines, its main rotor blade clearance from the middle phase line was about 2.5 ft, which resulted in an electrical arc to the main rotor. The pilot landed the helicopter away from the transmission line without further incident. A postaccident examination revealed substantial damage to the main rotor hub and two main rotor blades. The pilot reported no preaccident mechanical malfunctions or failures with the helicopter that would have precluded normal operation. According to Occupational Safety & Health Administration 1910.269(I)(10), the minimum approach distance (MAD) is to "ensure that workers do not approach or take any conductive object closer to the energized parts as set forth in the table below (excerpt)." For a voltage of 161 Kv, the MAD for this operation was equal to or greater than 4.00625 ft.

Quoted verbatim from the NTSB record.