Sikorsky CH-54B N719HT

Summary

On 7 April 2009 at about 22:30 local time, a Sikorsky CH-54B registered N719HT, operated by Helicopter Transport Services, Inc., was involved in an accident near Corvallis, Oregon, 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

7 April 2009 at 22:30

Classification

Accident

Location

Corvallis, Oregon, United States

Nearest airport

Corvallis Municipal (CVO)

Coordinates

44.4972, -123.2894

Aircraft

Sikorsky CH-54B

Registration

N719HT

Category

Helicopter

Engines

2

Operator

Helicopter Transport Services, Inc.

Operating rule

Part 91: General Aviation

Purpose of flight

Instructional

Phase of flight

Not recorded

Route

Corvallis → Corvallis

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

WPR09LA184

Nobody was injured.

The improper assembly of main rotor blade control components by the operator's maintenance personnel, which resulted in the main rotor blade's divergent path and their contact with the tail rotor drive shaft during ground operation following landing.

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

Read the full NTSB narrative

The pilot and certified flight instructor departed for a local area instructional flight during which the pilot practiced a series of takeoffs and landings. During ground operations, the crew stated that they felt an unusual vibration, which was partially mitigated by keeping the collective pitch raised about 2 inches from the full down position. The pilot reported that he decided to adjust his seat position so he landed and handed off the controls to the certified flight instructor (CFI). The CFI lowered the collective to the full down position in preparation for the seat adjustment operation. At this time he noticed a vibration, which was followed by a loud "bang." The subsequent helicopter examination revealed that two of the six main rotor blades had diverged from their normal plane of rotation and impacted the tail rotor drive system, resulting in the number 5 and 6 tail rotor drive shaft sections separating from the helicopter. The investigation and examination of the helicopter found that during maintenance performed at an undetermined date by the operator's mechanics, the bell cranks that connect to the main rotor blades' control rods had been incorrectly installed in a reversed manner. This allowed the swash plate to travel outside of its designed range.

Quoted verbatim from the NTSB record.