Eurocopter AS 350 BA N4010K

Summary

On 28 March 2007 at about 21:45 local time, a Eurocopter AS 350 BA registered N4010K was involved in an incident near Kahului, Hawaii, United States. 7 people were on board and nobody was injured. The aircraft was slightly damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

28 March 2007 at 21:45

Classification

Incident

Location

Kahului, Hawaii, United States

Nearest airport

Kahului (OGG)

Coordinates

Not recorded

Aircraft

Eurocopter AS 350 BA

Registration

N4010K

Category

Helicopter

Engines

1

Operator

Not recorded

Operating rule

Part 135: Air Taxi & Commuter

Phase of flight

Not recorded

Route

Kahalui → Unknown

Aircraft damage

Minor

Weather

VMC

Light

Day

NTSB number

LAX07IA115

Nobody was injured.

The loss of tail rotor control due to wear damage to the pitch control input rod that resulted ultimately in the fatigue failure of the upper support yoke arm. Contributing factors were the improper maintenance inspection of the expansion pin assembly and the loose bushing in the lower support yoke arm.

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

Read the full NTSB narrative

While in cruise flight at 2,800 feet mean sea level (msl) approximately 100 knots airspeed, the pilot experienced an uncommanded left yaw. The pilot pressed each rotor pedal and "found they were not functioning." The pilot turned back to the airport and declared an emergency. The pilot attempted a run-on landing. During the landing, the helicopter "wanted to turn left as the airspeed slowed." Subsequently, the helicopter twice spun to the left and came to rest upright partially on the runway and adjacent grass. The loss of tail rotor control was due to the lower support yoke arm bushing being loose in the lower support yoke arm. During operation of the tail rotor controls, the looseness transferred the cyclic operational stresses, via the expansion pin assembly, to the upper support yoke arm, which failed in fatigue. Under continued operation, the pitch control input rod then translated upwards into the path of the rotating tail rotor gearbox input flange. The pitch control rod wore down until the input rod no longer transmitted operational forces and it separated with the sequential loss of tail rotor control. During a recent 500-hour inspection, a visual check on the expansible pin was performed; however, only one end of the expansion pin assembly appeared to have been visually checked. The manufacturer's maintenance manual does not specify how the installation check should be performed.

Quoted verbatim from the NTSB record.