Eurocopter AS-350 N91DK

Summary

On 24 September 2010 at about 20:34 local time, a Eurocopter AS-350 registered N91DK, operated by Dekalb County Police Services, was involved in an accident near Covington, Georgia, United States. 2 people were on board and 2 had minor injuries. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

24 September 2010 at 20:34

Classification

Accident

Location

Covington, Georgia, United States

Nearest airport

Covington Municipal Airport (9A1)

Coordinates

33.6261, -83.8419

Aircraft

Eurocopter AS-350

Registration

N91DK

Category

Helicopter

Engines

1

Operator

Dekalb County Police Services

Operating rule

Public Use

Phase of flight

Not recorded

Route

Covington → Covington

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

ERA10TA501

2 people had minor injuries.

The flight instructor's loss of control of the helicopter during the intentional demonstration of a low speed, hydraulics-off maneuver, that was warned against in the helicopter manufacturer's flight manual.

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

Read the full NTSB narrative

According to the pilot of the helicopter, the instructor simulated a hydraulics failure by “turning off” the flight control hydraulics switch, in order to perform a hydraulics-off, run-on landing as the remedial action to the simulated emergency. As the helicopter slowed over the runway, the nose yawed to the left, and the pilot was unable to correct the yaw with right pedal input. The instructor took control of the helicopter, and completed a low-level, left-hand orbit to demonstrate and complete the maneuver. As the helicopter completed the left orbit and lined up for landing, it “rolled wings level” but then continued to roll to the right and collided with terrain. The pilot said that the entire maneuver was conducted hydraulics-off, and that he felt the instructor had control of the helicopter until it rolled past wings-level to the right. The pilot added that the instructor had successfully completed a similar maneuver earlier in the day, without restoring the flight control hydraulics. According to the manufacturer's Flight Manual (Emergency Procedures) and the Flight Manual Supplement, Hydraulic Pressure Failure Training Procedures, "CAUTION: DO NOT ATTEMPT TO CARRY OUT HOVER FLIGHT OR ANY LOW SPEED MANEUVER WITHOUT HYDRAULIC PRESSSURE ASSISTANCE. THE INTENSITY AND DIRECTION OF THE CONTROL FEEDBACK FORCES WILL CHANGE RAPIDLY. THIS WILL RESULT IN EXCESSIVE PILOT WORKLOAD, POOR AIRCRAFT CONTROL, AND POSSIBLE LOSS OF CONTROL." Both the pilot and the instructor stated that there was nothing wrong with the performance and handling of the helicopter.

Quoted verbatim from the NTSB record.