Gainesville, GA, USA
N696CH
Aerospatiale 350B
The helicopter collided with terrain during a demonstrated hydraulic servo-control system failure. The check airman brought the helicopter to a hover with hydraulics off. The check airman experienced a gust of wind which pitched and yawed the helicopter onto the right side of the fuselage. A Review of the Eurocopter training syllabus for the AS 350 B1/B2, states in simulated hydraulic servo-control system failures, the "HYD TEST" button should be used when conducting this procedure; and discussion and/or demonstration should be performed in cruise flight at approximately 90 knots. The Gainesville 1900 weather observation reported visibility 10 statue miles, wind direction 310 degrees, wind speed 17 knots, gust 23 knots.
On May 13, 2002, at 1900 eastern daylight time, a Aerospatiale 350B, N696CH, registered to and operated by Critical Care Medflight Incorporated, collided with the ground during a demonstrated "soft touch" landing, at Lee Gilmer Memorial Airport, Gainesville, Georgia. The instructional flight operated under the provisions of Title 14 CFR Part 91 with no flight plan filed. Visual meteorological conditions prevailed at the time of the accident. The helicopter was substantially damaged, and the check airman and airline transport rated pilot were not injured. The flight departed Gainesville, Georgia, at 1900. According to the check airman, he was conducting a pilot proficiency check ride, and was instructing the pilot on simulated hydraulic failure approaches and landings. The check airman assumed control of the helicopter to demonstrate technique items. As he brought the helicopter to a hover altitude, simulating the late stages of a normal approach with hydraulics off, a wind gust induced a left yaw and the nose pitched up. The check airman made the necessary control inputs to correct the yaw and pitch changes, but the helicopter did not respond. The check airman directed the pilot to restore hydraulic power; but before boost control authority became usable, the yaw rate became uncontrollable. The helicopter touched down on the right skid and rolled over. The rotor blades subsequently struck the ground. According to the airline transport rated pilot, he was undergoing a check ride at the time of the accident. After making a hydraulics off run-on landing, he brought the helicopter to hover with hydraulics off as instructed by the check airman. After demonstrating the handling characteristics of the helicopter, the airline transport pilot set the helicopter down. The check airmen then stated that he would demonstrate the handling characteristics of the helicopter in the hydraulics off configuration. The check airman brought the helicopter to a hover approximately three feet above the ground. At that time the helicopters nose appeared to pitch up dramatically. This attitude was followed by a simultaneous rotation about the yaw axis. As the spin accelerated the check airman instructed the airline transport rated pilot to restore the hydraulics, which was done by depressing the switch on the collective. The rotation of the helicopter continued, and the helicopter impacted the ground coming to rest on the right side of the fuselage. Examination of the helicopter revealed the right side of the fuselage had buckled. The right side skid was separated from the fuselage. The tail boom was separated from the airframe and the tail rotor gearbox separated from the tail boom. The hydraulic off horn silencer was found in the off position and operated normally. The hydraulic reservoir was full of hydraulic fluid. All three-rotor blades were broken off at the blade grips. The left seat was separated from the seat tracks. A Review of the Eurocopter training syllabus for the AS 350 B1/B2, simulated hydraulic servo-control system failures, states in section A) that the "HYD TEST" button should be used when conducting this procedure. Section B states: Landing with hydraulics off will be accomplished by making a shallow (4-6 degree) approach over a clear area and landing to the ground with slight forward speed. After landing, the collective should be lowered and locked down before re-engaging hydraulic pressure. Section D, states the AEC pilot should discuss and may demonstrate the use of the emergency hydraulic cutoff switch located in the collective pitch lever to disable a yaw or main servo, which has had a slide-valve seizure. Discussion and/or demonstration should be performed in cruise flight at approximately 90 knots. Review of the flight manual section 7.7 states; "In the event of a hydraulic pressure failure, this system provides hydraulic assistance for sufficient time to enter a flight configuration with acceptable control operating loads. The Gainesville 1900 weather observation reported visibility 10 statue miles, wind direction 310 degrees, wind speed 17 knots, gust 23 knots.
The check airman’s failure to follow prescribed procedures that resulted in the lost of control and subsequent in-flight collision with the terrain. A factor was gusting wind conditions.
Source: NTSB Aviation Accident Database
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