History of Flight
On November 23, 2014, about 1104 Pacific standard time, an Embraer EMB-505 airplane, registration C-GJOL, experienced an uncommanded severe yaw to the right immediately after takeoff from Palm Springs International Airport (PSP), Palm Springs, California. The airline transport pilot and four passengers on board were not injured. The airplane was operated by Hawkeye Aviation Holdings Ltd, Kelowna, British Columbia, under 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed for the planned cross-country flight to Springbank, British Columbia. An instrument flight rules flight plan was in effect.
The pilot reported that preflight preparations were normal, including removal of the control lock pin. During taxi, an abnormal feel to the rudders was detected, but all right turns were easily executed. After rotation, a significant yaw and roll to the right occurred, which were counteracted with left aileron. The pilot climbed to about 11,000 feet while continuously applying left rudder and adjusting yaw trim. A fuel imbalance warning activated due to uncoordinated flight. After advising air traffic control of a control issue, the pilot was cleared for a visual approach to runway 31L at PSP. A passenger in the right front seat, a private pilot, assisted by holding left rudder pressure. During the landing rollout, the airplane drifted right; the left wing tip contacted the runway, resulting in minor damage. The airplane was taxied to a fixed base operator without further incident.
Aircraft Information
The incident airplane was an Embraer EMB-505, Canadian registration C-GJOL, serial number 5050009, manufactured in 2013. It is a twin-engine low-wing monoplane with two Pratt & Whitney Canada 535E turbofan engines. The airplane is equipped with an Umbra Group gust lock actuator (serial number 00075) designed to prevent rudder movement from ground gusts. The gust lock system includes interlocks based on thrust lever angle and weight-on-wheels.
According to manufacturer documentation, the actuator was delivered to Embraer on February 28, 2011, and failed during tests on aircraft serial number 00052 on May 19, 2011. It was returned to Umbra, which replaced both microswitches and returned it on November 28, 2011. Embraer then installed the actuator on C-GJOL.
Examination Findings
Post-incident examination revealed that the gust lock actuator had failed in the locked position. Computed tomography (CT) scanning performed from December 2014 to March 2015 showed the extend limit switch contacts closed in standard focus scans and open in microfocus scans; high and medium density particles throughout the actuator; a discontinuity in one ball of the ball screw; distorted windings within the solenoid; and a high density particle in the solenoid piston-to-housing gap.
A subsequent examination by Umbra Cusinetti on June 16, 2015, found the actuator locked in a position close to extended. The solenoid/locking system was seized at approximately the full extended position. The pins were misaligned due to distortion of the solenoid plastic reel. The circuit board showed no mechanical failure but damaged surface coatings.
Embraer determined that with the screwshaft in the as-found position, the bellcrank would contact the rudder quadrant and could engage the slots. Embraer noted that the irreversibility of the actuator is provided by a solenoid plunger; if the solenoid fails energized, the actuator can be overpowered by spring forces. The spring force at the observed actuator stroke was about 7N, while the force to overpower the de-energized motor was about 40N. The investigation did not conclusively determine the reason for the solenoid failure.
Probable Cause
The investigation did not state a probable cause for the incident.