Overview
A pilot proficiency examiner (PPE) was using an airplane to conduct a pilot-in-command (PIC) proficiency check for two company pilots. After one pilot completed a check that ended with a full-stop landing and reverse thrust application, the accident pilot took the left front seat while the PPE remained in the right front seat. The flight crew then taxied for departure.
Flight Sequence
Data from the enhanced ground proximity warning system (EGPWS) showed the takeoff roll began with flaps retracted, thrust reversers armed, and both engines stabilized at 96 percent N2. About two seconds later, the cockpit voice recorder (CVR) captured the V1 call. Acoustic analysis indicated a decrease in N2 speed on one engine, likely the right, consistent with the PPE retarding that engine to flight idle to simulate an engine failure. The takeoff continued.
At an airspeed of 148 knots and about 18 feet radar altitude, the CVR recorded a command to retract the landing gear. The landing gear remained extended. About one second later, three seconds after becoming airborne and at 33 feet altitude and 149 knots, the CVR recorded a rattling sound consistent with deployment of the right thrust reverser, which continued to the end of the recording. About 1.5 seconds later, the PPE asked "…what happened," indicating the deployment was likely not annunciated.
Thrust Reverser Deployment
The right engine N2 speed continued to decrease gradually. The airplane rolled slightly left, then returned to wings-level. It continued climbing with landing gear extended, while pitch changes occurred. The flight crew exchanged comments showing confusion. As airspeed decayed from about 144 knots, the airplane began a right roll with decreasing speed. Nine seconds after the initial gear retraction call, the PPE requested gear retraction, which occurred one second later. Airspeed continued to decrease. About 11 seconds after the PPE's question, the EGPWS sounded a bank angle alert at a roll of about 30 degrees and airspeed of 132 knots. The right roll reached a maximum of about 39 degrees, the last valid bank angle recorded.
The airplane impacted the ground off the right side of the runway in a nose- and right-wing-low attitude. Postaccident examination found landing gear and flaps retracted, no preimpact failure or malfunction of flight controls or engines, and no evidence of mechanical failure in either engine.
Investigation Findings
A definitive reason for the right thrust reverser deployment could not be determined. No previous instances of inadvertent in-flight deployment were documented by the operator or airframe manufacturer for that make and model. Certification flight testing of an airplane with the same thrust reverser system determined controllability remained with the reverser deployed and throttle retarder system functioning, even with momentary peak thrust bursts. The throttle retarder system should have reduced engine thrust to idle within 4 to 8 seconds. Acoustic analysis showed the lowest N2 was about 84 percent, occurring over 8.5 seconds after deployment. No determination could be made why the throttle retarder system did not reduce thrust to flight idle, nor why the flight crew lost directional control.
The PPE had severe coronary artery disease, but the CVR recorded no evidence of impairment. Neither his heart disease nor medications would have impaired judgment or physical functioning. There was no evidence any medical condition affected the pilot being examined.
Probable Cause
The flight crew's inability to maintain airplane control during initial climb following deployment of the right thrust reverser for reasons that could not be determined because postaccident examination of the airframe and engine thrust reverser system did not reveal any anomalies. Contributing to the accident was the excessive thrust from the right engine with the thrust reverser deployed for reasons that could not be determined during postaccident examinations and testing.