Eclipse Aviation EA500 N539RM incident near Pontiac, Michigan

Probable cause

The inadvertent stalling of the rudder trim actuator motor during flight due to the pilot's unintentional exceedence of the motor's design limit for stalling while accelerating after completing a simulated engine-out maneuver.

NTSB analysis

The instructor pilot reported that the pilot receiving training had completed a simulated engine failure of the right engine. Upon completion of the maneuver, he attempted to re-trim the rudder trim since it was set at 58 percent left trim. The rudder trim did not respond. The instructor pilot switched to Alternate trim but without success. The pilots followed the checklist items found in the Quick Reference Handbook (QRH) but without success. The manual trim did not correct the condition with the airspeed at about 200 knots. The instructor pilot executed a precautionary landing without incident. The airplane was shut down. When the airplane was restarted, the condition was corrected and the rudder trim operated normally. On April 30, 2008, Eclipse Aviation issued a Customer Pilot Communication (CPC) No. 500-2008-007 titled "Rudder Trim Operation." The CPC stated, "There have been several instances of Eclipse 500 operators reporting an inability to actuate the rudder trim following acceleration from a practice single engine event. It was determined that this is caused by trimming rudder for a slow airspeed and then accelerating without removing trim, significantly increasing the trim tab loading and exceeding the trim motor design stalling point. This is considered normal operation, as it is a feature of the design to prevent excessive rudder loads."

Text from the NTSB. Open the NTSB docket for CHI08IA109 for the full record.