Incident Description
On April 17, 2008, at 1830 eastern daylight time, an Eclipse Aviation EA500, registration N539RM, encountered a stuck rudder trim while conducting a simulated single-engine instrument approach to Bishop International Airport (FNT) in Flint, Michigan. The flight, which had departed Detroit City Airport (DET) about 1815 on a local instructional flight under 14 CFR Part 91, was operating under visual meteorological conditions with an instrument flight plan filed.
The instructor pilot reported that after completing a simulated right engine failure, the pilot receiving training attempted to adjust the rudder trim, which was set at 58 percent left trim. The trim did not respond. Switching to alternate trim also had no effect. The pilots followed the Quick Reference Handbook (QRH) checklist without success, and manual trim did not correct the issue at an airspeed of approximately 200 knots. The instructor pilot diverted to Oakland County International Airport (PTK) in Pontiac, Michigan, due to more favorable landing winds, and performed a precautionary landing without incident at about 1845. Neither the instructor nor the pilot/owner was injured. After shutdown and restart, the rudder trim operated normally.
Manufacturer Response
On April 30, 2008, Eclipse Aviation issued Customer Pilot Communication (CPC) No. 500-2008-007 titled "Rudder Trim Operation." The CPC stated that several Eclipse 500 operators had reported an inability to actuate the rudder trim following acceleration from a practice single-engine event. It determined that this occurred when rudder trim was set for a slow airspeed and the aircraft then accelerated without removing the trim, increasing trim tab loading beyond the trim motor's design stalling point. This was considered normal operation and a design feature to prevent excessive rudder loads. The CPC explained that the rudder trim actuator incorporates a motor that stalls at a specific load to avoid excessive rudder forces, along with a no-back feature that holds the trim surface in position when the motor cannot support the load.
Guidance to Pilots
The CPC provided the following recommendations for operators:
1. Use proper rudder trimming technique: first reduce yaw with pedal pressure, then trim to relieve pressure, avoiding excessive trim input. 2. After practice single-engine events or similar situations where significant rudder trim is used, remove the trim once both engines are restored and before accelerating to substantially higher speeds. 3. If rudder trim cannot be reduced after acceleration, continue to attempt rudder trim adjustment using the throttle quadrant knob while reducing airspeed until control is restored. 4. Be aware that engaging alternate trim on the MFD disables normal aileron, elevator, and rudder trim controls until deactivated. 5. If rudder trim remains inoperative after reducing airspeed for approach and landing, contact Eclipse Customer Care or appropriate maintenance support. 6. Never cycle aircraft power with engines running to circumvent published AFM procedures. 7. The aircraft has been flight-tested and certified with full rudder trim input during approach and landing and is fully controllable throughout landing in that configuration.