Incident Description
After departing St. Louis and reaching cruise flight, the crew experienced a continuous trim pitch-up condition that had to be relieved by reducing airspeed. No aural indication was noted by the crew. The return to the departure airport was uneventful.
Inspection Findings
Follow-up inspection of the trim system revealed an out-of-tolerance trim actuator. The unit had accumulated 355 operational hours since an O-time overhaul. Normal service life for a trim actuator is approximately 2,000 hours. The unit had been certified as O-time by an FAA-certified shop.
Trim Actuator Condition
A teardown inspection of the trim actuator unit revealed that it had not been overhauled to the specifications of the unit manufacturer. The trim actuator was deemed inadequate for operation as overhauled.