B767-300 and 300 ER
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 151; Flight Crew Total 10145; Flight Crew Type 7091
Situational Awareness
Aircraft Equipment Problem Less Severe
General Maintenance Action; General Release Refused / Aircraft Not Accepted
Aircraft
This report documents a series of persistent UNSCHD STAB TRIM EICAS messages that were received on Aircraft X during my most recent pairing. The first indication was during taxi out an overnight-delayed flight. It appeared cyclically every few minutes; and [Maintenance Control] assisted in the clearing of the EICAS. We proceeded to ZZZ uneventfully. While taxi out of ZZZ 2 days later on ferry flight; the same EICAS appeared. Again [Maintenance Control] assistance cleared the caution through system resets. We gate returned and ZZZ maintenance confirmed a full system reset and that the previous cautions were nuisance only. At no time was actual stabilizer trim movement observed; and we elected to takeoff for ZZZ1. The UNSCHD STAB TRIM caution appeared passing 12;000 feet and began cycling on and off every few minutes; never staying on for more than a few seconds. We consulted the QRH; but as no actual trim movement was noted and the cautions were momentary; we did not run the procedure. Consultation with dispatch resulted in a non-emergency divert to ZZZ2. After mechanics and parts were flown in to ZZZ2; we attempted to fly [back to ZZZ1 on the] ferry flight. Again the UNSCHD STAB TRIM EICAS appeared; this time with engines off during the before pushback checklist; and the flight canceled. One more attempt by our crew was made to fly [the next day]; but flight was canceled pending further maintenance.
B767 First Officer reported multiple Stabilizer Trim anomalies.