As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE ON TAKEOFF ROLL IN DCA, FLIGHT NR 3516 HAD NR 2 ENGINE CONTROL MANUAL LIGHT COME ON, PROPS DROPPING TO 650 RPM. CONNECTOR ON ELECTRONIC ENGINE CONTROL AND TORQUE SIGNAL CONDITION UNIT WERE CLEANED AND AIRCRAFT WAS GROUND RUN AND OPERATIONAL CHECKS WERE GOOD. AIRCRAFT WAS RETURNED TO SERVICE.