What was found
AIR TURNBACK, LOST F/O'S ROLL PITCH HEADING AFTER TAKEOFF. PERFORMED POWER CK OF ALL BUSES, APU, STANDBY, ENGS, AND ALL INSTRUMENTS CAME BACK TO NORMAL. POWER DOWN AIRCRAFT FOR SEVERAL MINUTES, POWERED AIRCRAFT BACK UP AGAIN, RAN BOTH ENGS. ALL F/O'S INSTRUMENTS OP CK GOOD.