What was found
FLT 6193 - IAD-JFK - DURING CLIMB, THE FLT CREW EXPERIENCED A FAILURE OF THE LEFT ENGINE RPM INDICATION. CREW NOTIFIED DISPATCH AND MAINTENANCE CONTROL AND RETURNED TO IAD. MAINTENANCE CONTROL NOTIFIED LINE MAINTENANCE OPERATIONS AND MECHANICS WERE DISPATCHED TO THE AIRCRAFT. MAINTENANCE FOUND THAT THE LEFT ENGINE TACH GENERATOR HAD FAILED. MAINTENANCE REMOVED AND REPLACED THE TACH GENERATOR, PERFORMED REQUIRED ENGINE RUN VERIFICATIONS AND RELEASED THE AIRCRAFT FOR SERVICE. (M)