SA-227 AC Metro III
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Less Severe; Ground Event / Encounter Loss Of Aircraft Control; Ground Excursion Runway
General None Reported / Taken
Aircraft
Aircraft was unable to maintain directional control after landing resulting in the aircraft nose wheel departing the left side of the runway. Trainee pilot was landing and aircraft started to veer slightly left shortly after touchdown. As the aircraft continued off centerline (about halfway from centerline to the edge of the runway) I took control of the aircraft. Right brake was ineffective and while trying to use differential power and slow the aircraft enough for Nose Wheel Steering (NWS); the aircraft continued towards the left edge of the runway. Realizing that even with NWS it would be difficult to bring the aircraft back to centerline without hitting a runway light; I applied max reverse power and full braking and brought the aircraft to a stop between two runway lights. I notified ATC of the deviation; requested a tug and assistance and shut down and secured the engines. The nose wheel came to rest one wheel length beyond the edge of the pavement; all other tires remained on the runway edge. Tire skid marks were apparent behind the left wheel but barely noticeable behind the right side. Aircraft was towed off the runway and to ramp by a tug.
SA-227 Captain reported directional control was lost after landing; probably due to a right main wheel brake issue. Aircraft came to a stop with no damage.