A Q400 flight crew encountered recurring resistance to rudder inputs during the descent.
Synopsis
A Q400 flight crew encountered recurring resistance to rudder inputs during the descent.
Narrative
While leveling at 12;000ft and slowing to 250K; we received permission to speed up; so the First Officer applied power and needed to also apply right rudder to compensate for the yaw caused by the increase in power. I was talking to company during this time when I felt the aircraft yaw hard to the right. I asked; 'What happened?' The First Officer replied; 'The rudder was stuck.' We then needed to keep descending and slowing and with power pulled back we needed left rudder to compensate for the power change. The First Officer again said; 'The rudder is stuck.' I took the aircraft and disengaged the autopilot and pushed on the left rudder until it broke free; causing the aircraft to yaw hard to the left due to the amount of force I had applied to free it. Then; the rudders seemed to work normally again; I could move the rudder pedals normally with my toes. I gave the aircraft control back to the First Officer and he also said the rudder pedals felt fine. Shortly after that; he said they were locked up again. He and I could free them each time they locked up using much greater force than normal. The yaw was not as severe since we were now flying slower; being vectored onto the ILS. I believe they locked up at least 3-5 times. We did not declare an emergency. I felt the aircraft was flying normally during the arrival and approach. There seemed to be no danger.
Second reporter narrative
The rudder trim switch seemed to be responsive in a normal manner at all times. We landed without incident and contacted Maintenance Control; Dispatch; and the Duty Officer.
NASA callback
The Captain advised the Flight Crew had flown three legs immediately prior to the leg during which the event occurred. Although there was some weather and turbulence during the flight sequence he did not recall any significant in-flight icing conditions or heavy precipitation while on the ground that might have brought consideration of frozen water conditions impacting the rudder control mechanism or aerodyanamics.Although he has not seen the aircraft log book to verify maintenance actions he has been advised that the rudder feel control unit was replaced and that the aircraft is back in service.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.