Date: 201208
Local time of day: 0001-0600
Location: ZZZ.TRACON, US
Flight conditions: VMC
Weather elements / visibility: Turbulence; Thunderstorm
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Descent
Airspace: Class A ZZZ
ATC / advisory: TRACON ZZZ
Aircraft component: VHF
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Anomaly: Aircraft Equipment Problem Less Severe; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Loss Of Aircraft Control; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Overcame Equipment Problem; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Regained Aircraft Control; General Maintenance Action
Contributing factors: Aircraft; Weather
Primary problem: Ambiguous

Narrative: There were severe turbulence reports up higher and ATC had us at much lower altitudes from reports but we still encountered moderate/severe turbulence which started at FL220. Aircraft rolled right and left excessively and had to turn the autopilot off and regain control. I used a fair amount of time to access aircraft controls; hand flying and not forcing the issue and was also not sure if this was a turbulence issue alone. Aircraft has an on going deferred issue with the number two rudder PCU inoperative which was a real concern and complicated our assessment. The initial goal was to fly the airplane; navigate and communicate to ATC our issue. But we had a secondary communication issue; not knowing that the number one VHF radio started dropping out the last two digits in both frequency windows. Trying to communicate with ATC was a real issue; we lost communication with TRACON and went through four frequency's trying to relay our problem and inform them we would not be descending on schedule for crossing restriction. This radio issue continued with Approach and Tower; but we were now aware of it and when frequency changed we corrected it. We initiated a right turn talked with ATC; got vectors; reported the severe turbulence; advised that we would not comply with crossing restrictions because of the turbulence without a turn. TRACON seemed very satisfied with our decision and had no issues and we did not declare an emergency. We were vectored in for a visual approach with normal landing and park at gate. At gate we informed Maintenance of the moderate/severe turbulence and the number one VHF radio. Phone call was made to the Duty Manager; TRACON; and the North East Chief Pilot later in the day. Seat belt sign was on; no injuries at all. The aircraft did not overspeed; inspection was done and no damage found. The VHF radio was replaced. I have checked the box that I exercised Captain's Authority because while regaining control and accessing the aircraft; I knew not descending initially would be in conflict with our ATC clearance.




Synopsis: Air Carrier Captain reports being dispatched with an inoperative rudder PCU and encountering moderate to severe turbulence. The aircraft rolls excessively and he questions the role the inoperative PCU may be playing. VHF communication problems are also reported.