Air carrier captain reports being dispatched with an inoperative rudder PCU and encountering moderat...

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.

Original NASA ASRS Text

Title: 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.

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.

Data retrieved from NASA's ASRS site as of July 2013 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	1028334
Time
Date	201208
Local Time Of Day	0001-0600
Place
Locale Reference	ZZZ.TRACON
State Reference	US
Environment
Flight Conditions	VMC
Aircraft 1
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	Descent
Flight Plan	IFR
Component
Aircraft Component	VHF
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 150 Flight Crew Total 14000 Flight Crew Type 2000
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance Inflight Event / Encounter Loss Of Aircraft Control Inflight Event / Encounter Weather / Turbulence

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.