Date: 201307
Local time of day: 0601-1200
Location: ZZZ.ARTCC, US
Flight conditions: VMC
Light: Daylight
Aircraft: EMB ERJ 145 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Aeroplane Flight Control
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Flying
Reporter qualification: Flight Crew Commercial
Human factors: Confusion; Communication Breakdown; Troubleshooting
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Maintenance; Inflight Event / Encounter Other / Unknown
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Took Evasive Action; General Maintenance Action; General Release Refused / Aircraft Not Accepted
Contributing factors: Aircraft; Company Policy; Procedure; Logbook Entry
Primary problem: Aircraft

Narrative: Operation of a revenue flight that was mostly full; I believe 44 passengers. After established in cruise flight at FL270 we experienced a moderate shuddering/shaking/vibrating in both pilots control columns. Accompanying the shuddering of the control column was a loud humming noise. The autopilot did not disengage; there was no deviation in flight path either horizontally or vertically. After several minutes of assessing the situation; checking EICAS; trying to verify the source of the vibrations both the Captain and I decided to disengage the autopilot in the hopes that it might be a failed autopilot servo. Once disengaged from the autopilot the situation remained the same; no worse; no better. At this time we judged the situation to be severe enough to possibly warrant a diversion. A major airport was nearby but would require a steep descent to accommodate our arrival as well as the associated increase in workload to coordinate with ATC; Dispatch; Maintenance; and the Flight Attendant. Because of these factors and the closing proximity to our filed destination we elected to continue with the flight which would enable us to have a much more gradual descent. The timing to the nearby airport was only 6 minutes shorter than continuing (this was also a factor). We also elected to not inform the Flight Attendant or ATC. There was nothing we could think of to tell the Flight Attendant to prepare for and nothing we could think of to tell ATC. We asked for an early and shallow descent and it was granted without question. Had ATC not complied with our request we agreed that we would need priority handling to accommodate us. As soon as the vibrations began we elected to slow the aircraft down to reduce stress on the aircraft; we coordinated with ATC who complied with the request. Because of the vibrations we were extremely concerned of a flight control failure; an elevator cable breaking; aileron flutter; etc... We texted Maintenance who informed us they wanted us to return back to the departure airport. We told them no as this would keep us in the air longer. The last thing we wanted to do was stay in the air any longer than necessary. The safest option was to continue to the filed destination. After slowing the aircraft and maintaining a gradual descent into the arrival area; the situation stayed the same. Nothing that we did increased or decreased the vibrations emanating from the control column or the loud humming. On the approach it was decided to hand fly the aircraft and when configuring we elected to continue a normal approach with the fact that should the situation deteriorate we could go back to a previous aircraft setting. Once on the ground the shuddering ceased. Maintenance was once again contacted and we were told that mechanics were being sent up. We informed Operations and then contacted Maintenance on the telephone. The Mechanic then asked us why we did not know of the problem as they had been monitoring and tracking the aircraft since [last month]! There was a new logbook in the aircraft with no previous write ups associated with this problem. He also stated that he; nor anyone else in the Maintenance Department had no idea why or what was wrong with the aircraft. No one has been able to satisfy my question as to why this aircraft is still in service. Crew Scheduling then wanted us to ferry the aircraft. We told them we did not feel safe operating the aircraft. This ended the discussion and our participation with this aircraft. I am both surprised and dismayed that this aircraft was/is in service operating revenue flights with a known flight control problem. What exactly that problem is no one knows as of yet but whether it be serious or minor; the aircraft; in my opinion should be grounded until the problem is identified and fixed.This situation involved both threats; errors; and unsafe flight condition. Threats and errors were operating this aircraft with a known problem while not informing the flight crew. I have flown with MELs and other associated problems but never one with an unknown flight control problem. This in turn led to an unsafe flight condition that had no known solution. Where is the control column shudder in the QRH? Why would Maintenance ask us to return to the departure airport without knowing our position. The logbook is checked every flight to see what work was done or what problems were found and fixed. This gives the flight crew an idea of what potential problems could occur in flight or on the ground and at the least provides us a game plan of 'OK; this happened to this crew and this is what we will do...' The Company in my opinion should have grounded this airplane. I feel I was put into an unsafe flight condition without having the slightest idea of a potential problem. Maintenance Control and Operations need to work together so that at the least we are informed of a potential problem. If I had known this aircraft had a continuing problem with a critical surface such as the control column I would have refused the aircraft on the spot. I do not feel comfortable operating this aircraft with the problem; especially with paying passengers. It is my sincere hope that Crew Scheduling is not attempting to get another flight crew to reposition this aircraft without at least making them aware of this problem.

Callback: The reporter stated that the yoke shudder motion had a fore and aft as well as a side to component which extended all the way to the floor board. The shudder was more pronounce on the First Officer's yoke. The crew did not do much troubleshooting because the shudder's source was unknown and they wanted to err on the side of caution so as not to aggravate the condition. The Reporter believes that the aircraft was examined by the manufacture but he does not know the outcome of the inspections. The reason the crew did not see the previous flight control write ups was the aircraft maintenance log was new with no previous pages and no maintenance items carried forward from the previous book and so they assume the aircraft was airworthy. They did find out later that the shudder has been written up and Maintenance took some unknown action to put it back in service.



Synopsis: An EMB-145 First Officer reported an inflight control column shudder which caused concern for the aircraft's integrity. After landing Maintenance informed the crew that the vibration was an ongoing issue but it was not in the current aircraft maintenance log.