Date: 201410
Local time of day: 1801-2400
Location: ZZZ.Airport, CA
Flight conditions: VMC
Light: Night
Aircraft: B767-300 and 300 ER
Operator: Air Carrier
Operating under: Part 121
Mission: Cargo / Freight / Delivery
Aircraft component: Hydraulic System
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Troubleshooting; Confusion
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: Pre-flight
Result: General Maintenance Action; General Release Refused / Aircraft Not Accepted; General Flight Cancelled / Delayed
Contributing factors: Procedure; Human Factors; Aircraft
Primary problem: Human Factors

Narrative: Arrived at B767-300 for a scheduled flight from ZZZ-ZZZ1; October 2014. While walking under aircraft to the stairs both First Officer (F/O) and myself noticed a puddle of fluid under the aircraft. We called maintenance and after arriving maintenance discovered a leaky hydraulic brake valve. After a lengthy delay; the valve was fixed. Just prior to engine start we did a flight control check and I immediately noticed a shudder in the aircraft (not the yoke or pedals but the aircraft) while turning the ailerons right and left. I repeated the aileron check and felt a noticeable shudder in the aircraft again (approx. mid turn both left and right). My F/O noticed the shudder as well and I had him do the flight control check as well. We had the same results. We did notice that at full deflection of the elevator we felt it as well and passed the info along to the Mechanic X as well as write the anomaly in the logbook. He felt the shudder as well. We returned to the aircraft after maintenance looked at the problem and we tried numerous hydraulic configurations; tried it with the engines running; ran the flaps down full and extended the speed brakes. All to no avail. The shudder remained and I refused the aircraft with the continuing problem. The next evening we were again presented with the same aircraft. We noticed the puddling again under the aircraft as we walked up to it. When we got to the cockpit we immediately turned on the hydraulics to see if the airplane was still having a shuddering issue. It still was so we stopped our preflight; wrote the issue up again in the logbook and called maintenance. After a lengthy delay with maintenance trying to isolate the problem I was told everything checked out okay with their tests and checks and the airplane was green - HOWEVER the shuddering still continued during the flight control check.  My F/O and I did a full control check and then noticed at full deflection of the elevator we could feel the shudder and also using the stabilizer trim we felt the shudder as well. (The shuddering almost feels like a can is being rolled to the back of the airplane during loading).  I realize that maintenance checked the rigging and looked at many things; however no one can tell me what is causing the aircraft to shudder while moving the flight controls. I've never felt it in any other B767 that I've flown the past 17 years and it caused me some concern. I am no mechanic but it definitely feels like something hydraulic is cavitating or pulsating during flight control movement. I was just rescheduled to operate this aircraft again tonight to ZZZ1. They say that it is green and ready for flight.

Callback: Reporter stated that on the first and second time he was confronted with the same B767-300 aircraft; the shudder effect was an eight on a scale of ten. He and the First Officer (FO) could feel the shudder in the floor and through their seats. The ailerons would shudder about mid-travel; but the rudder and elevator shutter occurred during full travel.Reporter stated that hydraulic filters were replaced; but does not know which ones. When he was rescheduled to fly the same aircraft for the third time; he even had another experienced Captain operate the flight controls to get his opinion. Although the shudder was still apparent; the intensity was considerably less. He did fly the B767-300 aircraft that night.  No one has actually determined if air in the aircraft's hydraulic system was the contributing factor. Especially since the discrepancy started right after the leaking hydraulic brake valve was replaced.



Synopsis: Captain reports he and the First Officer felt a noticeable shudder in all control surfaces; not the yoke or pedals; but in the B767-300 aircraft itself during a flight control check; after a leaking hydraulic brake valve had been replaced.  He refused the same aircraft that night and the following night for the same reasons: the shuddering was still evident and cause could not be clearly determined.