Date: 201310
Location: ZZZ.Airport, US
Aircraft: B757 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight phase: Parked
Aircraft component: Nose Gear Wheel
Reporter organization: Air Carrier
Reporter function: First Officer
Human factors: Troubleshooting; Confusion; Situational Awareness
Second reporter function: Pilot Flying; Captain
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: Pre-flight
Result: General Maintenance Action
Contributing factors: Company Policy; Aircraft; Human Factors; Procedure
Primary problem: Human Factors

Narrative: Found right nose wheel inner bearing seal leaking grease. Called Maintenance and entered ACARS write-up. Maintenance wiped off excess grease; but did not address the actual leak; as stated in the Maintenance Release action. I have had two previous encounters with this exact same problem: The first in February 2012 in ZZZ and one in October 2013 in ZZZ1. Both times the wheel was replaced and we were told by Maintenance that there is no way of checking the condition of the bearing without disassembling it; and therefore the only solution was to replace the wheel. It is approximately a 20-minute procedure. In 2012; the Captain and I were pressured to take the flight; but we felt uncomfortable and the Captain insisted it be replaced. I was contacted by the Union Flight Safety Committee thanking us for insisting on the proper repair of an obviously potential safety of flight item. Last week; after discussion with Maintenance [about] my prior experience on the same item; they also chose to replace the wheel. On this occasion in ZZZ2; they did not. In fact; initially they did not even want to come and discuss it with us in the cockpit until we insisted they do so. At that point; the Maintenance Supervisor came to talk with us. He told us that Mechanic X had wiped the excess grease and signed-off the write-up referencing a section he referred to as Chapter 32-45-03 in the Maintenance Manual (M/M). He explained that there was no history of vibration or other problems with the nose wheel. I discussed my previous experience in ZZZ and ZZZ1; as well as the [comments from the] Chairman of the Union Committee from 2012. He [Maintenance Supervisor] insisted that there was no further maintenance required and it was a legal sign-off; even though they did not address the cause of the actual leak itself. Based on that conversation; the Captain and I discussed and decided that it was safe to continue. In hindsight; the question still remains as to why other Maintenance Stations conclude differently with exactly the same issue regarding the wheel bearing seal. In my 12 years of experience doing walk-arounds on this fleet; I have only found this issue three times; which leads me to believe it is not a common issue. Two out of three of these occurrences have been after we have changed our takeoff profiles to an unbalanced field concept; which has resulted in far higher rotation speeds. This could be causing more bearing problems and should be something we keep an eye on.

Callback: Reporter stated that since the merger; new Takeoff and Decision performance procedures have been implemented that require significant increases in aircraft speeds prior to rotation. Not uncommon now; with the new procedures; to be doing 200 MPH before rotation on their B757s. He suspects the higher speed wheel rotations and possibly higher bearing heat; are contributing to the bearing grease leaking pass the grease seal. What he questions is; if grease runs out of the bearing; will sand; dirt and debris get into the bearings. If so; that could lead to bearing disintegration and possibly wheel separation from the aircraft during takeoff because the wheel nut has nothing to hold the wheel in place on the axle.

Second narrative: My First Officer found grease on axle of right nose wheel. He wrote it up as evidence of a leaking wheel bearing. Maintenance cleared item by removing the grease. We called Maintenance and indicated that; that did not address the leak. Maintenance Supervisor came out to talk about the problem. He assured us that all applicable procedures were followed. I then accepted the aircraft. After thinking about it during the flight I felt that no attempt may have been made to correct the cause of the leak. [The errors were] flight crew communication with Maintenance [and] pilot communication to Operations.


Synopsis: Two pilots report the right nose wheel inner bearing seal was found leaking grease on a B757 aircraft during a walk-around. First Officer questions whether the newly implemented higher aircraft speeds prior to rotation are contributing to the leaking grease and why Maintenance Stations are not consistent with decisions  to replace the tire and bearings when faced with the same issue.