Date: 202105
Local time of day: 1801-2400
Location: ZZZ.TRACON, US
Flight conditions: VMC
Light: Dusk
Aircraft: B767 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise; Initial Climb
Airspace: Class A ZZZ; Class B ZZZ
ATC / advisory: Center ZZZ; TRACON ZZZ
Aircraft component: Rudder Control System
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Human factors: Troubleshooting
Anomaly: Aircraft Equipment Problem Critical; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Diverted; Flight Crew Overcame Equipment Problem; Flight Crew Requested ATC Assistance / Clarification; General Flight Cancelled / Delayed; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: Departed ZZZ 4L in windy gusty conditions with a normal takeoff. Passing approximately 500 feet; a Rudder Ratio EICAS caution message appeared. I followed the QRH procedure after doing the 'after takeoff' checklist. This procedure stated: Above 160 knots avoid large or abrupt rudder inputs; Crosswind limit is 15 knots; Do not autoland. I made a maintenance write up and we continued. Climb was in IMC with light chop since there was a weather system moving into the east coast.Approximately an hour and half into the flight at FL340 received a Cabin Alt EICAS warning along with Cabin Altitude light and aural warning. We performed the immediate actions: Donned the oxygen masks and established crew communication. I followed the Cabin Altitude checklist and when I came to the decision tree: Cabin altitude is controllable (I switched to the other alt controller without any change) or Cabin altitude is uncontrollable; I felt that I was in between the two since the cabin was slightly above 10;000 feet and HOLDING STEADY. I advised ATC and asked for a lower altitude to the mid 20;000 feet thinking the cabin would decrease below 10;000 feet. I was also reluctant to go any lower because there was weather and turbulence below us. I called the purser and asked if the cabin oxygen masks had dropped and she informed that they had not confirming that cabin altitude never got above 14;000 feet. The cabin altitude decreased below 10;000 but the EICAS message was still illuminated so I asked for lower again. Passing 20;000 feet the Cabin Alt warning went out and the cabin showed approximately 6;000 feet so I elected to stop at FL190. This kept us right above the weather with the FO deviating around the tops.I informed the purser of the situation and made a preliminary PA. Contact with Dispatch was next with Maintenance Control on the line. Maintenance Control was not able to rectify our situation so the Dispatcher and I started looking for a divert airport. Due to the weather and the cross-wind limit of 15 knots due to the Rudder Ratio issue I was very limited in airport selection since the cross winds were in excess of 15 knots in ZZZ1; ZZZ2; ZZZ3; ZZZ; ZZZ4. ZZZ5 was the only option with calm winds; 400 Feet broken; 3 MI visibility and rain.I made the decision to divert to ZZZ5 with dispatch concurrence. I informed the purser and made another PA.We began planning for landing into ZZZ5 and was told of moderate turbulence ahead. I seated the flight attendants. Approaching the IAF for [Runway] XXL ATC informed us of an aircraft ahead of us Going Around since they were unable to see the runway at mins. I inquired about XXR and was told there was another aircraft on approach for that runway. That aircraft landed and we proceeded to a normal landing. Fire and rescue greeted us and after getting the all OK we taxied uneventfully to the gate.




Synopsis: B767 Captain reported a Rudder Ratio EICAS message and loss of cabin pressure control resulted in a diversion.