Date: 201309
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: Regional Jet 200 ER/LR (CRJ200)
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Takeoff / Launch
Aircraft component: Nose Gear
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Flying; First Officer
Reporter qualification: Flight Crew Commercial
Human factors: Communication Breakdown
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Aircraft Aircraft Damaged; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Diverted; General Flight Cancelled / Delayed
Contributing factors: Company Policy; Procedure; Human Factors
Primary problem: Procedure

Narrative: Upon takeoff; the nose gear failed to retract producing a 'GEAR DISAGREE' warning message (and associated 'NOSE GEAR DOOR' warning message). The Nose Landing Gear (NLG) indicated 'Down and Locked' throughout the flight. We performed the QRH procedure for the Gear Disagree Message. This instructed us to manually extend the landing gear. Upon completion of the checklist; all three landing gears were 'Down and Locked'. I was the flying pilot; so the Captain ran the QRH while ATC vectored us in a box pattern near our departure airport. The QRH instructed us to land at the nearest suitable airport. Upon considering a landing back at our departure airport; we decided to fly to ZZZ1. It seemed more suitable in that it had longer runways.A quick calculation of available fuel determined that we had sufficient fuel to fly to ZZZ1 with the landing gear down at 200 KTS. The flight to ZZZ1 proceeded uneventfully. A few passengers were rebooked on different flights through ZZZ1; but the majority continued to our scheduled destination about 2.5 hours late with us; after we picked up a spare aircraft. A small metal plate that is supposed to slide on top of the Proximity Sensor Electronics Unit (PSEU) on the back of the nose landing gear strut when weight is removed from the gear was bent slightly downward. This prevented that plate from aligning on top of with the PSEU. It instead hit the rear side of the PSEU (a small scratch mark was visible after landing); preventing the nose landing gear from unlocking. This was not evident during the preflight inspection in our departure airport; as the bend was very slight and not very obvious while on the ground. We were not pushed back by a cart [small Electric Tug] in our departure airport. I have no idea how it might have been bent after the previous flight. The root cause of the diversion to ZZZ1 was the availability of additional services for passengers; longer runways and Maintenance.  [Recommend] to figure out a way to protect the nose strut PSEU. This is the third time this exact scenario has happened to this Captain.  During a normal preflight inspection it is not easy to spot an abnormality as small as this one was. We normally check that both components of this system appear to be in place and undamaged; but this abnormality was not obvious.

Callback: Reporter stated the 'small metal plate' that had a scratch on it was attached to the top of the upper scissor's link on the aft side of the Nose Landing Gear (NLG). Another plate mounted to the NLG above the upper scissor's link and normally slightly bent; was one of two plates; each with a post [sensor] attached that involve the Weight on Wheels (WOW) System and the Proximity Sensor Electronics Unit (PSEU).  Also; one of the two plates with a sensor was bent more than the other plate was and the sensor end had a chunk missing. The plate with a scratch on it was directly below. Reporter stated that prior to takeoff; they performed a power turnout from the gate instead of requiring a pushback with one of the tugs. Reporter suspects that at a previous station; the strap that wraps around the NLG strut when using the electric tugs for pushback or towing; may have damaged or bent the sensor plate downward that later contacted the lower [target] plate on the scissor's link. That contact probably caused the scratch on the lower plate. The CRJ-700 aircraft have a different arrangement.



Synopsis: A First Officer reports the nose gear on a CRJ-200 aircraft failed to retract on takeoff generating a 'Gear Disagree' and associated 'Nose Gear Door' warning message. Aircraft diverted. Pilot suspects the damage found to the Weight on Wheels (WOW) System proximity sensor support plate; above the nose gear upper scissor link; may have been caused by a strap used to secure the nose gear to electric tugs for pushback and tow.