Date: 201702
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: EMB ERJ 170/175 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Taxi
Aircraft component: Squat Switch
Component problem: Failed
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Anomaly: Aircraft Equipment Problem Less Severe; Ground Event / Encounter Other / Unknown
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Landed As Precaution; Flight Crew Returned To Departure Airport; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: [Before departure] aircraft required Type 1 to remove frost from the aircraft wings and surfaces. We pushed back from the gate 10 feet; configured and started deicing. After deicing was completed and all check lists were accomplished we requested a push clearance from ramp and we were cleared to push tail west. I said 'beacon on; brakes released'; released [the brakes]; simultaneously the tug started pushing and I heard a bang and asked if it that was the shear pin. Ground personnel initially said no but then stopped and looked a second time and notified us that we had indeed sheared the pin on the tow bar. We stopped the push [and] notified ramp and maintenance. Maintenance personnel came out; inspected the aircraft and tow bar and told us that no damage had occurred and we 'had a new tow bar' so a gear swing would not be required. After maintenance signed off in the maintenance logbook we continued as normal.After liftoff and positive rate gear up EICAS message 'Landing Gear (LG) Weight on Wheels (WOW) System (SYS) FAIL' appeared when the gear was fully up. I was flying and continued normal procedures until we got the flaps up. First Officer (FO) pulled the QRH for 'LG WOW SYS FAIL.' We then switched duties and he was pilot flying and I was pilot monitoring while I ran the QRH. At the bottom of the QRH it said to land as soon as possible so we notified ATC that we would like to level off; stay in the area; and needed time to run checklist and would be returning. At this point we had NOT declared an emergency. After finishing all our checklists; we prepared for arrival. We made our approach and after notifying our dispatcher; flight attendants; and passengers that we were returning due to a system failure. The flight attendants were briefed regarding a yellow emergency and I stated that everything should be normal for our landing. I did communicate to all that we would be staying on the runway and pulled off by a tug. We informed ATC that we would [need priority]; stopping on the runway; and would need to be towed off. We executed [an] ILS and landed as soft as possible and rolled until we came to a stop. While extending the gear down to the locked position the 'LG WOW SYS FAIL' EICAS message extinguished. As we stopped I made an announcement that fire trucks and emergency vehicles would be arriving and that it was standard precautionary procedure. Once the fire trucks and Ops met us on the runway along with a tug; we tossed the gear pins to the tug driver and had him pin the nose gear before being moved. While pulling the AC off the runway the tug driver made an extremely sharp turn and the EICAS of 'STEER FAIL' returned. Tug driver; fire trucks and Ops escorted us into gate uneventfully. Same maintenance personnel that signed off for the shear pin met us at the AC and started troubleshooting. All passengers safely exited the aircraft and I worked with all ground personnel to assist.




Synopsis: ERJ-170 Captain reported returning to departure airport after experiencing a WOW (Weight on Wheels) system failure on gear retraction.