Flight Crew Instrument; Flight Crew Commercial; Flight Crew Flight Instructor; Flight Crew Multiengine
Flight Crew Last 90 Days 130; Flight Crew Total 1474; Flight Crew Type 1015
Communication Breakdown
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew FLC Overrode Automation; General Maintenance Action
Aircraft; Procedure
91.205 VFR required equipment oil temperature gauge inoperative. Student did the pre-flight as I was running late to the flight school. I arrive and greet the owner of the flight school as they are getting ready to leave for the night. I tell them (the owners) I am going on a night flight tonight and they tell me to have a good flight. I do a briefing with my student on tonight's flight and we do a complete run-up not realizing the oil temp was inoperative. Once we reach ZZZ only do I realize that the oil temp has stayed in the same position the whole flight. We get back to our home airport and then I see the Discrepancies booklet indicating the oil temperature gauge has been noted.I failed to check the discrepancies booklet before the flight and continued the flight anyways. The owners of the flight school have known of the issue before my flight and failed to notify me of the issue. They continued to fly the aircraft today not fixing the issue.
Flight Instructor reported missing the log book entry for an inoperative oil temperature gauge that was required equipment for night VFR training flight and conducting the flight.