Helicopter pilot reported flying in a non-airworthy aircraft when maintenance logbooks indicated work compliance and aircraft was airworthy. Maintenance signed off on repairs and inspections that were observed to have not been completed.

Narrative

On Date 1 and Date 2 I flew the aircraft on normal interfacility transfers. All logbook entries; maintenance and signoffs etc were apparently correct and current. However; days after the last flight; through conversations between another pilot and a mechanic we found that maintenance items on this aircraft were not complied with. There was torque sensor maintenance done by mechanics that hadn't been documented in the logbooks for the aircraft. There was a main rotor mast uniball inspection that wasn't performed but signed off in the logbook by mechanics and there was work on the pitot static system due to a blockage and subsequent replacement of the steam gauge airspeed indicator done by mechanics. An operational and leak check on the pitot system was signed off but not performed. The main rotor mast uniball inspection was signed off in the logs but according to eye witness not performed; and subsequent torque writeups that are associated with that inspection were never entered into the logbook. Additionally the aircraft should have been put out of service for that inspection which wasn't done either. Due to the uncertainty of maintenance performed and/or missing follow up torque checks and the fact that the aircraft was flown by me after those inspections/work performed or not; there is a possibility that I unknowingly overflew either the uniball inspection or the associated torque checks. At the time of flight all logbook entries were current and complied with; which is why I was certain that the aircraft was in an airworthy condition. I want to emphasize that all these findings came to light several days after the flights had happened and that at the time of flight the aircraft - to my best knowledge and information available to me - was current and in airworthy condition.Only way I could have known or determined at the time of flight that the aircraft might not have been in compliance and airworthy.