The pilot in command is responsible for ensuring the aircraft is in airworthy condition and operated safely.
The pilot in command should determine if the aircraft is in safe condition for flight. The flight should be discontinued if there is an unairworthy mechanical, electrical or structural condition. The aircraft should not be operated in a careless or reckless manner as to endanger the life or property of another. In an emergency, the pilot in command may deviate from any rule to the extent required to meet that emergency.
14 CFR 91.3 Responsibility and authority of the pilot in command
14 CFR 91.7 Civil aircraft airworthiness
14 CFR 91.13 Careless or reckless operations