Regardless of what you fly, how it’s equipped, and how old or new it is, you eventually will encounter inoperative instruments and/or equipment during a preflight inspection. It can be something known to the operator and the maintenance department, or it can be something new. Once the inoperative component is discovered, you have to make a determination whether it’s legal to fly the airplane without repairs, and then decide if it’s safe to fly. The two are not the same.
The good news is you have some guidance in FARs 91.205 and 91.213, and you also may have a minimum equipment list (MEL) to help determine what is and is not required to be operational on your planned flight. And the aircraft’s type certificate data sheet (TCDS), plus any applicable airworthiness directives (ADs), also may need to be factored into your decision, as well as any supplemental type certificates (STCs). Needless to say, you need more operating equipment for a day VFR jaunt around the pattern than you need at night or under IFR.
