So, what does airworthy mean? That term is not specifically defined in the regulations, nor is it defined in any of the typical guidance provided to the pilot by the FAA, such as the Aeronautical Information Manual. However, the term has achieved some definition as a result of FAA enforcement cases and through FAA legal interpretations. It remains a strict liability standard for the pilot but a practical, simple definition is hard to come by.
According to the "legal" definition, to be airworthy, an aircraft must satisfy two conditions. First, it must conform to its type certificate, as modified by supplemental type certificates and airworthiness directives, if any. Second, the aircraft must be in a condition for safe operation. This definition has been interpreted to include the requirement that the aircraft has been maintained in accordance with the FARs and has had the appropriate annual inspection, transponder check, system checks, and VOR check in the case of IFR operations.
As a practical matter, when a pilot conducts a preflight, walk-around inspection of the aircraft, the pilot is making sure that the aircraft is safe to fly. Extra care should be taken in performing a walk around after maintenance. There have been occasions where pilots have picked up their aircraft from a maintenance facility, assuming that all screws and nuts had been replaced and all tools had been removed, only to discover after takeoff that an inspection panel was not properly secured or the landing gear wouldn't retract because a wrench was blocking the mechanism. Also, checking the aircraft logbooks for a timely annual inspection or a mechanic's statement that the aircraft has been returned to service as airworthy following some other type of maintenance also helps to satisfy the pilot that the aircraft has been maintained in accordance with the regulations and is safe to fly.
However, how often do you pull out and check the type certificate, the supplemental type certificates, and the applicable airworthiness directives for the aircraft before you go for that quick flight around the patch? Still, it is the pilot's regulatory responsibility to make sure that the aircraft conforms to its type certificates and the applicable airworthiness directives before he or she operates the aircraft on any flight. The standard that is often applied in evaluating whether a pilot has met that responsibility is whether the pilot knew or should have known that the aircraft did not conform to its type certificate or that it was not safe to fly. In some instances, the pilot may reasonably rely on the expertise of others in determining that this condition has been met. And, there are occasions when an aircraft may not have to strictly meet its type certificate to be operated as airworthy. If the item that takes the aircraft out of conformity is only a scratch, dent, pinhole of corrosion, missing screw, or other such minor defect, it may not adversely affect the legal definition of airworthiness.
Still, as pilot in command, it is your responsibility to judge whether or not an aircraft is airworthy. To properly fulfill your responsibility, you must be aware that determining an aircraft is ready for safe flight requires not only an outside review of the aircraft but also a check to ensure that it conforms with its type certificate, any supplemental type certificates, and any applicable airworthiness directives.
