Under what condition may an FBO choose to release an aircraft before full payment?

The correct answer highlights the importance of formal agreements and security measures in aviation transactions. An FBO (Fixed Base Operator) may choose to release an aircraft before full payment if signed promissory notes are on file with the FAA. This condition provides a layer of security for the FBO, as promissory notes represent a legal commitment to pay and can be recorded with the FAA to establish a lien on the aircraft. This means that the FBO has a legal claim against the aircraft for the debt, protecting its interests and allowing for the release of the aircraft, given the assurance that payment will ultimately be made.

Other options present scenarios that lack the necessary legal backing. A customer's good credit score, while potentially a positive indicator, does not provide the same level of assurance as a signed and recorded promissory note. Similarly, a verbal agreement from the aircraft owner is not legally binding and could lead to disputes regarding payment. Lastly, while having a third party guarantee payment might offer a degree of security, without formal documentation and the FAA's involvement, it does not ensure the same legal protections as promissory notes. Hence, relying on promissory notes filed with the FAA is the clearest and most secure condition under which an FBO may