To ensure security interest protection, what document may the FBO require from the aircraft owner?

The document that the Fixed Base Operator (FBO) may require from the aircraft owner to ensure protection of a security interest is the promissory note secured by the aircraft. A promissory note is a legal financial instrument that outlines the borrower's promise to repay a specified amount of money to the lender according to agreed-upon terms. When this note is secured by the aircraft, it gives the lender a security interest in the aircraft itself, which means that if the borrower defaults on the repayment, the lender can claim the aircraft. This not only protects the FBO’s interest but also provides a clear legal framework for recourse if necessary.

Other options do not provide the same level of protection for a security interest. A warranty registration from the manufacturer does not relate to financial obligations or security interests. A repair agreement without any lien attached typically pertains to services rendered rather than securing payment. Lastly, a verbal agreement regarding payment lacks enforceability and legal standing compared to a written promissory note, making it an inadequate choice for protecting a financial interest. Therefore, the promissory note secured by the aircraft is the most appropriate and legally robust option for securing the financial interests of the FBO.