Conversely, the aircraft's residual value at the end of the lease is an important consideration for the owner. The owner may require that the aircraft be returned in the same maintenance condition (e.g. post-C check) as it was delivered, so as to expedite turnaround to the next operator. Like leases in other fields, a security deposit is often required.
Though the early Lockheed Jetstar had four, most production business jets have two jet engines, mostly rear-mounted podded engine. If mounted below their low wing, it wouldn't allow sufficient engine clearance without a too long landing gear. The HondaJet is the exception with its over the wing engine pods. Dassault Falcon still builds three-engine models derived from the Falcon 50, and the very light jet market has seen several single-engine design concepts and the introduction of the Cirrus Vision SF50 in 2016.