Willis Lease Finance Corporation, together with its subsidiaries, operates as a lessor and servicer of commercial aircraft and aircraft engines worldwide. It operates in two segments, Leasing and Related Operations, and Spare Parts Sales. The company engages in the acquiring and leasing commercial aircraft, aircraft engines, and other aircraft equipment, as well as the purchase and resale of commercial aircraft engines and other aircraft equipment, and service and maintenance related businesses. It also purchases and resells after-market engine parts, whole engines, engine modules, and portable aircraft components.