Willis Lease Finance Corporation along with its subsidiaries is a lessor of commercial aircraft engines. The Company operates through two business segments, such as Leasing and Related Operations, and Spare Parts Sales. The Leasing and Related Operations segment involves acquiring and leasing, primarily pursuant to operating leases, commercial aircraft, aircraft engines and other aircraft equipment, and the selective purchase and resale of commercial aircraft engines and other aircraft equipment. The Spare Parts Sales segment involves the purchase and resale of after-market engine and airframe parts, whole engines, engine modules and portable aircraft components, and leasing of engines destined for disassembly and sale of parts. Its lease portfolio consists of approximately 200 engines and related equipment, 10 aircrafts and five spare engine parts packages. The Company's business activities also include equipment leasing and spare parts sales.