Over the past few years, multiple aircraft types have been grounded due to various issues. Two examples include the Airbus A320neo aircraft family, powered by the Pratt & Whitney PW1100G engines, the Boeing 737 MAX 8 family, and the 737 MAX 9 on a separate occasion. Manufacturers have also been forced to delay deliveries due to quality lapses, which has resulted in airlines either not being able to honor their schedule commitments or being forced to hire external capacity in the form of aircraft, crew, maintenance, and insurance (ACMI) services, another costly venture.