Air India Ltd. is ordering 300 narrow body jets, one of the largest orders in commercial aviation history as the formerly state-run airline looks to overhaul its fleet under new ownership. The carrier may order Airbus SE’s A320 neo family jets or Boeing Co.’s 737 Max models, or a mix of both. A deal for three hundred 737 Max-10 jets could be worth $40.5 billion at sticker prices, although discounts are common in such large purchases. Winning a narrow body order in India would be a coup for Boeing, as rival Airbus dominates the skies in the country, the world’s fastest-growing aviation market before the Covid pandemic. IndiGo, operated by Inter Globe Aviation Ltd., is the world’s largest customer for the European manufacturer’s best-selling narrow bodies, ordering more than 700, and others including Vistara, Go Airlines India Ltd. and AirAsia India Ltd. fly planes from the same family.Production and delivery of 300 planes would likely take years or even more than a decade. Airbus builds about 50 narrow body jets in a month, with plans to increase that to 65 by the middle of 2023, and 75 by 2025. An Airbus representative said the company is always in contact with existing and potential customers, but any discussions are confidential. “This order presumably involves new methods of financing to play out in the right manner, including factoring in macroeconomic trends notably the fluctuating rupee and rising inflation,” said managing partner of aviation advisory firm AT-TV. “Some airlines have placed voluminous orders only to find that they are unable to line up financing at favorable terms. While it is not an outcome that one envisions and certainly not with a group such as the Tatas, nevertheless it has to be planned for.”Air India’s owner Tata Group is also close to an order for Airbus A350 long-range jets that are capable of flying as far as the US West Coast from New Delhi. Once known for its premium services and advertisements featuring Bollywood stars, the airline still has lucrative landing slots at most major airports, but it faces competition from foreign airlines with nonstop services to India, as well as carriers that fly via hubs in the Middle East. Tata bought the airline earlier this year in the most high-profile privatization. It is expected to consolidate its aviation businesses, including four airline brands. An order for new planes, especially with favorable terms on long-term maintenance, would help it cut costs and compete better with rivals that offer very cheap fares.