Leahy said he was not anxious about an order for 100 Boeing 737 MAX 10s from United Airlines, converted from other models. Deal also includes an option for a further 50 Boeing 737 MAX 8 aircraft.
"This order is yet another endorsement for the 737 MAX from one of our African customers", said Van Rex Gallard, vice president of Sales for Africa, Latin America and the Caribbean, Boeing Commercial Airplanes.
Analysts expect jet orders at the Paris Air Show to decline despite its current positive years as airlines process a load of deliveries.
Ethiopian Airlines orders 10 A350-900 jets, worth about $3.1 billion at list prices.
Boeing's head of airplane developments meanwhile said he was "very optimistic" about the chances of establishing the business case for a mid-market jet project to open up new routes from the middle of the next decade.
The MAX 10 can seat about 10 more passengers than the MAX 9, sporting a maximum capacity of 230 seats.
The US planemaker continued to rack up orders at the Paris Airshow for a new version of its best-selling 737 aircraft, which was launched amid a flurry of deals.
The agreement, valued at $4.7 billion, is split evenly between 20 new orders for the 737 MAX 10 and conversions of 20 of the low-priced carrier's 737 MAX 8 airplanes from its existing order to 737 MAX 10s.
However, Airbus immediately hit back with an order for 100 of its A320neo planes from leasing firm GECAS, as well as a deal for 12 A321neos with Air Lease Corp.
Boeing Commercial Airplanes President Kevin McAllister poses with a model of 737 MAX 10, during the 52nd Paris Air Show at Le Bourget Airport near Paris, June 20, 2017.
Three airlines, Copa, Donghai and Malaysia added to the MAX 10's order book, but only as conversions from previous MAX orders.
Xiamen Airlines is an existing 737 MAX customer and plans to use the new airplanes with their subsidiaries, including Hebei Airlines and Jiangxi Airlines.
The Paris Air Show and its counterpart at Farnborough in Britain in even-numbered years are the biggest annual events in the industry where aircraft manufacturers often end up announcing a majority of the orders they take in over the year.
United also announced an order for four additional 777-300ER wide-body jetliners from Boeing.
Copa Holdings is a leading Latin American provider of passenger and cargo services.
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