Boeing (BA) struck a nearly $7 billion airplane deal with Turkish Airlines on Tuesday for 70 aircraft from its family of 737s, marking the biggest-ever deal between the two parties. 

Turkish Airlines finalized a firm order for 40 737 MAX 8s, 10 737 MAX 9s and 20 next-generation 737-800 jets, valued at $6.9 billion at list price. The order value could change as the companies work through traditional aircraft deal negotiations.

The order, originally announced as a commitment last month, also includes options for an additional 25 737 MAX 8s.

"We are delighted to finalize the order, which will considerably expand our fleet and contribute to our continued growth," Turkish Airlines CEO Temel Kotil said in a statement.

He added that Turkish Airlines, a global airline serving more than 220 cities and 99 countries, is building the “strongest network in the world.” Its long-time partnership with Boeing, he said, is one of the “key factors” behind that strategy and success.

The airline received its 100th direct delivery from Boeing in March of this year and currently operates next-generation 737s and 777-300 extended range jets. It has more than 100 Boeing 737s and 777s on order.

The deal brings Boeing’s total number of 737 MAXs ordered to date to 1,285, and the Chicago-based jet maker says it has more than 3,100 unfilled orders for 737s. The 737 is Boeing’s newest single-aisle jet, featuring the latest-technology CFM International LEAP-1B engines designed to improve fuel efficiency.

"Turkish Airlines currently operates more than 85 Next-Generation 737s, which are the foundation of its successful short-haul operations," said Todd Nelp, vice president of European Sales, Boeing Commercial Airplanes.

The latest order, he notes, demonstrates “the confidence Turkish Airlines” has in Boeing's next-generation 737, including its “proven reliability, performance and economics.”

Shares of Boeing edged about 1% higher to $95.50 in recent trade.

The order comes as Boeing is also expected to ramp up deliveries again of its highly-anticipated 787 Dreamliner, the company’s long-range twin-jet aircraft that suffered battery difficulties earlier this year. 

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