NEW ENGINE. BIG DEAL? Actually, yes. Boeing says the new engine will make the 737 4 percent more fuel-efficient than a competing Airbus plane. These days that's one of the main things airlines look for.
SIMPLICITY: A new engine requires fewer government approvals and less engineering work, too. Boeing Co. says it will keep other changes to the 737 minimal to simplify the process.
DELIVERY: Expected in 2017.