If next-generation rotorcraft will be more capable than today's fleet, they are also going to be considerably more expensive. It takes a lot of power to go fast, and bigger engines add both weight and cost. "If you want to go above 150 knots [173 mph], you're going to have to pay a premium of 50 to 100 percent," says Richard Aboulafia, an aviation analyst with the Teal Group. Pentagon-funded demonstrator programs allow manufacturers to work out the kinks of new designs and bring down prices.

If next-generation rotorcraft will be more capable than today's fleet, they are also going to be considerably more expensive. It takes a lot of power to go fast, and bigger engines add both weight and cost. "If you want to go above 150 knots [173 mph], you're going to have to pay a premium of 50 to 100 percent," says Richard Aboulafia, an aviation analyst with the Teal Group. Pentagon-funded demonstrator programs allow manufacturers to work out the kinks of new designs and bring down prices.

The talks give Dubai-based Emirates leverage as it pushes Airbus Group to upgrade its A380 with fuel-efficient engines, said Richard Aboulafia, an aerospace analyst at Teal Group. Boeing would gain momentum for a storied jet with few sales prospects aside from replacing the Air Force One fleet, he said. “It would keep the -8I going through the decade and deliver an unpleasant blow to the A380 that’s long overdue,” Aboulafia said of a potential Emirates order.

A similar Pratt engine will power the rival Airbus A320neo, but the risk of the CSeries test failure affecting the Airbus timetable is remote, said Richard Aboulafia, an aerospace analyst at the Teal Group, in Fairfax, Virginia. "Given all the testing the engine has been through, the incident is likely to be pretty minor," Aboulafia said. "But given all the headaches of the CSeries, this is another headache Bombardier doesn't need."

The FAA approval nevertheless moves airlines an important step closer to tapping the full potential of the Dreamliner, which burns 15 percent less fuel than the Boeing 767. The approval was of little concern to investors, one Wall Street analyst said. Boeing's stock was up 0.4 percent at $134.70. But the approval appeared to come sooner than expected and its timing was seen by some as a sign of continuing tension between the two agencies, one charged with investigating accidents and the other with ensuring safety. "It certainly does seem like there's some conflict between the NTSB and the FAA," said Richard Aboulafia, an analyst at the Teal Group in Fairfax, Virginia.