Boeing on Wednesday won FAA type inspection authorization (TIA) for the 787-9, marking the start of a new phase of flight testing in which agency personnel join the company’s engineers in Washington state’s Puget Sound region to gather the data required for certification. The authorization applies to 787-9 test airplanes powered by Rolls-Royce Trent 1000 engines—ZB001 and ZB002, the first two members of the fleet. The company expects to soon earn TIA for the third 787-9 test airplane, a General-Electric GEnx-powered Dreamliner carrying serial number ZB021, according to Boeing Commercial Airplanes vice president of marketing Randy Tinseth.

To earn TIA, Boeing test crews flew the 787-9 fleet at a variety of speeds, altitudes and configurations to demonstrate its capabilities throughout the flight envelope. For example, Boeing successfully completed flutter testing, demonstrating structural integrity. Test crews also conducted various maneuvers at high speeds to try to induce vibration into the airframe to demonstrate their ability to “dampen out” without problems.

The trio of 787-9s have so far flown for 285 hours during more than 100 test missions.