Boeing continues to investigate sensor issues on the 787’s Rolls-Royce Trent 1000 engines that caused the first aircraft (ZA001) to remain grounded for two days at Moses Lake, Wash, and have since led to the postponement of vital flutter tests.

The problems cropped up on ZA001 during the fifth day of the flutter campaign — a key evaluation that must be passed before the FAA certification program can begin. Commenting on his blog, Boeing Commercial Marketing VP Randy Tinseth says during the flight the crew experienced “an uncommanded loss of thrust in one of the engines,” and landed at Grant County International Airport (also known as Moses Lake). “Teaming with Rolls-Royce, we determined that the issue had to do with a pressure-sensing component within the engine. We located replacement parts and then got the parts and the right crew to Moses Lake — beginning the maintenance activity on Saturday. Later that day, we ran the engines to confirm that the replacement had been done correctly and that there were no anomalous readings.” The aircraft ferried back to Boeing Field without incident on Sunday Feb. 21, but later that day the next set of flutter tests ­ — scheduled to restart Feb. 22 ­— were pushed back to an unspecified time as it became clear more ground testing was needed.

Meanwhile, the impact of the engine issue on the rest of the flight test program remains unclear. First flight of the third 787 (ZA004), which was widely expected to take place today following the successful completion of ground tests over the weekend, has been put back to an undetermined date.

Tests of the second aircraft(ZA002), which to-date has amassed more than 48 flight hours on 18 sorties, also remain focused temporarily on ground work.

Trent 1000 engine on ZA003 photo credit: Guy Norris