Wrongly-refitted trim switch left pilots fighting to keep E175’s nose down

US investigators have determined that an Embraer 175 pitch-trim switch, inadvertently fitted upside-down, resulted in the crew’s experienced a serious flight-control incident on departure from Atlanta. The captain had already flown the American Eagle jet from Detroit to New York LaGuardia earlier in the day, but the crew noted a pitch-trim failure message during the journey, and chose to have the issue checked on arrival. Maintenance personnel partially removed the trim switch on the captain’s yoke, with the intention of replacing it, but then decided instead to defer the item. NTSB investigators believe the partial removal of the switch at LaGuardia resulted in its being accidentally re-installed upside-down. The deferral decision meant the switch was not tested. The switch was placarded as inoperative – but not deactivated, as there was no requirement for such action – and the captain was simply advised not to use it. During the second flight of the day, a service from LaGuardia to Atlanta, the first officer flew the aircraft, without any problems. But the captain took the role of the flying pilot for the next departure, from Atlanta back to LaGuardia, and the inquiry believes “highly-practised behaviour” meant the captain automatically reverted to using the yoke trim switch even though he had been told otherwise. It states that his use of the yoke switch resulted in the aircraft’s pitching up when he was attempting to trim down. As a result, the captain thought the aircraft was affected by a trim runaway as it climbed out of Atlanta, and the crew declared an emergency, seeking to return to the airport, less than 2min after departure. Story has details.<br/>