Minnesota company made sensors for Boeing 737 Max

A Minnesota company is attracting the attention of investigators looking into the October crash of Lion Air Flight 610, the first of two fatal accidents that led to last week's grounding of Boeing's 737 Max jet.

Rosemount Aerospace Inc., which employs about 1,600 people at its manufacturing facility in Burnsville, made sensors on the Lion Air flight that crashed into the sea soon after takeoff, killing all 189 people on board, according to a recent report in the Washington Post.

Investigators are now trying to find out if erroneous sensor inputs may have contributed to the Lion Air crash as well as last week's fatal crash involving an Ethiopian Airlines jet, which went down shortly after takeoff, killing all 157 people on board, according to the Post.

It's not clear yet who made the sensors on the Ethiopian Airlines jet, but the parent company of Rosemount, United Technologies Corp., has taken credit for the sensing system.

In a 2016 news release celebrating the first flight of the Boeing 737 Max, United Technologies touted its own role in developing the aircraft, saying that the company's "advanced technology helps to light, land, stop and protect the 737 Max. The aircraft carries a variety of systems from the company including the electric power system, cabin pressure control, lighting systems, wheels and brakes, landing gear, sensing systems, evacuation slides and fire protection."

Officials with Rosemount and United Technologies did not respond to a request for comment. Rosemount, which was founded in 1956, was acquired by Goodrich Corp. in 1993 and became part of United Technologies in 2012.

Investigators are now examining Rosemount's "angle-of-attack" sensors, which automatically push down a plane's nose if the control system indicates the plane is stalling. The Post reported that such sensors have caused problems on at least 50 U.S. flights in the past five years.

Last year, the Federal Aviation Administration issued an airworthiness directive involving another Rosemount sensor that was "indicating the wrong airspeed during flight." The FAA's directive required airline operators to identify and replace any affected sensors.

"We are issuing this AD [Airworthiness Directive] to address the unsafe condition on these products," the FAA said in its announcement.

In 2014, Rosemount was sued over alleged defects in its angle-of-attack sensors after a small plane crashed in Florida, killing six members of a prominent Kansas family. Also sued was the plane's manufacturer, Pilatus Aircraft, and several other companies that made the plane's equipment.

The family dropped its claims against Rosemount after the National Transportation Safety Board concluded that pilot error was the most likely cause of the crash.

Jeffrey Meitrodt • 612-673-4132