During the three weeks before Lion Air Flight 610 plunged into waters off Indonesia, Southwest Airlines Co. LUV, +0.25% replaced two malfunctioning flight-control sensors of the same type that has been publicly implicated in the crash, according to a summary of Southwest maintenance records reviewed by The Wall Street Journal.
Both U.S. maintenance issues involved a Boeing Co. BA, +2.56% 737 MAX 8, the same model that crashed last month in Indonesia. The sensors measure whether the jetliner is angled above or below level flight. Those sensors, or related hardware, needed repairs in the Southwest instances, according to the summary document. The document also indicates Southwest pilots reported they couldn’t engage automated throttle settings, similar to cruise control on a car.
A Southwest spokeswoman said the sensors didn’t fail and were removed as a precautionary measure as part of a troubleshooting process. She said at least one was repaired.
Investigators have confirmed the same type of sensor failed on the Lion Air flight, but they haven’t determined precisely what happened between that failure and the crash.
Since the accident, which killed 189 people, Boeing has warned airlines about the potential for erroneous data from what are called “angle-of-attack” sensors. “We have not experienced a sensor failure or flight issue as described in Boeing’s bulletin,” the Southwest spokeswoman said.
The Southwest incidents didn’t result in emergencies and no one was hurt. They prompted what appear to be routine reports by mechanics checking out problems with the sensors.
An expanded version of this report appears on WSJ.com.