Boeing releases statement on Lion Air Flight 610 preliminary report

Boeing issued (27-Nov-2018) a statement on the preliminary investigative report concerning the 29-Oct-2018 loss of Lion Air Flight 610, a Boeing 737 MAX 8 aircraft. According to Boeing, the Indonesian National Transportation Safety Committee report indicates:

• Maintenance logs for aircraft recorded problems related to airspeed and altitude on all four flights in the three days prior to Flight 610. Logs indicate various maintenance procedures were performed, but airspeed and altitude issues continued on each successive flight. Logs indicate that on 27-Oct-2019, one of the aircraft's Angle of Attack (AOA) sensors was replaced;
• Aircraft pilot and the maintenance engineer discussed on 28-Oct-2018 the maintenance performed on the aircraft. Engineer informed the pilot of the replacement and testing of the AOA sensor;
  • The report does not include records of installation or calibration of the new sensor, nor does it indicate whether the sensor was new or refurbished. Report states the pilot was satisfied by the information relayed by the engineer that the AOA sensor had been replaced and tested;
  • On the subsequent flight the pilots again experienced problems with erroneous airspeed data, and also experienced automatic nose down trim;
• Flight crew of the 28-Oct-2018 flight turned off the stabiliser trim switches within minutes of experiencing automatic nose down trim, and continued with manual trim through the end of the flight. The pilot performed three non-normal checklist procedures, including the runaway stabiliser non-normal checklist, which is a memory item prescribed by the 737 MAX Flight Crew Operations Manual. The remainder of the 28-Oct flight was uneventful and the flight continued to its destination. After landing, the pilot reported some of the experienced issues both on the aircraft maintenance log and to engineering. The report states the pilot ran the runaway stabiliser non-normal check list, but it does not state he communicated this fact in the maintenance documentation following that flight;
• On 29-Oct-2018, shortly after taking off, the pilots experienced issues with altitude and airspeed data that the pilots had previously experienced on the earlier flights, due to erroneous AOA data. Data from the flight data recorder makes clear that, as on the previous flight, the aircraft experienced automatic nose down trim. In response, the flight crew repeatedly commanded nose up trim. This sequence repeated for the remainder of the flight, during which the flight crew was able to maintain control of the aircraft for approximately 10 minutes. Unlike as is stated with respect to the prior flight, the report does not state whether the pilots performed the runaway stabiliser procedure or cut out the stabiliser trim switches. [more - original PR]