[ad_1]
JAKARTA: According to a preliminary investigation report, a faulty sensor at the center of the investigation into the crash of a Lion Air airliner into the Java Sea on October 29, n & rsquo; Was not repaired, even though it broke down. .
A mechanic worked on other sensors and equipment during a night shift before the early start, but not on the so-called "angle of attack," according to the Indonesian Committee on Transportation Safety.
Excerpts from the commission's report were previewed by Bloomberg News before their scheduled release on Wednesday.
The report does not indicate the cause of the accident, but provides the most detailed analysis so far in the chaotic minutes before the crash and in the measures taken to remedy the malfunctions in the aircraft the previous night. . On both flights, pilots indicated that they had difficulty finding basic information such as speed and altitude.
The pilots of Flight 610, who plunged into the Java Sea more than 11 minutes after taking off from Jakarta, did not seem to understand what was happening to them as they were radioing air traffic controllers demanding their altitude and speed . They said that they had an unspecified "flight control problem", according to the report.
The 188 people on board died in the accident. Officials initially estimated the death toll at 189, but the report lists one fewer: two pilots, five flight attendants and 181 passengers.
The Boeing 737 Max 8 angle of attack sensor, which measures the nose height of the aircraft in relation to the undercarriage, malfunctioned during the previous flight and in the minutes leading up to the accident, according to the report.
The sensor mistakenly concluded that the nose was too high and that the plane was in danger of losing the elevator, which triggered a stall warning in the cockpit and triggered the security software that was trying to to dive them.
Both groups of pilots reacted differently to multiple error messages and malfunctions. During the previous flight, the pilots were able to shut down the engine that was trying to push the nose quite quickly after takeoff.
For reasons that were not explained, the pilots of Flight 610 did not go through this step, which is part of a lengthy emergency procedure.
The crash-resistant cockpit recorder of the aircraft was not found. The investigators therefore have no idea what they thought when they responded to the emergency.
Boeing declined to comment on the preliminary report. He works as a technical advisor for the Indonesian investigation.
"We will analyze any additional information as it becomes available," the Chicago-based aircraft manufacturer said Tuesday in a statement. "We take all necessary measures to fully understand all aspects of this accident, in close cooperation with the investigation team and the relevant governmental authorities."
Earlier this month, the manufacturer sent a bulletin to Max's operators reminding them that such a cascade of failures could be addressed by an existing emergency procedure.
The manufacturer says it is confident in the safety of the latest version of its 737 model.
On the 28 October flight that landed safely in Jakarta, the captain told the investigators that he had swept the cockpit instruments and determined that the co-pilot's readings corresponded to a third watch and were accurate. He gave control of the plane to the co-pilot.
On the other hand, the pilot-in-command of the crashed flight radioed with a controller about a minute before the aircraft disappeared from the radar to announce that all the height indicators of the aircraft were different and that they could not determine their height.
The investigators will focus on how the airline has performed the maintenance of the aircraft.
The pilot-in-command of the October 28th flight reported speed and altitude reading problems and a system called Feel Differential Pressure, which controls the force required for pilots to push or pull. the control column that raises and lowers the nose, according to the report. There was no indication that the impact sensor was working badly.
An angle of attack sensor had been replaced and tested just prior to the flight on 28 October. According to the flight data of the aircraft, the left sensor read about 20 degrees differently than the right one.
On both flights, a device known as a stick shaker – a warning that the wings are about to lose lift, vibrate the control column and make a deafening thud – has been activated a few times. time after take-off for the captain but not for the co-pilot, according to the data. This was triggered by the faulty sensor.
It also triggered the newly added security software to the Max. The maneuvering feature augmentation system is designed so that the wings do not lose their lift, which is known as aerodynamic stall. It was programmed to automatically lower the nose and did so for most of the 11 minutes of flight, even though the plane was not close to stalling.
The pilots of the crashed flight reacted by pressing a switch in the control column that temporarily lifted their noses, but this only temporarily stopped the MCAS. Apparently, they never stopped the motor activating the movement as the pilots had done during the previous flight.
Indonesian authorities met with passenger families in Bangka and Jakarta on Tuesday to give an overview of the preliminary results. Those who attended the meeting stated that this did not indicate the cause of the crash.
"There was no explanation related to Boeing," said Ari Priawan, whose brother, sister-in-law and their child were on board flight 610.
The investigators hope to be able to resume searching for the voice data recorder of the aircraft when the equipment is acquired. A ship capable of holding its position at the same place without throwing the anchor is necessary because of the presence of many pipelines in the area, said Nurcahyo Utomo, senior investigator.
"The search for the voice recorder in the cockpit will resume," Utomo said. "We hope to start this week and will make every effort."
[ad_2]
Source link
