ZHUHAI, China / WASHINGTON (Reuters) – Boeing Co announced Wednesday that it has issued a safety bulletin reminding pilots how to deal with the erroneous data of a key sensor following Indonesia's crash last week.
FILE PHOTO: A representative of the National Road Safety Commission (KNKT) is investigating a turbine engine of the Lion Air JT610 at Tanjung Priok Port in Jakarta, Indonesia, on 4 November 2018. REUTERS / Beawiharta
The US aircraft manufacturer said that investigators investigating the Lion Air crash off the coast of Indonesia, where all 189 were killed on board, had found that one of the "attack" sensors on the Boeing 737 MAX aircraft was faulty data had delivered.
Experts say that the angle of attack is a crucial parameter that helps the aircraft systems understand whether the nose is too high relative to the airflow – a phenomenon that can throw the aircraft into an aerodynamic stall and cause it to crash.
Some modern aircraft have systems that automatically correct the position of the wings to fly safely.
There are also procedures that pilots must follow if data is missing from damaged sensors on the fuselage skin. However, it remains unclear how much time the crew of the JT610 flight had to react at the relatively low level at which they flew.
Boeing said his bulletin underlined "existing flight crew procedures" aimed at circumstances in which the information entering the cockpit from the sensors was wrong.
The Boeing 737 MAX has three such sensors. However, in some cases, the Boeing 737 MAX may point sharply downward due to incorrect readings to keep air under the wings and avoid stalling, according to a person who has dealt with the matter.
A source said on the condition of anonymity that the Boeing Bulletin referred only to the 737 MAX, of which just over 200 are in operation.
Service bulletins may be issued by the US Federal Aviation Administration for airline airworthiness directives, adding weight to the recommendations.
Boeing has delivered 219 737 MAX jets to customers worldwide. 4,564 orders for jets are still to be delivered.
The Boeing 737 MAX is a more fuel-efficient version of the manufacturer's best-selling single-aisle 737 series.
The Lion Air crash was the first to affect the new version introduced by airlines last year.
The Indonesian authorities have downloaded information from the flight data recorder showing that a cockpit indicator of the Lion Air jet has been damaged during the last four flights.
The search for the cockpit voice recorder, the second so-called "black box", continues.
Reporting by Tim Hepher and David Shepardson; additional reporting from Tim Hepher in Zhuhai, China, Jamie Freed in Singapore, Allison Lampert in Montreal, and Cindy Silviana in Jakarta; Machining of Himani Sarkar