Thursday, 22 November, 2018

FAA Issues Boeing 737 AOA Directive After Lion Air Crash

Crashed Lion Air jet flew four times with damaged airspeed gauge Crashed Lion Air jet flew four times with damaged airspeed gauge
Melinda Barton | 08 November, 2018, 20:20

United said: "We are in receipt of a Flight Crew Operations Manual Bulletin, issued by Boeing, which applies to the 16 737 Max 8 aircraft now in our fleet".

Lion - always been dogged by safety problems - has said the Boeing 737-Max 8 suffered a technical issue on the flight just prior to its deadly crash Monday and that it was fixed. If the angle is too extreme it can cause the wings to lose lift and the aircraft to stall.

Boeing is preparing to send a warning to all the operators that have taken delivery of its new 737 Max aircraft, according to an anonymous source cited by Bloomberg.

"We also plan to conduct a flight reconstruction to see the impact of the AOA sensor damage in the engineering simulator at the Boeing facility in Seattle". However, in rare instances, accidents have been caused by what investigators call a "startle factor".

Chairman Soerjanto Tjahjono said the airspeed indicator and sensor problems were related. The error erroneously tells pilots that there's a stall in airflow, triggering an automated system that points the plane downward in an effort to regain speed.

An angle of attack sensor had been changed by mechanics on the ground in Bali the day before the crash, Indonesia's National Transportation Safety Committee (KNKT) has said.

Flight JT610 radioed a request to return to Jakarta to land, but never turned back toward the airport, according to Indonesia's National Transportation Safety Committee.

The plane hit the water at very high speed just 13 minutes after take-off from Jakarta.

The jet was first delivered to Lion Air in mid-August, which one of the region's budget airlines.

"The plane and the pilot have been grounded for investigation", said Pramintohadi Sukarno, a senior ministry official. Indonesian officials say that all 11 such aircraft have been tested and declared safe to fly. Pilots are supposed to memorize a procedure to disengage the angle-of-attack inputs to the plane's computer system. The Boeing bulletin only reminds operators of the plane to follow the procedure and doesn't require any physical fixes that could take the aircraft out of service.

The US Federal Aviation Administration issued an order to domestic carriers to follow the new instructions on dealing with the erroneous sensor alert in 737-8 and -9 airplanes.

Industry insiders said that the completion of the Zhoushan plant, announced amid ongoing China-US trade frictions, reflects US companies' heavy dependence on both the supply chain in China as well as the country's huge market. The aircraft system that handles the nose up and down movement (called stabilizer trim system) will put the nose down in response to the erroneous AOA sensor. Once that happens, it may try to right itself by pushing the nose down, reports the Straight Times.