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Old 5th April 2019, 01:52 PM
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Philip Argy Philip Argy is offline
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Post EA preliminary report just released

http://www.ecaa.gov.et/documents/204...8-d7af1ee17f3e

The key finding from the FDR, is that this occurred AFTER the electric stabiliser trim cutout switches had been pulled:

Quote:
At 05:43:20, approximately five seconds after the last manual electric trim input, an AND automatic trim command occurred and the stabilizer moved in the AND direction from 2.3 to 1.0 unit in approximately 5 seconds. The aircraft began pitching nose down. Additional simultaneous aft column force was applied, but the nose down pitch continues, eventually reaching 40 nose down. The stabilizer position varied between 1.1 and 0.8 units for the remainder of the recording.
So automatic nose down trim commands were issued by MCAS and honoured despite the stabiliser trim cutout switches having been pulled. Boeing's only suggestion in that situation is to manually grab the trim wheel to stop it from rotating. Obviously if it's already at 40 degrees nose down grabbing the trim wheel is not going to help much.
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Last edited by Philip Argy; 5th April 2019 at 03:25 PM. Reason: Added key findings
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