Originally Posted by
jimtx
So if you have a malfunction where you apply the AD procedure you now have an aircraft with “unimproved” longitudinal handling characteristics and degraded trim capability. But FAA/Boeing does not think that would be a concern to warn you about because you will never approach the flight envelope where it would affect you?
The Engine Failure NNC does not specifically state to avoid high AoA or Steep Turns... ?
Flaps stopped MCAS inputs. The accident crew failed to notice that as well.
CATEGORY: Maintenance, Engineering, Flight Operations, Management, Safety
SERVICE REQUEST ID: 4-4298138108
ACCOUNT: Boeing Correspondence (MOM)
DUE DATE: No Action Required
PRODUCT NAME: Airplane
PRODUCT LINE: 737
PRODUCT: Several
ATA: 0000-57
SUBJECT: Information - Multi-Model Stall Warning and Pitch Augmentation Operation
REFERENCES: /A/ MOM-MOM-18-0655-018
A pitch augmentation system function called “Maneuvering Characteristics Augmentation System” (MCAS) is implemented on the 737-8, -9 (MAX) to enhance pitch characteristics with flaps UP and at elevated angles of attack. The MCAS function commands nose down stabilizer to enhance pitch characteristics during steep turns with elevated load factors in manual, flaps up flight. The system is designed to allow the flight crew to use the column trim switch or stabilizer aisle stand cutout switches to override MCAS input. The function is commanded by the the Flight Control Computer using input data from sensors and other airplane systems.
The MCAS function becomes active when the airplane AoA exceeds a threshold based on airspeed and altitude. Stabilizer incremental commands are limited to 2.5 degrees and are provided at a rate of 0.27 degrees per second. The magnitude of the stabilizer input is lower at high Mach numbers and greater at low Mach numbers. The function is reset once AoA falls below the AOA threshold or if manual stabilizer commands are provided by the flight crew. If the original elevated AoA condition persists, the MCAS function commands another incremental stabilizer nose down command according to the current aircraft Mach number at actuation.
The MCAS function is not incorporated on 737NG airplanes.
https://theaircurrent.com/aviation-s...em-mcas-jt610/