TO: KRWA NOUS2 142109
GENOT RWA 16/11
N JO 7110.711
FF ALRGNS 1/500/530 AMC-1 AMA-500 ACT-1 ALATFO XVM
EFFECTIVE: 04/14/2016
SUBJECT: EMB-300 PHENOM YAW DAMPER FAIL DUE TO UNRELIABLE
OR UNAVAILABLE GPS SIGNAL
GPS TESTING MAY RESULT IN UNRELIABLE OR UNAVAILABLE GPS
SIGNAL WITH WHICH THE FOLLOWING ANOMALY IS ASSOCIATED:
EMBRAER HAS RECENTLY RECEIVED A REPORT OF GPS 1 AND 2
SIMULTANEOUS SIGNAL LOSS DURING FMS NAVIGATION IN CRUISE
FLIGHT FOLLOWED BY A GPS HSI 1 AND 2 FAILURE INDICATION,
ATTITUDE AND HEADING REFERENCE SYSTEM (AHRS) 1 AND 2 FAULT
AND, AFTER A FEW MINUTES, A STALL WARNING PROTECTION
SYSTEM (SWPS) FAULT, VENTRAL RUDDER FAIL, YAW DAMPER FAIL,
AUTO PILOT FAIL, AND CAS MESSAGES ASSOCIATED WITH
UNEXPECTED ROLLING AND YAWING OSCILLATIONS (DUTCH ROLL) AT
HIGH AIRSPEEDS.
FURTHER ANALYSIS REVEALED GPS CONSTELLATION SIGNAL
INSTABILITY IN THE FLIGHT AREA LEADING TO LOSS OF BOTH GPS
INFORMATION DATA AND CAUSING THE EVENT DESCRIBED ABOVE.
THE AHRS CONTINUOUSLY CALCULATES AND APPLIES ALTITUDE AND
HEADING MEASUREMENT UPDATES TO CORRECT GYRO-INTEGRATED
ALTITUDE AND HEADING DURING FLIGHT MANEUVERS AND, IN NORMAL
OPERATION, THE AHRS RELIES UPON GPS, AIR DATA SYSTEM AND
MAGNETIC FIELD MEASUREMENTS SUPPLIED BY THE MAGNETOMETER
TO MAINTAIN PRIMARY AHRS OPERATION MODE.
THE DUTCH ROLL BEHAVIOR MAY BE EXPECTED FOR AN AIRPLANE
WITH NO YAW DAMPER AND/OR VENTRAL RUDDER PROTECTION,
ESPECIALLY ON AIRCRAFT WITH SWEPT WINGS.
IF THIS ANOMALY OCCURS CONTROLLERS CAN EXPECT THE PILOT
MAY REDUCE SPEED BELOW 240 KIAS/.63M AND INITIATE AN
EMERGENCY DESCENT.
ALL OPERATIONAL PERSONNEL MUST BE BRIEFED ON THIS NOTICE AS
SOON AS POSSIBLE.
DIRECT QUESTIONS TO LARRY BECK (202) 267-0862
Original Signed by Maurice Hoffman for
HEATHER HEMDAL
DIRECTOR, AIR TRAFFIC PROCEDURES, AJV-8
https://www.faa.gov/documentLibrary/med ... MB-300.pdf
