Regulators are proposing that operators of as many as 89 US-registered Embraer Phenom 100 business jets replace the twin-jet's two angle-of-attack sensors and cover plates to prevent possible loss of control problems.
If approved, the proposed airworthiness directive, issued on 31 January, would give operators 300 flight hours or one year to replace the sensors and plates, one of which is located on each side of the nose on the exterior of the fuselage.
The AOA sensors provide input to the Phenom's stall-warning-protection system, which activates a stick pusher if speeds decay too close to aerodynamic stall.
 |
|---|
© Jetbird |
"It has been found that moisture may accumulate and freeze, under certain conditions, in the gap between the AOA vane-base assembly and the stationary ring of the sensor's body," the AD states. "If freezing occurs, both AOA sensors will be no longer effective without alerting. This may result in inadvertent aerodynamic stall and loss of controllability of the airplane."
The FAA directive mirrors the original Brazilian AD, which itself is based on an Embraer service bulletin first issued in September 2010 and revised in November.
Source: Flight International
