AD NUMBER: 2009-23-11

MANUFACTURER: Empresa Brasileira de Aeronautica S.A. (EMBRAER) Model EMB-500 Airplanes
SUBJECT: Airworthiness Directive 2009-23-11

SUMMARY:It has been found the possibility of heating deactivation of Air Data System (ADS) sensors due to its inadequate automatic logic, when ADS/AOA knob is on AUTO position associated with the following messages:

--DC BUS 1 OFF displayed on Crew Alerting System --CAS in conjunction with STBY HTR FAIL (which means loss of power on DC BUS 1); or
--EMER BUS OFF displayed on CAS (which means loss of power on EMERGENCY BUS); or
--ELEC EMERGENCY displayed on CAS (which means Electrical Emergency).

The loss of airplane air data sensors heating may cause ice buildup on their surfaces, which in turn may cause wrong pressure acquisitions resulting in erroneous flight parameters indication to the flight crew. Since this condition may occur in other airplanes of the same type and affects flight safety, an immediate corrective action is required. Thus, sufficient reason exists to request compliance with this AD in the indicated time limit.

This AD requires actions that are intended to address the unsafe condition described in the MCAI

FMI: http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/0/F942E675AF7189D68625766C0051BDC3?OpenDocument