Aircraft
Certification Service Washington, DC U.S. Department of Transportation Federal Aviation Administration
NM-11-19
February 3, 2011
This is information only. Recommendations
aren’t mandatory.
Introduction
This Special Airworthiness Information Bulletin (SAIB) advises
registered owners and operators of ATR - GIE Avions de Transport
Regional Model ATR42 and ATR72 airplanes of an airworthiness concern
regarding incorrect calibration of certain angle of attack (AOA)
sensors.
Background
Thales Avionics has issued service information to provide operators
with guidelines for test and adjustment of AOA sensors identified
therein by part number and serial number. In addition, the European
Aviation Safety Agency (EASA), which is the Technical Agent for the
Member States of the European Community, has issued a Safety
Information Bulletin titled “Thales Angle of Attack Sensors, No.
2010-29,” dated October 7, 2010.
The affected AOA sensors were repaired at a North American repair
station and the bench used for the final acceptance test was not
properly controlled and calibrated; therefore, the accuracy of the AOA
vanes could not be guaranteed. Subsequent data received from ATR - GIE
and EASA indicate the maximum inaccuracy of an AOA sensor to be +0.7
degrees, this calibration is greater than that specified in the
component maintenance manual; therefore, this inaccuracy would result
in a conservative early indication of stall warning.
At this time, the airworthiness concern is not an unsafe condition that
would warrant Airworthiness Directive (AD) action under Title 14 of the
Code of Federal Regulations (14 CFR) Part 39.
Recommendations
The FAA recommends that all owners and operators of ATR - GIE Avions de
Transport Regional Model ATR42 and ATR72 airplanes comply with the
actions outlined in Thales Service Bulletins C16363A-31-002,
45150560-31-003, 45150561-31-003, and 45150563-31-002, all dated June
22, 2009.
For Further Information Contact
Tom Rodriguez, Aerospace Engineer, International Branch, ANM-116,
Transport Airplane Directorate, FAA, 1601 Lind Avenue SW., Renton,
Washington 98057-3356; telephone (425) 227-1137; fax (425) 227-1149;
email tom.rodriguez@faa.gov.