Following an incident on a Model ATR72-212 airplane it was determined that the left aileron surface position data recorded by the FDR was invalid. Further investigation revealed that incorporation of
Supplemental Type Certificate (STC) ST01310NY or ST01280NY yielded higher-than-expected levels of incorrect aileron surface position data, as reported from the FDR. As a result of this
incident, Delta Engineering redesigned the aileron sensors with high cable tension to reduce cable fatigue, and issued Service Bulletin 2301-06397-2030, dated September 26, 2008. The service bulletin provides operators with guidelines for replacing the existing aileron sensors with the new, improved sensors. 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 Aviation 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 Delta Engineering Service Bulletin 2301-06397-2030, dated September 26, 2008.

SAIB Attached