The US Federal Aviation Administration is proposing to remove 12 versions of the full authority digital engine controllers (FADECs) that manage thrust on GE CF34-8E engines powering Embraer E-170 regional jets.

The proposed updated airworthiness directive (AD), to be published Monday, reveals that an earlier fix to the FADEC software, issued in July 2008 in response to six "loss of thrust" incidents, was not fully effective.

According to the FAA, 20 additional reports of loss-of-thrust events have occurred since that time, all tied to the same fuel metering valve feedback faults that the first software fix was meant to correct. The faults were caused by "connector pin micro-arcing", says the agency.

"The improvements prevent loss of thrust control by detecting erroneous fuel metering valve feedback signals," says the FAA, adding that "no loss of thrust control events due to pin arcing have occurred with the (new) software version improvements incorporated into the FADECs."

The agency says the proposed AD, which would require switching out the software within 660h of the AD becoming final, will affect 273 engines in the US registry.

FAA notes the fix will take about 1h to complete for each engine. GE explains the upgrade can be installed while the engine is on wing, and about 75% of the fleet now has the upgrade. The manufacturer anticipates installations being completed on the remaining engines by year-end.

Source: Air Transport Intelligence news