MD Helicopters has added a second, single-engine helicopter production line at its Mesa, Ariz. plant. The company typically is set up for two production lines: one for its single-engine aircraft and the other for the twin-engine MD900-series/Explorer. It has now set up the second line to handle conversion of single-engine aircraft for an unnamed Middle East nation, MD Helicopters President Chuck Vehlow told Rotor & Wing. That work is being done under a license other than MD’s FAA production certificates for the singles, so it is segregated from the FAA-approved line to prevent the mingling of new or used parts between the two.  For related news