Citation modification specialist Sierra Industries last week received an STC for its Stallion conversion, a Citation 500/501 powered by Williams FJ44-2A turbofans in place of the twinjet's original P&WC JT15Ds. Sierra CEO Mark Huffstutler said the Stallion will climb straight to FL430 "at any weight or temperature and cruise at 380 knots on 620 pounds per hour of fuel for more than 1,400 nm." The FJ44-2A turbofans feature electronic engine controls that "virtually eliminate any engine-management issues," according to Huffstutler. These controls automatically determine the proper power setting from the conditions present and set the maximum power for those conditions. Said Huffstutler: "Push the throttles to the stop for takeoff and never touch them again until descent." Conversion price is about $1.47 million and downtime is about 10 weeks. Sierra's Eagle II conversion will add 730 pounds of fuel capacity to the Stallion to provide a range of up to 1,750 nm, but specific fuel consumption will be greater than for just a Stallion conversion.