Singapore Technologies Aerospace (ST Aero) plans to ask the U.S. FAA for a supplemental type certificate (STC) covering a 15-pallet freighter conversion program for the Boeing 757.

The Singapore-headquartered maintenance, repair and overhaul (MRO) company already has a 14.5-pallet freighter conversion program for the 757, but wants to offer 15 pallets so its program can remain competitive, says a ST Aero spokeswoman, adding that there is already a competitor offering a 15-pallet 757 freighter conversion program.

She also says ST Aero’s 15-pallet aircraft will come with winglets for improved fuel-efficiency.

ST Aero has a contract with FedEx to convert 87 757s to freighters, an announcement it made in Jan. 2007, and the spokeswoman says it has converted around 70 757 aircraft for FedEx so far. She also says it has an undisclosed customer for 15 757 freighter conversions. The first aircraft from this deal has yet to be delivered, adds the spokeswoman.

The spokeswoman declines to say who will be the launch customer for ST Aero’s new 15-pallet 757 program, because the customer has yet to sign a firm contract. ST Aero has also yet to apply for the STC, but aims to apply early enough so that it can receive FAA approval in July next year, she adds.

ST Aero says it “will be working closely with Boeing’s technical support, to develop and maintain a cost-efficient converted freighter that will enhance asset reliability and asset value while reducing cost.”

Besides offering a 14.5-pallet 757 passenger to freighter conversion, ST Aero also offers an eight-pallet 757 combi version.