The Boeing Co. Rotorcraft Division, based in Ridley Township, Delaware County, said it submitted its revised bid this morning to make a variant of the Chinook tandem-rotor helicopter the Air Force's new combat search-and-rescue aircraft.

The Boeing HH-47 won the initial CSAR-X competition in 2006, but rivals were successful in forcing a new round of bidding. Winning the competition could mean future orders for 144 helicopters, at a total cost of about $10 billion, and as many as 400 new jobs at Boeing's suburban Philadelphia complex.

"Our updated proposal builds on the inherent strengths of the HH-47 that have been recognized throughout the CSAR-X competition: low risk, exceptional performance, and significant combat-proven experience that meet all mission needs and requirements," Boeing spokeswoman Jenna K. McMullin said.