The Boeing Co. began offering a $10,000 reward Friday for help in the criminal investigation into who vandalized two Chinook helicopters on its Ridley Township assembly line earlier this month.

The reward, aimed at Boeing employees, came a week after federal authorities arrested a unionized assembly line worker on suspicion that he hacked wires on a nearly completed CH-47F.

A separate Defense Department reward for $5,000 also remains in effect.

Investigators are trying to determine who meddled with a rotor-blade part on a second of the dual-rotor combat helicopters being built on Boeing's 8-chopper Chinook line.

Spokesman Jack Satterfield said Boeing was circulating the reward flyer "for further information in connection with the investigation."

The $10,000 reward calls for information leading to identification and conviction.

The flyer urges tipsters to call a 24-hour hotline (267-228-2782) run by the Defense Criminal Investigative Service, which is leading the probe because the Chinooks are being built for the Army.

The vandalism, discovered May 12, shut down production for several days on the Chinook line at Boeing's Rotorcraft Division. Officials said the hacked wires and misplaced rotor-blade washer were discovered early and that no Chinooks sent to the Army were compromised.

DCIS resident-agent-in-charge Ken Maupin said his agency was aware of the new award but had no comment.

On May 20, DCIS and federal prosecutors announced that they had arrested Matthew Kevin Montgomery, a 32-year-old Chinook line worker from Trevose, in connection with the hacked wires.

Montgomery apparently had a grievance with the company, U.S. Attorney Patrick Meehan said. He has not been formally charged, and was released into his parents' custody.

Investigators have said they were treating the damage to the two aircraft as separate incidents.

Contact Maria Panaritis at 215-854-2431 or mpanaritis@phillynews.com.