A North Carolina college student who hid box cutters on airplanes to expose weaknesses in airline security was sentenced Thursday to two years supervised probation and a $500 fine.

Nathaniel Heatwole (search) of Damascus, Md., a student at Guilford College (search) in Greensboro, N.C., also must serve 100 hours of community service and reimburse his parents for up to $500 in legal expenses after sentencing in U.S. District Court.

Heatwole, 21, told Judge Paul Grimm that his intentions were "positive and constructive." He said he never meant to embarrass the Transportation Safety Administration (search) or put anyone in any danger.

"My goal all along was to assist TSA," in the agency's efforts to secure the nation's airlines. Heatwole also promised to continue to provide future assistance to federal authorities.

Federal prosecutors initially charged Heatwole last fall with a felony — taking a dangerous weapon aboard an aircraft — at Baltimore-Washington International Airport. That charge carried a possible 10-year prison sentence. The charge was reduced later to a misdemeanor.

Heatwole placed three disassembled box cutters and razor blades — with tape over the sharp edges — on a Southwest Airlines flight Sept. 14, along with strike-anywhere matches and about 8 ounces of liquid bleach. He also smuggled aboard modeling clay made to look like plastic explosives. During the flight, he hid the items in the rear lavatory.

Heatwole told federal authorities he concealed the items on Southwest Airlines flights in an act of "civil disobedience" to expose weaknesses in security.