L-3 Communications Vertex Aerospace, LLC, Madison, Miss., is being awarded an $18,530,000 modification to a previously awarded indefinite-delivery requirements contract (N00019-05-D-0023) to exercise an option for logistics support for TH-57B/TH-57C aircraft.  Work will be performed at Naval Air Station (NAS) Whiting Field, Milton, Fla. (99 percent), and NAS Patuxent River, Md. (1 percent).  Work is expected to be completed in March 2011.  Contract funds will not expire at the end of the current fiscal year.  The Naval Air Systems Command, Patuxent River, Md., is the contracting activity.