The Los Angeles Board of Airport Commissioners recommended on Wednesday amending a lease agreement with Signature Flight Support to allow the aviation company to do required improvements to property at Van Nuys Airport. The move was necessary because Signature would not have been able to do the necessary $6.3 million in improvements required by the lease because of objections from the Federal Aviation Administration. Signature had planned to build new facilities on the 17.4-acre site at 16233 Vanowen St., including hangar and office space. The FAA, however, said the construction would degrade the instrument landing system at the airfield that allows pilots to land when unable to establish visual contact with the runway. The airport commission granted Signature permission to spend only $2.5 million on the Vanowen property, which would include repair and maintenance of aircraft parking ramps and maneuvering areas and the rehabilitation of structures already existing on the premises. The remaining $3.8 million in improvements could be shifted to one of two other leaseholds that Signature has at the airport. The aviation firm has until the end of 2021 to make those remaining improvements. The Los Angeles City Council must approve the lease amendment.