Vought Aircraft Industries Inc. wants to fill more than 50 acres of wetlands next to Charleston International Airport to make room for its proposed $560 million manufacturing complex and future operations.

The plan, however, is encountering turbulence.

The U.S. Interior Department's Fish and Wildlife Service, an influential voice in environmental permitting matters, is recommending that the U.S. Army Corps of Engineers deny the request unless the company meets certain demands.

Fish and Wildlife said the aerospace company must specify how it will offset the lost habitat. Also, it said Vought needs to propose a development plan that is less speculative and less intrusive.

Texas-based Vought has applied to fill about 51 acres at the wooded 387-acre property. The land is at the entrance to Charleston International and is bordered by Interstate 526, International Boulevard, South Aviation Avenue and a rental car complex.

The economic stakes are high. Vought and its Italian joint venture partner, Alenia Aeronautica, announced plans in December to build a sprawling manufacturing complex on the tract to supply Boeing Co. with large structural components for its new 787 "Dreamliner" passenger jet starting next year.

The companies, operating as Global Aeronautica, said the partnership will create about 645 jobs for the Charleston region. The master plan for the property pinpoints future manufacturing locations and sites for suppliers.

Many of the long, shallow, low-lying areas around the airport are the legacy of the local phosphate mining industry.

While Vought is seeking a wetlands permit for its entire tract, the first construction phase will require 100 acres, nine of which would need to be filled, according to the state Office of Ocean and Coastal Resource Management.

The Corps of Engineers has received several comments about Vought's request since public notices were sent out last month. So far, the federal wildlife agency has submitted the only objection.

Vought officials could not be reached for comment Thursday.

In a letter dated Jan. 25, Fish and Wildlife said it agreed with the Corps' findings that the wetlands request will not adversely affect any threatened or endangered species and will not destroy any federally protected wildlife habitats.

At the same time, the wildlife agency described the property as "an isolated oasis" that performs important water-quality functions and provides food and cover for unspecified species "in an otherwise commercialized environment."

The loss of the wetlands would lead to "the continual degradation of the natural resources in the area," said Timothy N. Hall, a field supervisor with Fish and Wildlife's Charleston office.

Hall also said Vought's mitigation plans are vague and incomplete.

Aside from committing to preserve six acres of wetlands at the site, the company did not identify specifically how it will offset the loss of the other acres it wants to fill. Fish and Wildlife said it "does not believe it is appropriate to consider this project without a complete mitigation package."

Also, the agency said it is concerned about "the speculative nature" of the request. Hall noted that most of the wetlands Vought wants to fill are in areas being set aside for future uses.

Fish and Wildlife called for the company to redesign its site plan. The revisions, it said, should consider alternatives that minimize the impact on the wetlands to the maximum extent possible.

The Corps of Engineers will consider the recommendations and others after the public comment period ends at noon Monday.

At that exact moment, Gov. Mark Sanford and executives from the Vought-Alenia consortium are scheduled to be at the site to mark the official ground-breaking.