A long-planned effort to replace a World War II-era airplane hangar at Katama Airfield remains in limbo as the town grapples with the complicated process of amending a conservation restriction to allow the project to go forward.

Katama Airfield commissioners came before Edgartown selectmen again this week to press for a resolution to the issue, which revolves around a run-down hangar that commissioners say is too small.

The 90-year-old grass field airport is owned by the town and managed by the airfield commission and the conservation commission. The town purchased the airfield and more than 100 acres of surrounding land in the 1980s, with the stipulation that the land remain an airfield in perpetuity. A conservation restriction on the land is held by The Nature Conservancy. One facet of the restriction is a prohibition on the expansion of existing buildings — meaning the hangar could only be rebuilt in the same footprint.

The airport commissioners argue that the hangar needs to be bigger. In 1996, plans began to replace the circa-1945 airport hangar, which is about 2,650 square feet. The latest plans call for a new 6,000-square-foot hanger on a 60-by-100 footprint.

“We worked with everyone we can think of,” airfield commissioner Bob Stone told the selectmen. Town meeting voters and the Martha’s Vineyard Commission approved the project in 2010, and Mr. Stone said they’ve also received approval from all necessary town boards.

But expanding the hangar will also require amending the conservation restriction, a complicated process that the town has been dealing with for the last several years. Amending a conservation restriction requires an act of the state legislature. In 2011 a bill was approved that removes 2.02 acres of land from the conservation restriction to be used for the airport. But the amendment calls for further action: placing 62.5 acres of land, known as the Nickerson Property, under the conservation restriction; converting 6,700 square feet of land at the airfield into a natural state; and transferring about 21 acres of town-owned land off Pennywise Path into conservation land with a conservation restriction. The act also requires that The Nature Conservancy approve the hangar expansion.

The details of the agreement have yet to be approved at the town level.

Last June, Edgartown town counsel Ronald H. Rappaport came before the selectmen to register concern about the conservation restriction agreement, which he said was nearly completed. “The end product is much more complicated than any of us really contemplated,” Mr. Rappaport told selectmen at that time, noting that the conservation restriction had grown from two pages to almost 18 pages.

Airport commissioners have also had concerns about the agreement. Mr. Stone told the Gazette that he’s cautioned the town not to sign the agreement until they are given total relief from restrictions on their plans for the hangar.

“We haven’t been able to levy the proper pressure to have the new restriction be a reasonable one,” airfield commission chairman James Craig told selectmen this week.

Mr. Stone said that above all else, the hangar could not be rebuilt in the same footprint, which is too small to meet the town’s needs.

“All we want to do is expand the footprint of the current hangar that is falling down and an eyesore, to one that would be of use to the airfield,” Mr. Stone told the Gazette yesterday. But he said there has been reluctance on the part of The Nature Conservancy.

“You cannot imagine the frustration that we on the airfield commission have with this reluctance and unreasonableness,” he said.

Mr. Stone said that about $150,000 has been donated to the Katama Airfield Trust from private fundraising efforts for the project, and the town has approved $250,000 for the hangar, $200,000 of which is Community Preservation Act funding. But with the time that’s elapsed since the effort began, that amount is no longer enough to cover the cost. Mr. Stone said additional funds will be required now to complete the project.

The airfield trust has spent $70,000 on architectural and engineering costs.

“We’re not going to give up,” Mr. Stone said. “The thing of it is, is to build the hangar in its original footprint as it exists is not the way to go.” He said an expansion is required for the needs of the airport and the airport’s restaurant, the Right Fork Diner.

There are other changes ahead for the airfield. Michael Creato, who has been the lessee and manager of the airport since 2002, has said he does not intend to renew his lease. Mr. Creato is a grandson of Stephen C. Gentle, who originally owned the airfield and sold it to the town.

The town will need a new state-licensed manager for the airfield. Mr. Stone said Mr. Creato will continue to be involved with the airfield, perhaps as a commissioner.

The Edgartown selectmen plan to meet Tuesday with Mr. Rappaport and conservation agent Jane Varkonda to hash out the issues.

“It needs to be resolved because none of us want to see what’s out there go any different,” selectman Margaret Serpa said this week. “It works.”

“It is a lovely place,” Mr. Stone said.