Officials lacked information on ``operational life limit'' of aircraft operated by Neptune Aviation, of Missoula, Mont., and Minden Air Corp., of Minden, Nev., one of the criteria needed to help prove the air tankers airworthy, said Rose Davis, a spokeswoman at the National Interagency Fire Center.
If officials received the information _ and Davis said they continue trying - they would reconsider returning the air tankers to service, she said.
Right now, ``we don't have the stuff from when they were a young airplane to see what they've been through already,'' she said. Without knowing how many hours have been attributed to the airframe, she said, officials can't determine how long the aircraft is ``supposed to live.''
Both companies operate planes known as P2Vs, Davis said, and manufacturer Lockheed Martin may have the information available but it is considered proprietary.
The decisions to keep the planes grounded were made by officials from the U.S. Forest Service and Bureau of Land Management, Davis said.
In May, the Forest Service and Interior said they were ending the contract for 33 air tankers because of concerns with airworthiness and public safety. That decision came after an April 23 report by the National Transportation Safety Board on three air tanker crashes.
Federal officials later said some of the air tankers could be used to help fight fires this summer if their operators could prove they are safe to fly. In June, the Forest Service signed an agreement with DynCorp Technical Services, a Texas-based firm, to help in analyzing airworthiness documentation provided by operators of the large air tankers.
Officials earlier announced that air tankers owned by California's Aero Union Corp., had been approved, and Davis said Monday that decisions on requests by other companies are likely in the next couple weeks.
Sen. Max Baucus, D-Mont., said Monday that he will work to launch a congressional investigation into how the decision affecting Neptune was made, saying he's not convinced the Montana company received a ``fair shake.''
``They haven't been treated fairly, and this decision flies in the face of everyone who has been working to get them back in the air,'' Baucus said in a statement.
Davis said officials were consistent in the criteria the companies needed to meet. However, operational ``life limit data'' will vary depending on the type of airplane a company uses, she said.
Discussions will continue with Lockheed Martin to see if there are ways to secure the data, and Monday's decision does not completely ``shut the door'' on either company getting air tankers back in service this fire season, Davis said. Still, she said, it is not clear what kind of information might exist.
Janet Parker, president of Minden Air, the only private air tanker company in Nevada, said she's trying to be hopeful. So far, she said there have been no layoffs at the business but it's a possibility she may soon have to consider.
``This is our livelihood,'' she said Monday. The company was hoping to have two of its tankers approved for flight.
``We're generated enough documents that prove our aircraft are safe. There's nothing that shows there's any problem with them in the fatigue area,'' she said.
Minden Air's two former Navy twin-engine planes were built in the late 1950s and are capable of dropping as much as 3,000 gallons of fire-retardant slurry on a blaze.
Officials at Neptune Aviation did not immediately return a phone call seeking comment.
