Lawmakers again grounded an attempt to spend about $14 million to replace the two aging state-owned airplanes that are used to shuttle government officials around Utah, saying they first want more data to show whether the spending is wise.

Gov. Gary Herbert — who sometimes uses those planes to fly himself and visiting dignitaries around the state — had requested $12.5 million for that earlier this year, plus he counted on some additional money from selling them off to raise the total needed. Lawmakers did not approve it in the regular budget.

Then this spring, one of the aircraft had a critical wing flap failure that led to a close-call landing in Moab. With that problem on the plane’s permanent record, officials say it now has no trade-in value beyond being sold for parts — so replacement costs are rising. So are costs to maintain the 20-year-old aircraft.

The Utah Department of Transportation made a repeated pitch to replace the airplanes this week to the Legislature’s Transportation Interim Committee. But Sen. Wayne Harper, R-Taylorsville, co-chairman of the committee, wants more answers first.

Among answers he asked UDOT to provide: the benefits of purchasing vs. leasing; how to minimize repairs and downtime; and how often the state should replace its airplanes for maximum financial benefit.

“We need to have this information before next session so we can make intelligent, correct recommendations,” Harper said, and he directed UDOT to return with the information later this year.

“Our current aircraft are just flat old. They are at the end of their life cycle,” Jason Davis, UDOT deputy director, said as he asked to replace them with two new eight-person airplanes.

The state originally intended to replace the planes every 10 years, he said, but tight annual budgets led the state to avoid that and instead try to keep them flying longer.

UDOT compared the cost of flying officials around the state to sending them by car. Average annual savings by flying is “about $320,000 because of mileage, hotel and per diem travel expenses,” Davis said.

Flying offers other sometimes hard-to-see benefits, he argued. For example, the state persuades some doctors to fly to remote areas to conduct clinics. They can go and return the same day if they fly. Driving by car may require three days — so he said fewer physicians may be willing to take that extra time.

Utah’s state planes carry about 1,100 passengers a year from many state divisions, Davis said. Each agency that uses them reimburses UDOT for the cost. Herbert also pays out of the governor’s budget for his use of the planes.

The most frequent flyers are the University of Utah and the Department of Health, which use them to provide medical help in rural areas, Davis said. The planes also assist in search-and-rescue operations, including transporting search dog teams.

Legislative staff this year questioned replacing the planes and suggested that the state consider chartering airplanes instead. But Davis said, “The charter costs were just unreasonable. There was no reason to relook at those.”

UDOT found that leasing instead of buying might be able to save some money each year. “The issue you end up with is at the end of the lease period, you don’t own a plane so you lose the residual value,” Davis said.

Another problem is a lease would require annual appropriations from the Legislature.

“If for some reason one year the Legislature was unable to find the funding for this lease, we basically have mechanics, hangars and customers that would have no option because we wouldn’t have planes to fly,” Davis said.