An interisland service expansion by Island Air is expected to take flight at the end of the year on the wings of two new planes the carrier said it ordered Monday.

The order for two 71-seat Bombardier Aerospace Q400 NextGen turboprop aircraft estimated at a cost of $60.9 million will provide additional capacity to possibly increase service to Maui, Kauai and Lanai, the airline said.

"They will add to our existing fleet and allow us to explore new opportunities,"Paul Casey, Island Air’s president and CEO, said in a statement.

Delivery of the two Q400s is slated for November and December.

Passenger capacities for Q400s range from 71 to 86, and Island Air chose the lower configuration to offer two seating classes.

The two new planes, which Island Air could supplement with up to four more Q400 orders, are part of the airline’s ongoing restructuring effort to reverse financial losses about a year after billionaire Larry Ellison bought the struggling company with close ties to the island of Lanai, mainly owned by Ellison.

Adding the new planes will make Island Air operations more fuel-efficient, less costly to maintain and quicker, according to Bombardier, which said the Q400 can fly 30 percent faster than conventional turboprops.

Island Air operates more than 200 flights a week serving Oahu, Maui, Lanai and Kauai with five 64-seat ATR-42 turboprop planes. The ATRs are about 20 years old and have been prone to mechanical breakdowns.

Ellison said in a statement that the new planes will offer passengers a premium product coupled with unbeatable performance that will help Island Air in its effort to "redefine" regional travel in Hawaii.

"We are pleased to partner with Bombardier," Ellison said. "My experience with Bombardier over the years has been nothing but positive, which has further led to our selection of the Q400 NextGen aircraft for the next chapter of Island Air."

Incidently, Island Air briefly used an older version of the Q400 in 2006, but the entry of low-cost competitor go!Airlines that year prompted Island Air to abandon a plan to expand with more Q400s in favor of sticking with a fleet of smaller 37-seat Bombardier Dash-8 models before switching to the ATRs.

Go! ceased operations Monday.

The move by go! was announced about two weeks ago. Island Air, which reportedly had considered buying or partnering with go!, was also exploring the addition of Q400 planes and had worked out an agreement with pilots covering pay and work rules for the Q400 late last year.

Canadian-based Bombardier, which announced the order from Island Air, welcomed the airline back as a customer.

"I’m delighted that Island Air has chosen to re-join the Bombardier family and I wish the airline much success in its future ventures," Ray Jones, a senior vice president with the plane maker, said in a statement.