Flight operations at Japan Air System, disrupted since Jan. 19 by cancellations because of engine defects in its MD-81 and MD-87 jetliners, will return to normal Feb. 8, the carrier said Wednesday.

JAS, a unit of Japan Airlines System Corp., found cracks in the engines of 18 of the jets in emergency inspections carried out after the first incident was reported.

The carrier said it will be able to return to normal operations as it will finish replacing some of the engines of the 18 planes by Feb. 7.

It will also ask Japan Airlines to offer spare aircraft.

JAS and JAL are to be fully merged in April but have already integrated their management under the holding company Japan Airlines System.

The number of JAS flights that will have been canceled by Feb. 7 is estimated at 546, affecting some 40,000 passengers. The company started inspecting the engines Jan. 19.

The carrier said the loss caused by the cancellations is expected to amount to 500 million yen.

Meanwhile, Isao Kaneko, president of Japan Airlines System, voiced regret during a news conference that the cancellations have caused trouble and created anxiety among customers.

"We have been conducting maintenance and inspections (on aircraft) on instructions from the manufacturer," he explained.

He added that the firm has dispatched the deputy head of its maintenance department to the U.S. engine manufacturer, Pratt & Whitney Co., to investigate the cause of the trouble.

JAS has 17 MD-81s and eight MD-87s, which are midsize twin-engine planes. It found cracks on the stator blades in 21 engines on 18 of the planes. The stator blade controls the flow of air compressed by the rotor.

The airline had to ground so many planes for such a long time because it could not obtain enough engines from the manufacturer.

Nobuteru Ishihara, minister of land, infrastructure and transport, said earlier that Japan has asked the U.S. Federal Aviation Administration to look into cause of the cracks and recommend solutions.