* ANA says lost revenue at $127 million
* ANA costs may push airline to quarterly loss
* JAL says grounding may trim $40 mln in op profit
* Both airlines likely to seek compensation from Boeing
* Compensation talks likely after commercial flights restart
TOKYO, April 30 (Reuters) - ANA Holdings and Japan Airlines Co Ltd, which together operate nearly half the world's fleet of Boeing Co Dreamliners, estimate the jet's three-month grounding will shave a combined $110 million of operating profit, an expense they may ask the American aircraft maker to shoulder.
ANA, which owns 17 Dreamliners, estimates the revenue loss from mid-January up to the end of May from being unable to sell flights on its new jets at 12.5 billion yen ($127.36 million), with the subsequent operating profit loss at around half that level or around 6.5 billion yen.
The 787 squeeze on its earnings may have been enough to push the Dreamliner launch customer into a 3.6 billion yen loss in the three months ended March 31, Kiyoshi Tonomoto, a vice president at the airline, said at a briefing in Tokyo.
JAL, with seven Dreamliners, said the loss of 787 flights to the end of May plus the cancellation of charters this business year may add up to a dip in operating profit of 4 billion yen.
Both carriers reported their annual results on Tuesday with ANA saying operating profit in the year that ended March 31 rose 7 percent to 103.8 billion yen, while JAL posted a 4.7 percent dip in operating profit to 195 billion yen.
The latest estimates from the two Japanese carriers provide the best indication yet of how big a compensation bill Boeing may face once all 50 Dreamliners are back in the air. ANA will seek a cash payment from Boeing, a source familiar with the airline's intentions told Reuters in March.
ANA on Sunday took its first Dreamliner back into the air more than three months after batteries on two of them overheated in mid-January, one on an ANA plane in Japan and another on a JAL jet parked at Boston's Logan airport. A day earlier Ethiopian Airlines became the world's first carrier to resume flying Dreamliner passenger jets after regulators gave the go-ahead for flights to restart.
ANA and JAL say they will begin compensation talks with Boeing once commercial flights are restarted.
With hundreds of test flights planned in May to test new reinforced battery systems installed on their Dreamliners, revenue generating operations are unlikely to begin until June at the earliest.
United Airlines, the only U.S. carrier with the jet, said it will begin commercial flights on May 31. Eight airlines currently own Dreamliners and in addition to United, ANA and JAL include Air India Ltd, LATAM Airlines Group, Qatar Airways and LOT Polish Airlines.
In addition to the battery fix approved by the Federal Aviation Administration (FAA) in the United States, Japan's Civil Aviation Bureau has requested JAL and ANA to monitor battery current while the jet is in the air and regularly inspect used batteries.
The revamped battery is less prone to heat build-up, has a redesigned charger and is encased in stainless-steel box capable of withstanding an explosion. The new system also includes a metal exhaust tube to vent any gases outside the jet if it overheats.
The halt to Dreamliner flights, the first fleet grounding since regulators parked the McDonnell Douglas DC-10 jet in 1979 after a crash in Chicago killed 273 people, has cost Boeing an estimated $600 million and forced it to halt deliveries.
The U.S. aircraft maker on Saturday said it is, nonetheless, still on course to raise production to seven a month of the 250-seat aircraft by mid-year and to crank it up to 10 787s a month by the end of the year.
The carbon-composite Dreamliner cost an estimated $20 billion to develop and represents a leap forward in design, offering a 20 percent reduction in fuel burn and added cabin comforts such as higher humidity, larger windows and modern styling.
Boeing on April 24 said net income in the first quarter of the year jumped almost 20 percent despite the 787 troubles.