THE search for a Malaysia Airlines jetliner deep in the Indian Ocean was again cut short yesterday when technical problems forced a US Navy underwater drone to surface without finding anything, officials said.

While a massive air and sea search for flight MH370 is continuing almost 2,000 kilometers off the coast of Perth, hopes have been pinned on the Bluefin-21 autonomous underwater vehicle finding the first concrete sign of the plane in more than six weeks of hunting.

Malaysian authorities have still not ruled out mechanical problems as causing the Boeing 777’s disappearance, but say evidence suggests it was deliberately diverted from its scheduled route from Kuala Lumpur to Beijing.

An aircraft’s black box records data from the cockpit and conversations among flight crew and may provide answers about what happened to the missing plane.

An unspecified technical problem meant the Bluefin resurfaced early yesterday and analysis of the sonar data downloaded showed no significant detections, the Australian agency leading the search said.

It was later relaunched to continue its search.

The drone was forced to end its first deployment early on Monday after it exceeded its 4.5km depth limit in the remote stretch of ocean where search authorities believe that the jetliner crashed after its disappearance on March 8 with 239 people on board.

The introduction of the Bluefin marks a methodical, slower paced new phase of the search, now in its 40th day and described by the search coordinator, retired Royal Australian Air Force Air Chief Marshal Angus Houston, as the most expensive in aviation history.

An air and sea search for floating debris continued yesterday, but Houston has indicated that will soon end.

Up to 11 military aircraft, three civil aircraft and 11 ships were scheduled to help in yesterday’s search, covering a total area of about 55,151 square km in rainy conditions.

Authorities targeted the stretch of ocean based on four signals they believe are from the plane’s black box recorders.

But they have not heard a “ping” for a week and with the batteries on the locator beacons now 10 days past their 30-day expected life, authorities have decided to stop searching using a towed pinger locator and to use the Bluefin instead.