The robotic submarine searching for the wreckage from the missing Malaysian airliner was once again forced to cut short its mission Wednesday.
The Australian agency coordinating the search said an unspecified technical problem forced the Bluefin-21 autonomous underwater vehicle to resurface.
It said the vehicle was subsequently redeployed to continue the search, adding that an initial analysis of data retrieved has revealed "no significant detections."
The agency gave no explanation for what caused the interruption, or how long it lasted.
Earlier this week, the submarine's mission was aborted after just six hours when it reached an area that exceeded its operating depth of 4,500 meters.
The Bluefin-21 is using sonar to create a three-dimensional image of the floor of the southern Indian Ocean, where the Boeing 777 is believed to have crashed.
U.S. Navy officials have warned it could take up to two months for the submarine to search the 600-square kilometer area, which has never been mapped.
On the surface, a team of 14 aircraft and 11 ships continued Wednesday looking for debris and listening for black box signals, although authorities have warned that this effort will soon be ended.
It has now been a week since authorities last detected a signal they believe came from a locator beacon on the plane's flight data recorder, which is presumed to have run out of batteries.
The Malaysia Airlines jet, carrying 239 people, vanished five weeks ago while en route from Kuala Lumpur to Beijing.
Malaysian officials think the plane was intentionally diverted. But they have refused to rule out other possibilities, including a massive mechanical malfunction.