The air tanker that went down while fighting a wildfire near Yosemite National Park this week, killing the pilot, did not appear to have mechanical issues, officials announced Friday.
The finding by National Transportation Safety Board investigators prompted state fire officials to lift an order that had grounded California's fleet of S-2T air tankers.
"We are comfortable to say that we don't see anything that leads us to any mechanical issues," Josh Cawthra, an NTSB investigator, told reporters.
He added that his agency had concluded its on-scene investigation into the crash that killed veteran pilot Geoffrey "Craig" Hunt, but will have to wait until the Dog Rock fire is extinguished before the wreckage can be removed from the area.
The blaze has burned 245 acres at the edge of the park and is 10% contained, park officials said.
"It's a very complex investigation. We essentially leave no stone unturned," Cawthra said.
The plane, an S-2T tanker that carries 1,200 gallons of fire retardant, crashed near El Portal inside Yosemite on Tuesday afternoon.
Hunt, a 13-year veteran, was alone in the plane and was making his second drop for the day when the crash occurred.
"This accident is extremely tragic," he said. "These pilots put their lives out there on the line."
Despite the delay in moving the plane, investigators can continue with other elements of the probe, including reviewing digital recordings associated with the flight. Investigators are expected to interview witnesses, examine radio communications, radar data and any video of the flight that may be out there, said NTSB spokesman Keith Holloway.
Because the plane was not a commercial airliner, it doesn't have a black box, Holloway said, adding that nine of out 10 flight crashes the NTSB investigates don't involve black boxes.
A preliminary report on the crash could be issued in the next five business days, officials said, with the final report taking as long as 18 months.
Meanwhile, Ken Pimlott, chief of the California Department of Forestry and Fire Protection, said normal flight operations, as well as routine inspections, would be allowed to resume immediately.
Most pilots were eager to start flying again after the fleet was grounded right after the crash, but he said all had been urged to take whatever precautions they felt necessary before returning to the skies.
"We just want to make sure they are comfortable and they are ready," Pimlott said.