MIAMI BEACH - Divers will return to the ocean floor to look for small remaining pieces of the vintage seaplane that crashed just off the beach, but the initial recovery phase of the investigation is virtually complete, federal authorities said Thursday.

Many questions remain unanswered about Monday's crash that killed all 20 on board. The plane's right wing separated from the fuselage shortly before the crash, sending the plane plummeting into the sea, but it's not clear why the wing separated and whether it was the sole cause of the crash.

Investigators had hoped to glean information from the cockpit voice recorder, but when they recovered it Wednesday, they found it was unreadable, leading to more questions about its malfunction.

The Chalk's Ocean Airways plane crashed off Miami Beach shortly after takeoff on a trip to the Bahamas.

"I wish this were a faster process," said NTSB acting director Mark Rosenker of the investigation, "but we cannot skip steps, and we will not jump to conclusions."

Rosenker said video footage of the crash taken by bystanders and a port security camera would be extremely helpful in the investigation.

"Having a video is a rare type of tool to have in an aircraft investigation," he said.

Cranes had lifted 95 percent of the wreckage from about 35 feet of water by Wednesday night.

The recovery process stopped temporarily Thursday because not enough divers were available, but investigators planned to return to the water today to search for the remaining small parts such as door handles and window frames, Rosenker said.

"These are very small parts, but we want to get everything we can from the ocean floor," he said.

Rosenker said further tests would be run on the recovered plane parts in Washington. Investigators will also continue to review the lengthy maintenance and operations records of the 58-year-old seaplane and interview Chalk's employees.

Cracks in the support beam of the plane's right wing were being examined to determine if they caused the wing to fall off. The NTSB also was taking apart the matching left wing support to see if there was similar cracking.

Inspectors will try to determine whether fatigue cracks could have been found and repaired, and whether stress was a factor in the cracking that occurred.

The FAA is also working with Chalk's to figure out how to examine the company's four remaining Grumman G-73 seaplanes to determine whether they have similar stress cracks. The company voluntarily grounded its fleet Wednesday.

There is a strong incentive to work quickly, said Grant Brophy, director of flight safety and security at Embry-Riddle Aeronautical University, which trains safety investigators.

Authorities want to identify a possible cause of the crash so operators of similar aircraft can be notified of potential hazards, he said.

Eighteen passengers and two crew members were killed in Monday's crash. Only 19 bodies have been recovered. At least 11 victims were returning home to the Bahamian island of Bimini, many of them after Christmas shopping jaunts.

The plane's pilot, Michele Marks of Boynton Beach, and co-pilot Paul Joseph DeSanctis of Reading, Pa., had unblemished flying records with no accidents, incidents or enforcement actions against them, Federal Aviation Administration spokeswoman Kathleen Bergen said Thursday. Both were certified to fly single- and multi-engine seaplanes.

Marks' husband Mark told The Associated Press he found out about the crash by watching the footage on the television.

"She was an amazing person," he said, his voice breaking. "She was everything I ever had. You kiss your wife goodbye, and then she's gone."

The Federal Aviation Administration took no immediate action against Chalk's.

The company did not immediately return a message left Thursday. Earlier it promised to "be back in the air very soon."

The plane was retrofitted in the 1980s with more powerful engines, but it wasn't clear if that played any role in the cracking, Rosenker said. The engines' installer said it should not have played any role, and Rosenker said the engines appeared to still be running when the plane crashed.

He said the full investigation may take up to a year to complete.

It would require "very sophisticated testing," such as a special dye that penetrates the aluminum structure, said Bill English, NTSB investigator in charge of the Chalk's crash.

Chalk's, which flies between Florida and the Bahamas, had net losses of $244,000 on operating revenues of $5.4 million in 2002, according to data from the federal Bureau of Transportation Statistics. A previous owner was forced into bankruptcy in 1999.

The plane that crashed had few major reported incidents, and no passengers or crew were injured in any of them, according to the FAA.   from this link