Investigators from the National Transportation Safety Board yesterday examined the crippled Air France Concorde that made an emergency landing Thursday at Dulles International Airport.

The Concorde's two main landing gear tires burst on take-off, and debris punctured a fuel tank and ruptured some hydraulic lines. The sleek supersonic jet with 81 passengers and a crew of nine also lost its left main rear brakes but landed safely after 20 minutes in the air.

"We don't know the extent of the damage yet," said NTSB investigator Jack Lipscomb, who examined the Concorde with several Air France mechanics and expert engineers who arrived from Paris early yesterday.

A preliminary NTSB report is expected to be released next week, according to Lipscomb.

Air France spokesman Jim Collins said the Concorde - one of four owned by the company - will remain grounded at Dullies for several days.

"There's quite a bit of work to be done," said Collins. Air France is expected to fly needed parts to Washington from Paris.

Collins said a backup Concorde took off from Dulles at 2 a.m. yesterday - nearly 12 hours behind schedule - with 69 of the original 81 passengers aboard. Others decided to spend the night or travel earlier on other airlines, Collins said.

t"The passengers took it very well," he said.