Investigators probing a Dec. 6 commuter airplane crash that killed 13 people after takeoff from the Jacksonville airport have discovered five earlier takeoff accidents involving the same type of airplane but apparently different circumstances, federal sources said yesterday.

A team of National Transportation Safety Board and Federal Aviation Administration specialists is en route to Brazil to examine the records of those earlier accidents and to reconfirm the certification standards of the airplane in question, aviation sources said.

The plane is a Brazilian-made Embraer 110, known as the Bandeirante, or Bandit. About 130 of them are in use by commuter airlines in the United States. The Jacksonville accident occurred after the tail section fell off.

Since that accident, the tail sections of all U.S.-flown Bandeirantes have been inspected, and nothing the FAA considered serious was discovered.

Investigators are puzzled as to why that tail separated but are studying the possibility that the tail section was a victim of an aerodynamic phenomenon known as "flutter," a steadily increasing vibration that may result in destruction of the affected section. There are many possible sources for flutter, including engine vibration or vibration set up by uneven air flow over the wing or tail.

None of the five other takeoff accidents involved the loss of the tail section, the sources said. About 450 Bandeirantes are in service worldwide.