National Transportation Safety Board Chairman Jim Burnett, citing the need for passengers' quick escape from a fire after a crash, asked the Federal Aviation Administration yesterday to reconsider its approval of a reduction from 10 to 8 in the number of exits on a Boeing 747 jumbo jet.

In a letter to Donald D. Engen, now FAA administrator and a former safety board member, Burnett said the board's concern is based on accident history, which shows that "many postcrash fires involve an immediate loss of 50 percent of the exits (right or left side exits, or exits forward or aft of the wing)."

Engen has said he is reconsidering the decision, which was made by the FAA's Northwest Mountain Region in Seattle, the primary office for dealing with changes in Boeing airplanes. The Northwest region was following existing regulations, an FAA spokesman said. Those regulations require eight doors for airplanes with up to 440 seats. No domestic airline flying 747s has more than 440 seats, the FAA said, although several foreign carriers do.

A spokesman for Boeing -- which manufactures a kit to close off the two doors, one over each wing -- said 12 foreign carriers have purchased the kits for 69 airplanes, "although we don't know whether they have been installed." Foreign airlines are not subject to FAA regulations.

The issue was raised with both the FAA and the safety board by Matthew H. Finucane, director of air safety and health for the Association of Flight Attendants, a union. Finucane cited much the same accident history Burnett used in his letter to Engen.

Sealing doors has several advantages for an airline. A sealed door does not have to be maintained and the evacuation slide -- a troublesome, heavy device -- does not have to be carried or serviced.