The Federal Aviation Administration directed airlines Wednesday to do more to avoid possible electrical surges in wiring near the center fuel tanks of some Boeing 747 aircraft.

In its latest action, the FAA told airlines that over the next 12 months it wants them to install new equipment to shield certain wiring in the fuel monitoring system in some Boeing 747s. It also called on airlines to immediately inspect wiring in some fuel pumps in older Boeing 747s.

The FAA said the additional measures were based on recent tests by the National Transportation Safety Board as part of the TWA Flight 800 crash probe.