WASHINGTON (CNN) -- The Federal Aviation Administration wants new inspections and tests on older Boeing 747 aircraft, with an eye toward preventing the type of explosion suspected of bringing down TWA Flight 800 in July 1996.

In proposals issued Thursday, the FAA called for a closer look inside the center fuel tanks on board the jumbo jets and, on some planes, replacement of silver-plated wiring with new nickel-plated wiring, and installation of a flame arrestor in the scavenge pump assembly that removes leftover fuel from the tank.

The FAA will accept comments from the airlines and further analyze the proposals before they become final requirements.

Previously, FAA proposals and requirements have dealt with wiring and other parts on the exterior of the 747s' center fuel tanks. Some of Thursday's proposals responded to recommendations by the National Transportation Safety Board, but the FAA stopped short of requiring periodic fuel tank inspections as the NTSB had recommended.

"A requirement for periodic inspections will be determined under design review activities required by a proposed Special Federal Aviation Regulation, which will address long term maintenance issues," the FAA said in a statement.

The agency said that 251 planes would require one or more of the actions put forth in the proposals. Replacement of any wiring would have to be done within 24 months or 20 years from the date the plane was built, whichever is later. All other action would have a 24-month deadline. The airlines would have ten days to report inspections results to Boeing.

The owners of the planes would have to pay for any required work, which is expected to cost between $28,000 and $63,000.

TWA Flight 800, bound for Paris, exploded off Long Island on July 17, 1996, killing all 230 people aboard. Investigators suspect a spark ignited the plane's center fuel tank.

Since the accident, the FAA has published or proposed six airworthiness directives relating to the fuel tanks of 737s and 767s and well as 747s.