Sending shudders through the industry, the National Safety and Transportation Board in the United States has issued recommendations which, if they were enforced, could affect not just the older Boeing 747s but also every other Boeing aircraft in service and possibly some Airbus aeroplanes as well.
The recommendations are the most far-reaching yet to surface from the investigation into the July 1996 explosion which sent the TWA airliner plunging into the ocean off Long Island, killing all 230 passengers on board.
It is now up to the Federal Aviation Authority to decide whether to translate the recommendations into a mandatory order. However, the agency issued a statement saying that it "agrees with the intent" of the safety board.
Specifically, the safety board is concerned about the condition of the wires leading to fuel gauge probes in the aircraft fuel tanks.
While no cause of the TWA crash has been officially declared, investigators believe that something happened to spark an explosion in the plane's central fuel tank.
Airlines are likely to be asked to hunt for two potential problems: the presence of sharp edges on the fuel probes that may cause a fraying of wires and the bundling together of the low-voltage wires leading to the probes with higher voltage wires.
There is a suspicion that any fraying could lead to a jumping of high- voltage current on to the low-voltage circuits.
"Unsafe conditions may exist in other B-747s and should be addressed by the Federal Aviation Administration," the safety board said in a 10- page report which was issued late on Tuesday.
While scrutiny is likely to be focused on the older 747s, experts concede that similar wiring problems could equally exist on other Boeing models - 727s, 757s and 767s - as well as on some Airbuses.
If extensive inspections and modifications are ordered, the work to separate the fuel gauge wires could lead to the temporary grounding of thousands of aircraft world-wide. It could also imply heavy costs for carriers and for the manufacturers if the problems are traced to original design faults.
"The safety board recognises the difficulty and expense associated with physically separating [fuel-monitoring] wires from other wires and adding shielding to [the] wires on in-service airplanes," wrote Jim Hall, the board's chairman.
Boeing, meanwhile, said that it was already preparing a service bulletin for customers in regard to possible fuel tank wiring problems.
It said that it had been "actively working on a series of fuel system- related service bulletins that the company believes will address the [board's] recommendations".
For months after the crash, the FBI attempted to establish whether the jet had been the victim of criminal sabotage. However, all possible scenarios, including a strike by a surface-to-air missile were ruled out last last year.
The safety board doubled its scrutiny of the fuel gauge wiring after it discovered signs of fraying on the wires that were found on the wreckage of the TWA airliner itself, as well as on three retired 747s which it has been taking apart and examining as part of its investigation.