Darren Shannon / Washington DC

The US Federal Aviation Administration has proposed an airworthiness directive requiring operators to modify electrical supply systems and fuel quantity indicator (FQI) sensors in and around centre and wing tanks on some Airbus A319, A320 and Airbus Corporate Jetliner (ACJ) models.

Airbus says it issued a service bulletin to that effect in July 2001 and French civil aviation authority the DGAC ratified it with an airworthiness directive in May 2002, which has already been put into effect.

This is among the final measures taken in the industry since the 1996 TWA flight 800 disaster, when a centre wing tank explosion caused a Trans World Airlines Boeing 747-100 to crash on climb-out from New York Kennedy airport.

In its notice of proposed rulemaking, the FAA says the intended changes "are necessary to prevent overheating of the fuel probes [in the event of] a short circuit, and fuel leakage due to inadequate expansion of the area within the additional centre tank".

Airbus is also having to modify the A340-500's fuel system after the FAA required a tank lining to be fitted in the integral rear centre fuel tank in June. Meanwhile, Boeing is seeking to gain approval for a fuel-tank inerting system for the 747, seen as a more cost-effective solution for its older aircraft than design change and backed by the NTSB.

Airbus says another FAA requirement, to modify centre fuel tanks because of inadequate expansion capacity, applied to three specific ACJs and was dealt with in 1999.

The FAA and DGAC requirement includes the installation of fused adaptors for the fuel quantity indicator centre tank probes; the installation of fused plug connectors for the wing tanks FQI probes; the installation of fused adapters between the external wiring harness and the low-energy in-tank wiring of the connectors; and the operational testing of the refuel/ defuel system, leaks, the fuel transfer pump pressure switch, and the transfer pump.

Source: Flight International