Boeing 747, 757 and Next Generation 737 operators have been set more fuel handling rules by a US Federal Aviation Administration emergency airworthiness directive (EAD). This follows the discovery of serious pump overheating evidence in three 747s. The EAD says that parts of the pumps showed signs of having heated to more than 550ûC (1,000°F). The new requirements mainly reinforce earlier directives to ensure no dry-running of pumps by raising minimum fuel quantities that must remain in tanks. The published EAD at first banned the use of the 747-400 stabiliser tanks, but on consultation with Boeing, the FAA agreed to their use providing a minimum 590kg (1,300lb) fuel remains in them. An additional measure for older 747 models places an outright ban on the use of the centre auxiliary fuel tanks and auxiliary tanks 1 and 4.
Source: Flight International
