American and TDG Aerospace Develop Safety Device for B-757 Fuel Tank

American Airlines and its partner, TDG Aerospace, have developed a kit that allows an airline to eliminate 1,000 pounds of fuel, which is presently required to be carried in the center fuel tanks of B-757-200s and 300s, as a precaution against a spark leading to an explosion.

Without a modification such as this, B-757 operators are required to constantly carry the minimum fuel quantity as way to "smother" any possible fuel-vapor ignition source in the tank.

The equipment, called a UFI (universal fault interrupter), was developed by TDG in conjunction with American.  It protects the fuel tank from electrical faults, extended dry-pump operation, and un-commanded pump operation, which are believed to be the causes of fuel-vapor ignition, and are the subject of pending Special Federal Air Regulation 88.   The UFI also employs a redundant relay scheme that prevents the pumps from continuing to operate if a control relay should fail to function.

The FAA granted a STC (supplemental type certificate) approval for the American/TDG B-757 installation, as well as an AMOC (alternate method of compliance) to the fuel restrictions required by its Airworthiness Directive 2002-24-51.

American says its maintenance technicians in Boston have successfully proven they could do the necessary installation during a typical overnight, which of course is highly desirable since it eliminates out-of-service time for the aircraft asset.

The UFI is now available through TDG Aerospace. More information is available from American Airlines Maintenance Services at http://www.mroaa.com  or TDG Aerospace at www.tdgaerospace.com.  04-20-2007.

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