Proposed rule changes could have profound effects for operators of narrow-body bizliners with an auxiliary fuel system, and compliance could be costly for owners of some 75 airplanes.

FAA interest in these systems began with the NTSB’s findings following the 1996 crash of a TWA Boeing 747-100 near New York JFK Airport that killed all 230 people aboard. The NTSB concluded that even though the exact origin of the spark that ignited fuel vapor in the centerline tank was unknown, it was probably a short-circuit outside the tank that allowed a high-voltage surge to travel into the tank through the wiring of the fuel-quantity indication system.

Rule Changes
The FAA subsequently issued rules regarding fuel tank safety for new aircraft, along with Special Federal Aviation Regulation (SFAR) 88, requiring supplemental type certificate (STC) holders for existing aircraft to “substantiate that their fuel tank systems can prevent ignition sources in the fuel tanks.” Not surprisingly, the rule eventually included providers of auxiliary fuel systems, tanks and equipment used to increase the range of airliners that have been converted to executive aircraft.

l System Conversions to CRJ200 Executive

Modification, refurbishment and completion specialist MJet, which is offering a CRJ200 executive interior refurbishment, is adding the Elisen Elite auxiliary fuel system to the package. According to the Montreal-based company, the system “allows for significantly greater range by providing a total of 4,500 pounds of additional fuel, about 12 percent more than the capacity of the auxiliary fuel system offered for the Bombardier Challenger 850 or a similarly configured CRJ200.” Further, said Elisen Technologies executive v-p Taif Rahman, “The location of our tanks does not compromise the aircraft’s center gravity.” He noted that the auxiliary fuel system meets all the latest U.S. and European aviation authority requirements, including SFAR 88, and that the package allows for the additional fuel without increasing the aircraft’s mtow or reducing its useful load.   

In October 2007 the FAA issued a notice of proposed rulemaking (NPRM) that would require the installation of devices by Rogerson Aircraft to prevent the passage of high-voltage current into the auxiliary fuel tanks. Rogerson, of Irvine, Calif., holds auxiliary fuel tank system STCs on a number of aircraft that have been converted to executive use.

According to the Professional Aviation Maintenance Association (PAMA), 39 U.S.-registered aircraft will require the modifications, even though Rogerson no longer supplies the systems and is not working on modifications to bring them into compliance with the NPRM.

An NPRM issued in January specifically targeted auxiliary fuel systems made by Southeast Aero-Tek. The Cocoa, Fla.-based maintenance and repair facility holds STCs for the system for the Boeing 727 and several DC-9 models and the tanks have been installed in 37 airplanes.

Based on a self-funded analysis by Southeast Aero-Tek, the FAA decided that the company must install a transient suppression device on the fuel quantity indication system and the float-level switch in the auxiliary tanks. The requirement applies to the auxiliary fuel systems on 37 U.S.-registered aircraft.

Maintenance Implications
According to the FAA, the manufacturers have not provided some or all of the service information required under SFAR 88, which will force the “deactivation” of the fuel tanks.

Also affected by the SFAR 88 requirements is PATS Aircraft Completions, a DeCrane Aerospace company based in Georgetown, Del. According to George Toly, v-p of new business at PATS, if the rule stands as currently written, operators will either have to deactivate the system or perform the modifications necessary to convince the FAA that they are in compliance.

Toly said PATS has sold 40 of its own auxiliary fuel system kits for installation, has installed three and plans to install as many as 20 more. He added that the FAA has already approved a PATS-designed modification kit for its system and the company has been installing them on new aircraft for the past year. The price of the kit starts at $310,000 and may go as high as $360,000, depending on the aircraft configuration.

The comment period on the NPRM airworthiness directive (AD) ended on February 19.

The FAA is expected to issue the final AD by spring, with mandatory compliance likely in mid-December.