Operators of as many as 75 US-registered corporate airliners may be forced to deactivate their auxiliary fuel systems by mid-December under new fuel tank safety rules proposed by the Federal Aviation Administration.
While time is available to make appropriate fixes before the deadline, key manufacturers of the systems have either left the business or have not had modification packages approved by the FAA.
The action is part of a broader industry-wide fuel tank safety assessment that commenced after the in-flight centre fuel tank explosion that destroyed a TWA Boeing 747-100 in 1996 after departure from New York Kennedy Airport, killing all 230 on board. The US National Transportation Safety Board in 2000 concluded that while the exact origin of the spark that ignited the flammable mixture in the tank could not be identified, the source was most likely a short-circuit outside the tank that allowed high voltages to travel into the tank through the wiring for the fuel quantity indication system (FQIS).
Along with rules regarding fuel tank safety for new aircraft, the FAA in 2001 issued special federal aviation regulation (SFAR) 88, requiring supplemental type certificate holders for existing aircraft to "substantiate that their fuel tank systems can prevent ignition sources in the fuel tanks". That rule eventually trickled down to makers of auxiliary fuel systems, tanks and equipment used to boost the range of airliners converted to private jets.
A proposed rule issued on 2 January targets auxiliary fuel tanks made by Southeast Aero-Tek, one of three manufacturers that have built such systems for VIP conversions. Florida-based Aero-Tek holds STCs for the Boeing 727 as well as several models of the McDonnell Douglas DC-9. Based on Aero-Tek's self-funded analysis, the FAA determined that the company must install a transient suppression device (TSD) on the FQIS and the "float level switch" in the auxiliary tanks of 37 US-registered aircraft to prevent to possibility of high voltage levels travelling into the auxiliary fuel tanks. In October, the FAA proposed a nearly identical rule for California-based Rogerson Aircraft, which holds auxiliary fuel tank STCs for a variety of classic Boeing jets, among other VIP air carrier aircraft. Thirty-nine US-registered aircraft will require the modifications, although Rogerson no longer supplies the auxiliary fuel systems and is not working on fixes to the design.
In both cases, the FAA says the manufacturer "has not provided" some or all of the service information required under SFAR 88, forcing the regulator to "mandate the deactivation" of the fuel tanks.
Randy Smith, president of Aero-Tek, says his company has been working with the FAA on the issue since 2001 but that the agency "keeps moving the goal posts". "We've tried to work with them and it's been a hassle," Smith says. "We've come up with fixes and they don't agree." Smith says the company is in contact with 727 owners and fixes will most likely consist of alternative methods of compliance, which are allowed under the rules provided the local FAA certification office approves. For DC-9s, the company issued a service bulletin describing how to remove the tanks. "We didn't see a way it was economically viable to modify (the system)," says Smith. Aero-Tek is also working on modifications for Rogerson auxiliary tanks.
A rule focusing on fixes to auxiliary fuel systems built and installed by Delaware-based Pats Aircraft, a subsidiary of DeCrane Aerospace, is expected imminently. Pats is most notable for its auxiliary fuel tanks for the Boeing Business Jet, approximately 80 of which are currently installed.
George Toly, vice-president of business development for Pats, says the wording in the rule that applies to Pats will be different from the other two providers, requiring operators to either begin installing the FAA-approved fix that Pats has developed or to deactivate the system within the time period. Toly says more than half of the BBJ operators have already ordered the kits, which range in price from $270,000 to $360,000, not including installation.
Source: Flight International
