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Jetaire Bets On Foam To Improve Fuel-Tank Safety

Alternative to 737NG fuel tank inerting kit could open door wider for other flammability solutions.

With a little more than a year left to meet an FAA deadline to address fuel-tank flammability risks, an Atlanta-based aircraft modifications specialist is betting that its cost-effective alternative to systems backed by heavyweights Airbus and Boeing will be embraced by operators that must comply.

Jetaire Group is the final phase of demonstrating the systems it designed for the two most popular aircraft families, the Airbus A320 and Boeing 737NG. The FAA has signed off on all supplemental type certificate (STC) data, and all that remains is installing a kit on each aircraft type to demonstrate “conformity,” says Jetaire President Michael Williams. The company expects to have the A320 STC in hand later this year and will add the 737NG as soon as the company can arrange for an aircraft to serve as the conformity testbed.

Unlike inerting kits that use inert gas to replace air in a fuel tank, Jetaire’s design calls for lining a tank with a proprietary foam to suppress fuel ignition. Used in military aircraft for years, foam-based systems have not gained a foothold in the air transport market.

Part of the reason is that both Airbus and Boeing recommended the use of gas-inerting systems to meet the FAA’s 2008 Fuel Tank Flammability Reduction (FTFR) rule. Most large operators, facing the first deadline of retrofitting 50% of their center wing tank-equipped fleets by Dec. 26, 2014, opted for the OEM-backed kits. With the full-fleet modification deadline of Dec. 26, 2017, creeping up, Williams believes there will be a market for alternative approaches, including a foam-based kit.

“It has no moving parts, no failure modes and requires no maintenance for 60 months,” when the first inspection is conducted, he says.

While the system’s simplicity is part of the reason for Williams’s confidence, another is basic supply and demand. Major airlines wasted little time ordering the OEM-backed kits, creating a substantial backlog. One supplier says the lead time for an OEM-backed 737NG kit is close to 12 months, meaning operators that have not placed orders by the end of this year could be left with non-compliant aircraft. Boeing declined to provide a lead-time estimate.

Jetaire’s 737NG STC is a modification of an existing STC for 737 Classics. It would cover all 737NGs except for the 737-900, which has a different center tank design than the -600/-700/-800. The A320 STC would be new, but it is based on the same design as the approved 737 Classic STC, “so certification issues are not expected,” Williams says.

Jetaire’s kit is installed on about 20 737 Classics—mostly flown by charter operators with single-aircraft or small fleets. The company recently completed an installation on a 737-300 flown by a casino operator, Williams says. One U.S. mainline carrier was considering Jetaire kits for some of its Classics, but the airline has opted to phase out the aircraft before the FAA deadline.

The foam-based kit’s operational impact is that it uses space needed by the equivalent of about 4 min. of fuel on the 737 Classic—roughly 90 gal., Williams says. Fuel burn is not affected. Installation takes 2-3 days, compared to more than a week for a gas-inerting system. The weight penalty is “negligible,” compared to more than 400 lb. for the OEM system, Jetaire data show.

As the full-fleet modification deadline approaches, third-party kit suppliers could see more interest in their products. The air separation module (ASM), the heart of an inerting system, has been failing on some 737NGs after about half of its 20,000-25,000-hr. service life expectancy. Replacing an out-of-warranty ASM can cost $75,000. Boeing is working on an improved kit with its suppliers, including ASM manufacturer Parker Hannifin, but it is not expected to be available until next year.

Meanwhile, the FAA has said that while it will consider relaxing the deadline on an operator-by-operator basis, a general extension will not be granted. The FAA granted one exemption at the 50% compliance deadline, for a handful of Aeromexico aircraft.

This gives suppliers such as Jetaire the opportunity to win business from operators that are either looking for alternatives or find themselves painted into a corner because they did not place orders early enough. Once STCs are in hand, Williams says lead times for Jetaire’s kits will be 60-90 days, though he expects this to increase as orders arrive.

Jetaire is not stopping at equipping the venerable narrowbody families. It was slated to install a kit on a Boeing 767-200 VIP aircraft during an early-fall heavy check. Once the FAA signs off on the installation, an STC would be in hand.

The company also is working on kits for several other models, including Boeing 757-200s and the few remaining U.S.-registered 737-200s operating. 

TAGS: Airlines
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