Quiet Technology Aerospace (QTA) has the most
Gulfstream II/III hush kits installed, with more than 75 done so far. The Opa-Locka, Fla., company’s Stage III hush kit can be installed by a maintenance center of the customer’s choice and takes 10 days or less, according to director of engineering Martin Gardner.

“The mod is still finding customers,” he told AIN. “A lot of new money is coming into the market recognizing what a bargain the GII and GIII represents right now. The last three sales have all been to new buyers basing their aircraft in Egypt, Namibia and Lebanon who need the hush kit to be able to operate freely within Europe.”

QTA hasn’t obtained a European supplemental type certificate for its Stage III hush kit but would be willing to certify an STC for a customer wishing to register a hush-kitted GII/GIII in Europe. Non-European-registered and hush-kitted Gulfstreams “are accepted for operation within Europe,” he said.

Gardner explained that there are additional noise regulations in the European Union that affect “marginally compliant” aircraft. “The EU directive allows airports within a noise-sensitive location to require aircraft to be compliant with Stage III/Chapter 3 and be cumulatively [sum of sideline, takeoff and approach noise levels] 5 dB EPNL below the Chapter 3 value or more. Amsterdam Schiphol is the first major airport to impose this limit. QTA in 2008 received certification of the QTAPlus hush kit, which allows all aircraft to comply with the -5 dB requirement.”