Quiet Technology Aerospace (QTA) continues to install Gulfstream II and III Stage 3 hush kits at the rate of about one per month since being certified. The Opa Locka, Fla., company received an STC for the hush kit in January 2003 and expected to deliver its 20th completed aircraft last month. The company also recently received FAA approval for the QTA hush kit installation on tiptank GIIs (GII-TT), according to director of engineering Martin Gardner. “Our STC now covers all versions of the GII, GIIB and GIII–10 combinations in all,” he said.
The QTA hush kit uses a translating mechanism to enable integration of the acoustic system with the existing thrust reversers. The ejector is mounted on two carriage assemblies, one on each side, and slides on low-friction linear bearings. It is mechanically linked to the reverser, such that when it is deployed, two “translating” links push the ejector aft, allowing the reverser doors to deploy. When the thrust reversers are stowed the ejector is automatically pulled forward into the stow position. The QTA hush kit also incorporates acoustic treatment to the Spey engine’s inlet bullet to reduce the sound level of the fan. The installation adds 234 pounds to the aircraft’s empty weight.
Then There Were Two
At one time, three companies were in the race to develop and market Stage 3 hush kits for Spey-powered Gulfstreams. It’s turned out so far, though, that QTA is the only company that is doing installations. Really Quiet of Mojave, Calif., which received an STC for its hush kit on GIIs in January 2002–a year before QTA received its STC–has gone “belly up” after making no certified installations other than on its test airplane, according to v-p George Ottendorf. He attributed the failure of the program not to any technical problems, but to the long downtime–about six weeks, versus 10 days or so for QTA.
Said Ottendorf, “We had done a complicated structural kit that included beefing up the tail structure. That resulted in a long downtime. And also, perhaps we did a little bit of over-engineering. We could have come on the market earlier with a less complicated system.” The Really Quiet system is a translating-type system, too, but it includes a new reverser.
Meanwhile, Stage III Technologies in La Jolla, Calif., has yet to make any installations since being certified in December for its hush kit on the GII-SP. The time it has taken to develop cascade-type reversers has significantly delayed completion of the hush-kit program. When the reversers finally are ready, possibly by late next month, the company expects to have its STC amended to include all GIIs and GIIIs and installations can begin, according to director of sales and marketing Chris Hicks. To date, though, Stage III has taken no orders.
There are no moving parts on the Stage III hush kit, easing maintenance and installation, according to the company. In addition, “the ejector creates no additional load on the engine or vibration because it is attached directly to the fuselage,” the company said. “Moreover, engine load is decreased because of the lighter titanium thrust reverser employed.” Because the new thrust reverser is a cascade-type design, engine wear is “significantly less because the required reverse thrust can be created with significantly lower rpm.”
The company claims the kit adds no more than 20 pounds to the empty weight. Western Jet Aviation, a Gulfstream maintenance provider based in Van Nuys, Calif., will be a Stage III official installation center.
Stage III has also designated Aero-Propulsion Management Services in the UK as its European sales agent.
Both QTA and Stage III claim that their respective systems, which each sell for less than $2 million, have minimal adverse effect on performance.