By Daryl Murphy

Making jet aircraft acceptably quiet can be a dirty job. Owners don’t want to spend the money, engine makers don’t want to compromise their products’ efficiencies, and airport neighbors are rarely happy with the results.

To maintenance and modification shops, however, they don’t mind the trouble.

Business Jet Technologies got into the hush kit business by investing in a program three years ago with Quiet Technologies Aerospace (QTA) to develop and certify a silencing system for the Spey-powered Gulfstream II and III.

Quiet Technologies, founded in 1984, lays claim to being the world’s oldest hush kit designer and manufacturer; they have eight separate STCs for large commercial and military transports and corporate jets.

“We came to the market at the worst possible time,” admitted Business Jet partner Kevin Jordan. “When we started developing the hush kit [in 2000], a decent G-II was selling for about $6.5 million, a G-III for $12-14 million. Now they’re half that, and most owners are reluctant to invest in the hush kit unless they can see an increase in the value of the airplane, and we do not have enough market experience yet to see to what degree that will be the case.”

Martin Gardner, QTA Director of Engineering and Certification, adapted his credo from the company’s advertising campaign: “We don’t sell hush kits. We sell the freedom to fly anywhere, any time.” And that is essentially what quiet aircraft are about. He cited the experiences of one G-III customer who lived during the week in Atlanta and flew to his second home in Naples, Florida on weekends. Since his aircraft couldn’t qualify for landing privileges at Naples, he had to regularly divert to the Fort Meyers Airport and drive.

Gardner explained that the Gulfstream hush kit is similar to QTA’s Stage 3 application for Rolls-Royce Spey engines that was developed for the BAC 1-11. It has been engineered to be light weight and structurally simple.

“A translating ejector forces exhaust gases through a special nozzle and into an ejector shroud,” he said, “thereby decreasing exhaust velocity and noise. And the system retains the original Gulfstream thrust reverser.” The hush kit is purely mechanical. It has minimum parts, needs no structural reinforcement, no additional actuation controls and there are no systems changes. It’s a strictly bolt-on proposition with the exception of trimming a little sheet metal on the engine pylon, and it can be finished in ten days.

The weight of the entire kit is just 234 lb.-the equivalent of 35 gal. of Jet A-and the CG envelope is unchanged. While a slight degradation in performance was expected, so far QTA is hard-pressed to see any significant numbers. “Some of our early customers who use their G-II mostly on long flights reported no change from a standard airplane,” Gardner said. “Another customer who flies short legs thinks maybe they’ve lost one to one-and-a-half percent.”

Certification was granted January 27, and by September ten kits had been installed.

“It’s been disappointing this year,” Jordan said.

Business Jet’s quid pro quo–buy a QT 3, get an RVSM

However, Jordan has a merchandiser’s mindset worthy of Penney, Woolworth or Walton and the other noted retailers of history-a hook to get prospects to commit to the modification they must have to get into an increasing number of the world’s airports.

“Order a QTA Stage 3 for your Gulfstream II or III at its regular price ($1.35 million), schedule a time for installation, and Business Jet Technologies will give you our $175,000 RVSM modification free!” Since it’s necessary for the customer airplane to be down for three weeks for this combo offer, BJT will even make arrangements for an airplane to use during that time.

Business Jet Technologies has teamed with Shadin and AeroMech to produce a solution that is plug and play and uses existing wiring for direct replacement of any ADC installation.

Having a “two-fer” STC sale is a little unusual, but the day it was announced, two G-III kits were sold to one operator and an additional order came from Mexico the next day.