NBAA Convention News

Packed room shows need for hush kits

 - June 30, 2008, 10:05 AM

The race is heating up in the Gulfstream hush kit market, as three providers maneuver for the inside track. Stage III Technologies and Quiet Technologies Aerospace (QTA) continue their respective and long-time efforts to obtain STCs for hush kits for the Gulfstream II and III. An update on their programs, as well as one by the single company that already has an STC, were presented before a packed room of Gulfstream operators here on Tuesday.   

Miami-based QTA now projects its STC will be awarded in November, about two months later than the revised schedule announced at the 2001 NBAA Convention last December. The company has teamed with Business Jet Services (affiliated with Business Jet Center in Dallas) to install hush kits. QTA is retaining the $1.5 million price of the kit up to 30 days after receiving the STC, whereupon the price will increase to $1.65 million. These prices apply only to Gulfstreams already fitted with Stage 2 hush-kit installations. The cost is higher for non-Stage 2-equipped aircraft.

QTA officials told NBAA Convention News that its system is notably different from those available from Stage III Technologies and  Really Quiet–the only company to have an STC. First, the QTA kit retains the original reversers. Second, its system adds only about 230 lb to the aircraft, compared with more than 300 lb by the Really Quiet system and 900 lb by the Stage III product. Third, installation downtime is 10 days, compared with four to eight weeks for its competitors.  

QTA is also claiming its hush kit produces no loss of performance.

That statement was questioned by several people in the audience, but another member of the audience said that he has experienced no performance loss in his three BAC 1-11s, which are equipped with QTA’s similar hush-kit design. QTA’s test airplane (a GII) is at Static Display No. 59.

“We are shooting to comply with Part 36 without any trade-offs, such as reduced weight or thrust cutback,” said QTA officials. (Trade-offs are permitted for U.S. certification but aren’t allowed under the equivalent ICAO Chapter 3, Annex 16.) “The critical parameter for the Gulfstream is beating sideline noise limits,” QTA said. “We are shooting to meet or better the 94-dB sideline limit. Meet the sideline and you will be way under on takeoff and approach.”       

Stage III STC Next Spring

Ironically, it appears that the first company to announce it was developing a Gulfstream hush kit is going to be the last to receive certification. Stage III Technologies of La Jolla, Calif., expects to receive an STC for the hush kit this fall, but deliveries and installations won’t begin until after the company receives an STC for a new cascade thrust reverser next spring. The company has scrapped earlier plans to offer initial kit installations without reversers for $1.5 million and 10 days downtime. The price with the new reversers is about $2 million and downtime is projected at two to three weeks. Dallas Airmotive holds exclusive marketing rights for Stage III’s system and will make installations.  

The Stage III product is a fixed system with no moving parts (as the other two offerings have), consisting of a choked mixer nozzle and acoustically treated ejector. The system results in less than a 5 percent fuel consumption/drag penalty overall in cruise. Part of that penalty is likely a result of the system’s weight of 450 lb per side.

Problems in developing the new reverser, as well as a setback in its flight-test program, has caused the most recent delay. The test GII,  which had been loaned to Stage III for the test program, was grounded earlier this year as part of the aircraft owner’s bankruptcy court action. “Now we have to obtain another aircraft and redo some of the baseline work,” Stage III officials said. They added that the flight test program will take approximately two months from the time a new aircraft is secured. The company had been hoping to receive its STC this summer.

Despite problems in developing the reverser, Stage III said the new reverser will be more efficient than the airplane’s original system. Operators will see an “equivalent level of [reverser] performance at lower rpm.” The system has demonstrated 63-percent effectiveness on a test bench, officials said. Stage III Technologies will provide a two-year parts and labor warranty. Representatives of Stage III Technologies are available to talk with attendees at the Dallas Airmotive booth (No. 2101).

Really Quiet of Mojave, Calif., which received the first non-OEM Gulfstream hush kit STC in January, announced here that it has selected St. Louis-based Midcoast Aviation to provide sales, support and installations. Initially, Midcoast has opted to install 10 Really Quiet hush-kit sets with the first to begin this fall. Really Quiet expects to receive JAA approval “in the coming months.”

Really Quiet said its hush kit, which costs $1.95 million installed, will require downtime of four to six weeks initially, but the company hopes to reduce that to three to four weeks as installation experience is gained. A hush-kitted GII is at Static Display No. 44.

The system incorporates a translating ejector that is in the aft position during takeoff and landing. The kit forces exhaust gas through “uniquely designed” nozzles into an ejector shroud that reduces exhaust velocity and noise. Once the aircraft transitions out of the approach or takeoff configuration, the ejector slides forward. Really Quiet contends that a new, integrated thrust reverser provides “better landing safety margins and less brake wear” than the aircraft’s original system.

The hydraulically operated translating ejector takes two seconds to deploy and retract and does not require any changes in cockpit readout. Installed weight is about 155 lb per side. The company promises a maximum 4 percent overall performance penalty at higher airspeeds. “There’s hardly any at 0.8 Mach,” the company noted.

FedEx Aviation Services, whose parent company developed a Stage 3 hush kit for Boeing 727s, is providing Really Quiet with supply chain support, vendor management and a 24-hr customer service hotline.

One questioner at the seminar on Tuesday asked if Rolls-Royce and Gulfstream have given “written approval” to do the installations, wanting assurance that the hush kit would not result in a significant increase in maintenance or service expenses, particularly with Gulfstream’s new extended life program for the GII and GIII.  

The three companies were careful not to speak for either OEM, saying instead that these OEMs “should be okay” with the installation. Apparently not satisfied with that response, the questioner said he wanted an “approval in writing” from Gulfstream and Rolls-Royce before he’d buy.

The meeting ended with the hush-kit builders telling the audience they would address any customer concerns about written sign-offs by the OEMs.