Ian Sheppard/LONDON
European Aviation and Quiet Technologies have completed initial flight tests of a proof of concept BAC One-Eleven Stage 3 hushkit prototype, and are satisfied that the aircraft will meet Stage 3 noise limits.
The companies are to continue with development, having also shown that the fuel consumption increase is less than expected, at around 3% over the Stage 2 kit. "We're going ahead," says Trevor Whetter, managing director of Bournemouth, UK-based European, which operates 24 One-Elevens on charter work.
A One-Eleven Series 400 was flown in mid-July for a total of 4-5h from Quiet Technologies' base at Opa Locka, Florida, during which several alternative mixers (based on a 12-lobe fluted design) and nozzles were tested. The hushkit uses a carbon-graphite acoustic lining in the nose cowl, plus a Nomex honeycomb lining.
Ground runs on the larger One-Eleven 500, which has never been certificated in the USA, were also undertaken and European is now negotiating with the US Federal Aviation Administration with a view to attaining a supplementary type certificate (STC). This will be overseen by the UK Civil Aviation Authority, and is a simpler way of certificating the hushkit in Europe, says Whetter. He adds that the FAA will permit about 10h of flight testing to take place in October.
The kit will be certificated under the STC and then "-transferred to the CAA", says Whetter, who believes that this has "-never been done before". Initial production sets will take "a couple of months" to produce, starting in January 1999, with a full CAA certification programme concluded by mid-year, Whetter hopes
The company also tested a splitter and acoustic treatment of the tail outlet of the auxiliary power unit, which reduced its noise level by "around 6dB." says Whetter. Further modernisation of the type will be required for it to operate to the end of its airframe life, he says. This could include a new glass cockpit.
Source: Flight International
