QUIET NACELLE (QNC) has completed flight-tests of a Stage 3 hushkit for the Boeing 707, and is awaiting supplemental type-certification (STC). The hushkit was installed on a Pratt & Whitney JT3D-powered US Air Force Boeing WC-135B (the military 707) for acoustic testing at Moses Lake, Washington.

Miami-based QNC is hoping for an STC on the 707-100 in September, followed by certification on the larger, longer-range, -300 in November. The hushkit for the -300 has a lobed exhaust nozzle similar to that developed for QNC's McDonnell Douglas DC-8. The USAF has ordered one shipset for an OC-135 Open Skies treaty-verification aircraft and another for a VC-137 military VIP-transport version of the 707-300, to comply with European noise restrictions. QNC claims that it holds letters of intent for 707 hushkits, but has not revealed how many. Around 300 JT3D-powered 707s remain in existence, the majority -300s. The few 707-100s which remain operational are flown in the executive role, while the -300 is used primarily for cargo.

Flight-testing of QNC's DC-8 Stage 3 hushkit was expected to begin at the end of July, aiming for an STC in September. It will enable the "short-duct" JT3D-powered DC-8 versions (-50 and -61) to be Stage 3 compliant. The company has orders for ten DC-8 hushkits from US cargo carrier Fine Air. Fewer than 100 DC-8-50s and 61s remain in existence, mostly flying in the all-cargo role.

Burbank Aeronautical already offers a Stage 3 kit for the long-duct JT3D DC-8-62 and 63.

Source: Flight International