Raisbeck Engineering has won US Federal Aviation Administration certification for a Boeing 727-200 modification which reduces noise below Stage 3 levels without hushkits or re-engineing.
The package involves flat-rating the engines to 25íC, rather than the standard 29íC, "over-speeding" the take-off flap settings and restricting maximum take-off weight to 75,820kg. "We're optimising the procedures of the aircraft and reducing the drag for take-off and landing," says Raisbeck Stage 3 marketing director, Jeffrey Lown. Dubbed the Raisbeck Noise Abatement System, the kit costs $695,000 per aircraft.
A pre-requisite for the kit is Boeing Quiet Nacelles. The kit includes a new card file on a box in the E6 avionics rack, new wiring to the engine-pressure ratio (EPR) sensors for the new flat-rated EPR settings, and a lock-out for the flaps 30í setting on the detent. Take-off runs are increased by around 140m (450ft) and approach speeds are higher as the landing flap is restricted to 25í.
Sideline noise for the -200, equipped with any of the Pratt & Whitney JT8D-9/9A/15/15A/17 or 17A standard engines, is reduced to 97.9dB effective perceived noise level. Take-off is reduced to 96.6dB and approach to 97.6dB. The first kits will be available in April.
Source: Flight International
