Modification package for Classic versions of Boeing twinjet claimed to increase performance and save costs

Quiet Wing, the Washington-based engineering company, has been awarded US Federal Aviation Administration supplemental type certification for a flap-modification package that will increase performance and reduce fuel consumption for the Boeing 737-200 and other Classic variants of the twinjet.

Quiet Wing, which developed a similar package for the 727, says the adjustment droops the trailing-edge flaps by 4° and the aileron by around 1°.

The modification, which can be performed by the customer during routine maintenance, also includes rescheduling the flap settings to ensure they do not exceed maximum deployment. “It basically increases the wing camber to give you more lift, but throughout all phases of flight,” says Quiet Wing marketing director Peter Swift. “It also decreases drag for cruise, and increases the aerodynamic efficiency of the wing by between 2% and 3%.”

Swift says the new kit could allow 737-200 operators to make “dramatic” cost savings, as it enables them to replace the more expensive JT8D-15 engines with the original, but lower-cost and more efficient -9A engines. “Because of the kit, you would still get better performance from the -9A with big fuel savings.” Based on average use of 2,000h a year, it estimates fuel savings of around $500,000 per aircraft.

The FAA certification was approved initially for the -200 model, although the company plans to develop it for all “Classic” 737 models. “We’re not sure yet if the FAA will allow us to use the same STC for all models, and they may still require flight testing,” says Quiet Wing president Robert Olson. “However, we hold letters of intent for 22 -200s and 15 -300s, and we intend to offer it for the -400 and -500 as well.” Initial customers include South Africa-based Safair as well as two Mexican airlines, Aviacsa and new low-cost carrier start-up Avolar.

The modification package increases the take-off and landing performance, and allows payload to be increased by around 3,180kg (7,000lb). Quiet Wing says that as well as reducing fuel consumption by up to 3%, stall speed and low-speed handling is improved, with approach speeds reduced by 4-5kt [7.4-9.2km/h].”


Source: Flight International