Boeing's flight-test programme for its next-generation 737 family began smoothly on 9 February, with the 737-700 having a problem-free maiden flight from Renton, Washington.
The flight marks the start of an eight-month test effort for the 737-700 which will include 1,200h of flying. Certification is planned in September, with deliveries due to start in October to launch customer Southwest Airlines.
The aircraft, registered N737X, took off for its 3h 35min flight at 10.05 at a weight of just under 55,300kg. After initial tests at 10,000ft (3,000m), Mike Hewett, chief engineering test pilot and Ken Higgins, vice-president of flight operations, then flew the 737 up to 21,000ft for further tests. These were restricted to a maximum speed of 250kt (460km/h) for buffet-boundary reasons. Approaches to stall speed were made during which a minimum speed of 85kt was reached with 40í of flap as the stick shaker engaged.
One of the most important initial tests was conducted on the wheel-to-rudder interconnect system, which is intended to reduce the control-force inputs when flying in manual reversionary mode. The new connection automatically ties in rudder movement to augment control inputs on the wheel. On the current generation, a force of up to 27kg is required to turn the wheel through two-thirds of its travel in manual back-up. Boeing devised the new system for the next-generation 737 because of concerns over not meeting "-handling-quality requirements for people with nominal strength, particularly with the bigger -800 model", says flight-test chief pilot, James McRoberts.
The only significant failure of the test flight concerned the telemetry system which could not be activated. Although data were still stored by on-board recorders, tests of instrumentation for flutter tests due to be made in the next few flights have not been carried out.
The aircraft was returned to Boeing Field, Seattle, where it will be based for the test programme.
Source: Flight International
