I
Initial derivatives
The original engine nacelles
incorporated thrust reversers
taken from the 727 outboard
nacelles. They proved to be
relatively ineffective and
tended to lift the aircraft up off the runway
when deployed. This reduced the
downforce on the main wheels thereby
reducing the effectiveness of the wheel
brakes
An early-production, retrofitted United Airlines 737-200 with
deployed thrust reversers.
In 1968, an improvement to the thrust reversal system was introduced. A 48-inch tailpipe
extension was added and new, target-style, thrust reversers were incorporated. The
thrust reverser doors were set 35 degrees away from the vertical to allow the exhaust to
be deflected inboard and over the wings and outboard and under the wings.
The improvement became standard on all aircraft after March 1969, and a retrofit was
provided for active aircraft. Boeing fixed the drag issue by introducing new longer
nacelle/wing fairings, and improved the airflow over the flaps and slats.
The production line also introduced an improvement to the flap system, allowing
increased use during takeoff and landing. All these changes gave the aircraft a boost to
payload and range, and improved short-field performance.
In May 1971, after aircraft #135, all improvements, including more powerful engines and
a greater fuel capacity, were incorporated into the 737-200, giving it a 15% increase in
payload and range over the original -200s. This became known as the 737-200
Advanced, which became the production standard in June 1971.
Boeing B737
June 2017
www.alliance-airways.net
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