Designing the Next Generation Flying Test Bed

In 1985 Pratt & Whitney Canada purchased a Boeing 720B for use as an experimental flying engine test bed. The modification program involved major structural changes: the extension of the nose for the attachment of turboprop nacelles; the addition of a wing-like pylon on the right-hand side of the forward fuselage; and modification of the number three engine pylon to provide structural support for a large fan engine. Some secondary modifications were necessitated by the resulting unique configuration. The modifications, installations and flight tests are discussed, with particular attention to the pitot-static systems.