Quiet Technology Aerospace (QTA) has started production of replacement engine inlet barrels made of carbon fiber composites for the Learjet 60. The retrofit, which received FAA STC approval in the fall, provides a solution to corrosion issues with the original aluminum honeycomb inner acoustic barrels in the aircraft’s Pratt & Whitney Canada PW305 engines.
According to QTA, a combination of materials and environmental effects—namely, rain and pollutants—causes corrosion and delamination in the bottom of the inner barrel. Even when not delaminating, the acoustic face sheet can become disbonded due to surface corrosion. Either defect requires replacement of the entire inner barrel with new parts.
QTA said its design retains all of the other component parts of the nose cowl, replacing just the inner barrel to eliminate the corrosion problems. The company is currently working on similar STCs for the PW306-powered Gulfstream G200 and PW305-powered Hawker 1000, which both suffer from the same corrosion and screen delamination problems.