Abstract: A gas turbine engine fan casing duct wall comprises an intake section and a containment casing, provided respectively with flanges. An acoustic flutter damper is secured between the flanges. The acoustic flutter damper has a skin accommodating an internal structure that dampens fan blade flutter. The skin is secured to the flanges at separate locations. In normal operation of the engine, the internal structure is sufficiently robust to support loads transmitted through the acoustic flutter damper between the intake section and the containment casing. If a blade or blade fragment detaches, the resulting deflection wave in the containment case ruptures the internal structure, and the load path between the intake section and the containment casing passes along the skin, which consequently maintains the connection between the intake duct and the containment casing, while permitting substantial radial deflection of the containment casing relative to the intake section.

Abstract: A liner panel for a fan casing of a gas turbine engine includes a honeycomb layer, a septum layer and an abradable layer. The fan casing is provided with a containment system in case of fan blade failure. In use, ice may be released from a fan blade in a first direction, and (in the case of a blade-off event) a fan blade or part of a fan blade may be released in a second direction. The panel has a compressive strength greater in the first direction than in the second direction such that the released ice will be deflected by the panel but the released fan blade or part of a fan blade will pass through the panel.

Abstract: A gas turbine engine fan casing duct wall comprises an intake section and a containment casing, provided respectively with flanges. An acoustic flutter damper is secured between the flanges. The acoustic flutter damper has a skin accommodating an internal structure that dampens fan blade flutter. The skin is secured to the flanges at separate locations. In normal operation of the engine, the internal structure is sufficiently robust to support loads transmitted through the acoustic flutter damper between the intake section and the containment casing. If a blade or blade fragment detaches, the resulting deflection wave in the containment case ruptures the internal structure, and the load path between the intake section and the containment casing passes along the skin, which consequently maintains the connection between the intake duct and the containment casing, while permitting substantial radial deflection of the containment casing relative to the intake section.