Abstract: A riblet for a fixed leading edge (FLE) assembly is disclosed including a first riblet portion having a first aft mounting for attaching the first riblet portion to a wing box assembly and also having a forward mounting opposite the first aft mounting. The riblet also includes second riblet portion having a second aft mounting for attaching the second riblet portion to the forward mounting of the first riblet portion.

Abstract: A method for use in assembling an aerofoil structure. A torsion box has a first mounting feature and a second mounting feature. A fixed leading or trailing edge structure has a third mounting feature and a fourth mounting feature. The first mounting feature and the third mounting feature each have a fastener hole prior to aligning the leading or trailing edge structure to the torsion box. The second mounting feature and the fourth mounting feature are without fastener holes for joining the torsion box to the fixed leading or trailing edge structure prior to aligning the leading or trailing edge structure to the torsion box. The method includes aligning the fixed leading or trailing edge structure to the torsion box so as to align the fastener holes of the first mounting feature and the third mounting feature.

Abstract: A joint assembly has an eccentric bush for rotatably mounting to the first aircraft component. The eccentric bush has a rotational axis. A projection is mounted on the eccentric bush such that rotation of the eccentric bush about its rotational axis causes movement of the projection in both a first and a second orthogonal direction relative to the first aircraft component. The first and second orthogonal directions are substantially perpendicular to the rotational axis of the eccentric bush. A rail rotatably mounts to the second aircraft component. The rail has a longitudinal axis which extends in a direction substantially parallel to the second orthogonal direction. The projection has an aperture for receiving the rail. The rail has a threaded surface which is configured to engage with a correspondingly threaded surface of the aperture.

Abstract: A joint assembly for joining a first aircraft structural component to a second aircraft structural component. The joint assembly has a double eccentric bush for mounting to one of the first and second aircraft structural components, and a spigot mounted on the double eccentric bush. Rotating elements of the double eccentric bush enable adjustment of the spigot relative to the respective aircraft structural component in two orthogonal directions normal to a longitudinal axis of the spigot prior to joining the first aircraft structural component to the second aircraft structural component. A spigot receptacle is provided for mounting to, or is integrally formed with, the other of the first and second aircraft structural components. The spigot receptacle is arranged to receive the spigot. At least one fastener joins the first and second aircraft structural components together when the spigot is received in the spigot receptacle.

Abstract: Techniques are described for consistently moving powder from a hopper into a trough for subsequent delivery into a build area of an additive fabrication system. A powder delivery apparatus may comprise a hopper, a trough, and a doser. The doser may be configured to rotate about an axis and may include a recess that, when the doser is rotated about the axis, travels into and out of the hopper and into and out of the trough. As a result, when powder is present in the hopper, the recess may carry powder from the hopper to the trough when the doser rotates. The trough and doser may be configured so that when the trough contains the desired amount of powder for recoating, the doser does not transfer additional material from the hopper into the trough. As a result, the amount of powder in the trough may be self-regulating.

Abstract: Techniques are described for consistently moving powder from a hopper into a trough for subsequent delivery into a build area of an additive fabrication system. A powder conveyer may be arranged at least partially within the hopper and configured to be actuated to transfer powder to the trough. The powder conveyer may be formed as a screw conveyor, for example. Such techniques do not require complex closed-loop control systems and may be effective irrespective of the flowability of the powder. In at least some cases, there may be no production of excess powder because the amount of powder that is metered into the trough may be precisely controlled to be the amount needed for recoating.

Abstract: Techniques are described for consistently moving powder from a hopper into a trough for subsequent delivery into a build area of an additive fabrication system. A powder delivery apparatus may comprise a hopper, a trough, and a doser. The doser may be configured to rotate about an axis and may include a recess that, when the doser is rotated about the axis, travels into and out of the hopper and into and out of the trough. As a result, when powder is present in the hopper, the recess may carry powder from the hopper to the trough when the doser rotates. The trough and doser may be configured so that when the trough contains the desired amount of powder for recoating, the doser does not transfer additional material from the hopper into the trough. As a result, the amount of powder in the trough may be self-regulating.

Abstract: Techniques are described for tagging source materials for additive fabrication by incorporating a fluorescent and/or phosphorescent taggant into the source material. A light source within an additive fabrication device may direct light onto the source material and a light sensor may detect whether light having appropriate characteristics was produced from the source material through fluorescence and/or phosphorescence. If such light is detected, the additive fabrication device may determine that the source material is from an approved source and thereby has known properties that may be relied upon for fabrication. Otherwise, the additive fabrication device may determine that the source material is from an unapproved source and may take action such as inhibiting fabrication and/or providing a warning to a user.

Abstract: Techniques are described for consistently moving powder from a hopper into a trough for subsequent delivery into a build area of an additive fabrication system. A powder delivery apparatus may comprise a hopper, a trough, and a doser. The doser may be configured to rotate about an axis and may include a recess that, when the doser is rotated about the axis, travels into and out of the hopper and into and out of the trough. As a result, when powder is present in the hopper, the recess may carry powder from the hopper to the trough when the doser rotates. The trough and doser may be configured so that when the trough contains the desired amount of powder for recoating, the doser does not transfer additional material from the hopper into the trough. As a result, the amount of powder in the trough may be self-regulating.

Abstract: Techniques for designing and fabricating thermal support regions via additive fabrication are described. Defects produced as a result of temperature differentials within an additive fabrication device that forms parts by sintering particles of material may be mitigated or avoided by directing energy to regions around a part that is sufficient to heat the material and cause it to partially sinter, but not enough to fully sinter the material. The mechanical properties of such a thermal support region may resist the effects caused by temperature gradients. In addition, or alternatively, the heating of the thermal support region material may reduce heat lost by nearby sintered material. In either or both cases, the thermal support region acts as a kind of ‘volumetric armor’ that surrounds some or all of the part and protects the part from defects.