Assembly of aircraft wings

A method of joining a wing skin to a structural element of an aircraft wing, the method comprising:

• forming a locating through hole in the structural element, the locating through hole extending along a path between a first side of the structural element and a second side of the structural element;
• attaching a spark containment cap to the first side of the structural element, the spark containment cap covering an opening of the locating through hole;
• positioning a portion of the wing skin on the second side of the structural element;
• forming a fastening through hole, having a diameter larger than the locating through hole, through both the wing skin and the structural element and along the path of the locating through hole, such that the fastening through hole comprises:
• a first opening in the wing skin, and
• a second opening in the structural element and covered by the spark containment cap;
• and
• inserting a fastener into the fastening through hole and securing the structural element to the wing skin, an end of the fastener being covered by the spark containment cap,
• wherein attaching the spark containment cap comprises providing a temporary fastener within the locating through hole, the temporary fastener configured to secure the spark containment cap to the structural element,
• wherein the temporary fastener is threaded, and the spark containment cap comprises a corresponding threaded receiving portion configured to receive a threaded portion of the temporary fastener.

A method of joining a wing skin to a structural element of an aircraft wing, the method comprising:

• forming a locating through hole in the structural element, the locating through hole extending along a path between a first side of the structural element and a second side of the structural element;
• attaching a spark containment cap to the first side of the structural element, the spark containment cap covering an opening of the locating through hole;
• positioning a portion of the wing skin on the second side of the structural element;
• forming a fastening through hole, having a diameter larger than the locating through hole, through both the wing skin and the structural element and along the path of the locating through hole, such that the fastening through hole comprises:
• a first opening in the wing skin, and
• a second opening in the structural element and covered by the spark containment cap;
• and
• inserting a fastener into the fastening through hole and securing the structural element to the wing skin, an end of the fastener being covered by the spark containment cap,
• wherein attaching the spark containment cap comprises providing a temporary fastener within the locating through hole, the temporary fastener configured to secure the spark containment cap to the structural element,
• wherein the temporary fastener is a snap lock pin fastener and the spark containment cap comprises a surface arranged such that, when the temporary fastener is inserted into the spark containment cap, the temporary fastener engages with the surface to resist removal from the spark containment cap.