Where should drain grommets be positioned on airfoils?

The correct placement of drain grommets on airfoils is near the trailing edge, close to the rib. This location is strategic for facilitating effective drainage of any moisture or debris that may accumulate within the structure of the airfoil. Positioning the drain grommets in this area allows water and contaminants to exit the wing without being trapped, which can help in preventing corrosion and maintaining the structural integrity of the airfoil.

The trailing edge is typically where low-pressure areas form, and this positioning ensures that any accumulated liquid is naturally drawn out as airflow over the wing may create a suction effect. This drainage is crucial in maintaining optimal performance and safety of the aircraft by reducing the risk of water accumulation that could affect weight distribution and aerodynamic efficiency.

The other options do not provide the same level of efficacy for drainage. Placing grommets at the leading edge, on the top of the wings, or on the sides of the fuselage would not adequately encourage drainage due to airflow dynamics, potentially leading to moisture retention and associated issues like corrosion or structural compromise.