What is the primary function of an iron in fabric covering?

The primary function of an iron in fabric covering is to facilitate heat sealing and applying tension to the fabric. When fabric is applied to an aircraft structure, it needs to be tight and securely affixed. The iron provides the necessary heat to activate the adhesive used in the fabric covering system, allowing the fabric to bond properly to the underlining structure.

Moreover, using an iron helps to achieve the appropriate tension in the fabric. Adequate tension is crucial as it affects the performance and appearance of the fabric covering; a tightly fitted covering prevents wrinkles and sagging, ensuring aerodynamic efficiency and structural integrity.

In contrast, while performing structural repairs, shaping the aircraft, and cleaning the fabric surface are important aspects of aircraft maintenance, they are not the primary roles of an iron in the context of fabric covering. The iron's role is specialized to heat and tension applications, which are critical for the proper installation of fabric on an aircraft.