What statement is true regarding welding and straightening of rotating airfoils in turbine engines?

In the context of welding and straightening rotating airfoils in turbine engines, it's essential to understand the practices and guidelines set forth by manufacturers and industry standards. The correct understanding is that neither of the statements asserting the necessity of special equipment or manufacturer recommendations is accurate.

Welding and straightening of rotating airfoils is generally discouraged due to the complex materials and the precise engineering involved in these components. Most manufacturers do not support the idea of welding airfoils because of the potential for altering the mechanical properties of the metal and affecting the balance and structural integrity of the component. Instead, airfoils are typically replaced or repaired using approved methods that do not compromise safety or reliability.

Additionally, while it is true that supervision is essential in any maintenance activity, the concept of performing welding and straightening of airfoils under high supervision does not apply to standard practices within turbine engine maintenance, as such procedures are not routinely performed. Therefore, the rationale behind the response provided confirms that neither of the proposed statements aligns with the accepted practices in the industry regarding the treatment of rotating airfoils.