A __________ field approval may be acquired to deviate from the original covering process or material.

A "one-time" field approval is specifically designed to allow deviations from the original covering process or material, under certain circumstances. This type of approval is granted for a single instance, meaning that if an aircraft owner or maintainer encounters a situation where the standard procedures or materials are not suitable, they can apply for this approval. It acknowledges the need for flexibility in the maintenance and repair process while ensuring that safety and compliance with regulatory standards are upheld.

In essence, a one-time field approval allows for an exception to be made for specific instances without changing the established regulations or procedures permanently. It's particularly useful in scenarios where original materials are not available, or innovative solutions are required that still align with overall safety principles.