Vision Standards and Testing Requirements for Nondestructive Inspection (NDI) and Testing (NDT) Personnel and Visual Inspectors

摘要

Inspection tasks for aircraft maintenance inspectors are visually intense. Whether personnel are inspecting using only a flashlight, a simple magnifier, or sophisticated NDI/NDT equipment, visual identification is the primary method used to find cracks and other defects, which affect structural integrity. The National Transportation Safety Board (NTSB) has identified the failure by inspectors of finding visually detectable corrosion, cracks, or inclusions as a causative factor of several aviation accidents (NTSB 1989, 1990, 1998). Maintenance personnel working at aircraft maintenance facilities may have primary responsibilities as visual inspectors where they must use only their vision to assess the condition of aircraft and aircraft components; or they can work in areas where Non-Destructive Inspections (NDI) and Non-Destructive Testing (NDT) are performed. In these latter workareas, NDI/NDT inspectors often use highly sophisticated imaging and scanning devices to aid defect detection. However, even for these inspectors, performing a simple visual inspection is a vital component used to ensure that aircraft are safe to fly. In a recent survey of maintenance facilities, 52% of inspectors were classified solely as visual inspectors, 36% were classified as visual and NDI/NDT inspectors, while only 12% were classified solely as NDI/NDT inspectors (Nakagawara et al., 2003). To the greatest extent possible, vision standards should ensure that workers have the necessary visual skills to perform job-relevant tasks in an efficient and safe manner. For NDI/NDT inspectors, vision skills should be adequate to identify areas of concern (i.e., detect potential defects) and to determine if further action is required (i.e., decide if a possible defect is within tolerances or if special tests are necessary) (Drury, 2001). Although the NDI/NDT personnel have many tools to aid in the detection of defects (e.g., fluorescent penetrant and magnetic particle inspections, eddy current and ultrasonic devices, borescopes, magnification aids), simple visual inspection may account for up to 80% of all inspections (Goranson and Rogers, 1983). The FAAs Production and Airworthiness Division (AIR-200) (PAD, 2001) prepared a memorandum, dated September 26, 2001, to address the need for sharp vision for NDI/NDT personnel. This memorandum follows an FAA advisory circular (FAA, 1999) from February 1999 that addresses the same topic. Several national and international organizations have made recommendations for qualifications of NDI/NDT personnel. The September 2001 memorandum identified the standards found to be acceptable to the FAA for assuring that only qualified individuals perform NDI/NDT inspections and procedures. These standards provide recommendations for levels of initial and recurrent training, levels of competence, and vision testing.