The applicability of FAR 121.377 is not eliminated by a person's performing a mix of work such as you describe. Such an interpretation would defeat the purpose of the regulation which is to insure that person's performing part 121 maintenance or preventive maintenance are provided relief from duty.
The cause of rheumatoid arthritis is unknown, although it appears to be an autoimmune disease. When the body's immune system does not operate as it should, white blood cells that normally attack bacteria or viruses attack healthy tissue instead â in this case, the synovium, or joint tissue.
Rheumatoid arthritis (RA) facts. 1  Rheumatoid arthritis is an autoimmune disease that causes chronic inflammation of the joints and other areas of the body. 2  symptoms and signs that affect both sides of the body (symmetry).  Rheumatoid arthritis is a chronic disease characterized by periods of disease flares and remissions.