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.
Causes of Rheumatoid factor positive that are common . The following causes of Rheumatoid factor positive are diseases or conditions that affect more than 1 million people in the USA: Connective tissue diseases; Rheumatoid arthritis; Sjogrens; more causes...Â» Causes of Rheumatoid factor positive that are very rare The following causes of Rheumatoid factor positive appear in the population at a rate of substantially less than 200,000 people per year in the USA: