A quality assurance controller cover letter should detail to the employer your level of knowledge and experience in quality assurance. Your knowledge in quality assurance should be demonstrated through you previous work experience and academic qualifications. Include a description in you cover letter explaining your career objectives and goals and what you are hoping to achieve from this position. The main characteristics you may want to consider including in your cover letter are; high level of technical competency and good team player. Also include a description of the software and databases you are proficient in using.