Before April 1972, Bush had fulfilled more than the required hours of service, but with more than two years remaining before his discharge. He volunteered his services on several projects, including a political campaign. After April 1972, Bush may have failed to meet the attendance requirements established for members of the Air National Guard. In mid-1972, he failed to meet the Air Force requirement for an annual physical examination for pilots and lost his authorization to be a pilot. According to Bush's pay records, he did not attend any drills between mid-April and the end of October 1972. He drilled in Alabama in October and November 1972, and again in January 1973; what duties he performed are unknown. Bush returned to his home unit in Houston and was paid for his service in April 1973 through July 1973; again, what duties he performed are not documented in any way.