According to airplane maintenance records, the factory-new vacuum pumps were installed on the left and right engines on March 28 and April 10, 1997, respectively.35 According to an airframe and powerplants mechanic who worked on the airplane, the pilot contacted him on September 25, 2000, and stated that he thought his left engine vacuum pump had failed. The mechanic stated that he discussed the issue with the pilot and requested that he bring the airplane in for repairs. The mechanic stated that the pilot brought the airplane in on September 27th and that on September 28th, he removed and replaced the left engine vacuum pump.36 The mechanic reported that he performed a postmaintenance operational check on both vacuum pumps and that the pumps operated normally.