Previous research has identified maintenance information as one of the primary causal factors of maintenance error. Incorrect maintenance information has also been cited as a contributing factor in a number of recent aircraft mishaps. To date no one has studied the types of errors found in aircraft maintenance manuals published by manufacturers. The purpose of this research is to analyze Publication Change Requests (PCRs) to document the most frequently reported types of errors found in aircraft maintenance manual, to identify how errors vary across Air Transport Association (ATA) chapters, and identify the corrective actions required to address the cited problem. The most common request was for additional procedural information followed by requests to add or change the language to improve clarity. The results show that the majority of PCRs (42%) cited procedures found in Chapters 27 (Flight controls), 32 (Landing gear), and 71 (Powerplant).