This Preliminary Evaluation (PE) was opened August 21, 2018 based on 5 consumer complaints for unintended aerial platform movement on the subject vehicles. ODI complaint numbers 11101301, 11101303, 11101304, 11101305 and 11105134 allege there is a defect with the aerial ladder control mechanism that resulted unintended movement.ODI conducted several field inspections, meeting with local fire houses and municipalities to better understand and witness the alleged defect. In addition, ODI met with Pierce and the Fleet Operations Manager of the Montgomery County Fire and Rescue Service?s Central Fleet to discuss the known complaints, possible attributing factors and vehicles to be tested/instrumented.On November 30, 2018 Pierce met with ODI staff at DOT headquarters and agreed that a safety defect existed on their vehicle aerial devices. The subject vehicles may unintentionally rotate right when a command to extend the aerial ladder is given. This unintentional movement is the result of faulty Random Access Memory (RAM) chip configuration on the aerial ladder controller. If the aerial device is operated in this manner it may contract an obstruction, potentially causing property damage or injury. In addition, it may hinder the ability to perform emergency functions as intended. The effected population includes 886 2004?2018 model year Pierce Arrow XT, Dash, Enforcer, Impel, Quantum and Velocity fire trucks.This Preliminary Evaluation is closed with Safety Recall 19V-022.