PHILADELPHIA (AP) — The Boeing Co. says it informed federal authorities of its suspicions about drug activity at a suburban Philadelphia plant after an internal investigation.A company spokesman also says in a prepared statement Thursday that employees are tested if they're suspected of being under the influence of drugs or alcohol.Federal agents raided a Boeing plant that makes military helicopters in Ridley Park and charged more than three dozen people with distributing or trying to get prescription drugs.All but one of the 37 people charged were current or former Boeing employees.The arrests were made by the FBI and the Drug Enforcement Administration at the plant. Workers there build aircraft including the H-47 Chinook helicopter and the V-22 Osprey.