IOWA CITY, Iowa (AP) – The Federal Aviation Administration is investigating what caused a University of Iowa research drone to crash in a mobile home park near the Iowa City Municipal Airport. It came down Dec. 18 next to one of the homes, strewing shattered parts nearby but striking no one. The university reported that the 100-pound aircraft became unresponsive before crashing. The professor who was remotely operating it has declined to comment until the investigation is completed. The Gazette reported that the drone was bought for $300,000 in 2018. It has an 18-foot wingspan.