New documents released by crash investigators related to last fall’s UPS plane crash indicate the company did not require the more detailed inspection steps that could have identified the part failure that allowed an engine to separate from the aircraft. Multiple reports say investigators reference recommendations previously made by Boeing, which had urged more thorough inspections years earlier. The documents also include a submission from UPS to the National Transportation Safety Board (NTSB), in which the company disputes or responds to the investigators’ findings. While the reports focus on inspection requirements, they describe a central question for the NTSB review: whether UPS’s maintenance and inspection policies were sufficient to detect the condition that preceded the engine separation. The crash resulted in 15 deaths, according to the reporting. The new material is presented as part of the ongoing investigation and review process, with both investigators’ document-based claims and UPS’s response contributing to the record considered by the NTSB.