The National Transportation Safety Board has issued its preliminary report on the plane crash that took the lives of pilot Harry Bell and Michael Boolen on July 5 in an orange grove at Rancho Camulos.

The investigator on the case was unable to speak to the media, but a spokesman for the NTSB said that the average crash investigation takes about nine months to a year.

“This investigation is ongoing  and we don’t have a cause right now, but we are doing a very thorough investigation of three things: the man, the machine and the environment,” said Terry Williams, of the NTSB’s Public Affairs office.

“We’re examining the pilot; his health or anything that might have happened to him before or during the 72 hours prior to the crash; we inspect the machine, what inspections or maintenance were done and how did the aircraft act. Were there any indications of a problem with fuel or maintenance? Were there any witnesses? We want to talk to them.

“We’re looking for probable cause and contributing factors,” he continued. “How was the weather? Did something happen in the environment. We want to know exactly what happened so we know what caused this crash and so we might be able to prevent future accidents. There might be a cause, but also several contributing factors”

According to the NTSB report, Bell and Boolen left Whiteman Airpark in Van Nuys in Bell’s TL Ultralight SRO Stingsport, N177N on what was called an instructional flight. Because “visual meteorological conditions prevailed,” no flight plan was filed for the flight. They men left the airport at 1 p.m. and crashed 24 minutes later.

According to the NTSB report, “Multiple witnesses driving on Highway 126 within the vicinity of the accident site reported observing the accident airplane descending in a nose low attitude while spinning in a counter-clockwise direction before it descended below a tree line.”

Investigators recovered the all of the debris from the site and removed all structural components of the plan to a secure location for further examination. A final report will eventually be issued.

The interim report can be read here.