I have found one audio file which contains communications from N801DT near the beginning of the flight. I was not able to find anything more than that.
BVU does not have an airport traffic control tower; instead, pilots self-announce on a common traffic advisory frequency. That frequency (122.700) is not recorded by LiveATC and likely wouldn't tell us much if it were.
BVU is under the jurisdiction of Las Vegas TRACON. The frequency providing services in the immediate vicinity of the airport is 124.475, which is not recorded at LiveATC. At their altitude, the pilot would not have been required to be in contact with ATC.
As the aircraft climbed out of BVU and flew northbound, they entered the Las Vegas Class Bravo airspace. They were required to establish communications with Las Vegas TRACON prior to entering this airspace. They did this on the frequency 119.400. You may hear their initial communications beginning at the 28:20 mark of the KLAS4-App-NE-May-08-2022-1700Z.mp3
file accessible from the LiveATC archives, that is, the ~30-minute audio file which begins at 1700 UTC on May 8th. (The time referenced is elapsed time on the downloaded file. The file as played in-browser may have slightly different times.)
The pilot is instructed to enter a specific squawk code and is identified on radar.
The pilot requested flight following, meaning that even after they departed the Class Bravo airspace and were no longer required to communicate with ATC, they wanted to remain in communication and receive traffic advisories, etc. This bodes well for your goal to retrieve audio archives for their entire flight.
Unfortunately the pilot was instructed to contact Nellis Approach Control on 135.100, and that frequency is not recorded at LiveATC. Nor are some of the other likely frequencies for their route:
- Nellis Approach 126.650
- Salt Lake Center 133.450
- Salt Lake Center 132.250
- Salt Lake Center 118.050
Los Angeles Center 124.200 was recorded, but I listened to an hour of audio and it seems that N801DT did not enter that controller's airspace.
You can rest assured that the FAA is compiling the audio from this flight and preparing transcripts which may be released to the NTSB. I believe it is the policy of the NTSB to not release audio files, but you might have luck submitting a FOIA request to the FAA directly. I suspect they also might not release this data, though, particularly while the investigation is still underway. (See Chapter 3, Paragraph 9 of Order 8120.11 and Chapter 14, Paragraph 3 of Order JO 8020.16.)