Source: United States Navy
The investigation determined that the crash was caused by an in-flight failure of a damper hose, resulting in total loss of the main rotor damping which led to severe vibrations upon touchdown.
The Navy continues to mourn the loss of Lt. Bradley Foster, Lt. Paul Fridley, Naval Air Crewman (Helicopter) 1st Class James Buriak, Hospital Corpsman 1st Class Sarah Burns, and Hospital Corpsman 2nd Class Bailey Tucker, and our thoughts and prayers go out to their families and loved ones.
A redacted version of the findings from this command investigation is available on the U.S. Pacific Fleet on-line FOIA Reading Room: https://www.cpf.navy.mil/FOIA-Reading-Room/#release-181321