NHRA has released the preliminary findings of its investigation regarding the tragic incident in Phoenix, which took the life of a spectator, as well as precautionary measures being implemented.

Quote from the article:

Immediately after the incident, NHRA’s Technical Department, teams, and manufacturers all began analyzing what had happened, and why. NHRA’s investigation was aided by Dr. Juan Herrera, who holds a Ph.D. in Mechanical Engineering. Some of his specialties include metallurgical engineering, failure analysis, vehicle dynamics and accident reconstruction. Dr. Herrera worked closely with the Schumacher race team which gave him their full support and cooperation in conducting his analysis, as well as with the NHRA Tech Department. Although his investigation is ongoing, Dr. Herrera found that there was a complex series of events that led to the incident in question. At this time it appears that very quickly after the car launched, it experienced the loss of the No. 5 cylinder, severe tire shake, and rapidly decreasing acceleration forces. The left wheel then slipped slightly on the hub. The wheel studs experienced a bending force and then failure, which resulted in the wheel becoming detached from the hub. The studs themselves had some slight but preexisting cracking that likely was not detectable upon visual examination.

Source: Preliminary results from Phoenix