Date published: April 2, 2010
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.
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 has 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. After the left tire/wheel assembly came off, the race car arced to the left and the tire/wheel assembly struck the left side of the car. This strike changed the wheel's forward direction of travel and diverted it to the left, where it went off the left side of the track and tragically struck the spectator.
Immediately after the Phoenix incident, manufacturers responded by analyzing, inspecting, and servicing as necessary their respective parts. Certain technical changes have been made in some cases. As a precautionary measure, the type of stud involved in the Phoenix incident will no longer be in use. At the race in Gainesville, NHRA inspected certain aspects of Top Fuel and Funny Car wheels, hubs, and studs and will continue to spot check vehicles.
The entire NHRA racing community has responded to this incident and is working together on potential improvements. Preliminary testing conducted by teams of two new wheel-retention device designs was held on the Monday following the Tire Kingdom NHRA Gatornationals at Gainesville Raceway. The wheel-retention systems are intended to improve retention of the wheel to the race vehicle. NHRA will allow Top Fuel and Funny Car teams that choose to do so to use either of the two designs that were tested beginning at the NHRA Four-Wide Nationals at zMax Dragway in Charlotte.
NHRA will continue to work with the teams and manufacturers as they develop and test these two designs as well as others that are in the preliminary design and testing stage.