Definition
A jump is considered a failure when a competitor does any of the following treads on any ground beyond the takeoff line; takes off from either side of the takeoff board, even if this is before the takeoff line; walks back through the landing area; touches the ground outside the landing area closer to the takeoff line than to the impression in the sand from where any measurement would be made; or performs any kind of somersault.
Videos containing the term 'Failures'
http://www.sportsdefinitions.com/field-events-long-jump/Failures.html