It can be catastrophic if we are not aware of the consequences of norms and peer pressure. A classic example of a fatal norm was the norm of changing engines on a DC10 with a forklift. The practice saved about 12 hours in an engine change, but on May 25, 1979, it resulted in the crash of Flight 191 in Chicago with the loss of all 273 people on board. The number one engine and pylon assembly separated at a critical point during take off. This separation resulted from damage by improper maintenance procedures that led to failure of the pylon structure.