The energy that is suddenly released when a structure fails under load usually presents one of the minor problems in strength testing technique. Care has to be taken to ensure that the strain energy in the structure does not do further damage after primary failure and so obscure the location of the original weakness; and the possibility of risks to personnel must not be overlooked. As a general rule, however, aircraft structures fail in strength tests without untoward effects. Most of the strain energy within the structure is absorbed internally or dissipated in loading gear and anchorages, and the most noticeable effect is the noise and vibration which is produced.