This part of ISO 14085 describes a method for verifying the collapse/burst pressure rating of an aerospace hydraulic fluid power filter element. This represents the capability of a filter element to withstand a designated differential pressure in the normal (intended) direction of flow, created by flowing contaminated fluid through the filter element until either collapse/burst occurs or the maximum expected differential pressure is reached without element failure. The collapse/burst pressure test can be conducted in conjunction with an efficiency test performed according to the procedure defined in the ISO 14085-3 by continuing the contaminant injection until the designated filter element differential pressure is reached. This part of ISO 14085 is not intended to qualify a filter element under replicate conditions of service; this can only be done by a specific test protocol developed for the purpose, including actual conditions of use, for example the operating fluid or contamination. The tests data resulting from application of this part of ISO 14085 can be used to compare the performance of aerospace hydraulic filter elements.