Life testing is often misapplied during the acquisition process, with verification usually too late to influence the design.
Life tests should be scheduled for completion during EMD in order to establish life characteristics and allow the implementation of design changes prior to design release.
Life tests performed after the start of production result in costly engineering change proposals and retrofit programs which attempt to solve problems with less than optimum design solutions.
Test environments must be based on expected mission environmental profiles, not blindly applied MIL-STD or MIL-SPEC environments.
Life tests can be time consuming and costly and therefore must be planned for carefully.
Detailed analyses must be made of life characteristics concurrent with the initial design; aging failure data must be collected on components and like equipment from all possible sources.
Field and/or corporate experience on items similar to those being tested should be used to project life characteristics and to determine the initial equipment design.
The use of unverified acceleration factors can result in unrealistic projections of equipment life and, therefore, overdesign if the test is too stringent or underdesign if the test is too benign.
A well-designed life test is an excellent measure of design maturity.
Fatigue life tests should be conducted to loading spectra that will determine the inherent strength of the parts so that their lives can be recalculated should the operational mission profile be changed or revised test conditions differ from those calculated.
When parts are very reliable, life testing may not be feasible since many years of testing under actual operating conditions would be required; parts might become obsolete by the time their reliability is measured.
When accelerated life testing is used, care must be taken that unrealistic failure modes are not introduced (e.g., increase of temperature beyond a certain level may change a material's characteristics, which would negate any information secured from the test).