DO-160 allots the first three sections to establish some common elements applicable to the specific test sections.
Section 1 discusses the purpose of this standard is to standardize conditions and procedures to instill confidence that the tested device will perform properly when exposed to various environmental (including the electromagnetic environment) conditions. It is noted that proper performance is established by the equipment performance standard. The performance standard defines the allowed operation during less-than-optimal conditions. For example, a particular device may reset if a power voltage transient exceeding 1,000 volts occurs. The performance standard may allow a reset if the device does not require operator actions to accomplish the reset and the reset is complete within 3-seconds. If this performance is acceptable for the aircraft operation, then a reset that meets the performance criteria is acceptable for that application. The performance variation should not be a surprise to the user – full disclosure is documented on the Environmental Qualification Form.
Other conditions not included in the standard may need to be included in the overall acceptance for a particular device. These conditions may need to be evaluated if that condition’s compliance is necessary. It is the obligation of the device performance author to include the special conditions and the means to evaluate.
Not all conditions apply to each device. When applying the standard, the minimum operational performance standards (MOPS) for devices are examined to determine applicability. The party responsible for device acceptance must approve applicability for each of the test methods. As part of the applicability process, various categories are assigned based on device vulnerability to reduce applying excessive requirements unnecessarily.
Section 1 also refers to user guides for selected test methods. The user guides are meant to aid in understanding the goals of the test and assist in preparing procedures for the evaluation.
Section 2 is listed as definitions of terms. This is not just a list of acronyms but a guide in understanding the meaning behind the terms. Things like determining thermal stabilization, assigning categories and the like are discussed in this section.
Section 3 discusses conditions of tests providing general test setup guidance. Some test methods include details that may alter the general conditions. Unless otherwise stated, section 3 conditions apply.
Equipment connections and orientations should follow the manufacturer’s recommended installation practices, including required ancillary items such as cooling fans or remote controls. The interconnecting cables are at least 1.5 meters and configured to allow one common cable bundle of 1.2 meters. For most of the EMI/EMC test configurations, the cables have a different arrangement defined by the individual test methods.
Using multiple test articles is permitted except for when cumulative testing is necessary. The manufacturer is responsible for assessing the need for cumulative testing. For example, it may be appropriate to specify that conducted emission testing be accomplished on a unit that had been subjected to induced lightning. This sequence could identify defective filters that were damaged by high current induced by the lightning transient. Section 3 identifies certain tests that have a required sequence. Combining tests are also permitted, as long as the required conditions are met (combining EMI/EMC tests is limited to verifying multiple categories by accomplishing only the worst-case test).
Section 3 specifies the ambient conditions (temperature, humidity atmospheric pressure) for the test facilities.
Susceptibility tests are to be accomplished with the test article operating in the most vulnerable mode for that particular test. This could be the weakest transmit signal amplitude for a radio transceiver operating in the receive mode during radiated RF susceptibility testing. Although not stated, emission tests should use the mode that would produce the highest emission levels. Sufficient operational modes should be used to evaluate all circuits.