Downloaded from https://www.everyspec.com ADS-79D-HDBK background for acceptable approaches towards the development and verification of software applicable to the entire system. In addition, an alternate means of compliance to RTCA DO-178B may be pursued. Since the function of the HUMS may essentially perform nondestructive inspection (NDI) on critical components – rather than control the aircraft or provide actionable information to the pilot for control of the aircraft – the HUMS software requirements may not necessarily include compliance with RTCA DO-178B level A or B DAL.
Instead, similar to other NDI equipment employed in aviation, the HUMS may undergo a periodic functional check via fault stimulation to verify it will display the applicable alert to the maintainer when a fault is present on critical components. Analogous to stimulating an eddy current or ultra sound machine using a pre notched/cracked block to ensure proper equipment function before inspecting components, stimulation software with known fault signals may be executed on ground stations.
The stimulation software can consist of raw data from a known fault obtained from seeded fault validation and fed into the ground station to assure the applicable alerts for known faults are provided as output alerts from the ground station. If applicable alerts are not provided by the ground based stations, then the ground station software is not functioning properly. Otherwise, ground station functionality is verified and download of raw data from the aircraft may occur with confidence the ground station software is providing the correct output. K.6.2.2 Ground Station Acceptance Test Procedures (ATP).
Whether deploying a newly- developed system for the first time, or updating an existing system that is already in production use, some method of determining the acceptable performance of the delivered system is necessary. Acceptance Test Procedures (ATPs) are the recommended method of verifying system functionality whenever an update or modification to the system is fielded. Unlike the Verification phase testing, ATPs generally are simpler tests which provide the end-user confidence that the updated system is performing adequately and has not been damaged or incorrectly altered by the modification.
ATPs are designed to exercise the standard functionality of the system in a representative environment, using known inputs and expecting given outputs. They exercise the majority of the normal use cases of the system and are designed to provide sufficient confidence in the system (rather than full coverage of every feature and exception). By establishing a standard suite of functional testing that covers normal use of the system, an ATP can be developed that can be used repeatedly with little or no modification over time.
By having a standard ATP, changes to the system (whether they are functional software changes, maintenance updates, or even updates to the supporting environment—such as Operating System or Database patches, new printers or network hardware, etc.) can be easily and quickly verified and assessed for any unanticipated impact to the operation of the HUMS Ground Station and supporting software. A process that includes execution of the standard suite of ATP tests should be included in any plans for software updates, maintenance patches, or other system environment changes to fielded production systems.
The ATP itself should be evaluated at any change in system functionality (new features, etc.) to ensure that the ATP continues to cover the majority of the expected system capability over time. 224