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Revision Date April 30, 2020 || Document Number UM-E71-314 || Rev B
11 Reliability and Maintainability
11.1 Reliability
The Mean Time Between Failure (MTBF) for the Sierra is a minimum of 100,000 operating hours
calculated using the RIAC 217+ (AIC, +30°C, 65% duty cycle, 2190 cycles per year).
11.2 Maintainability
The Sierra is considered an LRU and is repairable only by Astronics CSC or an authorized repair
facility. Periodic maintenance of the Sierra is not required.
11.3 Mean Time to Repair (MTTR)
Repair time will not exceed 15 minutes, which entails replacement of the Sierra from its mounting
points and disconnection of its electrical connectors..
11.4 Failure Detection and Fault Isolation
LED indicators located on the system enclosure provide functional status of the Sierra.
11.5 Production Testing
Production units are subjected to Environmental Stress Screening (ESS) and a production Acceptance
Test Procedure (ATP) prior to shipment. These tests are intended to ensure that all elements of the
product are functional and capable of performing at both high and low temperature extremes and that
they are free of manufacturing defects. The Acceptance Test Procedure is run pre- and post-ESS to
test the functional characteristics of the product.
