TRYING TO PLAY A CD ON A RECORD PLAYER: TESTING A DIGITAL UPGRADE TO THE A-10 ANALOG FUEL QUANTITY SYSTEM

摘要

The Digital Fuel Quantity Intermediate Device (DFQID) is a Line Replaceable Unit (LRU) for the A-10C. It converts capacitance signals from the fuel probes inside the fuel tanks into a voltage signal read by the fuel indicator in the cockpit. The DFQID is designed to be an upgraded digital replacement for the obsolete analog Fuel Quantity Intermediate Device (FQID); equipment projected to be unsupportable beyond 2017. After design and manufacture, DFQIDs were fielded in 2004 bypassing standard developmental and operational testing. Inaccurate and unreliable fuel indications prevailed during the mainstay of DFQIDs fielding. The A-10 System Program Office (SPO) halted distribution of the DFQIDs in favor of utilizing remaining analog FQIDs. The test team at the 40th Flight Test Squadron (40 FLTS) was tasked by the A-10 SPO with testing the DFQID to characterize its performance. Intermittent failures observed during the onset of testing prompted the test team to reevaluate their test approach to isolate the contributing factor. Quality control, aging aircraft wiring, and environmental factors were all suspect. Conducting a test that fully incorporated these factors proved to be a nontrivial task. Testing encompassed 11 months to include 2 flight tests and over 30 ground tests. This led to the conclusion that humidity and moisture penetrated the outer casing of the DFQID into its circuitry causing it to misinterpret capacitance signals from the fuel probes and subsequently send an inaccurate voltage signal to the fuel indicator. As a result of testing, the DFQID is currently undergoing modification to properly seal the internal components to allow for further testing to be completed.