From: email@example.com (Ed Hahn) Organization: The MITRE Corporation, McLean, Va. Date: 07 Mar 94 15:12:48 PST References: 1 2 3 4 5 Followups: 1 2
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<stuff deleted> However, she swears that right after the crash, the pilot was telling anyone who would listen that the instruments indicated, as I recall, 200-300 lbs of fuel left in each wing when the engines went down. <stuff deleted> ---- 200-300 pounds of fuel is well within the realm of uncertainty in fuel quantity measurement, especially with the fuel quantity indication system (FQIS) of the era. FQIS is a perennial headache to maintain, as there is no good way to measure it. The standard method is to look at the capacitance of the fuel, which is loosely proportional to the amount of fuel in the wings. The capacitance is measured by looking for the resonant frequency in a fuel quantity probe, ala first year electronics. Naturally, the probe leads, which are soaked in fuel, will fall out of calibration fairly quickly. Most of the time, this doesn't matter, as the fuelers use dipsticks to verify the amount of fuel in the wings. However (this may be hindsight), they just aren't that accurate when the tanks are THAT empty. Even with new digital FQIS systems, FQIS is still a leading cause of maintenance delays ("call maintenance, the FQ is reading too low"), at least among the airlines I've worked with. Just my $0.02, ed //////// Ed Hahn | firstname.lastname@example.org | (703) 883-5988 \\\\\\\\ The above comment reflects the opinions of the author, and does not constitute endorsement or implied warranty by the MITRE Corporation. Really, I wouldn't kid you about a thing like this.