Abstract: A process for etching single crystal silicon semiconductor material of the N, P, N+ and P+ type slugs and wafers to delineate slip, lineage, dislocation, S-pit, twins, swirl and oxidation induced stacking fault defects involves the steps of:a) preparing a substantially metal-free etchant bath comprising nitric acid (70%), hydrofluoric acid (49%) and between approximately 35% to 98% by weight of glacial acetic acid (HAc) as a diluent, the minimum useful concentration of nitric acid being% Nitric acid.sub.min. =16.67?1-(% HAc/100)! and the maximum useful concentration of nitric acid being% Nitric acid.sub.max. =66.67?1-(% HAc/100)!, the minimum useful concentration of hydrofluoric acid being% HF.sub.min. =100%-% HAc % HNO.sub.3 max. and the maximum useful concentration of hydrofluoric acid being% HF.sub.max. -100%-% HAc-HNO.sub.2min.b) activating the etchant bath by generating NO.sub.x therein and allowing the temperature of the bath to rise to approximately 25.degree. to 34.degree. C.

Abstract: A device for measuring fuel flow to a power plant such as a turbo fan engine with a very high degree of accuracy, for example, .+-.0.5%. A tubular flow loop having quick disconnect fittings for detachably connecting the loop between the aircraft fuel system outlet and the engine fuel inlet is disclosed. Two specially calibrated mass flow transmitters are arranged in series, each preceded by a straight section of piping having a preferred given length to diameter ratio. Preceding each of the two straight pipe sections is a honeycomb flow straightener and three in-series perforated plates for removing any effects of upstream flow characteristics from the transmitters.