A fuel supply system for an aircraft engine, comprising: a gaseous fuel source (S1); and a fuel nozzle including: a housing having a housing interior chamber ; and a fuel swirler (40, 50; 40') disposed inside the housing interior chamber , the fuel swirler (40, 50; 40') fluidly connected to the gaseous fuel source (S1) for directing gaseous fuel to a combustor of an aircraft engine, the fuel swirler (40, 50; 40') defining a gaseous fuel path extending from a fuel inlet to a fuel outlet , the gaseous fuel path including a plurality of discrete apertures (46a; 84) distributed around a circumference of the fuel swirler , characterized in that the plurality of discrete apertures are defined through a radially exterior surface of the fuel swirler relative to a longitudinal axis (L) of the fuel swirler , wherein the plurality of discrete apertures are positioned at the fuel inlet of the fuel swirler , wherein each of the plurality of discrete apertures (46a; 84) has a cross-sectional area selected to prevent a flame from propagating in an upstream direction through the gaseous fuel path towards the gaseous fuel source (S1), and wherein the plurality of discrete apertures (46a; 84) have cross-sectional diameters of at most 0.610mm (0.024 inches). a gaseous fuel source (S1); and a fuel nozzle including: a housing having a housing interior chamber ; and a fuel swirler (40, 50; 40') disposed inside the housing interior chamber , the fuel swirler (40, 50; 40') fluidly connected to the gaseous fuel source (S1) for directing gaseous fuel to a combustor of an aircraft engine, the fuel swirler (40, 50; 40') defining a gaseous fuel path extending from a fuel inlet to a fuel outlet , the gaseous fuel path including a plurality of discrete apertures (46a; 84) distributed around a circumference of the fuel swirler , characterized in that the plurality of discrete apertures are defined through a radially exterior surface of the fuel swirler relative to a longitudinal axis (L) of the fuel swirler , wherein the plurality of discrete apertures are positioned at the fuel inlet of the fuel swirler , wherein each of the plurality of discrete apertures (46a; 84) has a cross-sectional area selected to prevent a flame from propagating in an upstream direction through the gaseous fuel path towards the gaseous fuel source (S1), and wherein the plurality of discrete apertures (46a; 84) have cross-sectional diameters of at most 0.610mm (0.024 inches). a housing having a housing interior chamber ; and a fuel swirler (40, 50; 40') disposed inside the housing interior chamber , the fuel swirler (40, 50; 40') fluidly connected to the gaseous fuel source (S1) for directing gaseous fuel to a combustor of an aircraft engine, the fuel swirler (40, 50; 40') defining a gaseous fuel path extending from a fuel inlet to a fuel outlet , the gaseous fuel path including a plurality of discrete apertures (46a; 84) distributed around a circumference of the fuel swirler , characterized in that the plurality of discrete apertures are defined through a radially exterior surface of the fuel swirler relative to a longitudinal axis (L) of the fuel swirler , wherein the plurality of discrete apertures are positioned at the fuel inlet of the fuel swirler , wherein each of the plurality of discrete apertures (46a; 84) has a cross-sectional area selected to prevent a flame from propagating in an upstream direction through the gaseous fuel path towards the gaseous fuel source (S1), and wherein the plurality of discrete apertures (46a; 84) have cross-sectional diameters of at most 0.610mm (0.024 inches). <EOS>