diff --git a/Models/Instruments/Lower-ECAM/Lower-ECAM.nas b/Models/Instruments/Lower-ECAM/Lower-ECAM.nas
index 8767911a..e8c19427 100644
--- a/Models/Instruments/Lower-ECAM/Lower-ECAM.nas
+++ b/Models/Instruments/Lower-ECAM/Lower-ECAM.nas
@@ -73,7 +73,6 @@ var final_deg = props.globals.getNode("/fdm/jsbsim/hydraulics/rudder/final-deg",
 var temperature_degc = props.globals.getNode("/environment/temperature-degc", 1);
 var gw = props.globals.getNode("/fdm/jsbsim/inertia/weight-lbs", 1);
 var tank3_content_lbs = props.globals.getNode("/fdm/jsbsim/propulsion/tank[2]/contents-lbs", 1);
-var apu_master = props.globals.getNode("/controls/apu/master", 1);
 var ir2_knob = props.globals.getNode("/controls/adirs/ir[1]/knob", 1);
 var switch_bleedapu = props.globals.getNode("/controls/pneumatics/switches/apu", 1);
 var apuBleedNotOn = props.globals.getNode("/systems/pneumatics/warnings/apu-bleed-not-on", 1);
@@ -610,7 +609,7 @@ var canvas_lowerECAM_apu = {
 			me["APUGenHz"].setColor(0.7333,0.3803,0);
 		}
 
-		if (apu_master.getValue() == 1 or apu_rpm.getValue() >= 94.9) {
+		if (systems.APUNodes.Controls.master.getValue() == 1 or apu_rpm.getValue() >= 94.9) {
 			me["APUGenbox"].show();
 			me["APUGenHz"].show();
 			me["APUGenVolt"].show();
@@ -634,9 +633,9 @@ var canvas_lowerECAM_apu = {
 			me["APUGenOnline"].hide();
 		}
 
-		if ((apu_master.getValue() == 0) or ((apu_master.getValue() == 1) and (gen_apu.getValue() == 1) and (apu_rpm.getValue() > 94.9))) {
+		if ((systems.APUNodes.Controls.master.getValue() == 0) or ((systems.APUNodes.Controls.master.getValue() == 1) and (gen_apu.getValue() == 1) and (apu_rpm.getValue() > 94.9))) {
 			me["APUGentext"].setColor(0.8078,0.8039,0.8078);
-		} else if ((apu_master.getValue() == 1) and (gen_apu.getValue() == 0) and (apu_rpm.getValue() < 94.9)) { 
+		} else if ((systems.APUNodes.Controls.master.getValue() == 1) and (gen_apu.getValue() == 0) and (apu_rpm.getValue() < 94.9)) { 
 			me["APUGentext"].setColor(0.7333,0.3803,0);
 		}
 
@@ -670,7 +669,7 @@ var canvas_lowerECAM_apu = {
 		
 
 		# APU N and EGT
-		if (apu_master.getValue() == 1) {
+		if (systems.APUNodes.Controls.master.getValue() == 1) {
 			me["APUN"].setColor(0.0509,0.7529,0.2941);
 			me["APUN"].setText(sprintf("%s", math.round(apu_rpm.getValue() or 0)));
 			me["APUEGT"].setColor(0.0509,0.7529,0.2941);
@@ -795,7 +794,7 @@ var canvas_lowerECAM_bleed = {
 		# APU BLEED valve
 		var apu_valve_state2 = apu_valve_state.getValue();
 		
-		if (apu_master.getValue()) {
+		if (systems.APUNodes.Controls.master.getValue()) {
 			me["BLEED-APU-LINES"].show();
 			if (apu_valve_state2 == 1) {
 				me["BLEED-APU-CIRCLE"].setRotation(0);
@@ -1647,7 +1646,7 @@ var canvas_lowerECAM_elec = {
 		}
 
 		# APU
-		if (apu_master.getValue() == 0) {
+		if (systems.APUNodes.Controls.master.getValue() == 0) {
 			me["APU-content"].hide();
 			me["APUGEN-off"].hide();
 			me["APU-border"].hide();
diff --git a/Nasal/ECAM/ECAM-logic.nas b/Nasal/ECAM/ECAM-logic.nas
index 482d0c78..f16b9cca 100644
--- a/Nasal/ECAM/ECAM-logic.nas
+++ b/Nasal/ECAM/ECAM-logic.nas
@@ -12,10 +12,8 @@ var emerGen      = props.globals.getNode("/controls/electrical/switches/emer-gen
 
 var state1Node = props.globals.getNode("/engines/engine[0]/state", 1);
 var state2Node = props.globals.getNode("/engines/engine[1]/state", 1);
-var wowNode    = props.globals.getNode("/fdm/jsbsim/position/wow", 1);
 var apu_rpm    = props.globals.getNode("/engines/engine[2]/n1", 1);
 var wing_pb    = props.globals.getNode("/controls/ice-protection/wing", 1);
-var apumaster  = props.globals.getNode("/controls/apu/master", 1);
 var apu_bleedSw   = props.globals.getNode("/controls/pneumatics/switches/apu", 1);
 var gear       = props.globals.getNode("/gear/gear-pos-norm", 1);
 var cutoff1    = props.globals.getNode("/controls/engines/engine[0]/cutoff-switch", 1);
@@ -226,7 +224,7 @@ var messages_priority_3 = func {
 			ECAM_controller.warningReset(dualFailmasteroff);
 		}
 		
-		if (dualFailapuoff.clearFlag == 0 and apumaster.getBoolValue()) {
+		if (dualFailapuoff.clearFlag == 0 and systems.APUNodes.Controls.master.getBoolValue()) {
 			dualFailapuoff.active = 1;
 		} else {
 			ECAM_controller.warningReset(dualFailapuoff);
@@ -1310,7 +1308,7 @@ var messages_priority_2 = func {
 		ECAM_controller.warningReset(apuAutoShutdown);
 	}
 	
-	if (apuAutoShutdownMast.clearFlag == 0 and pts.APU.masterSw.getValue() and apuAutoShutdown.active == 1) {
+	if (apuAutoShutdownMast.clearFlag == 0 and systems.APUNodes.Controls.master.getValue() and apuAutoShutdown.active == 1) {
 		apuAutoShutdownMast.active = 1;
 	} else {
 		ECAM_controller.warningReset(apuAutoShutdownMast);
@@ -2483,7 +2481,7 @@ var messages_right_memo = func {
 }
 
 setlistener("/engines/engine[0]/state", func() {
-	if ((state1Node.getValue() != 3 and state2Node.getValue() != 3) and wowNode.getValue() == 0) {
+	if ((state1Node.getValue() != 3 and state2Node.getValue() != 3) and !pts.Fdm.JSBsim.Position.wow.getBoolValue()) {
 		dualFailNode.setBoolValue(1);
 	} else {
 		dualFailNode.setBoolValue(0);
@@ -2491,7 +2489,7 @@ setlistener("/engines/engine[0]/state", func() {
 }, 0, 0);
 
 setlistener("/engines/engine[1]/state", func() {
-	if ((state1Node.getValue() != 3 and state2Node.getValue() != 3) and wowNode.getValue() == 0) {
+	if ((state1Node.getValue() != 3 and state2Node.getValue() != 3) and !pts.Fdm.JSBsim.Position.wow.getBoolValue()) {
 		dualFailNode.setBoolValue(1);
 	} else {
 		dualFailNode.setBoolValue(0);
diff --git a/Nasal/ECAM/ECAM-main.nas b/Nasal/ECAM/ECAM-main.nas
index 189a2b8b..db1b2dc8 100644
--- a/Nasal/ECAM/ECAM-main.nas
+++ b/Nasal/ECAM/ECAM-main.nas
@@ -223,7 +223,7 @@ var SystemDisplay = {
 	},
 	update: func() {
 		phase = pts.ECAM.fwcWarningPhase.getValue();
-		APUMaster = pts.APU.masterSw.getValue();
+		APUMaster = systems.APUNodes.Controls.master.getValue();
 		APURPM = pts.APU.rpm.getValue();
 		engModeSel = pts.Controls.Engines.startSw.getValue();
 		elapsedSec = pts.Sim.Time.elapsedSec.getValue();
diff --git a/Nasal/Libraries/property-tree-setup.nas b/Nasal/Libraries/property-tree-setup.nas
index 4f6b2a8a..fe9151fb 100644
--- a/Nasal/Libraries/property-tree-setup.nas
+++ b/Nasal/Libraries/property-tree-setup.nas
@@ -9,7 +9,6 @@ var Acconfig = {
 };
 
 var APU = {
-	masterSw: props.globals.getNode("/controls/apu/master"),
 	rpm: props.globals.getNode("/engines/engine[2]/n1"),
 };
 
@@ -74,6 +73,9 @@ var Fdm = {
 			aileron: props.globals.getNode("/fdm/jsbsim/fbw/aileron-sidestick"),
 			elevator: props.globals.getNode("/fdm/jsbsim/fbw/elevator-sidestick"),
 		},
+		Position: {
+			wow: props.globals.getNode("/fdm/jsbsim/position/wow"),
+		},
 		Propulsion: {
 			Engine: {
 				fuelUsed: [props.globals.getNode("/fdm/jsbsim/propulsion/engine[0]/fuel-used-lbs"), props.globals.getNode("/fdm/jsbsim/propulsion/engine[1]/fuel-used-lbs")],
diff --git a/Nasal/Panels/atc.nas b/Nasal/Panels/atc.nas
index 216cf0a8..d1f3d267 100644
--- a/Nasal/Panels/atc.nas
+++ b/Nasal/Panels/atc.nas
@@ -24,7 +24,6 @@ var Transponder = {
 	serviceableNode: props.globals.getNode("instrumentation/transponder/serviceable", 1),
 	knobNode: props.globals.getNode("instrumentation/transponder/inputs/knob-mode", 1),
 	identNode: props.globals.getNode("instrumentation/transponder/inputs/ident-btn", 1),
-	wowNode: props.globals.getNode("fdm/jsbsim/position/wow"),
 	ac1Node: props.globals.getNode("systems/electrical/bus/ac-1", 1),
 	tcasNode: props.globals.getNode("instrumentation/tcas/inputs/mode"),
 	aglNode: props.globals.getNode("position/gear-agl-ft", 1),
@@ -84,7 +83,7 @@ var Transponder = {
 				me.setMode(4); # on
 			}
 		} else if (me.mode >= 3) {
-			if (me.wowNode.getBoolValue()) {
+			if (pts.Fdm.JSBsim.Position.wow.getBoolValue()) {
 				if (me.knobNode.getValue() != 3) {
 					me.setMode(3); # gnd
 				}
diff --git a/Nasal/Systems/fire.nas b/Nasal/Systems/fire.nas
index cb25e0c6..89044210 100644
--- a/Nasal/Systems/fire.nas
+++ b/Nasal/Systems/fire.nas
@@ -32,8 +32,6 @@ var eng2AgentTimerTime = props.globals.initNode("/systems/fire/engine2/agent1-ti
 var eng1Agent2TimerTime = props.globals.initNode("/systems/fire/engine1/agent2-timer-time", 0, "INT");
 var eng2Agent2TimerTime = props.globals.initNode("/systems/fire/engine2/agent2-timer-time", 0, "INT");
 var apuAgentTimerTime = props.globals.initNode("/systems/fire/apu/agent-timer-time", 0, "INT");
-var wow = props.globals.getNode("/fdm/jsbsim/position/wow", 1);
-var apuMaster = props.globals.getNode("/controls/apu/master", 1);
 
 var fire_init = func {
 	setprop("/controls/OH/protectors/fwddisch", 0);
@@ -56,7 +54,6 @@ var engFireDetectorUnit = {
 	loopTwo: 0,
 	condition: 100,
 	fireProp: "",
-	wow: "",
 	new: func(sys, fireProp, testProp) {
 		var eF = {parents:[engFireDetectorUnit]};
 		eF.sys = sys;
@@ -65,7 +62,6 @@ var engFireDetectorUnit = {
 		eF.loopTwo = 0;
 		eF.fireProp = props.globals.getNode(fireProp, 1);
 		eF.testProp = props.globals.getNode(testProp, 1);
-		eF.wow = props.globals.getNode("/fdm/jsbsim/position/wow", 1);
 		eF.condition = 100;
 		return eF;
 	},
@@ -175,7 +171,7 @@ var engFireDetectorUnit = {
 			eng2FireWarn.setBoolValue(1);
 		} elsif (system == 2) {
 			apuFireWarn.setBoolValue(1);
-			if (me.wow.getValue() == 1) {
+			if (pts.Fdm.JSBsim.Position.wow.getValue() == 1) {
 				systems.APUController.APU.emergencyStop();
 				settimer(func() { # 3 sec delay - source TTM ATA 26 FIRE PROTECTION p102
 					extinguisherBottles.vector[4].discharge();