diff --git a/Aircraft/c172p/Instruments/kr87-adf/kr87.xml b/Aircraft/c172p/Instruments/kr87-adf/kr87.xml
index d9a4311a6..811eb9229 100644
--- a/Aircraft/c172p/Instruments/kr87-adf/kr87.xml
+++ b/Aircraft/c172p/Instruments/kr87-adf/kr87.xml
@@ -11,8 +11,7 @@
         <type>select</type>
         <object-name>indicator</object-name>
         <condition>
-            <property>/instrumentation/adf[0]/serviceable</property>
-            <property>/instrumentation/adf[0]/power-btn</property>
+            <property>/instrumentation/adf[0]/operable</property>
         </condition>
     </animation>
     <animation>
diff --git a/Aircraft/c172p/Nasal/kma20.nas b/Aircraft/c172p/Nasal/kma20.nas
new file mode 100644
index 000000000..e8770762e
--- /dev/null
+++ b/Aircraft/c172p/Nasal/kma20.nas
@@ -0,0 +1,41 @@
+##################################################################
+#
+# These are the helper functions for the kma20 audio panel
+# Maintainer: Thorsten Brehm (brehmt at gmail dot com)
+#
+# Usage:
+# just create one instance of kma20 class for each kma20 panel
+# you have in your aircraft:
+# kma20.new(0);
+#
+# KMA20 audio panel properties:
+# root: /instrumentation/kma20
+#    knob: microphone/radio selector (com1/2)
+#    auto: selects COM1/2 based on microphone selector
+#    com1: enable/disable COM1 audio (e.g. for ATIS)
+#    com2: enable/disable COM2 audio (e.g. for ATIS)
+#    nav1: enable/disable NAV1 station identifier
+#    nav2: enable/disable NAV2 station identifier
+#    adf:  enable/disable ADF station identifier
+#    dme:  enable/disable DME station identifier
+#    mkr:  enable/disable marker beacon audio
+#    sens: beacon receiver sensitivity
+
+var kma20 = {};
+
+kma20.new = func(rootPath) {
+  var obj = {};
+  obj.parents = [kma20];
+
+  setlistener(rootPath ~ "/com1", func(v) {setprop("/instrumentation/comm/volume",        0.7*(v.getValue() != 0));}, 1);
+  setlistener(rootPath ~ "/com2", func(v) {setprop("/instrumentation/comm[1]/volume",     0.7*(v.getValue() != 0));}, 1);
+  setlistener(rootPath ~ "/nav1", func(v) {setprop("/instrumentation/nav/audio-btn",          (v.getValue() != 0));}, 1);
+  setlistener(rootPath ~ "/nav2", func(v) {setprop("/instrumentation/nav[1]/audio-btn",       (v.getValue() != 0));}, 1);
+  setlistener(rootPath ~ "/adf",  func(v) {setprop("/instrumentation/adf/ident-audible",      (v.getValue() != 0));}, 1);
+  setlistener(rootPath ~ "/dme",  func(v) {setprop("/instrumentation/dme/ident",              (v.getValue() != 0));}, 1);
+  setlistener(rootPath ~ "/mkr",  func(v) {setprop("/instrumentation/marker-beacon/audio-btn",(v.getValue() != 0));}, 1);
+  print( "KMA20 audio panel initialized" );
+  return obj;
+};
+
+var kma20_0 = kma20.new( "/instrumentation/kma20" );
diff --git a/Aircraft/c172p/c172p-set.xml b/Aircraft/c172p/c172p-set.xml
index 19b41cc56..f27dffcc8 100644
--- a/Aircraft/c172p/c172p-set.xml
+++ b/Aircraft/c172p/c172p-set.xml
@@ -195,6 +195,16 @@ Started October 23 2001 by John Check, fgpanels@rockfish.net
   <encoder>
    <serviceable type="bool">true</serviceable>
   </encoder>
+  <adf n="0">
+    <ident-audible type="bool">false</ident-audible>
+    <volume type="double">0.7</volume>
+  </adf>
+  <nav n="0">
+    <volume type="double">0.7</volume>
+  </nav>
+  <nav n="1">
+    <volume type="double">0.7</volume>
+  </nav>
  </instrumentation>
 
  <engines>
@@ -214,6 +224,7 @@ Started October 23 2001 by John Check, fgpanels@rockfish.net
       <file>Aircraft/c172p/Nasal/doors.nas</file>
       <file>Aircraft/c172p/Nasal/light.nas</file>
       <file>Aircraft/c172p/Nasal/tanks.nas</file>
+      <file>Aircraft/c172p/Nasal/kma20.nas</file>
       <file>Aircraft/c172p/Nasal/ki266.nas</file>
       <script><![CDATA[
         ki266.new(0);