APM: allow ailerons to move fully during servo demo

ArduPlane/Attitude.pde

@@ -508,10 +508,13 @@ static void set_servos(void)
 #endif
 }
 
+static bool demoing_servos;
+
 static void demo_servos(byte i) {
 
     while(i > 0) {
         gcs_send_text_P(SEVERITY_LOW,PSTR("Demo Servos!"));
+        demoing_servos = true;
 #if HIL_MODE == HIL_MODE_DISABLED || HIL_SERVOS
         APM_RC.OutputCh(1, 1400);
         mavlink_delay(400);
@@ -519,6 +522,7 @@ static void demo_servos(byte i) {
         mavlink_delay(200);
         APM_RC.OutputCh(1, 1500);
 #endif
+        demoing_servos = false;
         mavlink_delay(400);
         i--;
     }

ArduPlane/failsafe.pde

@@ -39,7 +39,11 @@ void failsafe_check(uint32_t tnow)
         // pass RC inputs to outputs every 20ms
         last_timestamp = tnow;
         APM_RC.clearOverride();
-        for (uint8_t ch=0; ch<4; ch++) {
+        uint8_t start_ch = 0;
+        if (demoing_servos) {
+            start_ch = 1;
+        }
+        for (uint8_t ch=start_ch; ch<4; ch++) {
             APM_RC.OutputCh(ch, APM_RC.InputCh(ch));
         }
         RC_Channel_aux::copy_radio_in_out(RC_Channel_aux::k_manual);