Cross-connection test for aircraft landing gear

An aircraft landing gear comprising:

• a wheel;
• and
• a tachometer comprising a tachometer rotor configured to rotate with the wheel, and a tachometer sensor configured to measure rotation of the tachometer rotor to generate a tachometer signal indicating rotation of the wheel,
• wherein the tachometer rotor is connected to the wheel by a floating connection which is configured to enable the tachometer rotor to be rotated without rotating the wheel to generate a test signal.

An aircraft landing gear system comprising:

• first and second wheels;
• a first braking system comprising a first tachometer mounted to the first wheel, and a first brake configured to brake the first wheel, wherein the first tachometer is configured to generate a first tachometer signal indicating rotation of the first wheel and further configured to generate a first test signal, wherein the first wheel is not rotating during the generation of the first test signal;
• a second braking system comprising a second tachometer mounted to the second wheel, and a second brake configured to brake the second wheel, wherein the second tachometer is configured to generate a second tachometer signal indicating rotation of the second wheel and further configured to generate a second test signal, wherein the second wheel is not rotating during the generation of the second test signal;
• first and second tachometer output lines;
• a first braking command line associated with the first tachometer output line;
• a second braking command line associated with the second tachometer output line;
• and
• a braking control and monitoring system configured to:
• receive the first or second test signal via one of the tachometer output lines;
• issue a braking command in response to the receipt of the first or second test signal, wherein the braking command is issued via the braking command line which is associated with the one of the tachometer output lines;
• and monitor a response of the first or second braking system to the braking command to test for a cross-connection between the first and second braking systems.