“Nose Steer Fail” CAS message on landing

Effectivity: Global 7500 aircraft

ATA 32

Some operators of the Global 7500 aircraft have recently reported to Bombardier having a “Nose Steer Fail” CAS message on landing.

Upon investigation, it has been found that in all cases, the nose wheel steering was moved via the handwheel, before the nose wheel had contacted the runway.

It is imported to note that if the steering input is greater than seven (7) deg during WoffW-WOW transition, the Landing Gear and Steering Control Unit (LGSCU) will fail the system to prevent a runway excursion. This will result in a “Nose Steer Fail” CAS message and the NWS will switch to free castering mode. In free castering mode, aircraft manoeuvring would depend on the use of differential braking and rudder input as required to assist in directional control.

Once the system fault is latched, it cannot be reset by cycling NWS OFF/ARM toggle switch. The A/C power will need to be cycled to clear the message (LGSCU C/B cycling would also work but the C/B location are inconvenient during normal A/C operation).

Bombardier recommends that rudder pedal inputs should be used as required to assist in directional control. The nosewheel tiller steering should only be used at taxi speeds and below.

If the mentioned CAS message is posted, an AHMS analysis could confirm if it meets the described condition and therefore no maintenance action would be required.