Weather Radar Not Working - No response from Weather Radar system on both sides

Today I had a call for a faulty weather radar system.

The weather was bad. There were a lot of clouds and rained heavily. The Captain reported that the two weather radar systems didn't give any response on the display panels.

This was a No-Go situation. Since both systems were inoperative. 

When I performed the operational test I noticed that weather radar antenna motor was moving. That was confirmed by the normal sound of motor in action.

The systems didn't has near failures at the time and has no related faults in PFR Post Flight Report.


The problem was that the pilot closed the Avionics cooling system ventilation valves due to the heavy rain. This action did not comply with operation procedure in such weather.

Due to its large power consumption, the weather radar transceiver does not operate when Avionics system ventilation is inoperative.

That's why the antenna motor moved normally while there were no transmitted or received weather radar signal.

That's also why there were no recorded failures in PRF nor Ground Scanning reports.

The captain were informed by this fact and Avionics Ventilation put to ON again. Then the weather radar systems both worked normally.

REF.: GCD