B737 MAX Series Undifferentiated
Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Troubleshooting; Time Pressure; Workload
Aircraft Equipment Problem Less Severe; Ground Event / Encounter Weather / Turbulence
General Maintenance Action
Aircraft
While at Gate XX during heavy wet snow with wind blowing 10-15 kts. 90 degrees from the right side; the APU tripped off line 3 separate times. At some point; we also noticed zero duct pressure. The mechanic found no issues [and] suggested shutting the APU down for several minutes. Upon restart; pressure was normal for approximately 10 minutes; then it started to decrease again. [Contributing factors were] heavy wet snow; [flying] in direct right crosswind; [and] possible issue with design of MAX APU inlet. [I suggest] publishing a note in AOM or somewhere to let crews know this is a possibility on the 737-MAX and have Boeing examine this scenario.
While at Gate XX at ZZZ during heavy wet snow. [We] had issues with APU generator. [The APU] tripped off three times. [The APU] would reset after about 30 seconds. We also had zero duct pressure. The wind was a direct crosswind from the right. Maintenance came out and after resetting the APU and came up with a plan to shut down the APU so the door would close and allow the APU to stop ingesting wet snow. This happened to a MAX on gate XX and us on gate XX.After allowing 15 min for the shut down and restart of the APU; duct pressure came back up and the APU generated worked fine. [We had an] extended delay so [we] shut down the APU again. Direct crosswind with blowing heavy wet snow causes the APU to not operate correctly. [I made] a note in the flight manual to warn crews of this potential problem. [I recommend to] delay using the APU until you are ready to push and start the aircraft. If we had pushed with our original problem we would not have been able to start engine with no duct pressure.
Air carrier flight crew reported the APU on their 737 MAX continued to shut down while in service at the gate while in a heavy wet snow storm.