B737 maximum first officer reported that the aircraft pitched nose down after engaging autopilot on ...

Narrative:

Day 3 of 3 departing in a maximum 8 after a long overnight. I was well rested and had discussed the recent maximum 8 MCAS guidance with the captain. On departure; we had strong crosswinds (gusts > 30 knots) directly off the right wing; however; no LLWS or micro-burst activity was reported at the field. After verifying LNAV; selecting gear and flaps up; I set 'up' speed. The aircraft accelerated normally and the captain engaged the 'a' autopilot after reaching set speed. Within two to three seconds the aircraft pitched nose down bringing the vsi to approximately 1;200 to 1;500 FPM. I called 'descending' just prior to the GPWS sounding 'don't sink; don't sink.' the captain immediately disconnected the autopilot and pitched into a climb. The remainder of the flight was uneventful. We discussed the departure at length and I reviewed in my mind our automation setup and flight profile but can't think of any reason the aircraft would pitch nose down so aggressively.

Original NASA ASRS Text

Title: B737 MAX First Officer reported that the aircraft pitched nose down after engaging autopilot on departure. Autopilot was disconnected and flight continued to destination.

Narrative: Day 3 of 3 departing in a MAX 8 after a long overnight. I was well rested and had discussed the recent MAX 8 MCAS guidance with the Captain. On departure; we had strong crosswinds (gusts > 30 knots) directly off the right wing; however; no LLWS or Micro-burst activity was reported at the field. After verifying LNAV; selecting gear and flaps up; I set 'UP' speed. The aircraft accelerated normally and the Captain engaged the 'A' autopilot after reaching set speed. Within two to three seconds the aircraft pitched nose down bringing the VSI to approximately 1;200 to 1;500 FPM. I called 'descending' just prior to the GPWS sounding 'don't sink; don't sink.' The Captain immediately disconnected the autopilot and pitched into a climb. The remainder of the flight was uneventful. We discussed the departure at length and I reviewed in my mind our automation setup and flight profile but can't think of any reason the aircraft would pitch nose down so aggressively.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	1597286
Time
Date	201811
Place
Locale Reference	ZZZ.Airport
State Reference	US
Aircraft 1
Make Model Name	B737-800
Operating Under FAR Part	Part 121
Flight Phase	Takeoff
Flight Plan	IFR
Component
Aircraft Component	Autopilot
Person 1
Function	First Officer Pilot Not Flying
Qualification	Flight Crew Multiengine Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument
Experience	Flight Crew Last 90 Days 511
Events
Anomaly	Aircraft Equipment Problem Critical

B737 maximum first officer reported that the aircraft pitched nose down after engaging autopilot on departure. Autopilot was disconnected and flight continued to destination.