A detailed description of the Proximity Switch Electronic Unit and airground systems on the 737. (Updated)

Contents:
2:51 Background
6:23 PSEU
11:35 SPSEU
16:04 MAX Differences
21:48 Proximity Sensors
27:35 Airground
37:32 Airstairs control & warning
38:10 Door warnings & flightlocks
39:57 LGTU
41:21 Takeoff & landing configuration warnings
42:18 Landing gear position indicating and warning
43:44 Speedbrake deployed indication and warning
44:49 Twoposition tailskid
46:03 Crew procedures
48:43 Problems and updates