B737-CL MCP FROZEN DISPLAY A/P DISCONNECTEDIN FLIGHT

[vortex]

Any help please. When the aircraft goes into clouds in a flight the MCP keeps last information, HDG, attitude and speed a/p disconnected, what happens?
thanks

[vortex]

We fix the problem by complying Honeywell Service Bulletin 4051601-22-0035 (Pub. No. C21-1142-074)
Reason.
Modification J to Mode Control Panel (MCP), Part No. 4051601-932, -935, -936, -937, -938, -939, -940, -945, reduces the susceptibility to static discharge from the airplane windshield when encountering cloudy conditions favorable to “St. Elmo’s Fire”. Typically, MCPs encountering such conditions will exhibit autopilot disconnects, 50,000 feet in the altitude window, and a non-resettable altitude alert warning. The other windows will either be blank, unreadable, or displaying all 8’s. Sometimes, No. 2 Course will be the only display not affected. However, No. 2 Course may be the only display that is blank,unreadable, or displaying all 8’s. This condition is non-resettable. Removal and reapplication of power (power reset) will re-establish normal operation. Modification J will significantly reduce these types of squawks.
by vortex,thanks

[sjap]

Thanks for the update Vortex. Interesting issue. Keep sharing your experiences !

[vortex]

Sure I will SJAP.
have a nice weekend
vortex

[Shumway]

In the late 1990s or early 2000s I thought I came about and SB or SL regarding MCP freeze when flying through precipitation. It was caused by either #1 LH and or RH windshield not having their wire mesh bonding under the aerodynamic sealant.
The wire mesh normally gets thrown away during sealmat replacement.
There's supposed to be 1 wire mesh at each of the 4 edges of the windshield