Spoiler PCU shutoff-valve system A or B circuitbreaker trips
Auto speed brake ground oper test seems normal but after flight the speed brake do not arm light illuminates and Spoiler pcu shutoff valve sys a or b circuit breaker trips , a short circuit is created on a (any) flight spoiler actuator. First you must measure all flight spoiler actuators than replacement of the faulty actuator solves this problem. In my case we found # 4 flight spoiler actuator faulty with a short circuit involving the SOV (solenoid operated valve) on the spoiler actuator. They are only found on SFP (short field performance) aircraft and drive the flight spoilers to extend beyond the standard 33°/38°, to 56°/65°when ground spoilers are deployed.
Thanks to Umit for his input !
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