Downlock switches are not opening.
Power relay points stuck.
Defective limit switch.
C18. Landing gear pump motor continues to run when the gear is
extended or retracted, causing the circuit breaker to trip.
Weak power pack motor
Low voltage to the motor
Low fluid level.
Blockage in the hydraulic system.
C19. Landing gear pump motor operating longer than 14 seconds
in both the extention and retraction modes. The 2-ampere
circuit breaker does not trip.
C20. Landing gear pump motor operating longer than 14 seconds
in the retract mode, but the 2-ampere circuit breaker does
Faulty time delay PCB and pressure switch
C21.Landing gear pump motor operating longer than 14 seconds
in the extended mode, but the 2 ampere circuit breaker does
Downlock switches falling to open and/or
the time delay PCB is faulty.
C22. Landing gear LOW FLUID LEVEL light not
Defective fluid Indicator circuit.
C23. Landing gear circuit breaker trips.
C24. Landing gear warning horn inoperative when landing gear
control switch is in the up position and weight of aircraft is
on struts, but operates when a power lever is closed and the
gear is retracted.