Trimmable horizontal stabiliser actuator secondary load path detector

A secondary load path assembly comprising:

• a secondary load path comprising:
• a plate;
• a secondary nut;
• and
• a transfer plate secured to the plate and configured to connect the plate and the secondary nut in load transfer engagement, the transfer plate having an opening therethrough (therethrough, an axis defined through the opening, and the secondary nut protruding axially through the opening;
• wherein, in a state in which load is not transmitted via the secondary load path, a clearance is provided between the secondary nut and the opening;
• a locking unit configured to lock the secondary nut to the transfer plate when load is to be transmitted through the secondary path, the locking unit comprising a lock arranged to axially move to a lock position in which it is located in the clearance between the secondary nut and the opening to lock the secondary nut to the transfer plate;
• and
• means for indicating when the lock is in the lock position, wherein the means for indicating when the lock is in the lock position comprises a switch arranged to be activated by the lock in the lock position and a ball located between the lock and the switch the lock and the ball being configured such that as the lock moves into the lock position it pushes against the ball to engage with and activate the switch.