Hydraulically actuated mechanical lock assembly

A hydraulically actuated mechanical lock assembly of a thrust reverser system for an aircraft, the assembly comprising:

• a lock actuator consisting of:
• a lock housing having a first end chamber (A) and a second end chamber (B);
• a first return line connected between a high pressure fluid return chamber and the first end chamber (A);
• a control line connected to the second end chamber (B);
• a second return line connected between the first end chamber (A) and the second end chamber (B);
• a moveable element mounted in the lock housing;
• and
• a lock valve arranged in the fluid flow between the housing and the control line to control the flow of hydraulic fluid into the first end chamber (A) and the second end chamber (B);
• wherein when the lock assembly is commanded to be in a lock position, the lock valve is positioned to fluidly connect the first end chamber (A) and the second end chamber (B) via the control line and the second return line, and the housing is arranged to receive hydraulic fluid at the first end chamber (A) from the high pressure fluid return chamber via the first return line, and when the lock assembly is commanded to be in an unlock position, the lock valve is positioned to connect the second end chamber (B) to a supply of high pressure fluid via the control line, such that high pressure fluid is supplied from the supply to the second end chamber (B) via the control line to cause the movable member into the first end chamber (A);
• and whereby when the lock assembly is in the lock position, the first end chamber (A) remains fluidly connected to the high pressure fluid return chamber via the first return line even if the second return line ruptures;
• wherein the second end chamber B is connected to the high pressure fluid return chamber via the first end chamber A such that fluid flow between the high pressure fluid return chamber and the second end chamber must pass through the first end chamber.