Learning Objective: Recognize the purpose and operation of a frangible escape system.

A frangible escape system is an explosively operated system that cuts an exit through the canopy directly over the head of each occupant. The S-3A canopy removal system is an example of this type system, and it employs shielded mild detonating cord (SMDC) in lieu of hot gas and flexible linear shaped charge (FLSC) in lieu of actuators found in other hot gas explosive systems. Normal entry and exit of the S-3A aircraft is through an entrance hatch vice a canopy, as in other ejection seat type of aircraft. Therefore, the S-3A canopy removal system is used primarily for emergency ground egress and water rescue. Normal seat ejection is through the canopy glass for the front seats and through the hatch glass for the rear seats. In both cases, exit is made without benefit of having the glass removed or cut because the seats are equipped with glass crashers. Breaker plates are installed on each canopy and hatch to assist the seat during ejection. A brief description of the frangible escape canopy system components is provided in the following paragraphs.