​The ​​E​mergency Escape Sequencing System Tester (EESST) was designed to test the Emergency Escape Sequencing System (EESS) found on the F-22 aircraft. The EESST is the first in its class that provides the ability to check and detect all system faults in the escape system.  It was designed using Commercial Off The Shelf (COTS) components making it economically feasible in small quantities.

The EESST is an AC powered unit and is designed to safely permit detection and isolati​on of all system faults on the EESS.  The fail safe design, in addition to tester self-test, provides a wrap-around test capability for fault detection of test cables.  The EESST displays all faults to the operator to direct necessary maintenance, repair or disposition.  The EESST will not inadvertently fire or initiate any EESS component and it provides personnel safety during all tests.​

The EESST consists of all cables and connection jumpers necessary to perform a complete end-to-end check on the escape system, including continuity through the EED bridgewires.   

The EESST is equipped with a Built-in-Test (BIT), which provides better than 95% fault detection.  The BIT is initiated when power is first applied.  Only a successful BIT will allow the operator to continue with verification of the cable set to be used during flight line or maintenance testing.  An error code displayed during the cable self-test function will require corrective action and retest.