1. A fault detection and isolation apparatus for detecting and isolating faults in a helicopter comprising: an interface coupled to at least one helicopter subsystem and a processor, wherein said interface is a stand-alone module and comprises means for transferring data between the helicopter subsystem and the processor, and wherein the interface comprises a character conversion module comprising means for converting characters transferred between the helicopter subsystem and the processor, a data conversion module comprising means for converting data transferred between the helicopter subsystem and the processor and a format conversion module comprising means for converting a format of data transferred between the helicopter subsystem and the processor; wherein the processor includes a memory having software instructions embodied thereon for a test program sequence adapted to cause the processor to perform the steps of: identifying at least one subsystem of the apparatus for testing; generating a test sequence defining an order of testing of the at least one subsystem identified for testing and an order of individual tests to be performed on each subsystem identified for testing; skipping subsystem tests from a previous test program sequence that have been successfully completed within a predetermined period of time prior to beginning another test program sequence, wherein skipping is performed when a variable is a first state; generating periodic built-in-test commands; generating interface test commands; generating initiated built-in-test commands; generating manual test prompts receiving test result data from a periodic built-in-test, an interface test, an initiated built-in-test and a manual test; processing the test result data, wherein processing test result data comprises conversion of built-in-test codes from numeric values into text messages; detecting and isolating any faults to one or more candidate components associated with the detected faults; and storing a result of the detecting and isolating in a database, wherein the processor detects and isolates faults in the helicopter.