Published in Aerospace Testing International
New commercial and military aircraft production is preceded by extensive flight tests to prove the performance of the aircraft and its sub-systems. The Developmental Test (DT) and Operational Test (OT) stages are conducted via a suite of sensors installed to measure physical parameters and monitor the command and response messages between the sub-systems. Later, during operation, the aircraft may also need to collect data from onboard sensors. On-board recorders are used to capture multiple hours of data from the Flight Test Instrumentation (FTI), sensor suite, and aircraft avionics buses for post-test or post-flight download and analysis on the ground.
DT doesn't always require the aircraft's full suite of sensors and other permanently fitted sub-systems, which means there is usually adequate space for mounting the FTI, including the recorders. In contrast, during OT and operations, the complement of permanently fitted sensors and sub-systems will be installed, severely limiting the amount of space and mounting locations available for the FTI and on-board data recorders.