Thomas, S., "System Simplification Tools - An Airline Engineer's View of SST Reliability," SAE Technical Paper 620463, 1962, doi:10.4271/620463.
Despite the potential productivity of the System Simplification Tools (SST), poor reliability and maintainability can work economic hardship upon the airlines. The problem can be solved by a three-fold attack on systems design: make it simple; if complex, make it simple to trouble-shoot; and if potentially troublesome, make it easy to replace.The effect of relative simplicity can be illustrated by comparing refrigeration systems of contemporary jets. In service, SST system malfunctions must be simply diagnosed with capabilities included as part of the basic design. Replaceability must be insured with good accessibility coupled with great stress on modular design.