1. heat exchanger, new test section, new main balance 1954 New fiberglass fan blades installed 1959 Fan diffuser deflectors installed 1962 Bellmouth honeycomb installed 1963 Third cornerair exchanger modifications (matched velocity) 1970 Fan diffuser deflectors replaced with vorteflectors 1970 Fillet flaps installed 1976 Third cornerair exchanger modifications and screen removal 1978 ALDS computing systeminstalled 1979 3-mesh screen added tothe honeycomb 1992 AALDS computingsysteminstalled 1996 Replaced the drive motor and controls 2001 Tunnel circuit upgrade: new heat exchanger, dehumidification system,
2. 1997 1998 1999 2000 2001