The Centro Tecnico Aeroespacial - CTA developed in 1987 an in-flight refuelling (IFR) equipment for the AT-26s. The aircraft chosen as the prototype was the FAB 4600, belonging to the /VI GAV; it did several successful tankings from an KC-130H Hercules.
Project REVO (IFR in Portuguese) was executed in two phases, and consisted of designing, developing and testing an IFR system for the AT-26s, and was carried out by the Instituto de Pesquisas e Desenvolvimento - IPD from CTA.
In the first phase, the necessary modifications to the AT-26 airframe to install the IFR probe (of the same model used in the Northrop F-5E) were assessed, and after the installation of the probe it was flight evaluated, and "dry" contacts with an KC-103H were also carried out. It was found that the installation did not alter substantially the flight characteristics of the standard.
In the second phase of the project, the fuel system was modified to enable the AT-26 to receive fuel from the tanker. Both ground and flying "wet' contacts were succesfully made.
With the cancellation of the program, the AT-26 FAB 4600 was the only Xavante modified to IFR configuration. To see photos of this aircraft and a lot of old photos of other aircraft of the Brazilian Air Force, visit the link below:
http://aviacaoemfloripa.blogspot.com.br/2011/07/fundo-do-bau-memoria-aeronautica-da_18.html