Brazil is banking on seizing markets that use the C-130 Hercules and are looking to replace the workhorse aircraft with an economical tactical transport and refueling plane.
The KC-390 is touted as a cheaper alternative to not only the Hercules but other rivals from Europe, Russia and Asian manufacturers.
At about $50 million the KC-390 competes against C-130J at about $62 million.
Cobham said its auxiliary fuselage fuel tank will enable the aircraft's core mission capabilities, including increased range for search and rescue operations and maximized fuel offload for air-to-air refueling.
The Brazilian air force is the launch customer for the KC-390, which is to enter service in 2015. Embraer expects to secure significant additional orders for the KC-390 from export customers.
Embraer Vice President Luis Carlos Aguilar estimated about 695 military transport aircraft in the world will need to be replaced during the next decade, offering a multibillion-dollar potential market for alternative suppliers.
Cobham Mission Equipment Vice President Iain Gibson said: "Cobham is delighted with its selection by Embraer and the Brazilian air force to supply the Auxiliary Fuselage Fuel Tank for the KC-390. This award consolidates our position on the aircraft, building on the earlier selection of our wing aerial refueling pods, nose radome and aerial refueling probe."
Cobham Mission Equipment is also a systems solution provider for bomb disposal robot technology, unmanned ground systems and robots serving international homeland security and military markets, with more than 700 systems delivered to 55 countries.
Cobham says it has delivered more than 1 million tanks to customers around the world and will supply Embraer with a state-of-the-art tank system optimized for weight, while still providing for quick removal and re-installation.
In 2011, Embraer awarded Cobham a $60 million contract to develop and supply the KC-390 program with wing aerial refueling pods. Cobham has also been selected to provide the aircraft with aerial refueling probes and to design and manufacture the aircraft's nose radomes.
Cobham has headquarters in Britain and employs more than 10,000 people worldwide.
Embraer Defense and Security holds a strategic role in Brazil's multibillion-dollar defense development, with a portfolio that includes the turboprop Super Tucano light attack aircraft, intelligence, surveillance and reconnaissance products and services, jets for transporting government officials, aviation training and operations support and other related operations.