The Pentagon has added $12 million to its 2014 spending plans to equip its Boeing 737-based C-40s with a fuel-tank inerting system, the same upgrade mandated for U.S. operators of Boeing commercial aircraft.

The 2013 spending plan anticipated spending about $1 million more than fiscal 2014-17 for various required modifications. In the fiscal 2014 request, the figure jumped $6.1 million for 2014 and another $6 million for the outyear estimates through fiscal 2017.

In procurement parlance, the project to retrofit a fuel tank inerting system (FTIS) on the C-40 fleet is a “new start,” something Pentagon planners have been avoiding as budget pressures have forced tough choices. The most recently procured C-40C had FTIS. The Air Force plans to modify 10 remaining C-40B/Cs, which are used for official transport.

An FAA rule, finalized in July 2008, set deadlines in 2014 and 2017 for commercial operators to complete the retrofits. The Air Force’s 2014 budget justification document says the service maintains FAA certification on its fleet and cites the same deadline for the inerting system that commercial carriers must meet: 50% completed by 2015 and the remainder by the end of 2017.

Last July, FAA proposed a $13.57 million civil fine against Boeing for missing the Dec. 27, 2010, deadline for submitting for FAA approval the service instructions for its FTIS.

Honeywell designed the system for Boeing. The technology uses an onboard inert gas generation system (OBIGGS), which separates oxygen from engine bleed air and delivers the resulting nitrogen-rich air to continuously fill the center tank ullage space. The presence of the inert gas and absence of oxygen reduces the likelihood of an explosion or fire. The systems also are generically known by the terms flammability reduction means or flammability reduction system.

Hamilton Sundstrand supplied the inerting system for Airbus aircraft affected by the FAA rule, and a similar rule from the European Aviation Safety Agency.