Variants <DL><DT>Chinook HC1</DT><DD>New-build aircraft for the RAF based on the CH-47C, 41 built.</DD><DT>Chinook HC1B</DT><DD>Modification of the 41 HC1s with metal rotor blades, survivors converted to HC2.</DD><DT>Chinook HC2</DT><DD>Conversion by Boeing of 32 surviving HC1Bs to CH-47D standard, and 3 new build-aircraft</DD><DT>Chinook HC2A</DT><DD>Similar to the HC2 with strengthened fuselage using milled structure manufacturing techniques, 6 built.</DD><DT>Chinook HC3</DT><DD>Special forces variant based on the CH-47SD, 8 built.</DD><DT>Chinook HC4/HC4A</DT><DD>HC2/HC2A aircraft with upgraded engines and avionics under
Project Julius. 46 conversions planned.</DD><DT>Chinook HC5</DT><DD>HC3 aircraft with upgraded avionics under
Project Julius.</DD><DT>Chinook HC6</DT><DD>New-build Chinooks announced in 2009, expected to be delivered beginning in 2014. Originally 24, later reduced to 14 aircraft
[60] (12 helicopters plus 2 attrition replacements).</DD></DL>