The USAF ordered 12 Vertol 107/II (XCH-49) helicopters for Texas Tower and missile silo support in early 1962, but cancelled th contrac tin Sep 62 when it became clear that Vertol could not meet the stringent delivery schedule. The USAF ordered the Sikorsky S-61R ( CH-3C
) instead. As an interim measure, the USAF borrowed three SH-3A
s from the Navy. Sikorsky modified three SH-3As into CH-3As by removing all ASW equipment and adding USAF radios and avionics. The serials involved were 149009, 149011, & 149012. The Air Force re-serialled these as 62-12571/73. Eventually, the Air Force ordered three more custom built S-61As as CH-3Bs serialled 62-12574/76. The first three CH-3As were upgraded to CH-3B standard. All were eventually placed in storage at MASDC, Davis-Monthan AFB during the mid 1970s. CH-3B 62-12575 was pulled from storage and reworked for the US Navy as an SH-3H and served with the Sea King Replacement Air Group (RAG) HS-10.