The GE AC44C6M is a diesel locomotive that was built by GE Transportation Systems, and rebuilt by GE, American Motive Power, Inc., and Norfolk Southern's Juniata and Roanoke Shops, starting in September 2015. The AC44C6M retains the 16-cylinder 7FDL-16 prime mover used in the core locomotive prior to rebuilding, but features GE's alternating current 5GEB13B7 traction motors. Externally, the rebuilds have received new wide-nosed cabs and a new front hood section of the same design as on the ES44AC, while retaining the underframe and engine and radiator compartments of the original Dash 9 units. Internally, AC44C6M features a new under-floor air conditioner, cab signals, LSL, DPU systems, PTC, and ECP braking ability, a significant technological improvement from the GE Dash 9-40C units. Norfolk Southern Railway is a significant operator of this model. All 124 of their remaining Dash 9-40C units, numbered 8764–8888 were rebuilt from 2015 to 2018 and numbered 4000-4124. The first six rebuilds received special paint schemes. NS 4000 and 4001 were painted in a blue, gold and white scheme and have been called "The Sonic Bonnets", due to their similarities to the eponymous character from Sonic the Hedgehog. NS 4002 and 4003 were painted in black, tuscan red, gray, and white scheme, while NS 4004 and 4005 were painted in black, blue, gray, and white scheme. The tuscan and blue "manes" on these four units are indicative of their rebuilding at the Roanoke and Juniata locomotive shops respectively. All of these units have DC to AC Waveform lettering underneath the cab windows. In August 2017, NS made an agreement with GE for rebuilding of 500 Dash 9-44CW Locomotives into AC44C6M from 2018-2022, with 100 units to be rebuilt every year, 50 by GE and 50 by NS at Juniata and Roanoke Shops. One Dash 9 locomotive, 8946 was rebuilt using different electrical components by CAF USA. This unit was numbered 8520 and designated as AC44C6CF. By 2020, rebuilds numbered up to 4399 were completed. In October 2017, Canadian Pacific Railway started a similar program with their older AC4400CW fleet. They refer to these rebuilt units as AC44CWMs. Union Pacific Railroad signed an agreement for over 1,000 AC4460CW's to be converted into AC44C6M's, though they will be designated "C44ACMs" by Union Pacific. This agreement extends through 2033, with 175 units being rebuilt every year. CSX Transportation has rebuilt a small portion of their AC4400CW's into CM44AC's and CM44AH's.
Operators
Accidents
On April 15, 2017, NS AC44C6M 4001 along with SD70ACe 1036 and twenty hopper cars derailed in Bratton Township, Pennsylvania on Norfolk Southern's Pittsburgh Line. The locomotive was leading NS 593, an empty coal train returning to Shire Oaks, Pennsylvania. There were no severe injuries related to the derailment, and the accident was unrelated to the locomotive model. The unit, one of the two "Sonic Bonnets," was brought to Altoona Works for repair. In early 2020, 4001 was released from Altoona and is currently back in service, as is SD70ACe 1036, which awaited a new cab installation.
