None, the MRA role is carried out by the USN using the P-3 Orion. The P-3 was derived from the
Electra, which entered service around the same time as the Comet. The difference being the USN is replacing their P-3s with new build P-8 Poseidons, based on the 737, by about 2013.
The ongoing P-3C airframe sustainment program inspects and repairs center and outer wings while reducing Fleet inventory to the mandated 130 aircraft by 2010. The P-3C fleet has experienced significant fatigue degradation over its operational life as quantified through the Service Life Assessment Program (SLAP). The Navy has instituted special structural inspections programs and replacement kits to refurbish aircraft structures to sustain airframe life. The 12 active patrol squadrons (down from 24 in 1991) operate P-3C AIP and Update III configured aircraft. Other P-3 variants still in service include one VP-3A executive transport, four NP-3C and eight NP-3D research and development, testing and evaluation and oceanographic survey aircraft. Numerous countries also fly the P-3 Orion, making it one of the more prevalent Navy aircraft available for foreign military sales and support.