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P-3 Service Life

In the mid-1990s, the Navy identified concerns with airframe corrosion on P-3C Orion aircraft and initiated the Service Life Assessment Program to identify and quantify service life extension requirements. In 2003, the Navy completed the Service Life Assessment Program and determined that all P-3C Orion aircraft required varying degrees of fatigue inspections and repairs at periodic intervals throughout their service lives.

In 2003 the US Navy decided to cut by one third its fleet of aging P-3C submarine hunting aircraft after engineering evaluations determined airframes had less life in them than expected. Following structural tests of the P-3C fleet conducted earlier in the year, Adm. Vern Clark, chief of naval operations, directed the Navy in August 2003 to quickly reduce its fleet of 228 land-based surveillance aircraft to 150.

The Navy initially undertook a three-tiered approach to address fatigue-critical areas on the P-3C Orion aircraft that included structural inspections. The first tier included structural inspection, including fatigue inspection, and any subsequent repairs necessary to ensure safety of flight until maintenance crews could perform more comprehensive maintenance. The second and third tiers included enhanced special structural inspections and special structural inspection kits to provide preemptive modification and replacement of critical airframe structural components to enable the airframe to reach its required service life. The Navys objective in performing this effort was to minimize the investment required to safely sustain the P-3C Orion fleet until it could field the P-8A Poseidon aircraft.

The P-3 Service Life Extension Program (SLEP), projected to begin Engineering Manufacturing Development in early 2002, extended the Operational Service Life (OSL) of aircraft inventory as necessary prior to MMA IOC. The P-3C and EP-3E aircraft inventory was experiencing significant airframe corrosion and additionally began to reach the end of its fatigue life beginning in 2002. The US Navy conducted a series of programs to sustain the P-3/EP-3E aircraft inventory until a follow-on platform can be fielded to meet the Broad Area Maritime and Littoral Armed Intelligence, Surveillance and Reconnaissance Capability requirement through the Multi-mission Maritime Aircraft (MMA) program.

The MMA program was directed to provide Initial Operational Capability (IOC) no later than 2015. The P-3 Sustained Readiness Program (SRP), begun in 1994 and intended to address aircraft inventory material condition, completed only 13 aircraft. The P-3 Service Life Assessment Program (SLAP), initiated in 1996, was designed to analytically and empirically determine P-3C and EP-3E fatigue life, evaluate improved materials and develop the fatigue related elements of the SLEP airframe kit.

The program objectives for P-3 SLEP were to (1) extend P-3C/EP-3E airframe fatigue life by one life-time (approximately 24,000 hrs), (2) upgrade aircraft material condition to enable full capture of extended airframe fatigue life, (3) improve aircraft reliability, maintainability and availability through upgrade of aircraft subsystems, and (4) minimize SLEP production variability while optimizing manufacturing efficiencies.

The P-3 SLEP performed the required non-recurring engineering (NRE) to design, manufacture and install all elements of the SLEP kit. P-3 SLEP will produce two Engineering Development Models (EDMs) and execute Low Rate Initial Production (LRIP). The first EDM aircraft was expected to incorporate all airframe elements of the SLEP kit while the second EDM aircraft will combine the airframe elements with electrical upgrades and other systems improvements. P-3 SLEP also conducted the NRE necessary to facilitate transition of SLEP to complete remanufacture of the P-3/EP-3E.

In December 2007, the Navy grounded 39 of 148 P-3C Orion aircraft as a result of ongoing fatigue life inspections, which revealed that the aft lower surface of the outer-wing (designated as Zone 5) experienced fatigue at higher levels than previously estimated.

In January 2008, the Chief of Naval Operations approved the P-3C Orion Recovery Plan, which included modifying the outer-wings structurally, to return grounded aircraft back to the fleet. This modification approach encompassed targeted Zone 5 modifications, which included limited replacement of outer-wing components, as well as the manufacturing and installation of new outer-wing assemblies. The Navy continues to evaluate P-3C Orion fatigue and material condition. While P-3C Orion fatigue remained a persistent risk, the Navy has inspection, repair, and modification efforts in place to sustain the P-3C Orion fleet until the P-8A Poseidon starts replacing the P-3C Orion in 2013.

The program manager planned to transition from the P-3C Orion to the P-8A Poseidon aircraft by decreasing the number of P-3C Orion aircraft to zero while increasing the inventory of the P-8A Poseidon to 117 aircraft by FY 2020.



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