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The Navy and Marine Corps began planning Service Life Extension measures for the F/A18Cs and Ds a full decade ago. A 2001 statement estimated that 355 legacy Hornets would require a life extension to meet demand until 2020.32 At that time, the Service Life Extension measure of primary concern for extending the airframe's useful life was the replacement of the aircraft's center barrel. This process began in 1999.
The Center Barrel Replacement Plus (CBR+) modification is a process by which the aircraft is taken apart in order to remove and replace the central load bearing part of the aircraft, which will extend the service life of the aircraft significantly.33 The center barrel is centrally located within the airframe, where the main landing gear and wings attach to the aircraft. Replacing the part is a time consuming and costly process- costing approximately 2.5 million dollars per aircraft.34 lhe fix is for aircraft approaching the end of usable wing root fatigue life expended, which is an engineering metric that measures aggregate material stress around certain parts of the airframe. The CBR+ program is expected to continue through 2016.35
The process of extending the flight life of the Hornet through specific processes at the squadron level can be traced to 27 June 2004 with the introduction of the Service Life Management Program from the Commander Naval Air Forces (CNAF) and the Deputy Commandant for Aviation (DC/Air) via naval message. The Service Life Management Program detailed in this message provided guidance to F/A-18 leadership and aircrew in the handling of operational and maintenance issues that could affect the wing root fatigue life and methods of tracking it accurately, along with attempting to explain the nature of the problem facing the Hornet community.36
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Esa sustitución de la sección central (CBR+) se demostró cara y laboriosa. Más o menos de $2,5 millones y unas 14.000 horas de trabajo por cada aparato: https://apps.dtic.mil/dtic/tr/fulltext/u2/a530536.pdf
Otros programas más económicos para extender la vida útil fueron los SLAP ("Service Life Assessment Program") de 2002 y SLEP ("Service Life Extension Program") de 2008.
Respecto a estos últimos, otro documento más reciente, de 2017: https://docs.house.gov/meetings/AS/AS25 ... 170328.pdf
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The F/A-18 A-D was designed for, and has achieved, a service life of 6,000 flight hours, performing as expected through its design life. Ongoing service life management efforts have extended its designed 6,000 flight hour service life to 8,000 flight hours; with select aircraft being extended possibly up to 10,000 flight hours. Continued investment in the Service Life Extension Program (SLEP), High Flight Hour (HFH) inspection program and Air Systems Support (i.e. Program Related Engineering and Program Related Logistics) will remain crucial to the flight hour extension strategy. In order to maintain warfighting relevancy in a changing threat environment, we will continue to procure and install advanced systems on selected F/A-18 A-D aircraft such as Digital Communication System Radios, Joint Helmet-Mounted Cueing Systems (JHMCS) with Night Vision Cueing and Display, High Order Language Mission Computers, ALR-67v3 radar warning receivers, ALQ-214v5 self-defense suite, Multi-Function Information Distribution System-Joint Tactical Radio System (MIDS-JTRS), APG-73 radar enhancements, Advanced Targeting Forward Looking Infrared (ATFLIR) upgrades, and LITENING targeting pods. While investing in warfighting upgrades, the Services are unable to improve the reliability of this rapidly aging airframe. While we may upgrade them and return the correct number to our flight lines, we are concerned that we will not be able to effectively train or fight these aircraft due to low reliability.
Based on inventory modeling, a portion of the existing inventory of 557 Navy and Marine Corps F/A-18 A-D aircraft will be available through the 2030s. The DoN will continue to meet Navy operational commitments with F/A-18 A-D until 2027 for active squadrons, 2030 for Marine Corps active and reserve squadrons and through 2034 for Navy reserve squadrons. Using the Structural Life Management Program, fleet managers monitor and maintain the health of the legacy F/A-18 A-D fleet through analyses of TACAIR inventories and the management of usage rates at the squadron level. 92 percent of the F/A-18 A-D fleet has over 6,000 flight hours and 24 percent (142 aircraft) have flown more than 8,000 flight hours. As of February 2017, the highest flight hour airframe has attained over 9,799 hours.
The F/A-18 A-D Service Life Assessment Program (SLAP) demonstrated the airframe can be flown beyond 8,000 hours and up to 10,000 hours with a combination of further inspections and airframe modifications via Engineering Change Proposals (ECPs) to maintain airworthiness certification. The inspection results to date have matched the SLAP data. Depot throughput of these jets is complicated by on-going discovery of corrosion which significantly increases unplanned work on the inducted airframes. Depot leadership has an aggressive plan to design and develop inspections and standard repair packages for corrosion-induced work to better manage depot workload and increase throughput.
The F/A-18 A-D SLEP effort has featured a phased approach since inception. HFH inspections are required to assess the material condition and airworthiness of aging F/A-18 A-D aircraft and meet resourcing requirements as aircraft reach 8,000 hours. The HFH suite continues to be revised as a result of on-going HFH inspections and SLEP analysis. As a result, F/A-18 A-D airframe inspections and ECPs have been developed and fielded for those components and airframe areas at high risk of fatigue and corrosion. These efforts have reduced risk in airworthiness and reduced service life extension turn-around time providing program trade space to mitigate Strike Fighter procurement delays. To date, 194 HFH inspections have been successfully completed with 113 HFH inspections currently in-work.
The Department is conducting SLEP/HFH inspections/repairs at seven locations: Naval Air Station (NAS) North Island, California; NAS Jacksonville, Florida; Cecil Field, Jacksonville, Florida; Marine Corps Air Station (MCAS) Miramar, California; MCAS Beaufort, South Carolina; NAS Oceana, Virginia; and in Montreal, Canada. While less complex SLEP modifications can be incorporated at all sites, major SLEP modifications are done concurrently with major depot events.
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