Aging Aircraft: Cracks in USA’s F/A-18 fleet
In October 2008 a fleet-wide inspection program and limited grounding became necessary after aileron hinge cracks are discovered in some of the US Navy’s 630 or so F/A-18 A-D Hornet fighters. Discovery of new cracks in March 2010 led to a much wider grounding.
The USA’s is watching the average age of its fighter fleet rise, and will continue to do so even if all F-22s and F-35s envisioned in current Pentagon plans are purchased. The long saga of the USA’s F-15A-D fleet culminated in early retirement for a number of its aircraft. The A-10C re-winging program acquired added urgency with the revelation that wing cracks had been found in active aircraft. Now the US Navy’s long-serving F/A-18A-D Hornet fleet can be added to the list.
Events & Updates
“Headquarters Marine Corps – Aviation, who oversee the service’s aviation budget, were adamant the SLEP effort would go no further than the 9,000- to 10,000-hour extension… [Marine Corps spokesman Capt. Brian] Block told AOL Defense that the highest average flight time on any service F/A-18 Hornet is just over 8,500 hours. “Moreover, not a single F/A-18 Hornet in the Department of the Navy inventory has surpassed the 9,000 hour mark,” Block said… Block said that Marine Corps crews “are conducting routine maintenance at an accelerated pace due to higher utilization”… Maj. Gen. Jon Davis, commander of the 2nd Marine Corps Air Wing [said that] “You cannot keep it up forever.”
Feb 28/11: A Gannett Navy Times article details the efforts underway to keep the US Navy’s fleet of F/A-18 A-D Hornet fighters in service, until some of them can be replaced by F-35B/C jets.
The USN’s F/A-18 program manager, Capt. Mark Darrah, is quoted as saying that the Hornet fleet is averaging about 330 flight-hours per year, which means they’re consistently about 30% above planned usage. Many have now exceeded even their extended usage figure of 8,000 flight hours. Fortunately, their accident rate remains low.
Carrier Air Wing 7 commander Capt. Roy Kelley adds that the F/A-18E/F Super Hornet fleet is also burning through airframe hours, with 73 of the fleet 418 aircraft at over 3,000 hours – about half-way through their safe design lifetimes.
The Navy hopes to extend its Hornet airframes to 10,000 safe flight hours, up from the easier target of 8,600. Each plane costs about $15 million when put through the deep inspections and refurbishment program. It’s accompanied by detailed record-keeping, and a constant juggling act among the squadrons. Darrah says that NAVAIR/NAF’s quarterly modification review “literally makes the decisions every quarter on, bureau number by bureau number, what aircraft will be assigned to what units,” based heavily on flight hour and maintenance issues. Once on the carrier, that juggling continues. Networking has made flight data files compilable and accessible across the fleet, allowing for remote analysis by expert teams, and letting squadrons pick less demanding missions for high-hours airframes, in order to even out wear and tear.
Jan 6/11: As part of a plan detailing $150 billion in service cuts and funding shifts over the next 5 years, Defense Secretary Robert Gates states that he is placing the Marine Corps’ F-35B on the equivalent of a 2-year probation, extends the F-35 program’s development phase again to 2016, and cuts production of all models over the 2012-2016 time period.
In response, the Navy will add 41 Super Hornets, and perform service life extension work on another 150 F/A-18 A-D Hornets. Pentagon release re: overall plan | Full Gates speech and Gates/Mullen Q&A transcript | F-35 briefing hand-out [PDF] || Aviation Week | Fort Worth Star-Telegram’s Sky Talk blog.
June 24/10: Rear Adm. Mike Manazir, the US Navy’s acting chief of air warfare, says that keeping its oldest F/A-18 Hornets flying through 2020 will have to be the U.S. Navy’s main weapon against a decline in fighter numbers, while it waits for the F-35C. Defense News.
March 29/10: From The Florida Times-Union’s “Secondhand flight: Old planes revamped as Navy makes do” captures the 260 work-day process of refurbishing the Hornet fleet, and adds further background:
“The original F/A-18s, known as Hornets, are mainly at or beyond their expected life span, and even the newer Super Hornets are running into trouble with metal fatigue. Meanwhile, the F-35, the plane that’s expected to replace the older Hornets, is getting more expensive and taking longer than planned to come online… Dealing with the reality of an aging fleet – a situation recently thrown into sharp relief by the Navy’s need to ground 104 jets to check for cracks in their fuselage – has fallen on the shoulders of Fleet Readiness Center Southeast…”
March 12/10: U.S. Naval Air Systems Command grounds 104 U.S. Navy and Marine Corps F/A-18 A-D Hornet fighter jets, about 16% of the Navy/USMC Hornet fleet. The location was not specified, except to say that they were in a “high stress focus area” that engineers already knew about, and appears to be on the wings.
“Fleet Replacement” training squadrons have the lion’s share of the grounded aircraft, with 44. Another 28 are flying in Navy or USMC squadrons, 5 belong to the Navy’s Blue Angels aerobatic team, and the final 27 Hornets were already in maintenance. Squadrons have been ordered to perform a magnetic field inspection on jets included in the grounding, followed by visual wing inspections after every 100 hours of flight. Jets that cannot receive magnetic inspections will be limited to a maximum of 4gs during flight.
Dec 9/08: The crash of an F/A-18D Hornet in San Diego appears to be the result of engine failure rather than structural failure, though investigations will continue. Despite the pilot’s best attempts to steer the stricken jet away from populated areas, it crashed into several homes and killed 4 people. San Diego Union Tribune | The Times.
Nov 9/08: Inspections find aileron hinge cracks that result in the grounding of 10 F/A-18 Hornets, 2 of which were deployed overseas. Another 20 planes will remain in service pending repairs, but they will be under flight restrictions. Stars and Stripes.
Oct 23/08: The US Navy issues a fleet-wide inspection bulletin, after a routine post-flight maintenance inspection finds a crack in an aileron hinge, and inspections of Hornets from various squadrons find similar cracks on 14 other planes. The tests take about 15 days, and priority was given to the 112 deployed Hornets within the 636-plane fleet.
Aileron hinge replacement requires service back at a depot, however, and outer wing panel replacement is a 4-day exercise. Unlike the newer F/A-18 E/F super Hornets, the Hornets under scrutiny have 5,000 – 7,500 light hours on their airframes, in an aircraft initially designed for 6,000 hours. Life extension programs have extended that limit to 8,000 hours, and structural improvements that include center barrel replacements are expected to extend that to 10,000 hours.
Nevertheless, unforeseen problems can and do arise, as this incident illustrates. They will need to be manageable, because the US Navy already projects a shortage of strike aircraft from 2015-2025, due to forced Hornet retirements and slower replacement via Super Hornet and F-35C deliveries. 2017 is currently pegged as the nadir, with a shortage of 69 aircraft. Aero News Network | Flight International | CNN | Virginian-Pilot.