DOD Needs to Monitor and Assess Corrective Actions Resulting from Its Corrosion Study of the F-35 Joint Strike Fighter
(Source: Government Accountability Office; issued Dec. 16, 2010)
This report was undertaken because the House Armed Services Committee expressed concerns that the lessons learned regarding the prevention and management of corrosion in the F-22 Raptor had not been fully applied to the development and acquisition of the F-35 Joint Strike Fighter.
While it examines in stultifying administrative detail how various reports and agencies interacted on the F-22 and F-35 corrosion issue, the report also makes very interesting revelations on this very subject, but in a surprisingly low-key fashion given some of the potential risks it uncovered on the F-25 Joint Strike Fighter program.
GAO says that “corrosion of the aluminum skin panels on the F-22 was first observed in spring 2005, less than 6 months after the Air Force first introduced the aircraft to a severe environment,” and two years later, “by October 2007, a total of 534 instances of corrosion were documented, and corrosion in the substructure was becoming prevalent.” GAO notes that the government is paying $228 million to make F-22 corrosion-related repairs and retrofits through 2016.”
GAO also notes that corrosion was caused, at least in part, by the fact that “Drain holes in the F-22 were found to be too small to enable good water drainage.”
The study also discusses potential future corrosion issues for the F-35 based on F-22 lessons learned and how these issues could be mitigated by making changes to the current plans for the F-35. For example,
–Environmental and occupational health concerns drove the initial use of a nonchromated primer on the F-22 that did not provide corrosion protection, and the program later switched to a chromated primer. The F-35 has also chosen to use a nonchromated primer that has never been tested on an aircraft in a corrosive operating environment.
snip—————–
— The corrosion study concluded that, if the F-22 program had accomplished testing earlier in the program, many of the corrosion problems could have been addressed at greatly reduced cost and the associated readiness issues avoided. If the F-35 conducts tests that are planned and conducted properly and in full, these tests could reveal many corrosion-susceptible areas on the aircraft.
Given its experience with corrosion-relate issued on the F-22, it is more than just surprising that Lockheed Martin should have adopted such a lackadaisical approach to corrosion risks on the F-35 program.
Full report on above defense aerospace site…
Suprised that they went for non chromated primers on Aluminium I guess maybe they thought the internal sections will not retain moisture for long enough to cause a problem or have enough moisture to be an issue (this is obviously in contect of all the HS&E issues with chromated paints and primers)…
The final statement “lackadaisical” although seems to give a emotional summary, there is no retort from LM as to why they chose the same primer system for the F-35 and infact if they had addressed the root cause for corrosion. From actually looking at the document it is evident that they have infact tried to address the root causes of the corrosion.
The DOD corrosion study identifies severalareas where the F-35 program has incorporated lessons learned from the F-22’s corrosion problems; examples follow.•The F-35 program is mitigating corrosion risk associated with conductive gap filler3and paint by using a gap filler that is less galvanically dissimilarfrom aluminum, an alternative to the conductive paint, a design with fewer seams that require gap filler, and more representative verification and qualification testing. Many of the F-22’s corrosion problems were linked to problems with gap filler materials and paint.•The F-35 program made organizational changes that integrated the personnel working within the corrosion materials and processes functional area andthe low-observable (i.e., stealth) functional area. In contrast, personnel working within these areas for the F-22 program were “stove-piped.”•The F-35 drainage design is significantly improved with more, adequately sized drain holes. Drain holes in the F-22 were found to be too small to enable good water drainage.
http://www.gao.gov/new.items/d11171r.pdf
And some good stuff here
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December 20, 2010 at 11:06 pm