The extensive brown stains on the fuselages of the US Navy's F-35C stealth fighters

Contact with salt water has always been a source of problems for the maintenance of naval aircraft.

The US Navy shows two of its F-35C fighters with a curious mirror coating
The spectacular display of an F-35C, the largest and heaviest version of this fighter

These aircraft suffer the effects of corrosion to a greater extent than land-based fighters, with the exception of those based at coastal bases. However, some aircraft suffer the effects of contact with the sea more acutely than others: this is the case with the F-35C, the naval version of Lockheed Martin's stealth fighter for the US Navy's large CATOBAR aircraft carriers.

The first images of some F-35Cs looking shabby after extended deployments at sea began to emerge in 2021, despite the US Navy's efforts to openly display these aircraft. This photo was taken on December 13, 2021 (and published two days later) on the flight deck of the aircraft carrier USS Carl Vinson (CVN 70) while cruising in the Indian Ocean. The aircraft belongs to Strike Fighter Squadron (VFA) 147 "Argonauts" and showed a large brown patch on its upper body and smaller patches on the port side of the cockpit.

A few weeks later, on January 19, 2022, the U.S. Navy released this photo of three F-35Cs from VFA-147 aboard the USS Carl Vinson, an image taken four days earlier. It was a highly discussed photo on social media due to the brown stains the aircraft displayed on their backs and wings. It should be noted that the F-35C is coated with a radar-absorbent material (RAM) whose composition is secret, although iron is believed to be one of its components.

Unlike the F-35Cs, other aircraft, such as these two Super Hornets (the F/A-18E is from Strike Fighter Squadron (VFA) 192 "Golden Dragons" and the F/A-18F is from Strike Fighter Squadron (VFA) 2 "Bounty Hunters") that were photographed on January 15, 2022, on the same aircraft carrier, did not show these brown spots or any rust, despite being older aircraft. It should be noted that the problem continues. The photos you can see below were taken in 2025, and the most recent are from this July, also aboard the USS Carl Vinson.

Regarding the potential for this to affect the aircraft’s radar signature, Lockheed Martin claimed to have conducted tests simulating 600 flight hours of military aircraft operations in March 2008, noting: "RCS [radar cross section] measurements taken after the damage showed that the stealthy signature remained intact."It should be noted, however, that these tests were conducted before an F-35 ever embarked on an aircraft carrier.

On May 8, 2025, the F-35 Joint Program Office (JPO) acknowledged discoloration on F-35C airframes as an effect of long-range deployments aboard aircraft carriers, noting:

"Much of what the public sees as damage, such as the discoloration on jets returning from deployment, does not represent a degraded aircraft. During shipboard deployments, jets often experience coating discoloration due to the harsh maritime environment. Contributing factors include frequent exposure to sea water, contamination from grease, oil, and other fluids, as well as close proximity to jet blast and rotor wash.

While it may look severe, these marks do not indicate a loss of coating integrity nor stealth performance. The discoloration is limited to the coating and does not affect the structure of the aircraft."

The JPO notes that "has developed and introduced a new aircraft coating designed to significantly reduce or eliminate discoloration, enhance durability, and extend the coating’s service life. Over the coming years, this new coating will be applied to fielded aircraft as part of routine maintenance—similar to how coatings are restored on commercial and military jets. It will provide improved protection against operational wear and is part of a broader series of upgrades that support the program’s long-term, adaptive sustainability strategy."

The JPO also acknowledged how corrosion can affect the F-35C’s coating: "Corrosion doesn't come with flashing alarms or immediate system failures—it works quietly and gradually, often concealed beneath coatings or hidden within seams, joints, and fasteners. The F-35’s complex airframe, made from a blend of aluminum, titanium, and carbon composites, offers immense performance benefits but also introduces the risk of galvanic corrosion when these dissimilar metals interact in humid, salty environments."

While the JPO has implemented measures to combat corrosion, it has also acknowledged the following: "This was not always the case. For several years, the F-35 JPO operated without a fully developed corrosion management framework. This left field maintainers and depot crews playing "catch-up" as the fleet matured. Today, these teams, supported by a growing base of engineers and other experts, are bringing every jet up to standard and improved supply chain of consumables, ensuring long-term readiness and mission capability."

Obviously, new technologies always bring new challenges and new problems. In fact, the development process of a fighter aircraft never ends when it begins its operational life; rather, it is developed to solve unforeseen problems as they arise. The F-35 was not going to be an exceptional case, but what distinguishes it is that it is a sum of technological advances that has represented a great leap forward in military aviation.

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Photos: U.S. Navy.