Israel recently suffered some unusual damage to eight of its F-16 jets when an unusual 5:30 AM flash flood, caused by half an hour of intense rainfall and two overflowing streams hit the F-16 airbase and flooded several low lying reinforced hangers, partially submerging eight aircraft.
At first, the potential damage was thought to be extensive and might cost $10 million dollars or more to repair. After a few days, it was found that only three of the jets suffered extensive water damage and the repair bill would be less than a million dollars in maintainer time and replacement parts.
The components most at risk are electronic ones that are installed to prevent any rainwater from reaching them. The IAF (Israeli Air Force) sought to keep the flood damage a secret but a photo of one of the jets with water nearly up to its cockpit canopy reached the Internet and forced a public admission of what had happened.
All the aircraft were back in flying condition within a week. The five least affected aircraft were back in service within a few days. If a flash flood was anticipated the aircraft could have been moved to higher ground and covered with tarps to avoid water damage. Flash floods are not unknown in southern Israel, where most of the rainfall each year comes in the “rainy season” that lasts from December to February. Sometimes weather forecasters can predict the possibility of flash floods but these are so rare that there is not enough data to base an accurate prediction on.
While aircraft are built to handle heavy rain, submersion in water, especially saltwater, can cause extensive damage. Aircraft that regularly operate from aircraft carriers are modified to limit the saltwater damage from waves that often break on the flight deck in bad weather. Submersion in any kind of water is a more serious matter. The most serious problem is water getting into electronics, which combat aircraft have a large quantity. There is also the problem of water getting into parts of the aircraft that normally stay dry even when the aircraft encounters heavy rain in flight or on the ground. Even jet engines normally suck in a lot of water when flying in the rain and so are well protected from water damage but can suffer water damage if submerged for any length of time. Even freshwater can cause long-term corrosion problems if it gets into portions of the aircraft protected from rainfall.
The heavy cost of freshwater submersion initially comes from the maintainer personnel having to take apart many components to check for water. Just using external test equipment to see if all components are operational is not sufficient because water getting into normally rain-proof equipment will, unless found and removed, remain there causing corrosion damage or eventually getting to water-sensitive electronics when the aircraft carries out combat maneuvers during training or combat. Jets are built to roll over in flight and generally move around a lot, enabling any remaining water to reach other water-sensitive components. A submerged combat aircraft is thus in danger of having many expensive components replaced. This is especially true if the submersion lasts more than a brief period. The submersion of the eight F-16s was discovered quickly and the aircraft towed out of the standing water. It was not surprising that maintenance officers initially thought the damage might be extensive and cost millions of dollars per aircraft to repair. After the disassembly and inspection began it was found that only three of the aircraft were thoroughly soaked and in need of expensive repairs.