How long can an aircraft be immersed in seawater before irreparable damage is done? By ‘irreparable’ I mean ‘beyond reasonable repair’, since virtually anything can be repaired given enough money.
This is a hard question Johnny. I assume you know about some of the extreme but successful restoration attempts like Glacier Girl. Glacier girl was a P-38 that was abandoned after a forced landing in Greenland during WWII. It was found in 1992 under 260 feet on ice, melted out, and brought up for restoration. In 2002, it flew again and it about 80% original.
Now I know that Glacier Girl wasn’t in salt water but that at least gives us some idea about what people will go to in order to get a rare bird flying again. I know that there have been some long-term salvages and restorations from fresh water. I read about one a few days ago and it referenced the dark, cold water in some northern lake being kind to the aircraft.
I don’t know about the salt water part though. The aluminum airframe may not be so bad but I don’t know about the engine and other things.
Johnny, I think this is something of a special case question. There isn’t going to be a general set of conditions for a “Yes, that’s worth recovering to flight status.”
One must know how the aircraft got into the water, in the first place. If it is due to any kind of water crash at speed, I think that the corrosion factors aren’t going to matter - it’s been so clobbered by the impact, it’s not going to be easily repairable. Similarly, I doubt anyone’s going to look at the restoration of a common model Cessna, simply because the rarity of the bird involved isn’t going to justify the kind of expenses that the 'Glacier Girl’s recovery involved. (Which was done, and justified, for two reasons: They had good reason to believe that in the low temperature/low oxygen environment of being covered by snow, the bird wasn’t facing major corrosion issues; and P-38’s are incredibly rare.)
Similarly, from what I recall, the lake recovery that I think Shagnasty is talking about isn’t going after recovering the plane to flyable condition, just to museum condition. It’ll look real nice, but no one will be crazy enough to try to fly it, IOW.
Personally, my gut reaction is that unless there’s a strong motivator, like the rarity of flyable P-38s, or some special historical signifigance to one specific aircraft, once a bird has been immersed in salt water, it’s not worth reconditioning.
For example, this video shows the recovery of a Robinson R-22. The aircraft doesn’t look that bad.
This R-44 was submerged for four hours. I suspect it was an autorotation into the ocean, as it looks intact.
There’s really not that much to a helicopter. Lots of moving parts, but the airframe (at least in the examples I’ve found) is just welded tubing covered with aluminum and fiberglass, plus a structural tail boom. Obviously it would need a complete overhaul, but that’s a normal part of owning a helicopter. (Even tail booms have life limits – though I’ll be most civilian helicopters never reach them.) So what’s the deal? If it sinks, it’s junk? Or would helicopters such as in the examples likely fly again? (I’m asking about helicopters because you’re right: a fixed-wing aircraft would likely hit at speed.)
And in case anyone is wondering, I’m not thinking of buying a damaged aircraft – rotary wing or fixed wing. Just curious whether saltwater immersion is a death sentence for airframes.
I’ll admit, I hadn’t even thought about rotary wing craft.
I still suspect that four hours immersion, even followed by five fresh water rinses, is going to mean that all the electronic parts need replacing, and the tighter tolerance engineparts will at least need a thorough inspection. I agree that the airframe of the R-44 looks good, and may be just as good as it looks, but that’s only part of the cost of an aircraft. I can’t offer figures to go with it, but my suspicion is that the savings on the used airframe may not cover the cost of replacing the guts.
A really long time if it is a Catalina*… (until the paint comes off and the saltwater destroys the hull)
Brian
- or mallard, or albatross, or …
What is safe and what the FAA will sign off on are two different things.
Depends on your local FAA guys. Call the local safety officer at the nearest FAA station or call OKC and just ask.
Call PHI in Texas and ask the head of maintenance what their policy is.
Might get an answer that means something that way.
YMMV.