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Old 16th Mar 2017, 16:48   #1 (permalink)

Dog Tired
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Sea-plane corrosion

How do you protect the aircraft from salt water?
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Old 16th Mar 2017, 16:58   #2 (permalink)
 
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Paint and regular fresh water cleaning.
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Old 17th Mar 2017, 11:09   #3 (permalink)
 
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The ground crew of an SAR helicopter I flew with many years ago for a TV event sprayed the helicopter all over with something after the sortie. I can't remember the name of the substance now but it was a WD40 equivalent - water dispersing and corrosion protection fluid.
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Old 17th Mar 2017, 13:09   #4 (permalink)
 
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Salt-X and SaltAway are just two commercial, salt-removing products for marine use. There are no doubt more. Whether these products are approved for use on airframes is not something that I can advise.
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Old 17th Mar 2017, 21:33   #5 (permalink)
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but it was a WD40 equivalent

Careful. It is not generally understood outside the engineering fraternity that such fluids can have adverse effects if sprayed about without engineering consideration and approval.

In particular, many fixing items on a structure (eg higher strength nut/washer/bolt assemblies) rely on torque settings to achieve their intended purpose. It can transpire that some of these water dispersants may have an adverse effect on the torque values of a structural fitting with undesirable structural consequences.

Message - if it's not approved in the relevant maintenance documents such use needs to be referred back to the OEM or DERs for approval.
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Old 18th Mar 2017, 00:07   #6 (permalink)
 
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John T, thanks for your explanation. Would ACF-50 or Corrosion-X, both approved for use on aircraft, also affect torque values?
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Old 18th Mar 2017, 00:12   #7 (permalink)
 
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The Navy used some fluid which we pilots called WD40. Whether that's what it was, or some other propriety fluid have no idea, as that was all in the hands of the maintenance troops.
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Old 18th Mar 2017, 00:31   #8 (permalink)
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ACF-50 or Corrosion-X

Do not use WD40 it cracks plastics over time WD 40 is a lubricant.
When the inside of a connector is sprayed with WD 40 and reconnected contacts will have a higher resistances, its like having oil on your contacts.

Spray ACF50 in your connector and there will be very little change in the resistances of the connection .

Protecting the inside of a connector should be don with DC 4 compound , the outside of a Cannon plug can be protected with ACF 50.
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Old 18th Mar 2017, 09:01   #9 (permalink)
 
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Quote:
Originally Posted by chw View Post
Do not use WD40 it cracks plastics over time WD 40 is a lubricant.
WD-40 isn't, and is not intended to be, a lubricant. Its intended purpose is water displacement, hence the name,
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Old 18th Mar 2017, 10:13   #10 (permalink)
 
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Quote:
WD-40 isn't, and is not intended to be, a lubricant
What the manufacturer says.
Quote:
While the “W-D” in WD-40 stands for Water Displacement, WD-40 Multi-Use Product is a unique, special blend of lubricants. The product’s formulation also contains anti-corrosion agents and ingredients for penetration, water displacement and soil removal.

While WD-40 Multi-Use Product it is not a grease, it is formulated with strong lubricating oils and other ingredients, and is a terrific product to use for bike maintenance. It does not attract dirt or moisture to metal surfaces – just be sure to wipe off any excess WD-40 Multi-Use Product before riding.

For long-term lubrication and other specialized bicycle maintenance needs, check out WD-40 BIKE. Developed specifically for cyclists and mechanics, this high-performance line of bicycle care products is sure to become a mainstay in the toolboxes of bike mechanics for decades.
Due to its low viscosity, WD-40 is not always the preferred oil for certain tasks. Applications that require higher viscosity oils may use motor oils. Those requiring a mid-range oil could use honing oil.

Originally designed to be used by Convair to protect the outer skin and, more importantly, the paper-thin balloon tanks of the Atlas missile from rust and corrosion. These stainless steel fuel tanks were so fragile that when empty they had to be kept inflated with nitrogen to prevent them from collapsing. WD-40 was later found to have many household uses and was made available to consumers in San Diego in 1958.
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Old 18th Mar 2017, 23:41   #11 (permalink)
 
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WD40 should not be used on aircraft. It will eventually cause corrosion.

Instead, use LPS1, 2 or 3 from LPS Labs.
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Old 19th Mar 2017, 11:18   #12 (permalink)
 
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A short summary on corrosion control based upon my own experience and schooling:

For effective corrosion protection, any accumulated salt should be removed as soon as practical following flight. This is best accomplished by flushing all exterior areas of the aircraft with clear fresh water. Protect air data probes and other water-sensitive components I/A/W the MM instructions regarding aircraft washing prior to flushing. Dry the aircraft. That takes care of removing salt from the aircraft exterior.

The importance of salt removal cannot be overstated. In aluminum skinned aircraft left with salt on the metallic surfaces and fasteners, salty water is an almost ideal electrolyte for several types of electrolytic corrosion, particularly where dissimilar metals interface and between faying surfaces like lap joints. (remember the Aloha Airlines pop-top 737?) Corrosion cells can grow very quickly and cause severe damage in a relatively short time.

Removal of salts from the equation drastically reduces the speed at which corrosion oxidizes the materials. Nothing stops corrosion entirely. Even the most vigilant care and the most advanced protection materials cannot stop it entirely. At best, the rate can be slowed to an acceptable level. NASA, the US Navy and numerous other agencies and universities around the globe have published scads of scientific studies while manufacturers have invested heavily in developing materials and practices to reduce the impact of corrosion on the useful life of aircraft structures.

One critical aspect of corrosion control is regular inspection of protective surfaces like the paint and any sealing compounds. This applies to airframes and engines as well as all their respective components likely to be exposed to salt water incursion. Any breaches of protective surfaces should be inspected for developing corrosion and repaired in a timely manner before restoring the protective surface to a state of effectiveness.

Turbine engines may require more frequent compressor washes, depending on exposure level. Seaplanes operating on saltwater and certain offshore helicopter ops may require hours of corrosion mitigation work each day between rinsing, inspection and any necessary protective compound application. The bottom line is that salt removal and protection application when operating in a saltwater environment is a daily activity in most conscientiously run operations. The frequency of inspection and lubrication activities on the whole aircraft and most of it's components must be increased according the frequency and intensity of salt exposure. The inspection schedule approved for the airplane becomes entirely insufficient in a high salts operating environment.

The application of corrosion protective compounds is widely considered to be most effective when applied to clean, dry and salt-free surfaces. But that has never stopped operators from looking for shortcuts! And it usually costs them much more in due time. Use only manufacturer approved protective materials, or risk doing more damage than you prevent.

I just had to comment on this subject too.
Don't use petroleum based products to clean canon-type electrical plug connectors without manufacturer approval. Some of them eat the sealing and/or insulating material inside the plug. There are specifically designed and approved products for cleaning the connector pins and receptacles, both mechanical and chemical.

Last edited by westhawk; 19th Mar 2017 at 19:32. Reason: correcting a word usage error (fatigue can be as bad as alcohol impairment!)
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Old 19th Mar 2017, 11:25   #13 (permalink)

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Excellent, thank you all.

I posted the question thinking of the light float aircraft that can be hired at Vancouver but I can't think they go to all that trouble to clean them every day, can they?
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Old 19th Mar 2017, 11:56   #14 (permalink)

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I flew sea planes in salt water.
Corrosion is a big deal. We took it out every day to rinse and service it.
With heavy spray 16 times a day from take offs and landings salt get everywhere, including places you cannot inspect and rinse daily.
Made me nervous to see a flap bracket get thinner every day.
Those planes were made for fresh water lakes in Canada, not salty Carribean waters.
A few years after I left the company the same plane came apart killing everybody.
DHC-6-300. RIP
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Old 20th Mar 2017, 06:19   #15 (permalink)
 
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Though I can't recall the exact details another sea-based aircraft that crashed...Corrosion

Chalk Air (had to Google it
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Old 20th Mar 2017, 08:20   #16 (permalink)
 
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Chalk's Ocean Airways Flight 101 crash (a Grumman Mallard G-73T) was not caused specifically by corrosion, but by a crack in a stringer in the wing that was never repaired properly. The crack propagated to total wing separation in flight.

However, after the remainder of Chalk's Grumman Mallard aircraft were grounded, unacceptable corrosion was found in a number of their grounded aircraft. Sub-standard repairs on the aircraft were also noted.

Chalk's Ocean Airways Flight 101 crash - Dec 19, 2005
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Old 20th Mar 2017, 09:27   #17 (permalink)
 
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During the Berlin Airlift 1948/49 the British contributed their Short Sunderland flying boats operating from Elbe in Hamburg to Havel river in Berlin to transport goods into the soviet blockaded West Berlin. Especially salt as the RN aircraft were protected against seawater and could better withstand salt as cargo.

What did they do to protect them? Is this just WD-40 like some greasy oil cover you put on any metallic surface?

Sunderland unloading salt at Berlin:
http://www.flying-tigers.co.uk/wp-co...lift-1948-.jpg

Last edited by Less Hair; 23rd Mar 2017 at 08:11.
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Old 20th Mar 2017, 19:32   #18 (permalink)

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T dog best wishes from Fintas 12A3
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Old 20th Mar 2017, 21:01   #19 (permalink)
 
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Thanks for the clarification OneTrack
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Old 20th Mar 2017, 21:13   #20 (permalink)


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The military equivalent of WD40 is PX24. When I was serving on Wessex the Royal Navy used to wash and WD40 their Wessex both externally and internally every 28 days if I remember correctly. They used WD40 on them and not PX24 which I always thought was odd. WD 40 I was told stood for Water Dispersant ( effective for ) 40 days after which it attracts moisture, hence the Navies regime. I treat our aircraft with ACF 50 although we do not fly in a marine environment, damned good stuff.

As for washing, just look at the Nimrods, they used to taxy through a fresh water washing bay after they landed.. This is a P3 Orion going through a US one when taxying in.

http://www.navair.navy.mil/index.cfm...&gallery_id=48

Last edited by NutLoose; 20th Mar 2017 at 21:32.
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