Fuel dump risks. 2

[Macm_020171]

Hello,

Is it possible that when JP-8 or jet A-1 fuel is dumped during flight, cause damage to the paint and primer coatings. Thinking about military aircraft. I've seen F-16s refueling when the boom disengage the port, sometimes fuel is leaked over the fuselage. But if there is a need to dump fuel, the exposure time to the external surfaces will be much higher.

Thank you.

 

[3DDave]

Fuel isn't dumped onto the airplane.

 

[Macm_020171]

Ok, I'll ask the question differently then. Can Jp-8 or A-1 fuel damage the paint and primer coatings on the external surfaces of the aircraft?

 

[IRstuff]

The question is overly broad. As a general rule, paints and coatings used for such applications are supposed to be formulated/tested/qualified for fuel/chemical damage resistance. However, that rule cannot be 100% accurate for any given aircraft or manufacturer.

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[rb1957]

AIUI, when fuel is dumped the plume is not allowed to contact the plane. Demonstrated by flight test. Was working on a plane where we put an antenna downstream of the fuel dump. CFD showed there'd be a "small" impingement, so we moved the fuel dump away from the plane (spacers between the nozzle and the fuselage).

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[Macm_020171]

The Blackbird SR-71 was soaking wet in fuel while on the ramp. For sure than kind of paint was fuel resistant.

 

[WKTaylor]

Yes, decoupling during air refueling tends to over-spray a SMALL quantity of fuel ''at best VS a 'continuous flood-spray' with a stuck coupling valve... until hose or boom tube is depleted below the up-stream valve(s).

Modern 'cured' paint finish systems... Epoxy or polyurethane primers and polyurethane top coats are highly fuel and organic solvent resistant.

Non-curing paint systems... such as enamel, lacquer, etc are highly susceptible to paint damage from fuels and organic solvents.

Typical commercial jet fuels have minimal 'chemical additives'... anti-icing, anti-microbial, lubricity enhancement, etc... so the effects of the additives tend to be very limited.

Typical military jet fuels [JP-X and Jet-A+] have substantial additives that can damage paint finish systems [interior and exterior] if they are subjected to extensive fuel contact under high temperatures. Specifically JP-8+ and Jet-A+ anti-icing/anti-microbial additives can act like 'paint-strippers' to ordinary supposed-fuel-resistant primer finishes... over-time.

JP-4 and aviation gasoline tend to have highest solvent affects for non-cured paint systems... especially at high temps.

One unique/difficult problem USAF had was with a small jet during air and ground refueling. During disconnects [air and sloppy ground refueling], fuel overspray resulted in the acrylic outer-windshield pane experiencing transient fuel saturation that appeared to dissipate quickly, without any traces [the acrylic outer-ply was there to protect the bird-strike-resistant polycarbonate laminate from scratches/abrasions/chemicals/etc]. These windshields were then subjected to extreme heat [+170F] while the jet was parked [long-term] on desert Air Base ramps. The jet fuel infused into the outer few-thousandths-of-an-inch of the acrylic surface, which then reacted with the acrylic under the unusual high heat combined with windshield plastic expansion/contraction... which caused generalized crazing of the acrylic outer-ply. What a NIGHTMARE.

Regards, Wil Taylor
o Trust - But Verify!
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o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", HBA forum]
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[Macm_020171]

Great information. Appreciated!

 

[TugboatEng]

Fuels will stain most paints brown with long term exposure. This includes polyurethanes. This requires long term or repeat exposure.

 

[WKTaylor]

Tug, Your 25 Oct 22 01:59... are You referring to bunker oil and diesel for vessels? These tend to have higher 'tramp' sulfur and other chemistry/compounds and metal-ions.

Aviation gasoline and turbine fuels tend to a very high degree of refinement... relative to land and sea fuels... and additives for flight extremes.

Regardless... studying aviation fuels makes my head-hurt due to so many variables... but necessary... because a high % of the Acft I've worked on for last ~30+ years have been kerosene cargo jets.

Regards, Wil Taylor
o Trust - But Verify!
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation, Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", HBA forum]
o Only fools and charlatans know everything and understand everything." -Anton Chekhov

 

[Null Full]

It is possible for jet fuel to cause damage to paint and primer coatings on aircraft. Jet fuel can be corrosive and can strip away protective coatings, causing the metal underneath to become exposed. In addition, jet fuel can cause the paint to become discolored or faded. However, the extent of the damage will depend on the amount of fuel that is spilled, the duration of exposure, and the type of paint and primer that are being used. Military aircraft are often coated with more durable and resistant coatings to withstand the harsh conditions of flight, but even these coatings can be damaged by prolonged exposure to jet fuel. It is important for aircraft to be properly maintained and cleaned to minimize the risk of damage to their coatings.

Johnny Huang
Product Manager at Sonkit Industry, For Metal Ring Seal Solution,

https://www.sonkit.cn/en/

 

[WKTaylor]

NF Your 7 Jan 23 11:47... my curiosity is killing me... what is your background experience with jet [turbine] fuel?

My perception of jet [turbine] fuel and it's interaction with the aircraft is inconsistent with several aspects of Your brief statement. Be careful.

Turbine fuel is a actually a complex material: 'slurry mix of highly refined/purified hydrocarbons', plus additives for various purposes, plus tramp contamination [metal flakes, sand, plastic and rubber bits, etc] from delivery systems [tanks, piping, etc] and during open-tank maintenance; and moisture/water from various sources. OH YEAH... and in the right environment of excessive water and oxygen, biological contaminates can breed highly corrosive micro organisms at the fuel-water-boundary.

I could go on-and-on about turbine fuel: it's evolution, variations, additives; required testing and QA/QC; the evolution of fuel resistant finishes; other non-metallic materials resistance and durability [rubbers, sealants, over-coats, composite structures, open cell ballistic foam, etc]; slosh/G/inertia loading, fire/explosion hazards, etc... and horror stories 'when fuel purity can't be trusted' or when wrong-fuel is serviced into aircraft, when a substandard fuel is deliberately added to tanks in an emergency, etc. OH Yeah... and defueling and purging tanks for maintenance, etc.... and when fuel saturated [swollen] rubber is allowed to 'dry-out' over many weeks/months. Or long-term aircraft preservation/storage issues...

Sorry, I'm running-off at the mouth.

Regards, Wil Taylor
o Trust - But Verify!
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation, Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", HBA forum]
o Only fools and charlatans know everything and understand everything." -Anton Chekhov