Four inhibitors compared
Where to buy| Product | Type (as sold) | Specification stated | Source of the claim |
|---|---|---|---|
| ACF-50 (Lear Chemical Research) | Anti-corrosion lubricant fog; flash point 79.4 C, SG 0.9, 25 cSt at 40 C, about 90 g/L VOC | MIL-C-81309E (distributor listing) | Distributor listings |
| CorrosionX Aviation | Ultra-thin film corrosion inhibitor | MIL-PRF-81309H Type II and Type IV | CorrosionX product page |
| LPS 3 Premier Rust Inhibitor | Soft waxy self-healing film | MIL-PRF-16173E Grade 2 Class 1 (distributor) | Distributor listing; LPS data sheet |
| Boeshield T-9 | Carrier solvent plus paraffin wax; leaves a thin wax film | None stated in the sources | Manufacturer site |
Distributor listings and maker pages, not the full data sheets. Claims such as two years of protection are the makers' and are not independent test data.
What AC 43.13-1B asks for
The AC specifies MIL-C-16173 Grade 4 corrosion preventive compound for unpainted or unprotected parts, hinges, cables and fasteners, wiped on a cloth or soft brush, with excess wiped off and as little as possible left on exhaust pipes and collector rings because of the fire hazard (section 4, corrosion preventive maintenance).
Where removable steel fasteners go back into access panels, par. 6-135b gives three methods. The preferred one brushes corrosion-preventive compound on the substructure around and in the fastener hole, starts the fastener, puts a bead of sealant in the countersink and sets and torques it within the sealant's working time. The finish guide covers the sequence.
ACF-50
What it is. An anti-corrosion lubricant compound for aerospace, purple, applied as a fog (Lear Chemical). The distributor lists flash point 79.4 C, specific gravity 0.9, kinematic viscosity 25 cSt at 40 C and about 90 g/L VOC.
What it is for. Penetrating protection in joints, seams and hidden structure.
How it is used. Maker's equipment and method; the AMM or the aircraft maker's corrosion programme says where it is allowed.
Life and cure. Reapplication interval comes from the maker and the operator's corrosion programme; we found no neutral figure.
Safety. Lear's SDS (WHMIS 2015/GHS) lists pH 7 and notes toxicity data for some ingredients are unavailable. Read the SDS.
Specification. One distributor lists MIL-C-81309E; another lists MIL-C-81309 Class 1 Type 2 on the spray-on version.
Equivalents. The CorrosionX Aviation entry is the same kind of product but not the same material.
CorrosionX Aviation
What it is. An ultra-thin film aviation corrosion inhibitor qualified to MIL-PRF-81309H Type II and Type IV (CorrosionX page). A distributor describes Type III as an avionics soft film.
What it is for. Corrosion prevention in aircraft structure and hardware.
How it is used. Per the maker's sheet.
Life and cure. Per the maker.
Safety. SDS.
Specification. MIL-PRF-81309H Type II and IV.
Equivalents. Another MIL-PRF-81309 product of the same type and class may be accepted where the manual allows.
LPS 3 Premier Rust Inhibitor
What it is. A soft, waxy, self-healing film (LPS data sheet). A distributor states MIL-PRF-16173E Grade 2 Class 1. AC 43.13-1B names Grade 4 for aircraft use, so grade matters.
What it is for. Rust and corrosion protection on tools, hardware and steel parts; the maker claims up to two years indoors.
How it is used. Per the maker.
Life and cure. The two-year claim is the maker's and is indoor.
Safety. SDS.
Specification. MIL-PRF-16173E Grade 2 Class 1 (distributor). Not Grade 4.
Equivalents. Do not substitute Grade 2 where the AC or SRM says Grade 4.
Boeshield T-9
What it is. A Boeing-developed solvent-and-wax product: the solvent carries the wax into tight places, and a thin wax film is left (maker and retail descriptions).
What it is for. Rust protection and lubrication on tools and hardware.
How it is used. Spray, wipe excess, let it set.
Life and cure. Sellers suggest reapplying every 6 to 12 months for stored items; this is a retail suggestion, not a specification.
Safety. SDS.
Specification. None stated in the sources.
Equivalents. Not a MIL-PRF product as far as the sources show.
Questions people actually ask
Do I use these inside tanks or on rubber?
Not without the manual. Inhibitors can attack seals, wiring and sealants, and the AMM lists where each may go.
Which spec does the AC name?
MIL-C-16173, Grade 4 for unprotected parts and cables. MIL-PRF-81309 is a different family of thin-film inhibitors.
Does an inhibitor replace the conversion coat?
No. It is a maintenance film over a protected finish or on parts that cannot be painted.
Limits — when NOT to use this
What the sources support, and no further.
- Distributor listings. We did not read the full maker data sheets for these products.
- Maker claims such as two years of protection are the makers' own.
- Compatibility with sealants and rubber is not covered; use the AMM.
Where to buy
Distributors coming soon.
Sources
- FAA AC 43.13-1B CHG 1, Chapter 6 (corrosion control, safety precautions, finishes) — Pars. 6-90 (safety precautions), 6-134 to 6-136 (finish, conversion coat, 48 hour rule, fasteners), section 4 (corrosion preventive maintenance, MIL-C-16173 Grade 4); par. 5-63 (cleaner types).
- Lear Chemical ACF-50 13 oz (distributor listing) — Flash point, specific gravity, viscosity and VOC as listed by the distributor.
- ACF-50 Corrosion Preventative (distributor listing) — Listing states it meets MIL-C-81309E.
- Corrosion Technologies, CorrosionX Aviation (product page) — Qualification listed as MIL-PRF-81309H Type II and Type IV.
- LPS 3 Premier Rust Inhibitor (product page) — Distributor states MIL-PRF-16173E Grade 2 Class 1.
- ITW Pro Brands, LPS 3 Premier Rust Inhibitor technical data sheet — Self-healing soft waxy film; protection claim for up to 2 years indoors.
- Boeshield T-9 (manufacturer site) — Boeing-developed solvent-and-wax rust protection.