Disinfecting Cabins: Airworthiness Concerns

The FAA has issued a Special Airworthiness Information Bulletin on the potential negative impacts from excessively cleaning the cabin.

Recently on a transient ramp I watched a pilot dousing the cabin and cockpit of his turboprop with a can of Lysol disinfectant spray—and he wasn’t being gentle. The FAA’s Special Airworthiness Information Bulletin NM-20-17 (Nov. 4, 2020) was written for folks like him, and the bulletin contains some worthy guidance for the rest of us determined to keep our aircraft free of germs. While the bulletin mainly focuses on transport category airplanes, it might as we’ll apply to any aircraft because it addresses the potential long-term side effects of improper and too-frequent cleaning—from corrosion, increased flammability and electrical wiring issues.

The FAA is involved because any of those issues could, according to the agency, create an immediate or latent airworthiness issue. It’s sort of uncharted regulatory waters for the FAA because it doesn’t treat disinfection practices as “maintenance” under 14 CFR Part 43 because disinfection is not necessary for the airworthiness of a part or system. The guidance is mostly common sense, but worth adhering to.

For instance, you want to protect components and electrical wiring from any disinfectants that have potentially corrosive elements. Since we don’t know the long-term corrosive qualities of some cleaners, consider increasing the frequency of inspections in areas of the aircraft where these disinfectants are used. This includes circuit breakers, toggle switches and even critical trim and autopilot disconnect buttons housed in control yokes—which are commonly cleaned surfaces.

Avoid allowing liquids to pool, regardless of how they are delivered (wiped, sprayed, fogged) as liquids can more easily migrate into areas that are not suitable. Again, switches and circuit breakers come to mind. The bulletin also reiterates that excessive liquid intrusion can lead to electrical shorts in the near term and unexpected corrosion in the long term. 

It’s not just about preserving the operational integrity of switches. Consider cabin components. Ethyl alcohol-based disinfectants can cause crazing on windows and window dust covers, and can damage thermoplastics. As a result, windows on certain aircraft might not be able to continue to serve their intended purpose after multiple cleanings, the bulletin warns.

And how we deliver the shot of disinfectant matters, too. The FAA points out that electrostatic sprayers are different from electrostatic foggers, in that they provide more directional control through particle size or pressure (or a combination of the two) of the disinfectant being dispensed. Although both electrostatic sprayers and electrostatic foggers are effective in getting the disinfectant to areas that might otherwise be difficult to reach, foggers can more easily transport charged particles into unintended areas. According to the FAA, most aircraft interior materials can be treated with antimicrobial coatings with no negative effects to flammability, but Aerospace Material Specs. AMS-1452 and AMS-1453 should be used for guidance. 

The takeaway is to clean thoroughly and often, but don’t trash components in the process. Link to SAIB NM-20-17 from tinyurl.com/y42ha8vg. 

Editor in Chief Larry Anglisano has been a staple at Aviation Consumer since 1995. An active land, sea and glider pilot, Larry has over 30 years’ experience as an avionics repairman and flight test pilot. He’s the editorial director overseeing sister publications Aviation Safety magazine, IFR magazine and is a regular contributor to KITPLANES magazine with his Avionics Bootcamp column.