Aircraft
Certification Service Washington, DC U.S. Department of Transportation Federal Aviation Administration
NM-20-17
November 4, 2020
This is information only. Recommendations
aren’t mandatory.
Introduction
This Special Airworthiness Information Bulletin (SAIB) primarily
advises owners and operators of transport category airplanes of
important airworthiness information and guidelines with respect to
disinfecting airplane interiors. The information and guidelines may
also apply to other categories of aircraft.
At this time, the airworthiness concern is not an unsafe condition that
would warrant an airworthiness directive (AD) under Title 14 of the
Code of Federal Regulations (14 CFR) part 39.
Background
As a result of the coronavirus disease 2019 (COVID-19) public health
emergency, aircraft owners and operators may find it necessary to
increase the frequency with which they disinfect aircraft interiors and
to include additional areas of the aircraft not previously disinfected.
Consistent with Centers for Disease Control and Prevention (CDC)
guidance, FAA issued Safety Alert for Operators (SAFO) 20009,
describing recommendations for occupational safety and health on
aircraft. Although the SAFO notes that any disinfectants used should be
compatible with the aircraft and approved by the aircraft manufacturer
for use on board the aircraft, this SAIB focuses on the potential near
term and long term implications for airworthiness, and is directed to
all persons responsible for airworthiness.
Although disinfection is not directly related to aircraft
airworthiness, too frequent or improper application could result in
negative impacts, which could include the following conditions:
Corrosion
Embrittlement
Increased flammability
Electrical short circuit
Depending on the system or part
affected, any of these conditions could create either an immediate or
latent airworthiness issue.
FAA does not treat disinfection practices as “maintenance” under 14 CFR
part 43 because disinfection is not necessary for the airworthiness of
a part or system.1 Similarly, such practices have not been addressed in
the instructions for continued airworthiness under 14 CFR 23.1529,
25.1529,
27.1529, or 29.1529 because disinfection is not necessary to maintain
airworthiness. However, the FAA advises that aircraft owners and
operators should approach the disinfection process similarly to any
maintenance or repair action for which improper execution may
compromise airworthiness.
Recommendations
FAA recommends that all owners and operators as well as any other
person responsible for the airworthiness of affected aircraft implement
the aircraft manufacturer’s disinfection guidelines and be aware of the
potential negative impacts of disinfectants. Aircraft manufacturers
have published information on the products and methods they have
evaluated and found acceptable from an airworthiness standpoint.
Failure to follow the aircraft manufacturer’s recommended practices on
the use of materials for disinfection can lead to airworthiness issues.
FAA notes that although the Environmental Protection Agency publishes a
list of disinfectants effective at inactivating COVID-19, the majority
of the products listed may not be suitable for use on aircraft, except
in very limited and localized application.
In conjunction with the aircraft manufacturer’s recommendations
regarding the use of disinfectants, FAA offers the following additional
guidance and information regarding potential negative impacts that may
develop:
Make sure the disinfectant
and the method of applying it are compatible. For example, certain
disinfectants are suitable for wiping, but not suitable for spraying.
Flammable disinfectants, such as those that are alcohol based, should
not be fogged as this creates a dangerous atmosphere prone to sudden
combustion. Note that alcohol containing wipes that are disposed of in
bulk have the potential for any remaining alcohol to evaporate and
collect in the disposal container, creating a similar sudden combustion
risk, locally.
In general, fogging and
misting allow the ingress of disinfectant into areas where
disinfectants are not intended to be used (e.g., underlying structure,
fan cooled electronic boxes, smoke detectors). Running aircraft
ventilation will typically exacerbate this condition.
Protect structures and
electrical systems from any disinfectants that have potentially
corrosive elements. Consider increasing the frequency of inspections in
areas of the aircraft where these disinfectants are used.
Avoid allowing liquids to
pool, regardless of how they are delivered (e.g., wiped, sprayed,
fogged) as liquids can more easily migrate into areas that are not
suitable.
Be especially careful when
using liquid disinfectants in the flight deck, particularly when
attempting to achieve a long “dwell time” of the liquid disinfectant on
the surface if recommended by the disinfectant manufacturer. Liquids
can intrude into flight deck switches and seals. Excessive liquid
intrusion can lead to electrical shorts in the near term and unexpected
corrosion in the long term. Take care to prevent liquids from pooling
or dripping in the flight deck. FAA emphasizes that owners and
operators should follow, and not exceed, the disinfectant
manufacturer’s instructions for application of disinfectants identified
as appropriate for the aircraft by the aircraft manufacturer.
Ethyl alcohol based2
disinfectants can cause crazing on windows and window dust covers, and
can damage thermoplastics. As a result, windows on certain aircraft
types might not be able to continue to serve their intended purpose
after multiple cleanings.
Electrostatic sprayers are
different from electrostatic foggers, in that they provide more
directional control (e.g., through particle size, 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 that may be incompatible. Additionally, while FAA
recommends electrostatic spraying over fogging, in general, using
either technique with the ventilation system off will reduce the risk
of unintended application. Note that airframe manufacturers continue to
assess the implications of an operating ventilation system using
specific disinfectants and may identify exceptions to this general
advice.
Antimicrobial coatings have
the potential to persist and be effective for much longer than a
typical disinfectant surface treatment. However, while the rate of
antimicrobial coating application may be less frequent, any alteration
of the material properties of the surface upon which such coating is
applied could be more immediate than another disinfecting treatment
because the antimicrobial coating persists on the surface. Preliminary
investigations by aircraft manufacturers indicate that most aircraft
interior materials can be treated with antimicrobial coatings with no
negative effects to flammability (specifically its heat release rate);
but, such coatings should be assessed by the user regarding any other
potential negative impacts before use. SAE provides two Aerospace
Material Specifications (AMS) for disinfectant testing that may be
useful in assessing certain possible impact: AMS-1452 and AMS-1453.
These specifications apply to liquid disinfectants; however, many of
the tests the SAE AMS documents reference and the effects considered
are applicable to antimicrobial coatings.
FAA and some aircraft
manufacturers are currently investigating other methods for
disinfection, such as ultraviolet radiation and ionization, both for
effectiveness as a disinfectant and potential effect on the aircraft.
Therefore, FAA advises that owners and operators use caution with any
method of disinfection, including ultraviolet radiation and ionization,
and consider the potential short term and long term consequences, not
just on the equipment and furnishings deliberately treated, but also on
any equipment and furnishings that could be exposed during the
disinfecting process. Be aware that these processes may create
by-products that should also be evaluated for the effects on the
aircraft and personnel.
For Further Information on this SAIB Contact
Jeff Gardlin, Senior Technical Specialist, Policy and Innovation
Division, FAA, Aircraft Certification Service, 2200 S 216th Street, Des
Moines, WA 98198; 206-231-3146; e-mail: jeff.gardlin@faa.gov.
Jason Deutschman, Manager, COS Program Management Section, Compliance
and Airworthiness Division, FAA, Aircraft Certification Service, 10101
Hillwood Parkway, Fort Worth, TX 76177; telephone 817-222-5197; e-mail
jason.deutschman@faa.gov.
Related Information from Other Entities
International Civil Aviation Organization: Council Aviation Recovery Task Force, Take-Off Guidance, Aircraft Module
International Air Transport Association: Aircraft cleaning and disinfection during and post pandemic
European Union Aviation Safety Agency: Guidance on aircraft cleaning and disinfection in relation to the COVID-19 pandemic
CDC Updated Interim Guidance for Airlines and Airline Crew
1 Although the selection and use of improper chemicals
and cleaning methods could damage the aircraft and affect its
airworthiness, that possibility, in and of itself, does not make the
activity maintenance or preventive maintenance. It follows that
disinfection is also not maintenance. The FAA notes, however, that the
manufacturer’s procedure for cleaning and disinfecting an aircraft may
include tasks that might be classified as maintenance. These tasks
might be required either before or after cleaning, or as the result of
other maintenance tasks. Examples include pulling and tagging certain
circuit breakers, and the installation of protective devices to protect
sensitive areas.
2 An ethyl alcohol based disinfectant may also be referred to as an ethanol based disinfectant.