1. PURPOSE. This Advisory Circular (AC) contains guidance (test methods, acceptance
criteria, and process changes) for qualifying alternative chemical agents and/or processes used in
depainting or general cleaning of aviation products. Like all AC material, this AC in itself is not
mandatory, and does not constitute a regulation. It is issued to describe an acceptable means, but
not the only means, for selecting and testing alternatives to chemical agents and/or processes
currently required by some manufacturers’ maintenance instructions, including instructions for
continuing airworthiness.
2. BACKGROUND. The National Emission Standards for Hazardous Air Pollutants (NESHAP)
for Aircraft Manufacturing and Rework Facilities applies to major sources and limits the amount
of certain chemical agents used by aerospace facilities in depainting and cleaning aviation
products. Methylene chloride and methyl ethyl ketone are the most prevalent of these used. The
standards became effective September 1, 1998. Federal Aviation Administration (FAA)
regulations require that aerospace facilities follow the manufacturers’ maintenance manuals, or
other acceptable methods, which may specify use of the same chemicals which the NESHAP
would limit. Substitution of alternative chemicals without tests and an acceptable application
process could result in damage to the aircraft and loss of airworthiness.
3. DISCUSSION. This AC is intended to apply industry wide and as a guide when selecting
alternative maintenance chemical agents and/or processes to ensure that these chemical agents or
processes, when used in accordance with the manufacturer's instructions, will not degrade the
airworthiness of the aircraft or aviation product to which they are applied.
a. Each certificated person engaged in aviation maintenance is responsible for ensuring that,
when an alternative chemical agent or process is applied to an aircraft or aircraft product, the
results are equivalent to the original manufacturer’s maintenance requirements. A record of the
tests used to determine equivalency must be made available to the Administrator upon request.
b. Per Title 14 of the Code of Federal Regulations (14 CFR) part 43, section 43.13 for tasks
where use of FAA-approved maintenance data is required, changes in agents/processes must be
approved by the FAA. Repairs covered by Airworthiness Directives (AD) are examples of such
tasks. The usual procedure for obtaining approval of these changes is to submit a request for an
Subject: Guidance for Selecting Chemical Date: 9/25/98 AC No: 43-205
Agents and Processes for Depainting Initiated by: AFS-340 Change:
and General Cleaning of Aircraft
and Aviation Products
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