Interpretation Response #24-0042
Below is the interpretation response detail and a list of regulations sections applicable to this response.
Interpretation Response Details
Response Publish Date:
Company Name: Tym’s LLC
Individual Name: Brian Tyminski
Location State: AK Country: US
View the Interpretation Document
Response text:
June 26, 2025
Brian Tyminski
President and CEO
Tym's LLC
721 Depot Drive
Anchorage, AK 99501
Reference No. 24-0042
Dear Mr. Tyminski:
This letter is in response to your June 4, 2024 email and subsequent emails and a phone call requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to marking and labeling requirements for aviation cylinders (i.e., cylinders used on aircraft). Specifically, you present a scenario where it is your understanding that required markings and labels cannot be placed on Department of Transportation (DOT) specification cylinders packed in a strong non-bulk outer container because the cylinders are a component of a 14 CFR-approved aircraft part.
We have paraphrased and answered your questions as follows:
Q1. Is placing DOT 3AA specification cylinders in a strong non-bulk outer container (e.g., a fiberboard box) considered a combination package for purposes of the HMR? If so, can the DOT 3AA specification cylinder be transported without markings or labels in accordance with Part 172, Subparts D and E, respectively, if the strong non-bulk outer packaging is marked and labeled?
A1. No. The configuration described is not a combination package. DOT 3AA cylinders are considered a single packaging and therefore must be marked and labeled appropriately. DOT specification cylinders not specifically listed in § 173.301(a)(9)—such as DOT 3AA cylinders—that are further packed in an outer container such as a fiberboard box is not a combination package is considered an overpack configuration subject to the requirements found § 173.25.
Q2. Is placing DOT 3HT specification cylinders in a strong non-bulk outer container (e.g., a fiberboard box) considered a combination package for purposes of the HMR? If so, can the DOT 3HT specification cylinder be transported without markings and labels in accordance with Part 172, Subparts D and E, respectively, if the outside of the combination package is marked and labeled?
A2. Yes. DOT 3HT specification cylinders are listed in § 173.301(a)(9) and are required to be packaged in a "strong outer packaging." This combination package configuration requires marking and labeling of the outer packaging and does not necessitate marking and labeling the DOT 3HT cylinder. Furthermore, in accordance with § 173.301(a)(9), the outside of the combination packaging must be marked with an indication that the inner packagings (e.g., DOT 3HT cylinders) conform to the prescribed specifications.
For an explanation of 14 CFR requirements as it relates to DOT specification cylinders installed on aircrafts and whether they may display Part 172, Subpart D and E marks and labels, please contact the Federal Aviation Administration (FAA) at hazmatinfo@faa.gov.
I hope this information is helpful. Please contact us if we can be of further assistance.
Sincerely,
Dirk Der Kinderen
Chief, Standards Development Branch
Standards and Rulemaking Division
§ 173.25, § 173.301(a)(9)