{"operation":"document","citation":"25-0151","title":"Collins Aerospace — Hazardous Materials Safety Interpretation","source_type":"guidance","agency":"Pipeline and Hazardous Materials Safety Administration","status":"guidance","official":true,"published_on":"2026-03-23","effective_on":null,"summary":"25-0151 response to Collins Aerospace concerning 173.24, 178.601.","machine_formats":{"json":"https://regulus.evalyn.ai/document/phmsa-interpretation-25-0151.json","markdown":"https://regulus.evalyn.ai/document/phmsa-interpretation-25-0151.md"},"app_url":"https://regulus.evalyn.ai/document/phmsa-interpretation-25-0151","source_url":"https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/2026-03/250151_0.pdf","body":"<<<PAGE 1>>>\n\n1200 New Jersey Avenue, SE\nWashington, DC 20590\nU.S. Department\nof Transportation\nPipeline and Hazardous\nMaterials Safety\nAdministration\nMarch 23, 2026\nGeno R. Delfino\nSenior Tech, Logistics\nCollins Aerospace\n3530 Branscombe Road\nP.O. Box KK\nFairfield, CA 94533\nReference No. 25-0151\nDear Mr. Delfino:\nThis letter is in response to your October 31, 2025 email requesting clarification of the\nHazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to the general\nrequirements for different packaging types. You seek clarification on what constitutes a different\npackaging under § 178.601(c)(4) and what modifications are allowed without being treated as a\ndifferent packaging, particularly related to combination packagings. Moreover, you state that\nPHMSA has provided conflicting information in previously published Letters of Interpretation1\nover the years.\nWe have paraphrased and answered your questions as follows:\nQ1. If a combination packaging design passes United Nations (UN) design qualification\ntesting with a specific cushioning material (e.g., foam padding), can the cushioning\nmaterial be changed without the packaging being considered as a “different packaging?”\nSpecifically, would switching from one foam specification to another, or from loose foam\nsheets to loose cellulosic cushioning, be excepted from required retesting of the\npackaging?\nA1. No, regarding both questions. Changing the cushioning material is considered a\nmodification of the packaging design. The performance of a UN combination package\nrelies on the specific arrangement of inner packagings, and the cushioning system used\nduring testing. According to § 178.601(c)(4), “A different packaging is one that differs\n(i.e., is not identical) from a previously produced packaging in structural design, size,\n1 Ref. Nos. 00-0216, 02-0026, 05-0025, 20-0010, and 22-0057.\n\n<<<PAGE 2>>>\n\nmaterial of construction. . .” Therefore, any change to the cushioning material will\nrequire retesting for compliance.\nQ2. If cushioning material (e.g., foam padding) is permanently affixed to the inside of the\nouter packaging, and a later production run uses a different type of foam padding that is\napplied in the same manner, can this change be considered as differing only in “surface\ntreatment” consistent with clarification offered in a previous letter of interpretation (Ref.\nNo. 00-0216)? In other words, would this substitution avoid the determination as a\n“different packaging”?\nA2. No. Changing the permanently affixed cushioning material does not qualify the\npackaging as differing only in surface treatment. The HMR do not define the term\n“surface treatment,” but it generally refers to changes that do not affect the structural or\ncritical performance characteristics of the packaging. Changing the foam padding affixed\nto the inside of the outer packaging is a critical performance characteristic.\nQ3. Can you add an intermediate container (e.g., a fiberboard box) to a combination\npackaging configuration that originally had none (e.g., inner plastic bags placed directly\nin an outer fiberboard box) without it being considered a “different packaging”?\nA3. Adding an intermediate container alters the tested packaging configuration and may\nconstitute a design change. Since UN performance packaging is qualified based on the\ncomplete packaging system, this modification could be considered a different packaging\ndesign and might require new design qualification testing.\nQ4. Can you change the intermediate container in a combination packaging (i.e., from a\nplastic bag to a fiberboard box) without it being considered a “different packaging”?\nA4. Yes. An intermediate container may be replaced with a different design (e.g., substituting\na fiberboard box for a plastic bag) without being considered a “different packaging,”\nprovided the substitution qualifies as an authorized variation under § 178.601(g) and can\nbe demonstrated to be equivalent to or stronger than the original in material closure\nintegrity, dimensions, and any required cushioning or absorbent function. If the\nsubstitution exceeds the scope of permitted variations or materially affects the\nperformance of the packaging system, the modified configuration would be considered a\nnew packaging design and would require separate design qualification testing.\nQ5. Does § 173.24(c)(2) permit the types of changes described in Q3 and Q4?\nA5. No. Section 173.24(c)(2) permits the use of supplementary packagings to ensure\ncompliance with the general requirements; however, it does not specify whether\nmodifications to a packaging constitute a new packaging design as that determination is\nmade under § 178.601, which governs UN packaging design qualification and permitted\nvariations.\n\n<<<PAGE 3>>>\n\nQ6. If a combination packaging design is successfully qualified using a specified\nconfiguration of multiple cushioning materials (e.g., foam sheets, cellulosic sheets,\nbubble wrap), does § 178.601(g)(4) require that every type of cushioning material used in\nthe test must also be present in every subsequent production package?\nA6. Yes. Section 178.601(g)(4)(iv) requires every type and design of cushioning material that\nwas used during design qualification testing to be used in each production package. The\nHMR requires that the cushioning used in production provide the same overall level of\nprotection as that provided by the cushioning configuration used in the tested design type\npackaging. In addition, the thickness of cushioning material between inner packagings,\nand between the inner packagings and the outer packaging, may not be less than the\nthicknesses used in the tested design type packaging.\nQ7. Is it acceptable to use only one of the previously tested cushioning materials instead of all\ncushioning materials previously tested, provided that the void space is properly filled in\naccordance with § 178.601(g)(4)(v)?\nA7. No. In the design testing scenario described in question Q6, it is not acceptable to use\nonly one of the cushioning materials that was used in the qualified design. See answer\nA6. Additionally, if your design qualification test involves multiple cushioning material\n(e.g., a box filled with a mix of foam, bubble wrap, and cellulose all at once) and it\npassed, the test demonstrated that this specific mixture of cushioning material provides\nthe necessary protection.\nI hope this information is helpful. Please contact us if we can be of further assistance.\nSincerely,\nDirk Der Kinderen\nChief, Standards Development Branch\nStandards and Rulemaking Division\n\n<<<PAGE 4>>>\n\nBaker, Y.\n25-0151\nFrom: INFOCNTR (PHMSA)\nTo: Baker, Yul (PHMSA)\nCc: Hazmat Interps\nSubject: CFR 178.601(g)(4)\nDate: Monday, November 3, 2025 15:48:12\nAttachments: DOT LOI 22-0057.pdf\nDOT LOI 20-0010.pdf\nDOT LOI 05-0025.pdf\nDOT LOI 02-0026.pdf\nDOT LOI 00-0216.pdf\nFW: Letter of Interpretation Request: Conflicting LOI\"s on 49 CFR 178.601(c)(4), and one question regarding 49\nGood afternoon,\nPlease see the following request for a letter of interpretation. Let us know if you need anything\nelse.\nBest,\nAminah\nFrom: Delfino, Geno <Geno.Delfino@collins.com>\nSent: Friday, October 31, 2025 11:50 AM\nTo: INFOCNTR (PHMSA) <INFOCNTR.INFOCNTR@dot.gov>\nCc: Delfino, Geno (USA) <Geno.Delfino@collins.com>\nSubject: Letter of Interpretation Request: Conflicting LOI's on 49 CFR 178.601(c)(4), and one\nquestion regarding 49 CFR 178.601(g)(4)\nCAUTION: This email originated from outside of the Department of Transportation (DOT). Do\nnot click on links or open attachments unless you recognize the sender and know the content\nis safe.\nHello,\nI seek clarity from DOT PHMSA on what their current stance is for a different packaging\nunder 49 CFR 178.601(c)(4) and what changes are allowed to not be considered a\ndifferent packaging, specifically in regard to combination packaging. There appears to be\nconflicting information from multiple LOI’s over the years.\nLOI 22-0057 states that a change in cushioning material (i.e. no cushioning material in\nthe original design qualification testing and then adding cushioning material thereafter)\nis not considered a different packaging and would not require a design qualification\ntesting of the altered package.\nLOI 20-0010 states that the inner packaging must be the only component that differs\n\n<<<PAGE 5>>>\n\nwithin the combination package. It appears that cushioning material must remain the\nsame as tested and cannot be changed without design qualification testing using the\nnew cushioning of choice.\nLOI 05-0025 states that an intermediate container (i.e. liner) can be added and it is not a\ndifferent packaging.\nLOI 02-0026 states addition of a liner or other containment would not be considered a\ndifferent packaging.\nI have a few different scenarios and questions I would appreciate clarity on to help\nunderstand what is or is not allowed:\n1. 2. 3. 4. 5. 6. If a combination package passed design qualification testing with one cushioning\nmaterial (i.e. foam padding), could the cushioning material be changed to a new\nmaterial without being considered a different packaging? What if the change is\nfrom one foam padding to a different spec of foam padding? Or what if the change\nis from loose foam sheets to loose cellulosic cushioning? Can the cushioning be\nchanged without issue in either scenario without being considered a different\npackaging?\nFor Q1, if the cushioning material (i.e. foam padding) is permanently affixed to the\ninner surface of the outer package and the next build by supplier uses a different\nspec of foam padding still permanently affixed in the same manner, would it be\naccurate to view this as a change in surface treatment in accordance with LOI 00-\n0216 and the new build would not be considered a different packaging?\nIs it also possible to add an intermediate container (i.e. a fiberboard box) to a\ncombination package (i.e. inner plastic bags and outer fiberboard box) where an\nintermediate container did not exist previously, and it would be considered to not\nbe a different packaging?\nIs it acceptable to alter a combination package by making a change to the\nintermediate container? i.e. changing the intermediate container from a plastic\nbag to a fiberboard box?\nDoes 49 CFR 173.24(c)(2) allow these changes for Q3 and Q4?\nFor a combination package that passed design qualification testing with varying\nloose pieces of cushioning materials at one time (i.e. foam sheets, cellulosic\nsheets, bubble wrap sheets, etc.), if we decide to follow 49 CFR 178.601(g)(4),\nunder (49 CFR 178.601(g)(4)(iv) would we need to place all varying cushioning\nmaterials inside or would it be acceptable to place only one of those tested\ncushioning materials inside as long as void space is taken up by the cushioning\nmaterial per 49 CFR 178.601(g)(4)(v)?\n\n<<<PAGE 6>>>\n\nThank you,\nGeno R. Delfino\nSenior Tech, Logistics\nO: +1 707.422.1880 EXT. 1471\nF: +1 707.422.1684\nGeno.Delfino@collins.com\nCollins Aerospace | An RTX Business\nShipping | Logistics\n3530 Branscombe Road\nP.O. Box KK\nFairfield, CA 94533 USA\ncollinsaerospace.com | LinkedIn | X | Instagram | Facebook | YouTube\nThis message may contain RTX proprietary, business confidential, and/or privileged information. Unless you are the\naddressee (or authorized to receive mail for the addressee), you should not use, copy, or disclose to anyone this message or\nany information contained in this message. If you have received this message in error, please advise the sender by reply e-\nmail and delete this message; you should not otherwise use, distribute, retransmit, or reproduce this email. Thank you for\nyour cooperation.","truncated":false,"body_characters":11616}