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Interpretation Response #04-0249 ([URS Corporation] [Mr. Andrew N. Romach])

Below is the interpretation response detail and a list of regulations sections applicable to this response.

Interpretation Response Details

Response Publish Date:

Company Name: URS Corporation

Individual Name: Mr. Andrew N. Romach

Location State: NC Country: US

View the Interpretation Document

Response text:

Feb 10, 2005


Mr. Andrew N. Romach                 Reference No. 04-0249

Corporate Regulatory Manager

URS Corporation

1600 Perimeter Park Drive

Morrisville, NC 27560

Dear Mr. Romach:

This responds to your October 27, 2004 letter requesting clarification of the Hazardous Materials Regulations (HMIR; 49 CFR Parts 171-180) as applicable to jet engines. Specifically, you ask if jet engines may be classed as "Engines, internal combustion." In addition, you state that the exciter box, an integral component of jet engines, contains a component referred to as a "spark gap." You indicate that the "spark gap" contains a limited quantity of Kryption-85 gas, a radioactive material assigned to UN2910. You ask if a cleaned and purged jet engine and securely installed "spark gap" may be shipped as unregulated material in accordance with § 173.220(a)(1) and (d)(1), respectively.

Aircraft engines, whether piston-powered, rotary-powered, or turbine-powered, derive their power by heat and pressure produced by the compression and combustion of a fuel-air mixture. Therefore, aircraft engines including jet engines are properly classified as "Engines, internal combustion, 9, UN3 166."

In accordance with § 173.220(a)(1), an engine that is completely drained, sufficiently cleaned of residue, and purged of vapors to remove any potential hazard and that will not release liquid fuel in any orientation is not subject to the HMR. In addition, a limited quantity of radioactive material that is contained in a securely installed engine component that is integral to the operation of the engine is excepted from the requirements of the HIVIR (see § 173.220(d)(1)). Therefore, a cleaned and purged jet engine with a "spark gap" contained in a securely installed exciter box is excepted from the requirements of the HMR, provided the applicable requirements in § 173.220 are met.

I hope this information is helpful. Please contact us if you require additional assistance.



Edward T. Mazzullo


Office of Hazardous Materials Standards


Regulation Sections

Section Subject
173.220 Internal combustion engines, vehicles, machinery containing internal combustion engines, battery-powered equipment or machinery, fuel cell-powered equipment or machinery