High-pressure Gas Cylinders: Maintenance requirements

High-Pressure Gas Cylinders Maintenance requirements Joe Hertzler All new parts installed during the maintenance function have to be manufactured to one of the quality standards of 14 CFR Part 21.303. There are many misconceptions about...

The reason that the regulation takes precedence is because it is actually a regulation rather than an FAA accepted maintenance manual. An example of a regulatory vs. manufacturer maintenance requirement relationship more familiar to all of us is the relationship between an aircraft inspection program and an Airworthiness Directive. A specific example is that of the nose landing gear fork inspection requirements for the Raytheon Super King Air B200.

The inspection program for the King Air was once at a frequency interval of 150 hours. A problem was found in specific part number nose gear forks and the FAA issued an Airworthiness Directive requiring an inspection each 150 hours until the part was replaced. The inspection is to be performed in accordance with a Service Bulletin, also calling the inspection out at 150 hours. A few years later Raytheon revised the inspection program and extended the Look-Phase inspection frequency out to 200 hours. Shortly thereafter the Service Bulletin calling for the nose gear fork inspection was extended to 200 hours as well. The problem is, the Airworthiness Directive continues to refer to the original revision of the Service Bulletin (in this case Revision III) and continues to require the inspection be performed each 150 hours.

Now logic might say that the manufacturer has analyzed the situation and determined that a less frequent inspection is adequate to maintain a high level of safety and through issuance of the revised service bulletin has authorized the interval of the inspection to be extended. This however is not the case. Why? Because Airworthiness Directives are regulatory and accepted maintenance manuals and service bulletins are not.

Whenever a new Airworthiness Directive is issued it is issued as an amendment to 14 CFR Part 39. So in the case of the King Air nose gear fork inspection, until the Airworthiness Directive is revised the applicable forks must be inspected at 150 hours.

So you see, the DOT regulation found in 49 CFR Part 180 governing the inspection, testing, and replacement of cylinders is really the higher authority over the aircraft manufacturer’s maintenance manual. There are, however, a couple of ways that an operator might have a different inspection requirement than that contained in Title 49 CFR for gas cylinders. The manufacturer of the aircraft could place the requirement for inspections testing and replacement of cylinders in an FAA approved Airworthiness Limitation section of a maintenance manual, or in any other FAA approved maintenance requirement such as an air carrier’s operation specification. In those cases, the FAA is very careful to make reference to Title 49 CFR in an effort to keep the requirements the same. If by chance the requirements contained in an FAA approved document such as an Airworthiness Limitations Section of a maintenance manual or an Air Carrier Operation Specification are in conflict with those requirements contained in 49 CFR Part 180, the most restrictive requirement must be complied with.

The latest update
The Department of Transportation issued a new final rule on Aug. 8, 2002 covering the inspection, testing, and replacement of cylinders. The change to Title 49 reorganized and moved the cylinder requirements from the old familiar 173.34 to

180.205 — General requirements for requalification of cylinders
180.209 — Requirements for requalification of specification cylinders, and
180.213 — Requalification markings.

These new regulations can be found in various places on the Internet. Although there is no substantial change to the requirements contained in the new rule, the new organization of the rule makes reading and determining the requirements for cylinders manufactured to DOT specifications much easier.

Following is a brief outline of the new rule:

For our purposes, cylinder inspection requirements include all cylinders used to transport compressed gas in aircraft.

49 CFR Part 173.1 (a)(2) specifically includes air transportation — “Requirements to be observed in preparing hazardous materials for shipment by air, highway, rail, or water, or any combination thereof . . .”

49 CFR Part 173.1 (a)(3) refers to the inclusion of inspection and testing requirements — “Inspection, testing, and retesting responsibilities for persons who retest, recondition, maintain, repair, and rebuild containers used or intended for use in the transportation of hazardous materials.”

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