The Age Old Question

Are mandatory service bulletins really mandatory?


The question about mandatory bulletins has been around at least as long as I’ve been in this business. Although the guidance material out there continues to indicate conflicting positions within the FAA I think that the latest guidance makes it easier to determine the answer to the question “Is a mandatory service bulletin required for airworthiness compliance?” In this issue we will talk about what a service bulletin is and what the rules say about them being mandatory in the eyes of the manufacturer as well as the eyes of the FAA. Maybe we can come up with an answer that you will be able to hang onto for a while.

Let me start by making my personal position on this issue very clear. Compliance with mandatory service bulletins is one of the most important maintenance actions that an owner/operator can take to keep their aircraft in the safest and best possible condition. The manufacturer knows better than anyone else when special maintenance needs arise and the issuance of service bulletins is the chosen method for keeping us all informed. Not to mention what compliance with mandatory service bulletins can do for the resale value of the aircraft. My objective in this article is to help you understand the difference between the manufacturer’s highest level of suggestive maintenance (mandatory service bulletins) and the regulations.

Service bulletin
“Service bulletin” is a term that is used in our industry to describe notices that are sent out by equipment manufacturers to keep those who use and maintain the equipment aware of changes, errors, findings, new ideas, etc. It is an effective way for manufacturers to get information out to the market quickly. I’ve heard “service bulletins” called many things; service letters, customer bulletins, change notices, the list goes on and on. Each manufacturer has established its unique naming convention as well as numbering methodology. For the purposes of this discussion let’s just refer to them inclusively as service bulletins.

When manufacturers began issuing bulletins forever ago, I presume that they were just “bulletins” if only for a few months or years. But eventually the manufacturers must have realized that there were different levels of seriousness or criticality to a bulletin and began to further categorize them as recommended, optional, informational, mandatory, alert, etc. Having no standard for the terminology, it was left to the manufacturer to categorize the bulletins as they thought was best. The lack of standardization at least contributes to the confusion.

The evolution of the service bulletin, particularly in the business aviation community, has left us with a multitude of different types and different levels to hash through and try to make sense of. When the manufacturer attaches the term mandatory to a service bulletin, it’s human nature to ask the question, “Are mandatory bulletins really mandatory?” Or “What is mandatory anyway?” and look to the regulations for the answer. The manufacturer can categorize a service bulletin as mandatory, but where in the regulations does it say that service bulletins issued by the manufacturer are mandatory? Well, it doesn’t.

Airworthiness directive
Somewhere along the line, the FAA decided that a bulletin that had been issued by a manufacturer to correct a serious enough condition that operators needed to comply with the service bulletin, even though it was not considered “mandatory” by regulation, needed a new designation. It issued an airworthiness directive. 14 CFR Part 39 has been set aside for capturing all airworthiness directives issued by the FAA. This makes every airworthiness directive a regulation, and thus compliance becomes an issue of aircraft airworthiness. The distinction between mandatory and non-mandatory service bulletins is determined on a case-by-case basis and decided only by the FAA. Issuance of an airworthiness directive is one way that a service bulletin can be required by regulation. New guidance material issued by the FAA explains a few other ways that a manufacturer’s bulletin can become an airworthiness compliance requirement.

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