ISTOCK/ANDRESR
WORK SAFE By Zac Noble
Are Service Bulletins Mandatory?
Focusing on semantics over content misses the point and could lead to potential safety hazards.
T
HE OVERHAULED ENGINE had been running fine, with a normal break-in pattern.
Then, at about 170 hours, the owner received an email from his parts supplier alerting him that one of the through-bolts he purchased for the overhaul had been engineered incor- rectly and that he “could possibly” have one of the suspected parts. The manufacturer had issued a
mandatory service bulletin requiring that the affected through-bolts be replaced, and the supplier assured the customer the new part would be on its way soon, at no charge. This scenario sounds good—until
you realize that although the replace- ment bolt may be free, the labor cost to install it is double or triple the cost of the part itself, and the manu- facturer won’t be reimbursing you for the expense, even though it’s their fault you need the labor in the first place.
Service bulletins are
intended to inform aircraft owners of problems the
manufacturer has identified with their product. Ignore them at your peril.
The Purpose of Service Bulletins At this point, you might be wondering whether our bolt customer was required to change the suspected part based on a service bulletin mandate. If the aircraft is being used in accordance with 14 CFR Part 91, the answer is no, as long as it’s not part of an issued airworthiness directive (AD). But is it a good idea to ignore a service bulletin? Before we answer that ques- tion, let’s explore why service bulletins are issued.
Manufacturers issue service bulletins to make own-
ers aware of maintenance issues, manufacturing defi- ciencies, or product improvements that could affect
64 ROTOR DECEMBER 2021
safety. If the bulletin is highlighted with words such as “mandatory,” “emergency,” or “alert,” the manufacturer is telling you the information is of significant safety importance but hasn’t risen to the level of an airworthi- ness directive—at least not yet. The bulletin alone isn’t mandatory for Part 91 operators even though it uses powerful words implying that it is. In the bolt customer’s case, the manufacturer
couldn’t tell him whether the newly overhauled engine had a defective through-bolt; the company could only say the part was purchased during the time frame in which defective parts were manufactured. So, should the suspected through-bolt be replaced? Doing so would require removing several other assemblies in the way, parts such as the oil cooler, gov- ernor, and engine baffling, thus creating more work. Furthermore, the engine was running fine with no indication of an impending problem. We’re talking about hours of maintenance labor costs and aircraft downtime.
Expect the Unexpected
In the end, the bolt customer decided to have the main- tenance performed in accordance with the mandatory service bulletin. He expected the identified bolt would
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