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I’ve heard people talking about mandatory service bulletins. Do I really need to worry too much about them?

This is a very common question that people have, and it really has a two-part answer. First, let’s look at it from a legal standpoint. In almost all cases, aircraft being operated under Part 91 are being inspected in
accordance with the scope and detail of an Annual inspection, as found in FAR 43 Appendix D. Nowhere in this FAR does it state to comply with manufacturer’s service instructions. What this means is that it is permissible and legal to sign off an aircraft as airworthy even if the mandatory service bulletins have not been accomplished. 


That having been said, service bulletins are issued for a reason and accomplishing the service bulletins provide owners with a couple of different benefits. As we are all well aware, it seems that the FAA often requires some kind of incident to occur before they are willing to issue an AD on a particular item. But aircraft manufacturers are much more vigilant about their products, and often discover things long before they become major problems. As the manufacturer discovers things that they feel could become major issues down the road, they issue service bulletins that provide instructions for how to correct the problem BEFORE it becomes a major incident. In almost all cases if you read an FAA issued AD, you will see that the AD asks you to do something in accordance with a mandatory service bulletin that existed long before the FAA considered issuing an AD. The bottom line is that while service bulletins can sometimes be frustrating to deal with, they DO increase the safety and reliability of your aircraft overall.

Another important reason for keeping up with service bulletins is that it increases the resale value of your aircraft. During a pre-purchase evaluation, a good technician will evaluate the status of service bulletin
compliance. If you are selling your aircraft and many of the service bulletins have been deferred, it is highly likely the prospective buyer will attempt use that information to drive down the purchase price of the

Keeping up with service bulletins is also important purely because time is a major factor in the cost of completing most of them. Many times, when a service bulletin is first released, the manufacturer will offer
warranty coverage for the completion of the bulletin, even if the airplane is no longer under warranty! This is not always the case, but time still plays a major factor. For example, in 1984 Cessna released a service bulletin to upgrade the nose landing gear on the R182 to provide a stronger mounting clamp for the shimmy damper. This was not covered under warranty, and at the time the repair kit cost about $400.
For people who deferred this work and suddenly find themselves with a broken shimmy damper mount clamp, the repair kits are very hard to find, and can be priced as high as $15,000!

Complying with service bulletins is always the choice of the owner, and we will always respect that choice here at Granite Air Center. But just be sure you are making the smartest decision you can for your circumstances, so you don’t get bit by deferred service bulletins in the future!

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