Mandatory Bulletins and Service Bulletins vs. ADs, Limitations, and TCDs

A current controversy over the scope of mandatory service bulletins has been caused by a decision of the NTSB involving the field overhaul of a Lycoming engine. In the July issue of AMT our editor described his thoughts and those of others on the subject. A further review of the subject follows with some additional thoughts and concerns for technicians and others to ponder.

The Case

Here is a short review if you missed it in the July issue.

After an initial hearing, an administrative law judge suspended a technician's mechanic certificate for 180 days based on violations of FAR 43.13(a) and 43.2(a)(1) and (2). The complaint alleged that the mechanic approved the engine for service after he performed the overhaul. He had sent the crankshaft, connecting rods, and pistons to a non-certified shop to be balanced. The complaint further stated that Lycoming had no approved process for balancing these parts in the field. In addition, it also stated that an employee who magnafluxed the parts was not certified to do so and that he did not follow the inspection requirements of a Lycoming Service Instruction Bulletin. When he test ran the engine he did not follow an approved standard or technical data acceptable to the Administrator. (He did not use a checklist or run sheet).

The Board stated that the investigation began when the customer notified the FAA that he believed the engine work was not done in accord with the regulations and that therefore his aircraft was not airworthy.

The Response

In his appeal the mechanic argued, among other things, that contrary to the judge's findings, he was not required to comply with the manufacturer's service bulletins, instructions, or letters, absent an Airworthiness Directive (AD) to do so. (This is commonly accepted dogma for Part 91).

He stated further that the FAA failed to present adequate evidence that the engine was not tested properly and also that the law judge failed to follow the guidelines of the FAA sanction guidance table.

The theory presented by counsel for the mechanic was simple. He said that the "Administrator did not prove that respondent had failed to comply with the methods, techniques, and practices prescribed in the current manufacturer's manual, because the manual was silent on balancing the crankshaft, connecting rods, and pistons in the field.

What the Board Said

True, Lycoming did not set out any approved process for balancing parts in the field in its overhaul manual. But the Board said in essence that this did not open the door for the mechanic to simply send his parts out for balancing to any shop that did this kind of work.

"We have previously held that where the maintenance manual is silent on a particular issue, the mechanic should seek approval from the Administrator regarding how to address that issue."

The requirement to follow service bulletins, service instructions, and letters is in the nature of an advisory suggestion or opinion by the Board, is not authorized, and may be unlawful. The Administrative Procedures Act (APA 5 USC sec 552 et seq.) must be followed when a regulatory requirement is attempted to be established by an administrative body. This attempt at an underground regulation requires notice and a comment period as described in the APA before any regulation can be created. Manufacturers' service bulletins, service instructions, and letters are not subject to any regulatory examination.

The Board replied further to the compliance with service bulletins, instructions, or letters argument as follows ...

Lycoming in a Service Instruction (No. 1285B, 5-23-97) requires that personnel performing Magnetic Particles Inspection shall be qualified and certified in accordance with ASNT Personnel Qualification SNT-TC-1A or Mil Std 410. Respondent argued that he did not have to comply with this directive from the manufacturer because he is Part 91 and this is not an AD. He said this requirement is not FAA mandated.

Here's what the Board said that raised so much fuss….

"While compliance with service instructions, or service bulletins may not be mandatory in the absence of an Airworthiness Directive, a manufacturer may legitimately incorporate such service publications into a manual by reference. The Lycoming overhaul manual incorporates all future service instructions by reference."

Thus the Board concludes (many fear) that this Part 91 mechanic must follow the mandate of all the Lycoming service instructions, service bulletins, and letters of instruction since they are included by reference in the manual. This is just not industry practice today nor is it FAA opinion and policy.

More importantly, since when can future unknown and unstated service bulletins be incorporated by reference into overhaul manuals? This statement by the Board is just a little off the wall in the opinion of this writer.

Many observers feel that the Board's language is in conflict with current rules and policy as described in the FAA's own opinions on the subject. The FAA's position on the subject has frequently and unequivocally been stated in the past. Some of its comments on the subject follow below. There is a fear that FAA inspectors and mechanics could misinterpret this decision to mean that mechanics have to comply with all manufacturers' service bulletins, instructions, and other repair operations referenced to their manuals. This is not the rule nor is it required by any FAR for Part 91 aircraft operations.

FAA Statements on the Subject

This subject is not something new and the Board should have discussed FAA's clear position on the matter, before deciding this case. The Board is in error in this writer's opinion based on current practice and opinion of the FAA.

For example, in a position statement in April 2001 the FAA Small Aircraft Directorate stated: "Mandatory service bulletins … are to be considered advisory only."

Earlier in April of 1987 they said: "Small airplane design approval holders cannot unilaterally impose mandatory compliance with manufacturer's service bulletins. A statement that bulletin compliance is mandatory must be FAA approved to be included in the Airworthiness Limitations Section of Instructions for Continued Airworthiness. FAA policy does not permit this approval to be delegated to organizations or individuals.

"FAA policy does not permit a predetermination that compliance with some future document is mandatory. Thus, service bulletins issued after the Airworthiness Limitations section is FAA-approved cannot be made mandatory without FAA involvement."

In February 2004 the Aircraft Maintenance Division cited FAR 91.403(c) as the controling rule for following manufacturer's maintenance recommendations …

"No person may operate an aircraft for which a manufacturer's maintenance manual or instructions for continued airworthiness has been issued that contains an airworthiness limitations section unless the mandatory replacement times, inspection intervals, and related procedures specified in that section or alternative inspections intervals and related procedures set forth in an operations specification approved by the Administrator under Part 121 or 135 of this chapter or in accordance with an inspection program approved under FAR 91.409(e) have been complied with." (Emphasis added.)

In addition, the FAA has stated that for most general aviation aircraft, mandatory retirement times or life limits are the only approved airworthiness limitations. Airworthiness limitations are found in few other places: Type Certificate Data Sheets, Instructions for Continued Airworthiness, and more commonly in ADs. If a limitation is placed against an aircraft, engine, propeller, or accessory in a Type Certificate Data Sheet or an AD, the limitation is mandatory under the law.

Consider for example, time between overhaul for piston engines. Manufacturers recommend specific times in service where they should be removed and overhauled. These times are not set out in the approved limitations section of their manuals and therefore are not mandatory. Likewise the same rule should apply to service bulletins unless they are set out in an AD.


The Board said in the case that a manufacturer may legitimately include service bulletins by reference into their manuals. Most of us don't believe this is accurate. If so they could replace the whole manual with the simple statement "… incorporated by reference"... Any changes or additions to manuals have to be approved by the FAA. Where is the approval for these service bulletins and instructions? (Unless included in ADs.)

Even if they do simply incorporate by reference there is no requirement under the current law to follow them. They would be strictly voluntary and optional for compliance because they are not referenced as an approved airworthiness limitation. Unless the FAA approves and concurs in a mandatory bulletin, service instruction, or information letter, they need not be followed.

The Legal Significance

You might think that this case is of little significance. But it is a huge subject when it comes to the litigation of an aviation tort case. You can bet your money on the plaintiff's bar grabbing this case and using it to maintain that you have been negligent and in fact violating the law by failing to comply with manufacturers' service bulletins, service instructions, and letters pertaining to the maintenance of an aircraft. It becomes very easy to argue liability for damages when there is proof of violation of regulation, law, or statute. Where are the insurance companies when you need them?

Further Appeal

It is likely that this case will be appealed further by the mechanic. A Federal Circuit Court of Appeals either in Washington, D.C., or the airman's home circuit may hear this case and open up the issues for further examination. We'll have to wait and see.