Manufacturer's Instructions: How the maintenance should be performed

April 8, 2005
When it comes to performing maintenance on an aircraft it is a little different than what we do when we need to repair our car.

The critical nature of the business we are in has been joked about in many ways by both industry and consumers. We have all heard the comments about "100 mile an hour tape" and "you can't pull over up there to try to fix it". Comments like that are common and I believe they come from the fact that our industry is so safety critical.

When it comes to performing maintenance on an aircraft it is a little different than what we do when we need to repair our car. I often take my boys out to work on the car and use it as a learning experience where they can try to perform the task and fail without catastrophic results. Not the case with aircraft (obviously). This month we are discussing the regulations that cover how aircraft maintenance is to be performed and whose responsibility it is to ensure the correct maintenance instructions and procedures are used.

Who can perform maintenance?

First let's cover who can work on the aircraft. Many think that in order to work on the aircraft one must be certificated by the FAA. Not so. 14 CFR Part 43.3 spells out in detail who can perform maintenance. Basically, limited to their specific certification the following certificate holders can work on an aircraft: mechanic, repairman, repair station, air carrier, pilot, and manufacturer.

In addition to those who are certificated, a person who is working under the direct supervision of a mechanic or repairman certificate holder may work on the aircraft as well - limited by the limitations of the person supervising them.

This is interesting and at times can be confusing. Like so many things that seem to be obvious, there are a few strange underlying details to the apparent authorizations to perform maintenance. One is the tie back to 14 CFR Part 65, as is the case for the mechanic and the repairman. Part 65 tells us that the mechanic can be rated as an Airframe mechanic and/or Powerplant mechanic (A&P) and if rated as both Airframe and Powerplant, may hold the authority of Inspection Authorization (IA). So you can see that being a mechanic is just the start of it. What type of mechanic you are and what authority you have determines what type of maintenance you can perform.

A repairman is much different. A repairman may only exercise the authority of the repairman certificate while employed by the repair station. The ratings available for the repairman are limited also to the authority of the repair station and the knowledge, training, and experience of the repairman himself. The ratings that appear on a repairman certificate are usually "made up" by the FAA issuing the certificate, based upon the application that was submitted. We seldom find the same ratings on two repairman certificates issued by different FAA offices, but the ratings are usually very clear and unambiguous. (Another minor twist is that in special cases, an experimental aircraft builder can apply for and receive a repairman certificate for that aircraft, but for the purposes of this discussion we will stick with the repair station repairman certificate.)

One may get confused then when they think of the fact that a repair station is called out separately from the repairman in Part 43.3 when the repairman is limited to the rating of the repair station. Well - here is why - a person working under the direct supervision of a mechanic or repairman can perform work on the aircraft (as stated before) however, they cannot approve that work for return to service. A different regulation tells who can approve for return to service following maintenance - 14 CR Part 43.7. The list is a little different here and, basically, does not include the noncertificated person who must also be supervised to work on the aircraft in the first place. So, a repair station will need to have a repairman to supervise and approve for return to service if they employ anyone who is non-certificated to perform maintenance. Here is a list of those who can approve for return to service following maintenance: mechanic, repair station, manufacturer, air carrier, private pilot, repairman (light-sport aircraft type), and sport pilot. Again, each is limited to approval for return to service within their respective authority.

How it should be performed

So, we covered briefly who can work on the aircraft and comparatively, who can approve the work for return to service. Next I want to talk about how the maintenance is to be performed, meaning the instructions to be used to perform the maintenance. In referring to "how the maintenance is performed" I am talking about what we call the three T's: talent, technical data, and tools.

Obviously, being in the compliance business in a regulated industry the three T's have a regulatory origin. Let me explain. The first T, talent, refers to the requirement that all persons who perform maintenance on a U.S. registered aircraft must possess the appropriate knowledge and experience to do that maintenance, or be supervised by a person who possesses as much.

14 CFR Part 65.81 - General privileges and limitations: (a) A certificated mechanic may perform or supervise the maintenance, preventive maintenance, or alteration of an aircraft or appliance, or a part thereof, for which he is rated (but excluding major repairs to, and major alterations of, propellers, and any repair to, or alteration of, instruments), and may perform additional duties in accordance with ??65.85, 65.87, and 65.95. However, he may not supervise the maintenance, preventive maintenance, or alteration of, or approve and return to service, any aircraft or appliance, or part thereof, for which he is rated unless he has satisfactorily performed the work concerned at an earlier date. If he has not so performed that work at an earlier date, he may show his ability to do it by performing it to the satisfaction of the Administrator or under the direct supervision of a certificated and appropriately rated mechanic, or a certificated repairman, who has had previous experience in the specific operation concerned.

The fact that a certain level of talent is required is pretty well-known and adhered to. When a technician runs across something that he/she doesn't understand they will more than likely find help before moving forward rather than risk safety. A problem area however lies in the second and third T's.

Current technical data

The second T, technical data, refers to the requirement that all maintenance must be performed in accordance with the technical data supplied by the manufacturer of that equipment.

14 CFR Part 43.13 - Performance rules (general): (a) Each person performing maintenance, alteration, or preventive maintenance on an aircraft, engine, propeller, or appliance shall use the methods, techniques, and practices prescribed in the current manufacturer's maintenance manual or Instructions for Continued Airworthiness prepared by its manufacturer, or other methods, techniques, and practices acceptable to the Administrator . . .

The current manufacturer's maintenance manual means just that. The only way to know that you have the current manufacturer's maintenance manual is to hold an acceptable subscription to that manual and use that manual. Using a third-party work card or an outdated photocopy of the maintenance manual instructions is simply illegal. It is an unsafe disservice to your customer (the aircraft owner) and an unnecessary liability to you.

Why is it a problem? The manufacturers' maintenance manuals and instructions for continued airworthiness are dynamic and always in flux. To be sure you are using the most recent instructions (as required by the regulation) it is critical to use the actual maintenance instructions directly from the manufacturer. And with advancements in technology, accessing the real "McCoy" quickly is easier than ever.

I remember when I learned how to change the Stab Actuator on a Lear 35. I made copies of the maintenance manual section covering the procedures so I would have them to refer to while I was being trained. When we were done I felt compelled to put those copies in my toolbox for future reference. I had made some notes on it and wanted to look it over again a few times when I had a spare moment. The problem was, that document was then in my toolbox and too easy to use on the next job. Not to mention that the FAA frowned seriously on any copies of maintenance instruction in my toolbox - as I found out.

The third T, tools, refers to the tools required to perform the task. The tools required to perform the task are so tightly related to the current manufacturer maintenance manual that the only reason to refer to them separately is because the regulation does as well.

14 CFR Part 43.13 Performance rules (general):(a) Each person performing maintenance . . . shall use the tools, equipment, and test apparatus necessary to assure completion of the work in accordance with accepted industry practices. If special equipment or test apparatus is recommended by the manufacturer involved, he must use that equipment or apparatus or its equivalent acceptable to the Administrator.(b) Each person maintaining or altering, or performing preventive maintenance, shall do that work in such a manner and use materials of such a quality, that the condition of the aircraft, airframe, aircraft engine, propeller, or appliance worked on will be at least equal to its original or properly altered condition (with regard to aerodynamic function, structural strength, resistance to vibration and deterioration, and other qualities affecting airworthiness).

The methods and techniques we have learned through training and experience call for specific types of tools and equipment to perform these tasks. The maintenance instructions provided by the manufacturer assume some level of competence simply because of the requirement for certification of the person performing or supervising the work. The concern that is often missed is that when the manufacturer calls for specific equipment to be used, that must be used. The FAA helps to keep repair stations aware of this requirement and through periodic site visits, enforces the requirement. If you are not under the umbrella of a certificate repair station be aware of the legality of using tools and test equipment other than what is called out by the manufacturer.

In summary, maintenance that is performed on an aircraft is serious business. Using the current manufacturer's maintenance manual instructions to perform maintenance on aircraft not only makes sense, it's the law. Know your own limitations relative to your knowledge and experience and pay attention to the instructions you are following to perform the maintenance. If you need easier access to the technical data, call the manufacturer and find out if there is a CD or some other method of delivering the instructions. Technology is moving so fast you may not be aware of the latest developments. AMT

About the Author

Joe Hertzler