Read Reference Publications Before Engine Maintenance


People who fly should be concerned about the reliability of the aircraft they fly and the engine that powers that aircraft. One key to reliability is regular maintenance by a knowledgeable A & P mechanic. “Knowledgeable” does not necessarily mean the mechanic must have every detail of every job locked in his or her memory. It does mean that the individual should have relevant information readily available and be able to refer to it as needed.

What has been stated above is not just good common sense; it is the law. Aviation mechanics are licensed (certified in aviation terms) under Part 65 of the Code of Federal Air Regulations (FAR). FAR 65.81 (b) states: “A certificated mechanic may not exercise the privileges of his certificate and rating unless he understands the current instructions of the manufacturer, and the maintenance manuals, for the specific operation concerned. Is it possible for anyone to understand current instructions or maintenance manuals if they are not available for reference?

The point which a concerned pilot owner should be thinking about is this – does my A & P mechanic or maintenance shop have appropriate maintenance publications available for reference? While many maintenance activities do maintain a good reference library, others certainly do not. This can be easily determined from the questions that are asked of Lycoming service representatives who continuously respond to phone calls for help. While the service personnel who are available to provide help when troubleshooting does not readily reveal the source of, or solution to, a problem, their time is being wasted when they are asked to dig out information for a mechanic who has not made the effort to acquire required reference materials. Without these reference materials, the quality of maintenance is open to question.

How can publications that apply to Lycoming reciprocating engines be obtained – and which ones are needed? Starting with the last question, an operator’s manual should have enough information to satisfy the needs of the engine owner or pilot. For the maintenance person, what is needed depends on the depth of maintenance to be performed and the particular engine models to be maintained. Once these items have been determined, the latest revision of Lycoming Service Letter No. 114 is a guidesto all service publications that are available. It lists Lycoming Parts Catalogs and Overhaul Manuals which provide much of the information needed for major work on Lycoming reciprocating aircraft engines. Specialized procedures and amplifying information are provided from time to time in the form of bulletins, letters and instructions. These publications serve as supplements to the Overhaul Manual. Without these publications to provide the latest data published by the manufacturer, the A & P mechanic may not be reminded of a required inspection or may be unaware of a new and helpful maintenance technique.

Service bulletins are manufacturer publications that are likely to affect safety of flight. Therefore, a bulletin should be considered to be mandatory by every aircraft owner and by all maintenance personnel. In some cases, a bulletin will become the subject of an FAA Airworthiness Directive (AD). The AD gets very broad distribution to aircraft owners and is also mandatory by law. Because they affect aircraft safety, both the bulletin and the AD should receive the careful attention of all aircraft owners and maintenance personnel.

Service instructions are more routine items, but they do become a supplement to the FAA-required maintenance manual, so their content is both informative and mandatory. When changing spark plugs, for example, a copy of Lycoming Service Instruction No. 1042 provides a listing of recommended and approved spark plugs for each engine model. Use of this reference will ensure that the correct plugs are used.

There is a message here which aircraft owners should consider. Quality of maintenance cannot always be determined beforehand, but the chances for good quality will certainly be better when adequate reference materials are available. The idea of simply asking what reference materials are available in your mechanic’s reference library would seem to be a good one. It will encourage the mechanic or maintenance person to acquire and use appropriate reference materials, and it may help aircraft owners to determine the quality of maintenance they will receive.

Service Letter No. 114

For a reference guide to all Service Publications, refer to Service Letter No. 114.