The latest revision of Lycoming Service Instruction No. 1012 provides information on the location and assembly procedure for counterweights on each Lycoming crankshaft equipped with counterweights. The illustrations and engine listing in this service instruction show that some crankshafts may have two or more counterweights of the same part number attached to the crankshaft with rollers having...

In an attempt to reduce the cost of flying, some operators have resorted to methods of operation which are considered to be unsafe. Lycoming makes the following recommendations regarding these practices: Do not advance timing – set timing in accordance with the Engine Operator’s Manual for the specific engine model. Do not use a hotter spark plug for low-power cruise – unless it is approved for...

Damage to an aircraft that has been struck by lightning is often confined to a specific area of the structure. In such instances where the engine and its accessories, controls, fuel or exhaust systems are involved, it is necessary to evaluate and repair the damage before the aircraft is flown again. Although the path of the lightning may appear to have been around the external housings of the...

As an engine manufacturer, we are often asked to guide pilots and mechanics concerning what to do about an engine after sudden stoppage, or a ground strike by the propeller. Lycoming Service Bulletin No. 475C states Lycoming’s position concerning this problem. These important publications point out that there may be hidden internal engine damage from such an incident. From the experience of...

Many starters manufactured by Prestolite and Electro Systems are in use with Lycoming engines. From time to time, these starters used on our direct-drive engines are returned to the factory reported as malfunctioning, but investigation here revealed the problem to be dirt. The location of the starting motor on many aircraft engines subjects the Bendix Drive of the starter to contamination from...

What is Engine Balancing? explains that certain engine parts are organized in matched sets, by weight, before they are installed in an engine being built at the Lycoming factory. Occasionally, it may be necessary to replace one of these parts during the operational life of the engine. When this happens, mechanics in the field should know that Lycoming parts which are matched by weight when an...

Perhaps the first step in discussing this subject is to first get the terminology correct. The latest revision of Lycoming Service Instruction No. 1324 calls it a crankshaft oil seal. Although almost everyone knows exactly what you are talking about when the term nose seal is used, correct terminology can be important. Should this seal leak immediately after installation, it is possible that the...