Doctors learn that a certain bedside manner is helpful when conveying bad news to a patient. Airplane mechanics-at least the ones we know-don’t necessarily feel the same obligation, thus when catastrophe looms large during an annual inspection, you might hear, “Hey, we found a crack in your case, youre hosed.” The medical analogy is apt, for a cracked case is the equivalent of plugged arteries; surgery isn’t just an option, its a must. In most cases, a cracked case will ground the airplane and an overhaul will follow. No matter how much time is on the engine, splitting the case to fix a crack and reassembling it makes little sense. A full overhaul or reman is the way to go. But it can be a little tricky economically. Shops have been weld-repairing cases for years, with good results. If the repair is done correctly, the case might not be as good as new, but it will probably remain serviceable through another TBO run. If the case isn’t repairable or its marginal, the decision may not be so black and white. On four-cylinder Lycomings, for instance, buying a new case may be at least plausibly affordable. On six- cylinder engines of any size or type, it probably wont be. We think any owner confronted by a cracked crankcase should sit down with a clean pad and a sharp pencil and compare costs carefully. In most cases, welding the case is the no-brainer option.
Tiny Industry
The case welding business isn’t what it used to be. There are now only a handful of shops doing this specialized work and we recently visited two of them, both in Tulsa, Oklahoma, within walking distance of each other. The shops are vastly different in size and personnel, but they both put out impressive repair volume and are respected in the industry.
Of all of the businesses that repair cases, four are located in Tulsa, three of them just a few hundred feet apart on Sheridan Road. Two others are ECI in San Antonio, Texas, and Nicksons Machine Shop in Santa Maria, California. Teledyne Continental does case repairs as well, although it used to farm out this work to the Sheridan Road shops.
What owners need to understand about case repairs is that the process is more involved than just grinding out the cracked metal, building it up with welding and