- Service Limit Overhaul – A service limit overhaul means that parts will be put back into your engine that are within ‘serviceable limits’. Basically, this means that if a part is allowed to measure + – .010” it can be put back if it is .009”. The big question here is how long does it take to wear an extra .001”? Don’t you want enough time to wear your parts out until the next TBO? If so, Service limit overhaul is out of the question. Shops only recommend these for lower-time prop strikes. In fact, many will refuse to do them. Note: Lycoming offers a service limit engine called a “Factory Overhaul”
- New Limit Overhaul – The engine and its parts must meet criteria for a new engine. For all practical purposes, your engine will be restored to ‘new’ limits. It will have margin for its parts to hopefully wear and stay within ‘service limits’ through its TBO (time before overhaul) life. As a personal note – I called every shop in the country for an engine overhaul and every single shop quoted a ‘new limit overhaul’. But after the engine is in the shop’s hands, how do you know they are actually putting ‘new limit’ parts in, and not ‘service limit’ parts? There’s certainly financial incentive to do the latter so read The Dark Side of Engine Overhaul so you don’t fall in this trap.
- Factory Rebuild and Factory New – Only the factory, or reseller thereof can give you a ‘factory rebuild’ or ‘factory new’. Factory rebuilds have some used parts that meet or are reconditioned to new limits. Factory new engines are comprised of completely new parts. About 10% of pilots buy factory rebuilds and 3% spring for the factory new engines.
Since practically no one gets a service limit overhaul at TBO, the real question that people face is to buy a new limit engine overhaul at a shop, or buy a factory engine. We know the factory is most expensive and recognized name of the two options. But does it carry added value? The next post answers that question.
← 3 Levels of Overhaul