Limited life components or LLC’s, a formal way of describing anything that has a finite life span or a mechanical limit. Open the cowl on any aircraft, close your eyes and point and you’ll find one. What are they exactly? Alternators, belts, hoses, tires, light bulbs, spark plugs to name a few.
Having to adhere to that life span can mean taking something off your aircraft that literally looks like it’s brand new and replacing it. For example, engine hoses. They might look ok, but they are usually recommended to be replaced every five years or as needed. You get something in return for it, the predictability of your aircraft operating without failure, at least for that part anyway.
Not everyone follows the time and cycle schedule though. Some replace parts on what is known as “On Condition”. The folks that use this method swear by it. What is it exactly? On condition is simply a way of inspecting and checking that a component functions properly or within OEM specs. It is with the inspecting and a functional check that one can determine if the item needs to be replaced before it fails. On Condition is not to be confused with replace when the part fails or as it is also known; fit until failure.
Yes, you can fly until your alternator goes out and as long as you are not flying your aircraft for hire, you don’t have to replace the hoses unless they look like they need to be replaced. Many LLC components can and will just fail, while others give ample warning signs for example, a fluctuating amp meter, frayed hoses or dry rotted belts.
So, what can you do to head off any LLC issues that could leave you stranded? If you are renting, then you shouldn’t have too many worries since the aircraft has to go in for a 100hr inspection, however what if you are renting and it’s eight more hours until the 100hr inspection? It’s always a good idea if you are a renter and leaving for a trip to go out the day before and give the aircraft a good once over so that if there is anything wrong you can get it corrected or schedule another aircraft.
All in all, the best thing to do is keep a close eye on the items that wear and tear the fastest. That way you can have some expectation of when you’ll need to schedule maintenance. How does that old saying go? An ounce of prevention is worth a pound of cure.
