Last week, you learned that the difference between a 100-hour inspection and an annual inspection is when they are performed and who can perform them. You also learned that the inspection process is extensive; not a bolt or wire or the airplane goes uninspected. This week, you will find out what happens during the second phase of an inspection.

Service Items

The second part of the 100-hour or annual inspection is the service items. Maintenance facilities that can assign two mechanics to an inspection can allow one mechanic to focus on the inspection, while the other works on service items. At Elon Aviation we have both an Airframe and Powerplant (A&P) mechanic and an Inspector Authorization (IA) working together to complete our 100-hour and annual inspections.

Service items on a normal inspection are usually consistent from inspection to inspection and aircraft to aircraft. Each inspection must address items on the discrepancy sheet, which the mechanic compiles during the run-up at the beginning of the inspection. The inspection must also address the list of required service items. Once an item is completed, one mechanic signs the list, and a second mechanic will verify the work and countersign.

Service items typically start with the oil change, which involves draining the engine oil, replacing the oil filter, and checking the oil filter screen for fragments and particles, which may indicate more serious issues within the engine. The mechanic pours new clean oil in the engine, making sure to add only the proper amount of oil for that aircraft.

Next is a compression check on the aircraft cylinders to make sure they still hold the proper pressure. The oil change and compression check are best completed while the engine is hot, for this allows the oil to drain quicker and the cylinders to be hot and expanded a bit to ensure they still hold compression at proper heat while the engine is running.

As in the inspection, the inspector or mechanic doing the servicing items develops a flow the order in which to accomplish every task. A detailed list of items helps track what has been done already. Certain areas have more service items than others. Some tasks can take few minutes; other tasks require half a workday. One quick task is checking the Emergency Locator Transponder (ELT). This item needs to be properly checked every 12 calendar months for proper operation and for determining when the battery is due to be changed.

In contrast, servicing the bearings on the landing gears takes significantly longer to accomplish. If the plane needs to be placed on jacks, then setting it on jacks is time-consuming. The time spent is well worth the effort. With the plane lifted on jacks, the wheels and tires are relieved of weight, making it easier to remove the wheels and tires.

The oil change, compression check, ELT inspection, and bearing servicing, along with other service items all maintain the aircraft’s continued airworthiness and safety. Thus, it is important to do them every 100-hours or annually.

The last tasks that usually happen during a 100-hour or annual inspection are the repairs required by the discrepancy list. Such repairs include installing a screw missing here, replacing worn hardware there, and are generally the small things left over after any replacing or repairing other parts of the plane.

A typical 100-hour or annual inspection for a small training aircraft can take about three days, but it may take longer depending on the aircraft and the steps the A&P or IA uses to accomplish the inspection.

After the inspection process is completed, the mechanic reinstalls the inspection panels and cowlings and runs the engine up again to ensure that everything was put back correctly and that everything seems to be working normally. After the aircraft receives a clean bill of health, the A&P or IA includes a proper writeup in the maintenance logs and the aircraft returns to service. The process starts all over 100 hours or one year later.

It all seems like a lot of work, but it is a process that keeps aircraft safe for those operating them. If a mechanic loves their job and is passionate about the aircraft they are working on, then their service will help keep the aircraft they maintain flying decades from now.

As the Inspector at Elon Aviation, I take it upon myself to thoroughly inspect every aircraft that comes into my shop. I know it is important to keep these planes maintained and airworthy not just for me, but also for our customers. I hope to see these aircraft continue to fly for many years to come.

You could say Joseph Cala was born to be in aviation. According to his mother, Joseph's first word spoken was "airplane." During his childhood, he and his parents frequented the local airport to watch planes take off and land. But it was his experience flying a plane at aviation camp when Joseph was 14 that sealed his fate: He would pursue an aviation career. Learn more about Joseph and the rest of the Elon Aviation staff at www.elonaviation.com.