In this series about performing your pre-flight checks properly, we started by looking at the external checks of the airframe. You can read that post here.
In this second post we’ll still be outside, but this time looking at the engine and the proper checks you need to do, and what to look out for.
It’s important to remember that the checklist is a guide, but it doesn’t beat your eyes and knowledge of the aircraft. Inspect it in a logical way and think about each step and each area you look at.
Every aircraft is different. Therefore engine checks are never as straightforward as checking the airframe.
Check the Oil
Some aircraft don’t have covers that can be lifted or easily removed to gain access to the engine, but all will have a dipstick to check the oil. This is the first important step, and in your particular aircraft’s handbook you will be told what the correct maximum and minimum level of oil should be. The dipstick will show you the current level (you may need to wipe it with a cloth and then re-insert to check properly).
If the oil level is below the limit, there may not be a sufficient amount available to properly lubricate the engine parts. This could be catastrophic for your flight, causing the engine to seize or get damaged. Make sure you have a bottle of the correct oil for your aircraft handy and know where to top it up (usually the same place as the dipstick) if you find the level is low. Wait for it to settle and check again.
Look for Damage
If you are able to remove or lift the cowling cover this is much easier. It is important to visually inspect the engine for any damage or problems.
Check for signs of wear and tear on the metal parts of the engine and anything that appears loose.
Also check the wires for any that are loose, frayed, or showing any signs of damage or burning.
Finally, whilst engines are dirty from use, any oil leaks should be obvious around the casing and engine itself.
If anything seems out of place, it could indicate a problem with parts of the engine or wiring which could get worse if flown. Naturally as a backup you will be performing engine runs and tests prior to flying, which are a second chance to discover any problems. But visually inspecting is the easiest way to spot any obvious issues before you even get into the cockpit.
Look Underneath the Aircraft
Any signs of oil leaking from the engine can usually be seen underneath the aircraft in fresh puddles and drips, or streaming from joins around the cowling where it has leaked during flight. Oil leaks are a sign of failed parts or seals within the engine and need to be checked and repaired by a mechanic before flying as it can easily lead to the engine failing.
Inspect the Propeller
Along with the engine we’ll include checking the propeller before flight.
The propeller is prone to damage from external objects, such as stones, and from clipping the ground during particularly bouncy landings! It is also under a lot of stress from moving at high speeds for extended periods of time.
First, check the blades of the propeller for cracks, chips and damage to the edges. All propellers that have flown a while will have some minor signs of wear, and you may see evidence of previous repairs where chips have been filed and smoothed out. You’re looking for anything new, anything that seems large, and anything that could damage the integrity of the propeller. If in doubt, seek advice.
Also check the spinner for damage, and ensure the propeller doesn’t wobble or rock about if it is not supposed to.
Propellers are incredibly hardy and are often repaired repeatedly through the course of their lives with no issue. However, problems need to be spotted early to make sure it is not going to fail or reduce the performance of the aircraft in flight.
I’m sure you don’t need to be told how important the engine is to the safety of your flight, so a thorough inspection is vital to ensure you don’t miss anything on the ground that could cause problems in the air. If in doubt, don’t risk it and seek professional advice before flying.