Here’s a quick note that can make you feel good (or maybe worse if you don’t see it) when looking at a used engine. Paint wear on the nut that holds the oil suction screen in place is a good thing! It tells you that the screen has actually been removed and checked – at least occasionally. If you find the nut safety wired with no paint wear at all—as if it has been in place once the engine was built, then run away quickly, or at least be very suspicious as to how the engine has been maintained. This screen is supposed to be checked at every oil change, so the paint wear should be proportional to age and hours. This is on our 270 hour IO-540 that we bought used, and it looks to me as if the paint I scratched just amount for the number of oil changes the engine has seen. And the screen was clean!
In Case You Missed It
Wind Tunnel
When is an airplane in trim? At least to the pilot, the airplane is trimmed when no stick force is required to maintain equilibrium. So how do we achieve this? Barnaby Wainfan explains any number of ways to go about it, including the use of trimtabs, spring systems, sparrow strainers and variable incidence tails.
