Do You Smell Something Burning?

Unlike driving, there's always something to learn in aviation.

Annual inspection in progress.

Normally, I park my plane in a hangar. This past weekend, I visited Long Island for Mother's Day and left  my plane tied down outside, next to the runway. When we took off the next day, we noticed a burning smell inside the plane. I had spilled a little oil on the engine, the previous day, but the smell wasn't an oil burning or plastic smell. It smelled more like burnt wood or paper, much like a wildfire. Since nothing became of it - and the smell went away after a few minutes - I didn't think about it.

This week, I brought my plane in for it's annual inspection. During an annual inspection the aircraft seats and carpeting are removed and the engine, along with all of the access points, are opened up. The entire inspection process can take five to ten days.

Today, I dropped by the shop to check on the progress and the mechanics showed me what was causing the burning smell. It turns out, even though my plane was only outside overnight, that birds had started to make a nest inside my engine --- way in the back of the engine near the firewall.

Part of a bird nest found in the aircraft engine.

As part of my preflight inspection I explicitly check the engine for bird nests by looking into it from the front. But, I can only see into the front of the engine. It's not possible to see the back of the engine from the front and opening up the cowling (hood) is not viable since it's screwed down.

The bird's nest in my engine could, in theory, present a fire hazard. So, it looks like it's time to buy some cowl plugs to cover the front of the engine. The mechanics gave me a good tip when parking outside: turn my prop straight up and down, instead of horizontal, so birds can't perch on it.

I can only hope to keep learning things the forgivable way.