Posts Tagged ‘CRJ; flaps; magnetos’

Airplane noises and the messages they send

Tuesday, August 23rd, 2011

Flying is a very sensory activity. In fact, at times, it can lead to sensory overload, especially in the beginning. But over time, you begin to learn what things are supposed to look like and how a few things are supposed to feel.

The view of the runway during a landing, for example, is probably one of the most difficult things to learn because it all happens so fast, and no two attempts to land are ever the same. That is, in fact, what makes teaching the art of landing so challenging as an instructor.

As for feel, you develop that as well. Think of the effort you need to put into flying a steep turn, or the mushiness of the controls that develops as you approach a stall. You learn to feel not just normal control force tension, but also deviations from the norm. It’s all part of the learning curve.

But how much do you pay attention to the sounds around you? The sounds of aviation—both normal and not-so-normal—are something you pick up on with experience as well, though you may not realize it at first. When I was teaching full time, I tended to put a lot of emphasis on listening to what was happening around us. For example, the engine makes varying levels of normal sounds throughout its operation: idle, during the runup, full power operations, cruise, et cetera. Each should sound a certain way. Even the mag check has a proper “normal” sound.

During flight, you probably subconsciously use the sound of the slipstream around the airplane to give you hints. It gets quiet when you are slow, loud when you are descending, and it changes in pitch when you extend flaps. In fact, the flap motor has a normal sound as well.

As you experience more complex aircraft, all the noises actually become even more important. On the Embraer Brasilia, the 30-passenger turboprop, there was a certain rhythm to extending the gear and adjusting the propellers. It had to sound a certain way, or something was wrong. On the CRJ, I once called for the first officer to extend the gear. The gear extension on the CRJ has a definite sound and normal sequence of events that all starts with opening of the nosewheel doors. On this occasion, there was a very abnormal thunk instead. I immediately said—well, I can’t type what I said—and the FO asked what was wrong.

“Just wait,” I said. That was immediately followed by the warning telling us that the gear was unsafe. Within seconds, the problem had resolved itself, and the gear was properly extended. But it was my experience that let me know that we would have at least an indication of a problem before that indication every showed up. Fortunately, it was all a non-event.

On another occasion, I walked on to an airplane parked at the gate. When I went to power it up, the normal sequence of clicks, clacks, groans, and avionic cooling fans coming on was replaced by what sounded like R2-D2 getting tasered. It turned out to be a faulty ground power unit. Again, it was the change in normal sounds that caught my attention first.

While your sight and feel can tell you much about your bird, pay attention to the hints that it is giving you by way of your ears. Chances are that if it sounds different, something is indeed different, and that should give you pause. But as always, fly the airplane first!

–Chip Wright