Did that Sound Right to You?

After a hundred hours, I thought I knew my airplane. After all, I had started the engine and stopped it, extended and retracted the landing gear, and operated in every configuration in the Pilots Handbook. After flying a distance equivalent to crossing our great nation several times, I had become comfortable in my knowledge of my airplane and its characteristics. That was soon to change…

A problem with my starter drive brought this issue to light. The starter drive had failed … and caused an oil leak. My engine shop replaced the starter drive with a serviceable unit after some wrangling and, of course, flushing of the engine to get any metal particles out. I got a ride out to the airport from a friend, and we discussed what had happened, and how I could have stopped the issue before it caused damage.

In any event, it was time to start the plane up and get going. A visual inspection for oil leaks and a thorough preflight had already been completed, and no leaks had been found. The engine bay was as clean as a whistle, thanks to the solvent and pressure washer that had been used to strip the oil out of the area. I thought I was ready for anything!

I TURNED ON THE MASTER SWITCH, AND PRIMED THE ENGINE. The sounds of the primer, and the rise in fuel pressure was as I expected it to be. Following the checklist, I closed the throttle, and then reopened it the recommended quarter inch, or four turns on the vernier. Everything looked good-to-go, and my hand moved to the starter key.

I popped open the side vent window, and despite the fact nobody was in sight, shouted a good, loud ‘CLEAR!’ to warn anyone not in sight that my engine would be started. After pausing to listen for anyone to say they weren’t clear of my propeller, I took the key switch to the start position for a few seconds… AND THEN PROMPTLY RELEASED IT.

The sound the engine made on start wasn’t anything like what it used to. Instead of the brash, loud growl I had expected, the engine made a whirring sound, more akin to a sewing machine. The difference was the new starter drive. The shop manager explained it simply: The new starter drive had the proper clearance, and they had cleaned out the accessory case. The engine was now making the sound he expected on start.

I WAS SURPRISED BY THE NEW SOUND, because it didn’t sound like the old sound. Still, when I thought about it, I knew which sound I should be more comfortable hearing. A whir is better than a growling grind any day of the week, so I quickly adapted my acceptance to the new ‘whir‘ when the key was taken to start.

KNOW WHAT YOUR ENGINE AND ACCESSORIES SHOULD SOUND LIKE. If you are flying around in an older plane, and someone has a plane like yours and gets an engine or accessory overhaul, ask to go for a ride.

  • LISTEN — as it occurs — to each specific activity of the engine and accessory.
  • ASK YOUR MECHANIC to check out any differences you hear during this check.

In some cases, the year a particular engine was produced may make a difference in the noise it makes, but in others, you may find problems before they spring up unexpectedly in flight to find you. The key to success in this approach is to be an active listener. This philosophy applies regardless of when you fly your plane — it should sound ‘right’ every time. If you hear something that doesn’t sound normal, stop the engine or activity and get it checked out!

THE BOTTOM LINE — Listening to your engine when it starts and shuts down, your electric fuel pump, your landing gear and flap motors, and even the wheels as you taxi can help you find problems before they become events. Unless you thrive on the rush of adrenaline that comes when a problem occurs in flight, active listening will help keep your flying the way it should be — safe and event-free!