When Go Becomes No

The following editorial is guest written by Jared Jacobs.

Recently, I decided to take our F33A to Little Rock, Arkansas, to visit family. Between work and personal matters, I had plenty on my mind that morning, and I was ready to get out of town early to make good time.

As soon as I rotated, however, I knew something was up. There was a distinct and unfamiliar vibration in the yoke and floorboards. I scanned my engine instruments and found no obvious abnormalities, so I decided to continue the climb to a safe altitude for further troubleshooting.

As I gained altitude, I did my best to narrow down the source of the vibration. Controllability was fine despite the shudder I was feeling in the ailerons. When I selected the gear up, there was no noticeable change to the feeling. When I reduced propeller RPM from 2700 to 2500, I noted a slight difference, but could not tell if it was better or worse. All throughout the climb my eyes were glued to the engine gauges as I monitored the indications and aircraft performance. To my relief, all were still completely normal.

Upon reaching a cruising altitude (and with a suitable landing airport nearby), I closed the cowl flaps and conducted a magneto check. Neither action gave me a better understanding of the source of the vibration. The final check was to lean the mixture for cruise and again monitor the engine indications. Every engine indication was exactly as I would have expected.

Having exhausted the troubleshooting possibilities that came to mind, doubt began to creep in my mind. Was I really feeling something that was abnormal? Was it bad enough to abort the trip that I had been looking forward to? Was it worth taking the aircraft to the shop? I had been flying turbine aircraft the last few weeks; maybe I was just being overly sensitive to a totally normal shake coming from a piston engine.

As I convinced myself that this was all in my head, I pressed on. But there was an uneasy feeling still nagging at me…was flying two hours like this a good idea? Should I really continue from the flatlands of Kansas into the Ozark wilderness of Northwest Arkansas with a misbehaving aircraft? If I made it to Little Rock, would I end up being forced to do maintenance at an unfamiliar shop if the issue got worse?

Thinking back, the only thing that made a difference was the reduction in propeller RPM. So, I made another adjustment from 2500 to 2300 and noticed a definite reduction in the vibration. This told me everything I needed to know. From experience, I knew that this engine had run noticeably smoother at 2500 RPM than it did at 2300 RPM on previous flights. This was not normal. Something was different.

Despite the pressure to make it to see family, I made the 180-degree turn back to Wichita. I have made the “no go” decision plenty of times in my professional flying, but for some reason, this decision seemed harder. The only explanation is that my emotional desire to “go” was stronger in this scenario than it’s been in the emotional vacuum of corporate flying. Get-there-itis snuck into the cockpit with me that morning, and I let it take the controls for longer than I am happy to admit.

Decision made, I set a course for Jabara (AAO) instead of our home airport of Augusta (3AU). I had good maintenance options at both locations, but friend and aircraft partner Ryan worked across the street from AAO. I wanted a second set of eyes on this before we decided to put 1RW in the shop. I remained at cruise altitude much longer than I normally would and made a circling descent within gliding distance of three suitable airfields – just in case.

After an uneventful landing, Ryan met me on the ramp at AAO. I went over the story, we checked out a number of theories, and ultimately decided to have the shop dig into the aircraft and see what they could find. I phoned my parents to give them the news, and instead of being disappointed, they were relieved and convinced that I had made the right decision. As an aviator, I knew that I had come to the right conclusion to return when I was sure that the aircraft was behaving differently. Still, hearing confirmation from other parties did make the weight of the choice feel lighter.

So, what did the shop find? Nothing actually. Not anything that would directly lead to the vibration. It was a day later when I had the idea to search BeechTalk for “Bonanza vibration” and saw the first search result titled “Flying with Tip Tanks” and I found the answer. As it turns out, something was different that morning. It was the first time I topped off our Bonanza with full fuel in the main and tip tanks. Previously unbeknownst to me, when the aftermarket tip tanks are full of fuel, they will cause a very noticeable harmonic vibration which can be felt in the floorboards and yoke of the aircraft. The remedy? Transfer about 3 to 5 gallons from the tips to the main tanks and the vibration will go away. I had obviously never heard of this, so I was caught off guard and never thought to try transferring fuel during my troubleshooting.

Knowing what I know now, I still stand by the choice to abort the flight. When I was sure something was different with the aircraft that I could not explain, there was no good reason to press on, especially with the external pressures I put on myself to make it to the destination. The urge to go should always come second to a clear reason for no.