When Your Engine Talks To You

A mid-season engine change


Patty Wagstaff and Allen Barrett in the BPE Test Cell

If you drive down Sheridan Road just outside the perimeter of the Tulsa International Airport, you'll find a row of small industrial buildings housing aviation engine, machine and hose shops. There are some pretty smart people who run these shops, but behind the doors of one small, nondescript building lies true aviation genius: the headquarters of Barrett Precision Engines (BPE).

BPE was started by Monty and Betty Barrett about 30 years ago. Monty's background includes corporate pilot, engineer and homebuilder, but maybe it was his experience as a flat track racer, aerobatic competitor and air show pilot that gave him a talent for getting the most out of an engine while keeping its integrity and reliability. Along the way, Monty also found time to be the U.S. Aerobatic Team mechanic and build his genius in-house dynamometer test cell that can measure performance and test-run engines before they ever leave the shop. While Monty and Betty still stay active in the business, the shop is now run by their son and daughter, Allen Barrett and Rhonda Barrett-Bewley.

BPE isn't a big shop, but it has a big heart. The Barretts know the meaning of family and treat their customers as such. Whether operating an Extra or a Bonanza, I recommend all of my friends to BPE for their engine work. BPE has taken care of my engines as long as I've been flying aerobatics, and Monty has driven an engine to me overnight more than once so I could compete at a championship. So, when my engine started talking to me earlier this season, I went to Monty and Allen for advice.

Unlike my previous engines, modified Lycoming AEIO-540s, I currently fly a Lycoming AEIO-580 Thunderbolt, a relatively new development. Due to visionary leadership at the time, Lycoming decided to build their own super weapon---an engine with more HP right off the factory floor that could compete with the engine modification shops. Good news is that it's a powerful and reliable engine; bad news is that while Lycoming has supported a number of us over the years, the support has diminished, and a new Thunderbolt 580 is très expensive and not easy to get on short notice.

For pro akro pilots, engine overhauls are a hard fact of life. Because logistics are key to having a successful season, we plan for them off-season, during the winter. And, while we hope to get as much life out of them as we can, we run them hard and hot, and don't expect to see TBO. My normal cruise power settings are around 23 inches of mp, 2,350 rpm with a fuel flow of 18 gph, but air show settings will be whatever mp I can get, 2,875 to 2,900 rpm on my MT-Propeller with a thirsty fuel flow of 34 gph. Most engine time is spent in cruise, but it's the combination of high rpms and +10 Gs to -8 Gs that puts the most wear and tear on the engine and its components. Sooner or later, G forces and gyroscopics take their toll, and when it does can't always be predicted.

I'm not an A&P mechanic, but I do know that the engine is the heart and soul of the airplane, and it's best to listen to it when it starts talking. Sometimes the message is subtle, but for the pilot willing to listen, there can be plenty of warning when something is "going on." An engine that's ready to come apart can sound as strong as the day it was built, so while you may not hear anything unusual, the engine speaks to the pilot in other ways ---usually through critical engine instruments: oil pressure, oil temperature, cylinder head temperature and sometimes fuel flow or fuel pressure.

When flying my Extra, it's hard not to stare at those critical gauges because the instrument panel is close and spare. Other than airspeed, altimeter and a G-meter, there isn't much else to look at. It was on my way to an air show earlier this season when I first noticed a small, subtle drop in oil pressure. The oil temp was good and everything else seemed normal, so I kept on going. During my performance, I then noticed a slightly larger drop in oil pressure when the temps got hotter. This is something I expect, but it was subtly lower than in previous flights, so I called my maintenance team, Richard Hamilton and Chris Rudd. We knew the compressions were good and the engine was still strong, so after some discussion, we decided to call out a local A&P to turn the oil pressure spring to increase the pressure and see if that made a difference.


After the show, I flew back to Florida with no new indications, so Chris decided the airplane was fine to ferry to our next air show in Snyder, Texas. Chris, who specializes in maintaining and ferrying high-performance aerobatic airplanes, kept a close eye on things and flew the 1,000-mile trip from KSGJ to KSNK. During my performance, the engine felt strong, except for a slightly higher drop in oil pressure when the oil temp heated up.

Our next stop was the Dayton air show, and we had already planned a stop in Tulsa to visit the Barretts. Chris and Allen had been discussing the oil pressure issue, and when I discussed it with Monty he said, "Patty, the engine is talking to you. It's telling you it's tired. It needs some bottom-end work, including replacing the main bearing." The consensus was that while the engine still had some life left in it, it would have to be done soon and quickly. So much for all my carefully planned logistics!

I had many questions: Would the airplane be ready in time for Oshkosh just a few weeks away? Where would we hangar the airplane, as the shop isn't directly on the airport? How would Chris get back and forth to Tulsa from his home in southern Georgia? Would the July 4th weekend create time issues?

After a lot of discussion and exploring some of Tulsa's excellent dining options, we decided to continue to Dayton and fly the air show, but made the tough decision to cancel our next air show in Truckee, Calif. Chris would fly to Tulsa after Dayton and remove the engine. I'd fly the Bonanza back to Florida, and when BPE had finished the engine overhaul, Chris would return to Tulsa to help reinstall it and then deliver it to Oshkosh. There were other considerations, too. Because BPE isn't on the airport, we had to line up a hangar close by, so I called my good friends at the Spartan College of Aeronautics and Technology and asked if we could use one of their "classrooms" (a big hangar) for a week or so while we did the engine change. They graciously offered to help. And since an overhaul is an ideal time to change engine mounts, LORD Corporation sent us some posthaste.

As the Barretts predicted, when they took the engine apart, they found the bottom end was "tired." After replacing the main bearing and some other parts, they reassembled it. Chris returned to Tulsa to help with the installation, test-flew it and then flew the airplane to Oshkosh. All of this happened within a few short weeks, and I got to fly Oshkosh and will finish out the season with a perfect, strong engine.

I'm often asked how many engine failures I've had. I've had very few major engine problems, and the ones I have had happened over a runway while practicing in a box. I've been lucky, but I believe some of my luck is attributable to, for the most part, having the luxury of owning and flying the same equipment. Becoming intimately familiar with the same airplane and engine gives a pilot greater insight into small and subtle changes---if they're willing to listen and pay attention. I've always had the best maintenance and best engine shop in the world taking care of me and my equipment. I have fantastic longtime sponsors like LORD Corporation, Champion Aerospace and, in the past, Aeroshell and Lycoming, helping with supplies and parts.

We plan for everything and hope the season goes the way we plan, but sometimes things change. You do what you have to do to get the airplane in the air and keep flying. That's show business. When the going gets tough, the tough keep going, and we get 'er done. It takes a village, but it also takes the right engines, the right maintenance and the right engine shop. I've been lucky and am grateful for that, and I'm also grateful to be supported by the best people in the world---people in aviation.

Patty Wagstaff is a 3-time U.S. National Aerobatic champion, and one of the world's top airshow pilots. Visit pattywagstaff.com/school.html or reach Patty via email through pattyaerobatics@gmail.com.

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