By Vic Syracuse, EAA Lifetime 180848
This piece originally ran in Vic’s Checkpoints column in the September 2025 issue of EAA Sport Aviation magazine.
The title of this month’s column is one of the most oft-asked question by pilots, which is usually followed up by “Why won’t it stop?” Most of the time the question is due to the automation in the aircraft either being programmed incorrectly or a lack of understanding by the pilot.
There are many accidents in the NTSB aviation accident database that list cockpit confusion as a contributing factor. Sometimes, though, an understanding of the interaction between various cockpit indications can help the pilot decide on the best course of action, which may be no action. I want to share with you a recent example I experienced.
I was flying a Schweizer 269C helicopter from Penn Yan, New York, to my home in Georgia. It was a recently completed ground-up restoration, which included a new Lycoming HIO-360-D1A engine along with a new Garmin radio stack.
It only had a few hours on it when I picked it up. Luckily, Carl Olson, a retired Schweizer test pilot, was there. We flew together for an hour and a half before I headed home. It was an honor to fly with him.
Of note was that this very helicopter was built in 1992, and Carl’s signature was in the logbook for the factory acceptance flight! His signature was also now in the logbook again as having performed the flight check after the restoration.
I treat ground-up restorations no differently than a new amateur-built aircraft. Don’t trust them until they have completed at least 100 hours of flight time or at least four oil changes, with thorough inspections occurring at each oil change.
Aircraft, whether restored or newly created, are complicated projects with lots of moving parts and connections, even more so on helicopters.
The flight home included multiple stops and more than 14 hours of flight time. Some of it was over territory that reminded me of parts of Alaska, in that emergency landing sites were few and far between. Once I got into the mindset that I was in a helicopter, I noticed a lot more potential sites if needed, including many forest service fire breaks.
For a new engine, one of the first unknowns is the oil consumption. The pilot’s operating handbook for the 269C specifies no less than 6 quarts of oil should be in the 8-quart sump. That is totally different than the IO-360 in our RV aircraft, as anything more than 6 quarts is usually blown out through the breather, leading you to think oil consumption is higher than it is. I started the flight back with 7 quarts showing on the dipstick.
Fuel stops were planned for every two-and-a-half hours, which would leave more than two hours of fuel remaining in the tanks, as it was equipped with two fuel tanks totaling 49 gallons.
Fuel consumption was estimated to be about 12 gph. I checked the oil level at the first fuel stop, and the dipstick still indicated more than 6 quarts. Truth be told, it is hard to identify the actual reading on the dipstick of a hot engine with fresh oil in it, and the long twisting dipstick on the 269C makes it even more difficult to get a good reading.
The oil temp gauge had been consistently indicating 125 degrees Fahrenheit for the entire flight, which is too cold. I figured I would address that once I got home. About halfway through the second leg, I noticed the oil temp was now showing 150 degrees Fahrenheit. It was a really rapid movement, as I assure you I had constantly been scanning engine instruments at least every 30 seconds due to my trust issues. Of course, one’s mind immediately goes to the dark side. Was the oil quantity lower than I thought? Was there a leak?
Oil pressure had not changed at all. Usually, you can see a drop in oil pressure as oil temp rises. On my RV-10, digital gauges make it easy to see how a couple of degrees’ change in the oil temp can change the pressure by about 1 psi. Here I was looking at old analog gauges whose needle width was probably 10 degrees or more.
At first, I checked for the nearest airport. Then I said to myself, “Why do I need an airport? I’m in a helicopter.” Duh! I started looking for a good field to set down in, all the while scanning the oil temp more often than before. It stayed at around 150 degrees, and then it happened. I saw it flick rapidly back down to 125 degrees! Well, that’s hard for the oil system to actually do that, so I decided not to set down. I kept my eyes glued to the gauge for the remainder of the flight. Eventually, I saw it do that a couple of more times. I concluded it was an indication problem. No need for immediate action.
Another anomaly I noticed was that the cylinder head temperature indication was running a little hot, but I attributed that to a new engine. However, I also noticed it seemed to take longer to cool down during shutdown. As luck would have it, I finally noticed the CHT gauge would flicker occasionally. Aha! Perhaps there is a loose ground or common failure point for both gauges, as they both use resistance probes as their sensors.
Once I got home, I started troubleshooting. While the cause for each one was different, I have seen similar symptoms on other aircraft and wanted to share them with you.
One of the easiest ways to verify a proper temperature indication is to remove the probe from the engine and place it in a pan of boiling water, with the wires connected of course. The cockpit indication should be close to 212 degrees Fahrenheit at sea level, lower if at higher altitudes. In this case, the oil temp probe was perfect! Since both probes work by measuring resistance to ground, I had a pretty good idea of the source of the problem.
I measured the resistance of the probe housing to the Airwolf remote filter adapter housing, to which the probe was mounted. It showed a resistance of 62-104 ohms. It should have been zero ohms. The only way to get a good ground on the adapter was to use a Dremel with a wire wheel on it and remove the anodizing underneath one of the adapter’s attach bolts and the probe. I finally achieved zero ohms of resistance. On multiple subsequent flights, the oil temp indication has remained rock solid, and the accuracy has been verified by using a laser thermometer aimed directly at the probe.
The CHT was a different problem. It is a bayonet probe and has a small 4-40 threaded connection at the top of it for the wire to connect to the cockpit indicator. Whoever installed it had overtorqued the nut, which is easy to do on small brass threads.
This caused a high resistance and sometimes intermittent connection, which resulted in higher indications. Replacing the probe solved that problem. Since then, I’ve also added a four-cylinder CHT/EGT instrument, so I am not single-threaded to one gauge.
The moral of the story here is to try to understand your aircraft’s systems so you won’t take unnecessary actions in flight that could put a damper on the fun factor.
Vic Syracuse, EAA Lifetime 180848, is a commercial pilot, A&P/IA mechanic, designated airworthiness representative, and EAA flight advisor and technical counselor. He has built 11 aircraft and has logged more than 11,000 hours in 75 different types. Vic founded Base Leg Aviation, has authored books on maintenance and prebuy inspections, and posts videos weekly on his YouTube channel. He also volunteers as a Young Eagles pilot.