By Vic Syracuse, EAA Lifetime 180848
This piece originally ran in Vic’s Checkpoints column in the March 2022 issue of EAA Sport Aviation magazine.
Sometimes we can still have a good time with our airplanes, even if flying is not in the cards. This is especially true in the off-season. I do this by getting caught up on some maintenance items when the weather is crummy. Rather than a whole column on one single topic, here’s a list of some things you might consider checking. They might keep you from missing a morning breakfast fly-out with your buddies later in the season.
Since we can’t go anywhere unless we can get it started, the ignition system is important. For some reason, spark plugs do not get the attention they deserve. We see way too many worn-out, lead-fouled, and high-resistance plugs than we should. A practice I have always maintained on my own airplanes is to pull the spark plugs every 50 hours and check them. I have found that 50 percent of them will usually need a gap adjustment, as well as a good cleaning to remove some lead deposits. Occasionally, I will find a plug that does not meet my resistance specification of greater than 500 ohms and less than 2.2K ohms. It doesn’t take long to check all of them, and you can usually accomplish it while the oil is draining.
Don’t forget to check the other end of the spark plug wire, especially for those of you who have electronic ignitions with the coils mounted on top of the engine. We see a lot of corrosion on these connections, especially on ones that fly in the rain or are in damp environments. Remove the wires and clean the contacts. We will also add some Dow Corning 4 insulating compound to them, which seems to protect the connection.
With this practice, in more than 6,000 hours of flying airplanes I have built, I have never had a fouled plug during a runup, or a failed start due to a spark plug or ignition problem.
For those of you who have new engines that haven’t quite broken in yet, or those of you who have “oil-burner” engines, take the time to solvent clean any of the oil-fouled plugs. The oil seeping past the piston rings during periods of nonuse will tend to fill up the spark plugs, sometimes causing them to misfire or not fire at all. If you are running auto plugs on an electronic ignition system, it might just be easier and more cost-effective to replace them.
The lower spark plugs can easily get oil-fouled from oil leaking past the piston rings. Wet oil, as seen here on plug 1, is leaking past during periods of inactivity. Clean it out with a solvent. If running auto plugs on the lower plugs, just consider replacing them due to the low cost.
While you’ve got the cowling down checking the spark plugs, take the time to look at the intake gaskets. On Lycoming engines, we are finding that they need to be changed every 300-500 hours. They’re not that hard to do. They take around 20 minutes per cylinder and cost around $10 in parts. New gaskets will make for a smoother-running engine at idle, and leaking ones will cause a cylinder to run lean. A quick check is to pull the throttle to idle while on base or final and take a quick look at the EGTs. They should decrease in temperature immediately. A leaking gasket will be indicated by an immediate rise in the EGT indication. Blue stains from the 100LL dye can usually be seen around the gaskets, and sometimes there are even streaks running down the intake tubes.
Intake gaskets are overlooked most of the time. They harden with age and will leak, causing a lean running cylinder, which is most often indicated by poor idling. Read the column for a quick in-flight test to check yours.
I’ve mentioned this next tidbit in multiple columns — when you remove the cowling, take the time to look for rubbing and wear marks on it, which can indicate the engine is contacting the cowling during operation. It’s not just good enough to check the cowling when it is installed to verify there is no contact with anything, as the engine moves around quite a bit during normal operation, especially at startup and shutdown. We are seeing a lot of cracking of the air box mounting plate on Van’s RV aircraft due to this type of contact. Take the time to check your air box mounting plate with a bright light and look for any hairline cracks. Van’s Aircraft now has a new air box design with some long-needed modifications that should preclude some of the cracking and wearing as long as cowl contact is not made. If you have an older RV, consider installing the new air box.
Take the time to look at some other areas while the cowling is down, especially the hoses. Unless Teflon-lined hoses were installed during the build, most hoses have a life expectancy of eight years. I know at first glance it can look daunting to replace all the hoses, especially if you are a nonbuilder. But just like every journey starts with that first step, each hose can be replaced individually. Of course, you can always remove them all and send them off to someone who will build new ones for you, making replacement quite simple.
It is also a good time to get caught up on service bulletins (SBs). You do pay attention to those, right? Take the time to go to your airplane manufacturer’s website and download a list of the SBs for your aircraft. Pay special attention to any that have been issued within the last year. Many of them are one-time inspections or fixes, but some of them are recurring. An example is the SB for potential leaking of the Kavlico engine sensors. Some seem to leak, and some don’t, but it’s a good idea to check them regularly.
If the airplane is new to you, it’s a really good idea to download all the SBs at least once and verify they have been completed. Every month we see aircraft during prebuy inspections that have not had everything completed, and sometimes they are just one failure away from being stranded somewhere. A most recent example pertains to an SB issued by Van’s Aircraft in 2006 for poor crimps on battery cables. Just this past month I tugged on a couple of them on an RV, and the wire separated from the crimp quite easily. What happens with loose crimps over time is that the junction will corrode and build up such high resistance that it eventually prevents current flow. I know of more than one customer who has replaced a battery and a starter before discovering it was the wire crimp.
Another area that seems to get neglected is the tail strobe and position light. No doubt this item is in one of the worst environments on the aircraft, especially on taildraggers. All the oil from the belly, exhaust residue, and grime tossed up while taxiing seems to collect on the tail light. And if the gasket is not in great shape, it finds its way inside the unit and burns out the strobe and light bulb. Plus, all the grime on the inside and outside makes it difficult to see through the lens to verify the condition of the bulbs. It’s also in a very-high vibration environment. Replacing the tail strobe units are expensive. Not so much the light bulb. If you can afford it, consider replacing the tail unit with one of the LED units, which are sealed and seem to last much longer.
The last item I want to discuss has to do with propellers. Propellers have a recommended time before overhaul, just like engines. Most of them have a calendar limit as well as an hour limit. Most of us doing sport flying reach the calendar limit long before reaching the hourly limit. I also know in Part 91 flying they are only “recommended” times, and we don’t have to follow them. Some recent articles seem to speak to that concept, giving owners and pilots some ammunition that they don’t have to comply. After all, most of us are cheap and would rather not spend money if we don’t have to.
For the record, I strongly disagree with some of the opinions that are being voiced. Think about it for a minute — we are flying single-engine airplanes, which means one propeller. These are no longer the days of only flying a tube-and-fabric aircraft with no electrical system for the Saturday $100 hamburger. We are flying very well-equipped airplanes, sometimes at night, on instruments, with trusting family and/or passengers on board. My belief is that if the propeller manufacturer recommends a certain calendar time for an overhaul, we should pay attention. After all, it sees a whole lot more propellers daily than we ever will. From experience, we send off about three propellers for overhaul every two months from our shop. Most of them end up just requiring an overhaul. But about 20-30 percent of them need something more, such as bearings or other parts replaced. In one case, we sent two out the same day that had the exact same hours and calendar time on them, and one needed nothing except the overhaul, while the other needed some real work done on the internals. That was the eye-opener for us.
Most recently on our field, where there is the attitude sometimes that if it isn’t broken, don’t fix it, one of our friends was convinced to not send his prop out for overhaul due to exceeding the calendar time limit. We convinced him otherwise, and his also needed extra work inside.
Why risk it? For me, safety is paramount. I might let a prop go one to two years past calendar overhaul, but much beyond that is risky. Just this month we had one come in that was 16 years past calendar overhaul, along with 2,000 hours on it. After a discussion with the owner, we did send it off for overhaul. Prop overhauls do cause some downtime, so wintertime is a good time to get them done.
Hopefully, this shortlist of maintenance items, if addressed, will increase the fun factor for you during the flying season!
Vic Syracuse, EAA Lifetime 180848 and chair of EAA’s Homebuilt Aircraft Council, is a commercial pilot, A&P/IA, DAR, and EAA flight advisor, and technical counselor. He has built 11 aircraft and has logged more 9,500 hours in 72 different types. Vic also founded Base Leg Aviation and volunteers as a Young Eagles pilot and an Angel Flight pilot.