This piece originally ran in Lisa’s Airworthy column in the May 2022 issue of EAA Sport Aviation magazine.

Kate stepped out of the truck and shivered as a spring wind disguised as winter met her face. She shivered and pulled up the collar on her jacket as she walked to the small hangar access door. “It’s supposed to be spring,” she thought as she looked at the melting snow piled by the sides of the ramp.

Inside, she flipped the lights on. In the corner sat the Pulsar, ready to fly. The day before, she had spent hours going over every inch of the aircraft to make sure it was ready for flight after months of being locked in the dead of winter. She smartly thought to do her condition inspection before putting it away in the corner months ago. The Pulsar was high time, and she wanted to keep everything shipshape.

Ten minutes later, her friend Ted walked through the access door.

“Are you sure you want to fly? It’s still winter out there.”

“I know,” Kate said. “It’s always like this in April. Spring teases, and then it’s winter again. Be bold.”

“Okay. Ready?”

“Ready.”

They pulled the small airplane outside, climbed into the cockpit, and pulled the canopy closed against the wind.

The Rotax 912 started easily. After a few minutes, the oil temps came up and they taxied to the runway. After a runup and checks, Kate looked over at Ted. “This throttle cable feels sticky,” she said. “It could be the cold.”

“Did you lube it?”

“Sure. The indispensable WD-40.”

“We are right on the coast here with salt air. I’m not sure a solvent spray is going to help it.”

“I’m sure some use will free it up,” Kate said.

They took off and headed out over the coast. The sea was angry with whitecaps as waves rolled onto the rocky shore.

“A beautiful sight,” Ted said. “But I wouldn’t want to land in it.”

As they reached 3,000 feet, Kate pulled some power off. Suddenly, the engine went to full power.

“Whoa! Throttle isn’t working,” Kate shouted.

“Head back, Kate. We can turn the engine off when we get close. I bet the cable broke.”

“Have to be careful on V_NE descending,” Kate said as the Pulsar gained speed.

They weren’t far from the airport. Once Kate assessed they could make it, she turned the ignition to off. “Now we’re in a glider.”

“I’m glad you’ve practiced this already.”

“Well, not quite. Not with the engine off. But I suppose we could always turn it back on.”

Kate announced an emergency over the common traffic advisory frequency, even though there was nothing stirring at the tiny rural airport. Abeam the numbers she put in flaps. They were high. Turning to final, she executed a slip, and the Pulsar dropped rapidly. A quarter of the way down the runway, the Pulsar landed lightly and securely.

“That was one of your best landings,” Ted said.

“Thanks, but I’m not sure I want to repeat the circumstances.”

After exiting the airplane, they pulled the airplane onto the grass. The sun was higher in the sky and the air was warming up. They removed the cowling.

“Aha!” Ted said. “Look, the cable is broken all right.”

He pointed to a rusted nub that had been hidden inside the cable.

Kate shook her head. “Well, I sure missed that.”

How Do You Know What to Use on What?

If you’ve owned and maintained a bicycle or a motorcycle, you know about cables and chains. You might have learned the hard way not to use some lubricant types. For example, using motor oil on bicycle chains works for the first few miles, and then it gums up the works with dirt and debris.

WD-40 (the WD stands for “water displacement”) is not a lubricant; it is a solvent and rust dissolver containing petroleum distillates. While it’s a terrific product with dozens of household uses, it’s not a cable lubricant (see sidebar).

How do you know what to use? Dozens of products claim to be the best. The best for what?

The right answer here is to look in your aircraft manual to find exactly what products to use on what components. Certificated aircraft owners know this. Do you have an experimental? You may not have any information on what lubricants to use. Because many components of homebuilt aircraft are the same or similar to certified components, if we can find the advice for the certified components, we can transfer that knowledge to our homebuilts.

Knowing what to use can be critical, as we discovered in the story above. Here are the top five mistakes owners make.

Wrong Cable Lubricants

Don’t just grab any can. Most of us will have WD-40, silicone spray, 30-weight oil, a penetrant, and some kind of multipurpose spray.

 In my homebuilts, I sprang for the expensive Teflon cables for throttle and choke. These need a bit of grease only at the ends where they enter and exit the housing. Check the manufacturer’s recommendations on what to use and where.

Many certified engine control cables and aircraft control cables are sealed. It’s important to check the instructions for continued airworthiness and what sections need inspections. If you have an ordinary cable with a standard housing, you should only use cable lubricant, not thin solvent sprays.

Not Lubricating the Entire Cable

Where a cable is not sealed, the sections you can’t see are usually the trouble spots. It’s a chore to remove a cable. In some situations, you can easily use a luber tool. It’s less than $20 at your favorite aircraft supply store. These work well. Make sure you see the lubricant arrive at the other end.

Forgetting the Things That Are Out of Sight

Humans have a habit of forgetting what they can’t see. A checklist for lubricating hidden components is a good idea.

Using a Substitute Oil Filter

In our cars, a filter housing, seal, or bypass valve failure is usually not fatal. In our airplanes, it is serious. Engine oil is engine critical, and a failure in the system will stop everything. Non-OEM filters can have poorly fitting seals, inoperable bypass valves, thin housings, and cheap pleating material.

Use exactly what the engine manufacturer recommends, with exactly the oil and type it recommends. It’s a little more money, but I believe all pilots will agree that saving a few bucks on a cheap one-off filter isn’t worth risking an accident or losing an engine.

Not Cutting the Oil Filter Open for Inspection at Every Oil Change

“Gee, it was fine on the last one. I’ll skip it.” I hear this more often than I’d like. Your airplane is not your truck. It’s trickier to “coast to the side of the road” in your airplane. Albeit, we are accustomed to not experiencing problems in our cars and trucks. But in our airplanes, we want to be safe and go as long as we reasonably can between engine overhauls.

A close inspection of the pleats in the filter will tell us a lot about engine condition and tip us off to growing issues. If you’re not doing this now, you’re missing a big opportunity. Find out from the engine manufacturer what to look for, and ask an A&P mechanic to step you through it the first time if this is new to you. Periodic oil analysis is also a great way to keep tabs on engine condition.

Any large particle screen in the oil system should also be examined by a trained eye. If it’s too hard to get to (think Lycoming), the next best thing is to stir the bottom of your oil bucket with a magnet. You can also pour the oil through fine screening or cheesecloth to see what you get.

Is this a lot of trouble? Not if you’re an owner who really wants to discover problems before the problems discover you. For a discussion of best practices on oil inspection and analysis, see Mike Busch’s Mike Busch on Engines book, available for purchase via the link at EAA.org/Extras.

Tips

I talked to an accomplished metallurgical engineer several years ago who told me, “The purpose of a lubricant — any lubricant — is to transfer heat as efficiently between two mating surfaces as practicable. Friction, being necessary for any work to take place, becomes the source of the heat that reduces component wear. In a cold engine, friction can cause wear — but in a properly lubricated engine it helps bring components up to operating temperature and actually minimizes pitting, fretting, and galling damage at microscopic levels as surfaces make and break cold welds.”

This argues for using the correct lubricant in the right place at the right temperature. Yes, wait for the oil temps to come up before flying.

One reason this topic can be confusing is that the market offers us dozens of products. Whether we’re looking at engine oil, synthetic oil, chain lube, or penetrating oil, multiple variations line the shelves. And sometimes the detail in the manual either is not there or doesn’t narrow our choices.

Going by the Book

Advisory Circular 43.13-1B, Acceptable Methods, Techniques, and Practices — Aircraft Inspection and Repair, which you can read via the link at EAA.org/Extras, offers advice on corrosion protection in Chapter 6. It even provides the specifications for corrosion treatment for carbon steel cables. Even this specific advice can confuse people when we’re using different cable jackets, sealed cables, and different materials for the cables themselves.

Go from grabbing a spray can to notating your owner’s manual and condition inspection checklist with exactly the lubricants the manufacturer wants you to use.

Lisa Turner, EAA Lifetime 509911, is a manufacturing engineer, A&P, EAA technical counselor and flight advisor, and former DAR. She built and flew a Pulsar XP and Kolb Mark III, and is researching her next homebuilt project. Lisa’s third book, Dream Take Flight, details her Pulsar flying adventures and life lessons. Write Lisa at Lisa@DreamTakeFlight.com and learn more at DreamTakeFlight.com.