Episode 5: It’s All About the Pre-Flight

Episode 5 · Published March 27, 2020 · 40 minutes, 14 seconds · Hosts: Ron and Tom

A dependable RC airplane flight begins before the wheels ever leave the ground. In Episode 5 of the RC Plane Lab podcast, Ron and Tom walk through the quick pre-flight checks they perform before takeoff and the much more detailed inspection they perform before the beginning of a flying season.

Along the way, Ron shares a battery-charging mistake involving two identical-looking connectors wired with opposite polarity, while Tom tells the painful story of rebuilding a Pica Duellist all winter only to destroy it on takeoff because the ailerons were reversed.

Free RC Plane Lab Pre-Flight Checklist

Ron mentions in the episode that he carries a small laminated pre-flight checklist with his transmitter. That original RC Plane Lab checklist is still available below.

Download the Pre-Flight Checklist PDF →

Print it, laminate it if you’d like, and keep it with your transmitter or field box so it is available regardless of which airplane you take flying.

A Battery-Polarity Lesson

Before getting into pre-flight checks, Ron shares an unexpected lesson involving small one-cell LiPo batteries.

He had several 500 mAh batteries and some 250 mAh batteries from different manufacturers. Because they used the same physical connector, Ron connected all of them to the same five-port USB charger and walked away.

Shortly afterward, he smelled smoke.

The charger itself had begun melting. Ron eventually discovered that the positive and negative wires on one battery type were reversed compared with the other—even though the connectors were physically identical.

The Control Check Before Every Flight

Ron and Tom both make the same basic recommendation: stand where you can clearly see the airplane, move the controls, and verify that the airplane does what you are commanding.

• Elevator: Pulling back on the stick should move the elevator trailing edge upward. Pushing forward should move it downward.
• Ailerons: Right stick should raise the right aileron and lower the left. Left stick should raise the left aileron and lower the right.
• Rudder: Right rudder should move the rudder trailing edge right. Left rudder should move it left.
• Throttle: Confirm that the power system responds in the expected direction and manner.

While moving the controls, also look for binding, disconnected linkages, unusual servo noise, loose hardware, or anything else that doesn’t look normal.

It takes only a few seconds once the routine becomes a habit.

Check the Power System

On a nitro or gasoline airplane, Ron and Tom recommend running the engine up before takeoff and making sure it transitions properly and can sustain full power.

For electric airplanes, verify the power system safely as well. When initially setting up an electric power system, remove the propeller whenever practical before programming or testing throttle direction.

Tom also discusses using the transmitter’s flight timer. His radio starts a countdown timer when full throttle is commanded for the first time, giving him a reminder of how long that particular airplane has been flying.

Runway, Airspace, and Wind

Before moving onto the runway, check that nobody is retrieving an airplane and that another model is not in your intended takeoff path.

Then look at the windsock.

Ron and Tom emphasize taking off and landing into the wind whenever conditions and field procedures allow. A tailwind during landing increases groundspeed for a given airspeed and can make judging the approach more difficult. What matters aerodynamically is maintaining sufficient airflow over the wing.

The Pre-Flight That Would Have Saved Tom’s Duellist

Tom’s story provides the clearest reason in the episode for checking control direction every time.

He acquired a fuel-soaked Pica Duellist, a twin-engine pattern airplane. Tom completely stripped the airplane, treated the fuel-soaked structure, recovered it, installed equipment, and spent much of a winter returning it to flying condition.

Because the airplane had flown before and he believed everything had been reinstalled exactly as it had been removed, he assumed the controls would still operate correctly.

At the field, both engines were running beautifully. The retracts worked. The airplane accelerated down the long paved runway and made what Tom remembers as a picture-perfect takeoff.

Then he commanded a turn.

The Duellist rolled violently in the opposite direction.

The ailerons were reversed.

Because the airplane was already fast and low, Tom had almost no time to understand what was happening. The Duellist continued rolling until it hit the ground.

The wreckage went home in what became known as the “Duellist bucket.”

Repeat the Check Before Every Takeoff

Ron and Tom don’t limit the pre-flight to the first flight of the day.

If the airplane lands, a battery is changed, the receiver is turned off, equipment is connected or disconnected, or the model is otherwise handled between flights, they recommend performing the quick control check again before the next takeoff.

The whole point is to develop a repeatable routine. Once the movements become familiar, something unusual stands out immediately.

The Preseason Inspection

The quick pre-flight at the field is different from the inspection an airplane should receive after sitting for a long period of time.

Before returning an airplane to service, Ron and Tom go much deeper.

Check the Batteries

Inspect and test every battery system used by the airplane, including receiver packs, ignition batteries, electric flight batteries, and transmitter batteries where appropriate.

Tom discusses cycling NiMH packs and comparing measured capacity with rated capacity. Ron also talks about testing battery voltage under load rather than relying only on an unloaded voltage reading.

If a battery cannot safely deliver the expected capacity or maintain appropriate voltage under load, it does not belong in an airplane.

Inspect the Airframe and Hardware

Look over the complete airplane and check for loose hardware, bent landing gear, damaged pushrods, worn hinges, loose control horns, cracked mounts, and any other structural problem.

This is also a good time to notice damage that may have occurred while moving or storing the airplane.

Check and Balance the Propeller

Tom likes to remove and check the propellers on airplanes he expects to fly during the season.

An out-of-balance propeller creates unnecessary vibration. Vibration can loosen hardware, shorten bearing life, fatigue structures, and make life harder on electronics and electrical connections.

Inspect Nitro and Gas Engines

With the propeller removed, inspect the engine carefully. Tom recalls finding a dark oily residue underneath one airplane and tracing it to a leaking front crankshaft bearing.

Finding that problem in the shop is much better than discovering it at the flying field—or after takeoff.

Inspect Electric Motors

With the battery disconnected and the propeller removed, rotate an electric motor by hand and pay attention to how it feels.

The magnetic detents are normal. Grinding, roughness, unusual looseness, or a gritty-feeling bearing is not.

Inspect Fuel Tanks and Fuel Lines

For nitro and gasoline airplanes, inspect the fuel tank, fittings, clunk, and tubing.

Make sure the clunk can move freely throughout the tank. Tubing can harden with age, potentially leaving the clunk stuck in one position. Inspect tank seams for leaks and replace brittle or questionable fuel line before it creates an engine problem in flight.

Don’t Forget About Storage Damage

Airplanes stored in garages, sheds, trailers, or other less-controlled spaces can develop problems even when they haven’t been flown.

Mud Daubers and Other Visitors

Tom mentions mud daubers, which can build nests inside muffler outlets, carburetor openings, fuselages, and other protected spaces.

Inspect openings before starting an airplane that has been stored for an extended period.

Check the Covering

Heat, fuel, age, and storage can cause covering seams to loosen. On fuel-powered airplanes, oil contamination can eventually make it impossible to simply iron a seam back down.

A loose piece of covering is much easier to repair in the shop than after it begins peeling away in flight.

Moisture and Trailer Leaks

Ron describes discovering that his storage trailer had developed a leak. By the time the problem was found, moisture had caused wood to swell and warp badly enough that he estimated approximately three airplanes were lost.

Corroded or rusty hardware can be an early warning that moisture or excessive humidity is present even before the wooden structure looks severely damaged.

Episode 5 Takeaways

• Check control direction before every takeoff.
• Never assume controls are correct because the airplane flew previously.
• Matching battery connectors do not automatically mean matching polarity.
• Verify the power system before entering the runway.
• Check the runway, airspace, and wind direction.
• Repeat the pre-flight after landing and before taking off again.
• Perform a more detailed inspection before returning stored airplanes to service.
• Test batteries rather than assuming a full charge means a healthy battery.
• Inspect propellers, hardware, engines, motors, fuel systems, covering, and airframes.
• Storage can damage an airplane even when it never leaves the ground.

Episode 5 Transcript

This transcript has been lightly edited for readability. Timestamps are retained.