Spring Preflight Checklist

Written by Greg Gimlick
Ensure your aircraft are flight ready
As seen in the Spring 2018 issue of
Park Pilot.

>>Break out your stuff! Spring has arrived in most parts of the country and it’s time to pull out the gear and get it ready for flying season. Depending on your hangar, this can be a daunting task, but if taken in small, logical steps, it doesn’t have to be hard. In fact, it can be fun and motivating.

Where Do I Begin?

That is a good question, and the answer is, “It all depends.” I usually start with a trainer aircraft if I haven’t been flying for a few months. That goes for my helicopters, multirotors, and airplanes. I start with the ones I’ll fly first then work my way through the rest.

Because everything depends upon my radio and batteries, I start with them. My chargers automatically handle much of the battery maintenance, so I let that happen while doing other things. Remember, you don’t want to leave those chargers working without being nearby!

It’s time to look through your hangar and start preflight checks for the season.

I assume that you left all of your batteries in storage mode—meaning somewhere between fully charged and fully discharged. If you left them fully charged or discharged, be prepared for poor results.

I put each pack on the charger for a couple of charge/discharge cycles to wake them up and see how they compare with my notes from last year. Don’t use a parallel charging board for these initial cycles. You want to see each individual pack by itself.

If you find a couple of packs that are “sort of” okay, but not what they used to be, designate them for less demanding applications. If there is a pack with a dead cell or one that’s lagging behind the others, don’t trust it. Voltages might look good, but it’s how it holds under load that tells the story.

Check your transmitter packs. Some use rechargeable packs and others use alkaline. I automatically replace the alkaline batteries before the first flight of the season. Cycle your rechargeable packs and see how they measure up. Never take a chance on a questionable transmitter pack!

This pack on Greg Gimlick’s PowerLab 8 BUMP Controller looked good until he checked the internal resistance. One cell is heading for trouble.

General Rules

Whether it’s an airplane, multirotor, or helicopter, some things just cover them all. I’ve mentioned batteries, so let’s move on.

Place the aircraft on your bench or floor then stand back and look at it. This is something we often fail to do, but it’s a critical step.

Look at the total picture. Does anything jump out at you? Does it look square? Does one wing sit lower than the other? Is the landing gear bent? Does anything just look “off?” How does it look overall? Make a note of anything you notice so that you remember to check specifics.

Control surfaces: Look at the hinges and check each one’s security. Give them a gentle tug to feel if they’re loose. Inspect each hinge, whether it’s a taped hinge, a pinned hinge, or CA hinge type. If there is a crack, replace it. If a taped hinge is coming loose, replace it.

Control linkages: Look at each one! Clevises come in various forms. Some are nylon, some are metal, and others use Z-bends or L-bends and keepers. Metal clevises are often secured with snap tabs. Be sure that they are still there and secure. If your clevises use rubber keepers, check to see if they are still firm and not dry rotted. A thin slice of fuel tube works well as a replacement.

Is the control horn still attached firmly to the control surface? Check the bolts or screws if that’s how it’s held in place. Some are glued directly to the surface and should be checked for security. If one is loose, remove it, clean up the surface, and re-glue it with the appropriate adhesive. Remember that not all glue is foam compatible.

Servos: Check each servo mount to ensure that it is still secure. Inspect the horns to see if they’re secure. Check the gear train by running the servo. If there are rough spots or binding, replace the servo.

This view of the bottom of Greg’s T-28 wing shows its servos and controls. Check each servo mount to ensure that it is still secure and inspect all servo horns. Check the gear train by running the servo.

If the rubber grommets have dry rotted, replace them. Check the servo wire to see that it is still in good shape—not chafed or cracked—and is firmly plugged into the receiver. If you have servo extensions, ensure that they are secured with tape or shrink-wrap.

Receiver: Check to see that it’s securely mounted and the antenna wires aren’t cracked or rubbing against anything. If your receiver wires have small plastic extrusions at the base, use a piece of air line to reinforce and protect the wire. If your airplane uses a switch harness, check it for proper operation. If the switch feels odd, replace it.

Most of our park flyers employ BECs (battery eliminator circuits) and don’t have switches, but check the wire from the ESC to the receiver for a solid connection.

Battery mount: How is your pack held in place? Do you have Velcro on a battery deck? Is it securely glued down? Do you have a Velcro One-Wrap strap? Inspect its operation and replace it if it’s showing signs of wear or doesn’t stick as it used to.

Is the battery deck securely glued in place? Chances are, your battery is under some sort of hatch cover. Is it still operational? Check the magnets or latch to ensure that it still holds everything down.

Motor/ESC mounts: Is the motor firmly attached to the mount/firewall. Is the mount firmly attached? Reinforce any mounts that you find loose. Check for stress fractures near the mount and firewall.

Are the wires all secured so that they can’t rub against anything? Check for sharp edges on the firewall that could chafe the wires where they pass through. Protect the wires with some sort of wrap.

Propellers/rotors: Look carefully at each propeller or rotor blade. Tip damage is usually easy to spot, but be sure to check near the root of the blade. Stress fractures often appear there and are hard to find. Sometimes slightly flexing the blade under a bright light will you help see them. Don’t bend the propellers or blades so far that you break them! Never repair a propeller or rotor blade—replace it!

Are the propeller mounts secure? Whether it’s a collet or propeller adapter, check that they are secure.

Landing gear: Most landing gear damage is near the root of the leg where it bends and is bolted to a fuselage. That goes for all types of aircraft. Check for security and cracks. Inspect any setscrews holding the wheels on. Use threadlocker on all of the screws.

Wing attachment: Most of our airplanes use either rubber bands or screws to hold the wing on. Don’t use old rubber bands! They will dry rot over time and wear out. The sun wears on them and degrades the compound. Start with all fresh rubber bands and use enough of them.

If your wing is held on with nylon bolts, check the threads for signs that they’ve been cross-threaded or “stretched.” Replace anything that’s questionable. Check the mount points to see if they’re still securely glued to the fuselage.

Wiring: Our aircraft have a lot of wires—look at all of them. Neatness really counts here and can save your aircraft. Ensure that nothing is chafing, kinked, pinched, or damaged. Check the condition of all of the connectors and replace them if necessary. Look for pitted contacts in connectors and replace them.

Covering/canopies: Look for cracks, holes, and the security of the covering or your canopy. Seal the edge of any loose covering and shrink any wrinkles that occurred while in storage.

On your multirotors and helicopters, check the rubber grommets that are holding the canopy on the mounting posts. Replace any that appear loose or degraded. Look for any stress fractures in the fiberglass and repair them with CA glue or epoxy.

Radio check: After everything is checked and repaired, examine each airplane’s radio. Ensure that nothing has changed, nothing has been accidentally reversed, etc. If you haven’t set up a throttle-kill switch for each aircraft, do it now. Always perform a range check on aircraft before flight.

Helicopter Specifics

Ball links: They’re everywhere and each one needs to be checked. If they’re loose, replace them. Not all of them can be installed in any direction. Check your manufacturer’s recommendations for how to properly install them.

Linkages: Look for bends and ensure that they are securely attached to the ball links. If they have been adjusted, ensure that there are still enough threads into the link for a secure connection.

The gears on Greg’s Blade 330X are looking good, along with the linkages.

Bearings: Have you lubricated them? Are they secure? Are they clean? If you find any that are loose or grinding, replace them. Clean and lubricate them thoroughly or replace them if they are defective.

Belt drive: Check for proper tension and condition. If it’s an old belt, replace it while you’re taking things apart to check them. Treat your belt with a silicon lubricant appropriate for your climate to prolong the life of the belt and protect it against any static electricity buildup. If you fly in dusty areas, stick with a dry lubricant.

Some modelers use WD-40, but there are certain belt compounds that don’t play well with it. I don’t recommend using it for tail rotor belts.

Drive gears: Are the teeth in good shape? If any are showing signs of wear (unevenness, curled edges, etc.), look for the cause and correct it. It’s often an alignment/mesh issue.

Check the bushings or bearings in the gear for play and replace them as necessary.

Threadlocker: Helicopters have a zillion screws and bolts. Check that they are secure and apply threadlocker where needed. Sometimes new helicopters arrive without threadlocker on their bolts, so check them before flying.

Gyro/flight controller: These miracles of technology require proper mounting and will give you fits if they come loose or are poorly mounted. Ensure that they are properly oriented and secured according to the manufacturer’s guidelines. Most use a double-sided mounting tape or PU adhesive gel tape.

Multirotor Specifics

Propellers: Be sure that the correct propellers are on the right motors. Some indicate direction and others don’t, so check your specific machine.

Flight control updates: This is up to you. If it flew well when you put it away, why mess with it? If new features that you want are available or safety updates have been released, then you might need to flash your flight controller. Always remove the propellers before doing any programming.

There’s a lot going on with a quadcopter. On this one, the camera mount came loose. The only thing that kept it from exiting the aircraft was the zip tie.

Gimbals: Many multirotors have cameras attached that require gimbals. If you have a gimbal, check that it’s secure and replace any vibration mounts that show signs of wear. I run a zip tie through a couple of the mounts to keep the camera from coming off if a rubber mount should fail. Keep the tie loose. It’s only there in case it comes apart. You don’t want to cinch down on the mount.

Motor arms and frame: Quadcopters come in all forms. Some use carbon-fiber “X” frames and others have tubes through clamp mounts that go out to the motors. Check the clamps’ security and look for any cracks in the tubes/arms. Sometimes cracks can be repaired, but it’s often best to replace the cracked parts.

FPV: Ensure that you have a solid video link before flying FPV. Check your frequency and power settings to ensure legality and compatibility. There are some delicate wiring plugs with the micro video gear and they should all be checked for condition. Wiggle the wires and plugs while checking the feed.

When stepping back to look at the Hyperion Vengeance 280, Greg could see that one front arm had rotated, making its motor angle different from the others.

You’re Ready!

If you go through everything I’ve mentioned here, you’re all set to do your happy dance and enjoy your time at the field. Remember that a good seasonal preflight can get you off to a great start, but regular preflight and postflight inspections will ensure a safe and happy flying season.

Greg has checked everything out, the weather is great, and it’s happy dance time!

-Greg Gimlick


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