Author: P. Tradelius
Edition: Model Aviation - 1994/04
Page Numbers: 89, 90
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RADIO CONTROL HELICOPTERS

Paul Tradelius, 6704 Santiago, Ft. Worth, TX 76133

SPRING HELICOPTER SAFETY

The worst of the winter should be behind us now, so this would be a good time to inspect your helicopters and ready them for the upcoming flying season.

To ensure that nothing is missed, I recommend beginning the inspection from the nose. This is a general list; your particular model will dictate the criteria you use and the degree to which you make your inspection. Modify the list as needed. Starting from the nose...

  • Canopy:
  • Remove and look for any cracks or splits. If it is the type that has been glued together, pay special attention to the seams.
  • Check mounting rubber grommets, latches, and similar parts; they should be in good condition and not worn from vibration.
  • Servo tray:
  • Examine for cracks in metal trays or broken glue joints in wooden ones.
  • Twist and push-pull gently to test for a solid tray and to ensure it is well-mounted to the frame.
  • Pushrods:
  • Inspect ball-links for wear and overall snug fit. Both balls and links can wear easily if they get dirty or have fuel on them from being near the engine or exhaust.
  • Disconnect pushrods from the servos and push/pull by hand to test for slop or binding.
  • Make sure all pushrods are straight.
  • Bearings:
  • Although you should have given all bearings a coat of oil when the helicopter was put away for the winter, oil them or pack with bearing grease as needed.
  • Landing gear / skids:
  • Ensure they are secure and straight. If metal, they may need to be bent back into proper position so the helicopter sits level.
  • Frame:
  • Secure all nuts and bolts.
  • Look for vibration or stress cracks around engine and skid mounts.
  • Head:
  • Although not imperative, it is a good idea to remove the rotor blades and head.
  • If it has been a while since the thrust bearings were greased, now is the time to do it.
  • Removing the head enables closer inspection for bent links, pushrods, or flybar.
  • Use a High Point or Du-Bro balancer to verify the balance of the head/flybar.
  • Main blades:
  • Give special attention to main blades — they are the most dangerous part if they fail.
  • Inspect tips for nicks or scrapes from near-tipovers. Check for warps and ensure blades are straight and true.
  • Examine blade reinforcement at the root for signs of fatigue or enlarged mounting holes.
  • If using wooden blades and there is any doubt, remove the covering and inspect the wood itself — the covering can hide problems.
  • Tailboom:
  • If using a wire-driven tail rotor, relubricate the drive wire.
  • If belt-driven, check the belt for wear and adjust tension.
  • Tail rotor gearbox:
  • Disassemble, inspect, and relubricate all gearboxes.
  • Pay special attention to the security of the tail rotor and associated linkages; stress and high RPMs can loosen bolts.
  • Set screws:
  • After ensuring everything is lubricated and not binding, reapply Loctite to all set screws.
  • Look at the plans for the helicopter so you remember where all the set screws are located, and disassemble as required to reach them.
  • Suggested technique: remove the set screw, clean both the hole and the screw, place a drop of removable Loctite in the hole and another on the screw, then install the screw. The extra Loctite in the hole fills small gaps and helps prevent loosening.
  • Fuel tank:
  • You should not have stored the helicopter with fuel in the tank, but if you did, now is the time to remove old fuel and clean the tank.
  • Inspect all fuel lines in and outside the tank for holes or splits that will cause erratic engine running.
  • Ensure the clunk weight is secure and its tubing is free to move, especially if planning inverted flight.
  • Radio:
  • Cycle both transmitter and receiver batteries after storage to monitor cells' ability to hold a full charge.
  • Closely examine connectors and wires for breaks, frays, and stress where wires enter connectors; wires can become dislodged.
  • Ensure rubber servo grommets are secure between the servo and tray but not so tight that they eliminate vibration protection.
  • Check foam rubber that protects the receiver and battery. Consider using a Strongbox (LDM Industries) for crash protection of the receiver and airborne batteries.
  • Inspect servo arms for cracks or enlarged holes. Disconnect servo arms and inspect shaft output splines.
  • Check the antenna for wear (cracks, rubs). Minor damage to the wire covering can be corrected with heat-shrink tubing.
  • Tugging on the antenna can weaken the wire or solder connection to the receiver circuit board — consider opening the receiver case to inspect the board and antenna connection.
  • When everything looks good, perform a range check as you will fly the helicopter. Do not route the receiver antenna differently or remove canopy pieces during the check; you need an accurate reading.
  • Compare this range check to last season’s distance and confirm it exceeds the manufacturer’s minimum. If the radio fails, do not start the engine — have a qualified technician inspect it.

Gyro

  • Inspect wiring and connectors.
  • Test for proper servo movement with the radio turned on as if flying. As the helicopter’s nose is moved gently right and left, the gyro should give smooth commands to the tail-rotor servo.
  • If something looks wrong, open the gyro case and check that springs are in place, weighted wheels spin freely, and the electronic pickup is clean.
  • A small drop of lightweight oil on the bearings may help.

Engine and Muffler

  • Remove the carburetor and glow plug. Disassemble the carburetor as much as possible and look for foreign matter, dried fuel, oil, and soot. Clean with solvent and relubricate.
  • If the engine has caked-on black oil residue, it can be restored to near-new condition using Z-Best engine cleaner. Be careful — it is corrosive to paint and some materials.

I'm sure there are more tests you can perform to suit your particular helicopter, but this should get you on the right track. The inspection may seem time-consuming, but once you get started it should not take long (unless you find additional problems).

Rossi RX Exhaust Adaptor

Ron Pound (9021 Greencastle Rd., Terre Haute, IN 47805) read a previous article where I asked for help locating a header mounting clamp for a rear-exhaust Rossi engine. Ron was kind enough to send one he makes, and it works great.

The adaptor is machined to fit neatly around the neck of the exhaust and is tapped to accept the mounting flange of either a muffler or header. My only concern was that the adaptor is made in two halves and the mounting holes are tapped right in the middle of the break, but it works fine. If any of you want to try the rear-exhaust five-port Rossi, Ron is making the only header clamp I know about.

Transcribed from original scans by AI. Minor OCR errors may remain.