Buying an ultralight aircraft? How to buy USED not ABUSED  ultralight aircraft.

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Most manufacturers are now building specialized aircraft to fit target groups. While this may cut down on market share, it allows increased profit margins. Selling and producing one aircraft at $40,000 with a 25% profit margin is more profitable than selling and producing 8, $5,000 aircraft at an even lower profit margin (remember the average new engine sells for around $5,000).

Canada with a population of 28,000,000 has approximately 4,000 registered ultralights (our aircraft are registered, and our pilots licensed). The United States, has roughly 280,000,000 people assuming the same percentage of people own ultralights then that would mean 40,000 ultralights. Combine the Canadian and US market and you have 44,000 USED ultralight aircraft. Which ones are a better buy? How much are they worth? Which are the safest? Where do you get parts and pieces for them?

This is the second in a series of articles dealing with purchasing an ultralight. The first in the series was a 10 point system used to evaluate an ultralight, new or used. Next in the series will be a Buyers Guide of used aircraft, with information on where to get parts and pieces and the estimated value of certain craft.

Now let's look at areas to examine when buying a USED ultralight. In order for any aircraft to get into the air and back down again you require, an airframe, a propulsion system, a control system, landing gear, a wing assembly.

Lets take a look at these:

Airframe: This is the basic structure of the craft, the center section or the area the pilot sits in. Found in the airframe (in conventional ultralights) are: the joystick, rudder pedals, rudder cables, throttles, throttle cables, usually the fuel tank. It is also the area of the craft that the landing gear, wing struts and tail surfaces connect to.

Propulsion system: Powers the craft, engine, exhaust system, carburetor, fuel pump, reduction drive, and propeller make up the propulsion system.

Control system: This is what controls the craft, usually a joystick and rudder pedals, connected to the ailerons, elevator(s), and rudder(s).

Landing gear: These are the parts of the aircraft that contact mother earth during taxiing, take off and landing. It is the area that must "take a licking and keep on ticking."

Index

Wing assembly: The parts that make up the wing, and connect it to the airframe.

These parts together make up the aircraft. In many ways they are similar to the parts making up the human body, and like the human body, with age, neglect, and lack of proper care and feeding, things once done all night, now take all night to do, or can't be done.

The advantage that an ultralight has over the human body is it consists of replaceable parts. The disadvantage is that when you are buying it, the seller may stretch the truth a little by forgetting to mention that the little old lady that flew it "only to church on Sundays," was 200 miles from that church. That the only field she had to land on was plowed, and that several time on take-off she clipped the top off several trees. Since ultralights do not require engine or airframe logs, it is very hard to disprove the actual hours of use an ultralight has on it.

When negotiating the price of a car, you would take tire wear, paint and interior condition, dents, rust, etc. into consideration. You should do the same when buying an ultralight. Let's look at these areas in a more detailed way.

Airframe: This is really the main frame of your aircraft sort of like your skeleton minus feet, arms, hands. Connected to it is the landing gear (feet) and wings  (arms). All the control systems (muscles, nerves) usually run along or inside it.
While many other parts are replaceable, you are not likely to replace the fuselage. For this reason it is important to check it for signs of wear. Wear will be most evident in areas of the fuselage that connect to the landing gear, or a moving part like the steerable nose wheel, or engine attachment points.

Look for bent or cracked tubing , tubing with elongated holes , tubing worn from metal on metal contact . If your aircraft is riveted together examine the rivets at areas of the craft that might flex, or is subject to vibration . If you are buying an aircraft that features an enclosed cockpit look very carefully on the floor of the enclosure, under the seat or gas tank, (this is an area that is difficult to clean) for signs of rivet heads. This could indicate recent repair or a hard landing.

Check the area where the landing gear passes through the fuselage for cracking or damage. Check the area of the fuselage where the rudder attaches to the vertical fin for cracks . Check the area where the pilot's enclosure or hull contacts the airframe for wear . Check nuts and bolts for bending .

Many older designs used pit pins. These are no longer used! These corrode, are weaker than an AN nut and bolt, resulting in failure under load . If the aircraft you are looking has pit pins you should deduct the cost of replacing them with AN nuts and bolts from the cost of the plane.

• Check the engine mount for cracks.
• Check the rubber mounts for cracks, failure, or UV deterioration .
• Check plastic saddles for signs of failure
• Check bolts securing struts to wing on early model wire braced aircraft for failure of the securing bolts.
• Check cable ends for signs of stretching .
• Check all cables where they may contact metal for fraying .

Approximate cost of replacement parts.

Index

Propulsion system :  The propulsion system consists of -- Fuel system, exhaust system, reduction drive, engine, and prop.

Fuel system : Many ultralights come up for resale because the owner has medical, financial or family problems (or has simply lost interest.) The decision to sell usually does not come easily. This can mean that the aircraft has been used sparingly, and has been tied down, out in the open at a flying field, at the mercy of the elements, or hangared for long periods of time. If the reason for the sale is financial, aircraft maintenance should be of prime concern!

In many cases the aircraft is left with fuel in the gas tank, and carburetor. Pull the cap off the gas tank, or the bowl of the carburetor you will know immediately whether the plane has been in storage. The smell will knock you off your feet! Adding fuel, or starting the engine without first draining and cleaning the complete fuel system can severely damage the engine, your body or the aircraft, when the engine quits from a clogged fuel system during takeoff! Consider the cost in time, and parts necessary to bring the fuel system back to 100%, when buying an ultralight.

Recommended replacement parts: The fuel shut off valve, fuel filter, fuel line , primer lines, rubber intake manifold(s) , primer bulb, carburetor bowl gasket(s) main jet and idler jet , and gas tank grommets . With storage, gas and UV deterioration will make it necessary for most if not all of these to be replaced or cleaned. If the engine has a sponge air filter, replace it with a K & N air filter.

Many older ultralights came equipped with 503 Rotax or Hirth engines using a single Mikuni fuel pump. Both single and dual carb 503 Rotax/Hirth engines should use the dual Mikuni fuel pump . The pump should be; rubber mounted, a maximum of 12 inches, from the vacuum source on the engine, away from heat, and with the vent on the pump, (found in the middle of the vacuum elbow) facing down.

Another common problem on aircraft equipped with either the Mikuni or Bing carburetor was wear in the needle valve and or retaining clip. This wear would cause the needle to fall down into the carburetor resulting in the engine dropping back to an idle .

Approximate prices:

Index

Exhaust System: The exhaust system on a two stroke engine plays a very important role in the life and performance of the engine. When buying an ultralight look for cracks, in the exhaust system, or recent welds, which would indicate someone has repaired the exhaust or modified it. Either is cause for concern! Repair work would indicate; improper exhaust mounting, modifications can result in engine overheating, loss of performance, and or engine failure . Other areas of concern are the rubber mounts used to support the exhaust system. Check them closely for separation, cracks, or other damage .

Approximate replacement costs:

Reduction drive: The first type of drive used on ultralights was direct drive. This means that the propeller bolts directly to the crankshaft. Engines that used this type of drive were the JPX, Rotax 9.5, Pioneer Chainsaw, Koenig, Chrysler West Bend, Mac 101, Global and some early model Cuyuna engines.

The load exerted by the propeller, on the crankshaft, during changes in aircraft attitude, and speed, are very extreme. This has resulted in reports of crankshaft failure, on most of these engines . If you are considering buying a craft that uses a direct drive system grab the output shaft and see if it will move up and down, an indication of imminent failure. Look at the casings, where the output shaft exits the engine. Hairline cracks seen in this area may also indicate crankshaft failure.

Ed. note - Many thousands of safe flying hours have been logged by pilots of Lazair's, Mitchell Wings, N-3 Pups and Gold wings using this kind of system.

Approximate replacement cost:

Index

Belt drive systems:. This was the second type of system used in ultralights. These drives used an upper and lower pulley, of different diameters, and a single or series of belts, to reduce the prop RPM. This allows the use larger propellers for better performance and reduced noise. When buying a craft equipped with a belt drive system check out the two pulleys for wear or damage, the condition of the belts, shaft bearings wear . Also check the reduction drive casings for signs of cracks or damage . Early model Quicksilver MX aircraft used a coupler to connect the driveshaft to the engine. This coupler failed and was updated to a large diameter coupler ).

Many early designs used belt drive systems on the Rotax engines. On early model 277 engines over tightening the drive belt can result in failure of a plastic liner used to support the crankshaft PTO end bearing. Failure has also been reported on 377/447/503 crankshafts using belt drive systems. If purchasing an aircraft with over 100 hours on it using a belt drive on a Rotax engine, a complete tear down and rebuild of the engine is recommended!

Planetary systems: Several planetary systems were used over the years on ultralight aircraft. Most are no longer available. One widely used system was the Winters reduction drive. Failure of this system forced the manufacturer to stop production. Failure has occurred at the output shaft, resulting in the propeller exiting the aircraft. Failure also occurs in the aluminum ring supporting gears inside the casing, usually resulting in seizure of the drive system, resulting in a forced landing.

Recommendation: If the craft you are considering, has this re drive system; DO NOT FLY until you change the drive system. Consult aircraft manufacturer or someone knowledgeable in the industry for advice.

Rotax gear drive:  Updates have occurred to the Rotax A/B reduction drives.

The first was an update from 2 groups of four spring washers on the output shaft to 3 groups of 4 washers . Reason -- failure of the spring washers resulting in hard starting.

The output prop hub was also update from a two piece steel shaft/aluminum hub arrangement to a one piece steel shaft and hub. Reason -- failure of the aluminum hub, and stripping of the prop bolt retaining threads in the hub.

Another update was going from a 3 bolt gear box to engine adapter plate to a 4 bolt engine adapter plate. Reason - failure of the bolts holding the adapter plate to the engine, causing loss of drive, or damage to engine case. .

Vent cap update-Rotax has updated the vent cap on the gear drive to that shown here . This update helps prevent loss of gear drive oil due to siphoning action of the propeller, or gear drive internal pressure, which can result in gear drive failure due to lack of oil .

Another update changes the main gear in the drive from a gear with holes in the sides of it to a solid gear . Failure of this gear was evident by missing teeth or cracks running from the gear teeth to the holes.

The Dog hub has also been update from a two dog hub to a 4 dog hub. On the old system if the engine has a prop strike the gear drive would have to be taken apart to reposition the hub. With the new 4 hub system it simply jumps to another hub .

On C drive model gear drives the torque value has been updated on the gear retaining nut. Another common problem with the C drive is a leaking seal at the back of the drive. Signs of failure of this seal will be gear oil coming out of the two holes on the side of the drive, where the rubber coupler is visible.

Index

Approximate prices

Engine: In the early days of ultralight aviation we would strap just about anything that would turn a propeller onto the front or back of our craft. A rule of thumb was not "if the engine quits" but "when the engine quits," be prepared for a forced landing!

When buying, try to buy a craft powered by an engine that parts or a replacement engine, are readily available. You will find that replacing an engine, with another make and model, will usually mean that you will also have to buy a new prop and redrive as well.

A good way of judging the condition of the engine is to remove the exhaust/ intake manifolds, and the cylinder heads. You can do this for the cost of replacement gaskets and about 30 minutes worth of work. This allows you to view the pistons, both front and back, as well as the top. Any kind of scoring means the engine has had a seizure requiring in most cases an engine overhaul. If carbon deposits are visible below the rings it means ring seizure, or piston/cylinder wear. This also means engine rebuilding. If the top of the piston shows signs of foreign material embedded in the head it usually means, the engine has ingested something or an internal engine component has failed! A damaged piston dome could indicate; a problem with ignition timing, spark plug heat range, lean fuel mixture, low octane fuels.

For better understanding read Troubleshooting the Cuyuna Engine Ultralight Flying Magazine. Trouble shooting the Rotax Engines Volume 1 - 2 - 3  L'il Hustler Enterprises,  Ultralight Advisory Bulletins Ultralight Flying, or in video form, from L'il Hustler Aviation.

Other areas to look at are; the cowls surrounding the engine , the fan tower , intake manifold(s) recoil housing ignition wiring especially on Kawasaki, Cuyuna engines using CDI ignition, failure of the wiring occurs where wires engine CDI box. If engine is equipped with Rotax electric start look to see that spacer between magneto and flywheel has been update from that shown on left to that on right. Check the magneto for damage, caused by improper propeller balance, loose magneto nut, substandard motor engine installation. Also check to make sure wiring has not been pinched or burnt . A poor ground on electric start, will result in severe damage to electrical system.

Look at the physical appearance of the engine! It should be clean! Any sign of leakage from gaskets, or seals means the engine requires disassembly, replacement of parts and reassembly. A leaking seal or gasket can result in, erratic engine performance, overheating, lack of performance and or engine failure!

Index

Propeller: The propeller is usually the most neglected part of the propulsion system. Yet it is what takes the power and creates the thrust which result in the wings developing lift. An improper propeller can cause the engine to over rev, resulting in overheating and engine failure. Under rev resulting in poor climb, usually resulting in an accident. It also is subject to a great deal of stress, from changes in engine RPM, aircraft attitude, and vibration from the engine, and improper prop balance. It is also subject to environmental damage from the sun, wind, rain, and ground. Propeller failures have resulted in engines being completely separated from the aircraft, resulting in loss of control, causing serious injury and death!

• Check the prop for nicks or cracks
• Check it for signs of environmental damage, rotting, paint pealing.
• Check the inside of the hub area on older Warp Drive and IVO props for cracking .
• Check bolts that hold it to the reduction drive for bending, rust, corrosion.
• Check the prop spinner for cracks . On aircraft using the Ultraprop, in a tractor configuration it is recommended that the prop spinner not be used, or be securely wired on.
• Check the prop for proper diameter and pitch, for reference use the prop guide chart found in the CPS, Leaf, catalogues. For more prop information it is suggested you read Ultralight Flying, on props.

If the craft you are buying is going to be on floats make sure the prop has some kind of leading edge protection. Without leading edge protection your prop will be a wall ornament after the first take-off! Props range in price from $150 - $1,000.

Control system: The control system is a part of the craft that has to be checked thoroughly! Some older designs used ROPE, to operate control systems . Do not fly any aircraft that uses rope and knots to operate a control system. Have these replaced with steel cable, using proper NICOS, and AN fittings. shows a manufacturer using a plastic clip to connect rope to control system. In Canada one of these, operating the elevator control system, failed during winter conditions, when under load it cracked and broke resulting in the owner of the aircraft being hospitalized for 6 months. The aircraft was completely destroyed!

Another problem in enclosed ultralights is dirt and debris collecting around the control cable where it enters, a plastic outer cable. The dirt acts much like sandpaper or a file, resulting in the cable fraying and failing . If the outer plastic coating moves in the retaining clamp, it allows metal on metal contact, resulting in failure of the control cable, or failure of the retaining clamp. This can result in loss of elevator or rudder control as happened at Sun N fun, causing a CGS Hawk to crash.

Other control system failure may result form the cable rubbing against tubing or metal .If your aircraft control system uses clips and rings to connect push pull tubes or cables to a elevator or rudder it is recommended that this be replaced with AN nuts and bolts .

Many ultralights use teleflex cables to operate control systems. When subjected to environmental conditions such as severe wind, these have failed, or partially failed. I test flew Buccaneer SX without noticing that the cable, operating the ailerons was cracked. It failed in a turn it resulted in a spiral turn, luckily it was not very steep and I was able to right it with rudder, and landed safely. When storing a craft outside it is suggested that you make up a set of aileron/elevator stops.

Check all moving parts of the control system for wear or damage. Look at the aileron hinges for cracks. In an aircraft using rivets look for loose fitting hinges, a sign of rivet wear. Examine elevator horns, aileron push pull tubes, rudder pedals, at attachment points for wear at hinges or eye bolts.

Index

Landing gear:

• Check the tires for wear
• Check the wheel bearings for signs of failure.
• Check the rim for signs of damage.
• Check the landing gear welds or attachments area where the wheel and landing gear join together.
• Check the landing gear for signs of bending
• Check landing gear for signs for cracking or elongation of holes .

Landing gear:

Wing Assembly: Use a Maule tester/fabric tester to test fabric. My recommendation is not to fly on fabric that tests less than 41 lbs. on Maule tester . (Another tester available from Leaf/CPS/Airstar/Southern Mississippi uses a different kind of
scale).

Look at the fabric on top of the wing which has been exposed to UV, and the fabric on the underside of the wing. If there is any significant difference in color, then the fabric is ROTTEN. Before buying a craft run your hand along the fabric, if it comes away feeling greasy then the fabric has been coated with AP 303 or Armoural. These products make old rotted fabric look like new! Reports done by several groups have shown that UV deterioration can happen in as little as 6 months to aircraft left unprotected in the sun.

Check baton tips for breaks or cracks. On many older designs it was necessary to safety wire the batons, directly in front of the prop, as they tended to move out during flight! OUT INTO THE PROPELLER!

If Velcro is used on the aircraft check to make sure that it is still "STICKY". Many pilots have reported the Velcro attachment points coming "unstuck", in some cases this has resulted in fuselage covering material entering the propeller .

Check the leading and trailer edge for signs of damage. Check the strut attachment points. Check the wing attachment points. Many early manufacturers used the type of bracket shown on the left in fig 71. These have failed in flight. Most are not using that shown on the right in fig 71, it is suggested to you consult the aircraft manufacturer or someone knowledgeable in the industry for advise if the craft your craft uses these stainless steel brackets.

Fabric replacement cost:

Index

Parachutes: If your parachute is more than 5 years old it more than likely needs to be updated to a new system. There have been several manufacturers producing units for ultralight aviation. Today there is only one North American company BRS. BRS systems have undergone extensive changes over the years that they have been in business. It is suggested that you contact them directly at:

BRS - click here to go to our BRS section!

Two areas of major concern are in the deployment handles, or firing mechanism. These corrode! This corrosion results in system failure!

Another area of concern is in the mounting location. To date I know of several incidents where the parachute has been fired, but the system deployed into part of the wreckage of the aircraft, causing late or only partial deployment.
BRS repack and update


As you can see there are a great deal of things to take into consideration when buying a used ultralight. You can also see that the aircraft you are considering buying for $10,000 could be worth considerably less!

In our next installment we will look at the prices for some good used aircraft, where to find parts and pieces for them and their approximate retail value in . After nearly 50 hours of writing!
U.B. Judge 

Airborne Edge - weight shift trike powered by Rotax 582 two stroke engine.

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