10-1 CHAPTER 10. ULTRALIGHT ENGINE/FUEL SYSTEM INSPECTION S ECTION 1. ENGINE INSPECTION
10.1 Objective. To provide the amateur builder/ultralight pilot with a suggested engine and fuel system inspection program in addition to the manufacturer’s checklist items.
10.1.1 E ngine.
10.1.1.1 Check the engine mount, vibration isolation mounts, and attach points before each flight.
Note: If slippage marks are painted across the bolt heads, engine mount, and fuselage at the time the mount bolts are torqued, a break in the paint will give advance warning the mount is coming loose.
(Again, red nail polish works adequately.)
10.1.1.2 Check all hose clamps for tightness.
10.1.1.3 Check for fuel and oil leaks.
10.1.1.4 Check air filter for condition and attachment.
10.1.1.5 Ensure that all spark plugs are the correct ones, properly torqued. Check that the ignition wires, caps, and plug cap restraints on inverted engines are secured and safetied. Ensure that the kill switch, if applicable, is within easy reach and works as advertised.
10.1.1.6 Check that the carburetor and the throttle cable are secured and both operate freely from idle stop to full power stop.
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10.1.1.7 Check carburetor boots for cracks that will suck air and may create a lean mixture, high CHT and EGT, and possible engine failure.
10.1.1.8 Check the fuel on/off valve, fuel filter, and crossover valve for proper operation and position.
10.1.1.9 Drain the fuel system of water and sediment.
10.1.1.10 Ensure that the fuel tank is secured, full, and if applicable, contains the proper mix (ratio) of fuel and oil.
10.1.2 Exhaust System.
10.1.2.1 On most 2-cycle engines, the exhaust system is tuned to the engine in order to have the proper amount of back pressure. Sometimes, due to installation demands, the exhaust system is modified. If modifications are necessary, contact the engine manufacturer before incorporating any exhaust systems changes.
10.1.2.2 The exhaust system should be mounted on vibration-damping elements and be safety wired. The exhaust system ball-joints should not be mounted under a tension load and they should be lubricated with an anti-seize, heat resistant grease to allow the ball joints to move freely. Some exhaust systems use springs to keep pressure (compression) on the ball-joints. If the engine is so equipped, run a piece of safety wire through the spring and secure it to the exhaust system. This would prevent a broken spring from coming loose and hitting the propeller in a pusher configuration or hitting the top of the wing or tail in a tractor design.
10.1.2.3 Another approach to prevent propeller damage from broken springs is to lay a bead of high temperature silicon length-wise across the spring. If a spring does break during flight, the silicon bead will hold some or all of the broken pieces of spring material in place until the ultralight lands.
10.1.3 Fan Cooling.
10.1.3.1 It is particularly important that installations of fan cooled engines with enclosed cowlings are designed so that the hot cooling air exits the cowl and cannot recirculate back into the cooling fan intake. If there are any doubts, tests should be carried out by measuring the temperature of the air entering the cooling fan.
10.1.3.2 In most cases, it is unlikely there will be a problem with cooling belt tension on a new engine. On older engines, however, the belt may have bedded down in the V of the pulley causing a significant reduction in belt tension. If corrosion is present on a pulley, the belt wear rate will be rapid. During the visual inspection of the fan cooling belt and pulley, look for evidence of wear and corrosion on the pulleys.
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10.1.4 Reduction Drive.
10.1.4.1 A large percentage of engines used on ultralight vehicles are 2-cycle air cooled engines fitted with an rpm reduction drive. The reduction drive is usually a bolt-on unit which drops the high 2-cycle engine rpm down to a propeller rpm that is more efficient.
10.1.4.2 To check tension on most V belts on the reduction drive, grab the belt and twist. The belt should allow no more than a half a turn.
10.1.4.3 Ensure that the reduction gearbox is filled with oil to the proper level in accordance with the manufacturer’s instructions and that the drain plug/filter is safetied.
10.1.4.4 Grasp the propeller (switch off and spark plugs disconnected) approximately halfway down each blade. Try first to move the prop in an up and down motion. Pull away from the ultralight and then push in the opposite direction.
No appreciable bearing slop should be detected in the reduction gear bearings.
10.1.4.5 Eccentricity of the driving or driven pulley will cause variations of belt tension with rotation, possibly leading to rapid failure of the belt and engine or propeller shaft bearings. Remove the spark plugs and rotate the engine slowly by hand for several turns in small steps (approximately 45 degrees of engine rotation per step). There should be no noticeable change in belt tension at any position. Any noticeable change should be investigated further (e.g., by measuring the run out of the engine pulley and propeller shaft pulley with a dial indicator).
SECTION 2. FUEL SYSTEMS
10.2 General. Many problems with lightweight engines used in ultralights can be directly traced to the type of fuel used. Many states allow automotive fuels to be sold containing 10 percent alcohol without requiring a label stating so. Alcohol can cause serious problems in these engines so first ensure that the fuel source is a reliable one.
10.2.1 Test for Alcohol in Automotive Fuel. Take a thin glass jar, mark it 1 inch from the bottom of the jar with tape or indelible ink, and fill the jar with water up to that mark. Fill the jar to the top with a sample of the fuel to be tested. There is a clear separation between the water and the fuel. Put the lid on the jar and shake. Let it settle for about a minute and check. If the water line is now above the first mark, the fuel has alcohol in it.
Try another source for fuel and do another test.
10.2.2 F uel Primer System. Perform a careful inspection of fuel primer bulbs fitted in suction lines because they deteriorate over time and are a possible source of air leaks, resulting in a lean mixture. Primer bulbs with plastic one-way valves have been known to break loose and completely block the fuel in the fuel line. Positioning the fuel line so the fuel flows upward through the primer bulb will help minimize the possibility of this problem occurring. A permanently fitted fuel pressure gage is recommended because it can check
10-4 fuel system operation during engine break-in and fuel flow during extreme angles of attack.
10.2.3 Filters, Fuel Lines, and Throttles.
10.2.3.1 Finger screens in fuel tanks should be checked every 10 hours for debris or varnish build up from fuel. Nylon mesh fuel filters are preferred with 2-cycle engines. Paper element filters should be avoided because they may severely and invisibly restrict the fuel flow. This is due to a reaction between water and oil detergents. The fuel filter should be distinctly located, between the fuel pump and the carburetors, to facilitate preflight inspection and avoid the possibility of air leaks on the suction side.
10.2.3.2 Check plastic fuel lines for age hardness, discoloration, and overall condition.
Fuel line attach points should be checked before each flight. Always clamp a fuel line at the inlet and outlet. A slip-on line might slip off in flight. Leave a little slack in the fuel lines to minimize cracking from vibration.
10.2.3.3 If the 2-cycle engine has two carburetors, make sure the throttles are exactly synchronized. If not, one carburetor will run rich while the other runs lean, causing cylinder overheating and a possibility of the piston seizing or being holed.
10.2.4 Causes of High Fuel Consumption.
1. Dirty air filter causing a rich mixture.
2. Propeller is not matched to the engine.
3. Carburetor float improperly adjusted.
4. Fuel pressure set too high.
5. Wrong carburetor jets installed.
6. Defective float valve.
7. Extreme vibration (propeller/engine) that keeps float valve open.
11-1 CHAPTER 11. ULTRALIGHT TEST FLYING RECOMMENDATIONS S ECTION 1. THREE RECOMMENDATIONS
11.1 Objective. To list additional items applicable to ultralights that will need to be addressed in the FLIGHT TEST PLAN.
11.2 Recommendations.
11.2.1 Even if the builder/owner or pilot is a B747 airline captain with 20,000 hours in type, the pilot should NOT climb into an ultralight without first receiving flight instruction from a flight instructor. This sometimes can be done in a two-seat aircraft that is of similar design as the single-seat ultralight. The two-seat aircraft will be registered as either a special light-sport category aircraft (SLSA), an ELSA, or an E-AB. The owner or authorized instructor will need a LODA for the ELSA or E-AB to be used for compensated flight training. SLSA, ELSA, or E-AB will require a properly rated certificated flight instructor (CFI) to give the flight training. Ultralights by their very nature are highly susceptible to winds above 15 mph. All ultralight test flights should be conducted in light or no-wind conditions.
11.2.2 Even more so than America’s top fighter pilots, ultralight pilots should vigilantly manage airspeed. Due to its small speed range between stall and full power; high drag and low weight, airspeed should become the single most important concern of the ultralight pilot.
11-2 SECTION 2. AIRPORT SELECTION
11.3 Objective. To choose an airport to test fly the ultralight.
11.3.1 Most ultralights are flown out of unimproved grass strips. Before test flying the ultralight from one of these locations ensure that a windsock or even a flag is installed nearby to give some indication of the wind direction and speed.
11.3.2 Carefully examine each airstrip. Note and record in the FLIGHT TEST PLAN the surrounding terrain, man-made structures, power lines, phone wires, and trees. Record the probability of these factors contributing toward or causing mechanical turbulence during certain times of the day, or presenting a hazard to flight in other ways.
11.3.3 Make sure that the strip is orientated towards the prevailing winds. Before selecting a strip, make certain emergency strips are located close-by in case of engine failure.
SECTION 3. TAXIING
11.4 General. As explained in Chapter 2, taxiing should be designed and conducted to achieve the FLIGHT TEST PLAN goals. In addition to identifying the ultralight’s ground handling characteristics at low and high taxi speeds, braking, monitoring engine operation, and developing pilot proficiency, the FLIGHT TEST PLAN should consider developing the following:
1. Cr oss -wind handling characteristics during taxi.
2. Addressing the ultralight’s response to rapid changes in power (tractor design versus pusher).
3. Practicing the procedures for starting and stopping the engine.
Note: When taxiing a nose-gear ultralight, the input response on the rudder bar will be positive, similar to a car. If operating a tail dragger design, anticipate an initially larger input with a decreasing amount of pressure upon entering the turn.
If the pilot is slow in getting the pressure off, the larger moment arm—main gear to the tail versus main gear to the nose wheel—will set the ultralight up for a ground loop.
SECTION 4. FIRST FLIGHT DIFFERENCES
11.5 Use of Power. One of the biggest differences between a general aviation aircraft and an ultralight is the effect very quick changes in power can have on airspeed. In a lightweight aircraft, it is possible to go from cruise speed to a stall in less than 4 seconds. This is due to the low-mass, high-drag configuration, and smaller speed range characteristic of the majority of ultralights. To avoid unplanned stalls, make small power reductions over a longer time period while always monitoring the airspeed.
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11.6 Control Feel. Due to the slow cruise speed and lower weight of ultralights, their flight controls feel light or sensitive. Once the flight control input has been made, however, the rate of response tends to be slower than inputs on faster and heavier aircraft.
11.7 Stalls. Because of their high angle of dihedral, most ultralight stalls tend to be straight forward, particularly during a power-off stall. These ultralights experience little airframe buffeting. The only stall indications the pilot may recognize are the ultralight’s slowed forward movement, a rapid decrease in altitude, and controls that are suddenly mushy and mostly ineffective.
11.8 Steep Turns. When performing steep turns in an ultralight, the increasing weight (G load) and high drag tends to bleed off energy very quickly. The pilot should vigilantly monitor the airspeed to avoid inadvertently setting up a stall/spin scenario.
SECTION 5. EMERGENCY PROCEDURES
11.9 Engine Failures. The single most common emergency in ultralight and amateur-built aircraft is engine failure. When an engine fails, FLY THE ULTRALIGHT! Push the nose down to maintain airspeed, pick the landing field, and try to land into the wind.
11.9.1 If the pilot knows the cause of the engine failure (e.g., failure to change tanks) and can easily fix it in flight, they should do so. Do not focus all attention on restarting the engine. If preoccupied with the restart, the pilot may be distracted from flying the ultralight, inadvertently allowing the airspeed to bleed off, and setting the ultralight up for a stall/spin.
11.9.2 The best way to prepare for an engine out procedure is to practice, practice, and practice until the real thing is a non-event.
11.10 Loss of Control. Another emergency procedure the FLIGHT TEST PLAN should address is sudden loss of a control function such as ailerons/spoilers (roll), rudder (yaw), or elevator (pitch). In all emergency situations, all corrective control movements should be small and slowly initiated.
11.10.1 Loss of rudder authority or a jammed rudder can usually be overcome with opposite aileron. Be advised this is a cross control situation. Large or rapid control inputs could initiate a stall/spin maneuver, especially when the ultralight is in a landing configuration and/or operating at a low airspeed.
11.10.2 Loss of aileron authority usually can be overcome with rudder. The turns should be shallow while avoiding rudder inputs that would generate large yawing movements.
11.10.3 Loss of the elevator is the most serious loss of control function a pilot can experience. If the elevator is jammed in one position, or remains in a trail position behind the horizontal stabilizer, the pilot should experiment with engine power to determine whether an increase in power will raise or lower the nose.
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11.11 Catastrophic Failure.
11.11.1 The chance of loss of life or personal injury due to a catastrophic failure of the ultralight can be reduced with a ballistic recovery system (see Chapter 2, Section 3). If control of the ultralight cannot be regained, and the ultralight is equipped with a ballistic parachute, deploy the parachute before running out of time and altitude.
11.11.2 The pilot should be sure that activation of the parachute is a better choice than any other options available. Once the canopy is deployed, the pilot becomes a passenger.
11.11.3 Even with a canopy deployed, however, the pilot should remain alert to the danger of power lines, trees, rocks, water, and highways below which may obstruct their attempt to safely land.
Appendix A A-1 APPENDIX A. SAMPLE CHECKLIST FOR A CONDITION INSPECTION AIRCRAFT IDENTIFICATION:
TYPE/SN.
ENGINE MODEL/SN.
N NUMBER
PROPELLER MODEL/SN.
PROPELLER
TOTAL TIME
A/F TOTAL TIME ENGINE TOTAL TIME
OWNER GENERAL:
S = SATISFACTORY U = UNSATISFACTORY (correct all unsatisfactory items prior to flight) Builder/Inspector
S U S U
REGISTRATION/AIRWORTHINESS/OPERATING LIMITATIONS
AIRCRAFT IDENTIFICATION PLATES INSTALLED
EXPERIMENTAL PLACARD INSTALLED
WEIGHT AND BALANCE/EQUIPMENT LIST (updated for each flight)
RADIO STATION LICENSE WINGS:
REMOVE INSPECTION PLATES/FAIRINGS
GENERAL INSPECTION OF THE EXTERIOR/INTERIOR WING
FLIGHT CONTROL BALANCE WEIGHTS FOR SECURITY
FLIGHT CONTROL PROPER ATTACHMENT (NO SLOP)
FLIGHT CONTROL HINGES/ROD END BEARINGS
SERVICEABILITY
Appendix A A-2 S = SATISFACTORY U = UNSATISFACTORY (correct all unsatisfactory items prior to flight) Builder/Inspector
S U S U
FLIGHT CONTROLS PROPERLY RIGGED/PROPER TENSION
INSPECT ALL CONTROL STOPS FOR SECURITY
TRIM CONTROL PROPERLY RIGGED
TRIM CONTROL SURFACES/HINGES/ROD END BEARINGS SERV.
FRAYED CABLES OR CRACKED/FROZEN/RATCHETING
PULLEYS
SKIN PANELS DELAMINATE/VOIDS (COIN TEST)
POPPED RIVETS/CRACKED/DEFORMED SKIN
FABRIC/RIB STITCHING/TAPE CONDITION
LUBRICATION
WING ATTACH POINTS
FLYING/LANDING WIRES/STRUTS FOR SECURITY
CORROSION
FOR ULTRALIGHT CHECK
FLIGHT CONTROL BOLTS/PINS FOR SAFETY AND
CONDITION
WING/STRUT/CABLE ATTACHMENTS AND HARDWARE FOR
SAFETY AND CONDITION
Appendix A A-3 S = SATISFACTORY U = UNSATISFACTORY (correct all unsatisfactory items prior to flight) Builder/Inspector
S U S U
FUEL SYSTEM:
CORROSION
FUEL LINES FOR CHAFING/LEAKS/SECURITY/CONDITION
SUMP ALL FUEL TANKS FOR WATER OR DEBRIS
FUEL CAPS FOR SECURITY
FUEL PLACARD
FUEL VALVE/CROSS FEED/FOR OPERATION AND SECURITY
CLEAN FUEL FILTERS/GASCOLATOR/FLUSH SYSTEM
INSPECT FUEL TANK VENT SYSTEM
LANDING GEAR:
INSPECT STRUTS/TORQUE LINKS FOR ATTACHMENT
INSPECT STRUTS FOR PROPER EXTENSION
INSPECT FOR HYDRAULIC LEAKS
CHECK ALL BUSHINGS FOR WEAR/FREE PLAY
CHECK LUBRICATION
INSPECT WHEELS FOR ALIGNMENT
WHEEL/TIRES FOR CRACKS AND SERVICEABILITY
WHEEL BEARINGS FOR LUBRICATION
Appendix A A-4 S = SATISFACTORY U = UNSATISFACTORY (correct all unsatisfactory items prior to flight) Builder/Inspector
S U S U
INSPECT FOR CORROSION
INSPECT NOSE GEAR FOR CRACKS AND TRAVEL
INSPECT TAIL WHEEL FOR CRACKS AND TRAVEL
PERFORM GEAR RETRACTION TEST/CHECK INDICATOR LIGHTS
EMERGENCY GEAR RETRACTION SYSTEM
CHECK TIRE PRESSURE
BRAKE LINING WITHIN LIMITS
BRAKE DISKS FOR CRACKS, WEAR, AND DEFORMITY
BRAKE HYDRAULIC LINES FOR LEAKS AND SECURITY
FUSELAGE: