71 CHAPTER 9. ULTRALIGHT ENGINE/FUEL SYSTEM INSPECTION ‘‘Do not let ego overcome reason.’’ Al Hodges, Ultralight pilot, Homestead, FL (1994) SECTION 1. ENGINE INSPECTION
1. OBJECTIVE. To provide the amateurbuilder/ultralight pilot with a suggested engine and fuel system inspection program in addition to the manufacturer’s check list items.
a. Engine.
(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.)
(2) Check all hose clamps for tightness.
(3) Check for fuel and oil leaks.
(4) Check air filter for condition and attachment
(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.
(6) Check that the carburetor and the throttle cable is secured and both operate freely from idle stop to full power stop.
(7) Check carburetor boots for cracks that will suck air and may create a lean mixture, high CHT and EGT, and possible engine failure.
(8) Check the fuel on/off valve, fuel filter, and crossover valve for proper operation and position.
(9) Drain the fuel system of water and sediment.
(10) Ensure that the fuel tank is secured, full, and if applicable, contains the proper mix (ratio) of fuel and oil.
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b. Exhaust System.
(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 must be modified. If modifications are necessary, contact the engine manufacturer before incorporating any exhaust systems changes.
(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.
(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 aircraft lands.
c. Fan Cooling.
(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.
(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.
d. Reduction Drive.
(1) A large percentage of engines used on light-weight aircraft are 2 cycle air cooled engines fitted with a 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.
(2) To check tension on most V belts on the reduction drive, grab the belt and twist. The belt should allow no more than approximately a half a turn.
(3) Ensure that the reduction gear box is filled with oil to the proper level in accordance with the manufacturer’s instructions and drain plug/filter is safetied.
(4) Grasp the propeller (switch off and spark plugs disconnected) approximately half way down each blade. Try first to move the prop in an up and down motion. Pull away from the aircraft and then push in the opposite direction. No appreciable bearing slop should be detected in the reduction gear bearings.
(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 must 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
1. GENERAL. Many problems with lightweight aircraft engines 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 aircraft engines so first ensure that the fuel source is a reliable one.
a. Test for Alcohol in Automotive Fuel.
Take a thin glass jar, mark it one 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.
b. Fuel 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 fuel system operation during engine break-in and fuel flow during extreme angles of attack.
c. Filters, Fuel Lines, and Throttles.
(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 pre-flight inspection and avoid the possibility of air leaks on the suction side.
(2) Check plastic fuel lines for age hardness, discoloration, and over all 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.
(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.
d. Causes of High Fuel Consumption
(1) Dirty air filter causes 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.
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75 CHAPTER 10. ULTRALIGHT TEST FLYING RECOMMENDATIONS ‘‘Hurrying is a visible sign of worry.’’ Arnold H. Glascow SECTION 1. THREE RECOMMENDATIONS
1. OBJECTIVE. To list additional items applicable to ultralights that will need to be addressed in the FLIGHT TEST PLAN
2. RECOMMENDATIONS.
a. Even if the builder/owner or pilot is an B- 747 airline captain with 20,000 hours in type, he/ she should NOT climb into an ultralight without first receiving flight instruction from a properly certified or authorized ultralight flight instructor. This must be done in a two-seat ultralight trainer operated in accordance with the EAA or USUA exemption to FAR Part 103.
b. Ultralights by their very nature are highly susceptible to winds above 15 mph. All ultralight aircraft test flights should be conducted in light or no-wind conditions.
c. Even more so than America’s top fighter pilots, ultralight pilots must 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.
SECTION 2. AIRPORT SELECTION
1. OBJECTIVE. To choose an airport to test fly the ultralight.
a. Most ultralights are flown out of unimproved grass strips. Before test flying the ultralight from one of these locations ensure that a wind sock or even a flag is installed nearby to give some indication of the wind direction and speed.
76 5/24/95AC 90-89A
b. Carefully examine each air strip. 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.
c. 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
1. 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 handing characteristics at low and high taxi speeds, braking, monitoring engine operation, and developing pilot proficiency, the FLIGHT TEST PLAN should consider developing the following:
a. Cross-wind handling characteristics during taxi.
b. Addressing the ultralight’s response to rapid changes in power (tractor design versus pusher).
c. Practice 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 ‘‘Fly as if angels are watching you and taking notes.’’ Dr. Anthony Romanazzi, DMD and Ultralight pilot (1994)
1. 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 aircraft speed. In a light-weight 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.
2. 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.
3. 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.
4. 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 must monitor the airspeed to avoid inadvertently setting up a stall/spin scenario.
77 SECTION 5. EMERGENCY PROCEDURES
1. 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.
a. 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.
b. The best way to prepare for an engine out procedure is to practice, practice, and practice until the real thing is a non-event.
2. 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.
a. 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.
b. Loss of ailerons authority usually can be overcome with rudder. The turns should be shallow while avoiding rudder inputs that would generate large yawing movements.
c. 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 must experiment with engine power to determine whether an increase in power will raise or lower the nose.
3. CATASTROPHIC FAILURE.
a. 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 chap.
1, sec. 3). If control of the ultralight cannot be regained, and the ultralight is equipped with a ballistic chute, deploy the chute before running out of time and altitude.
(1) The pilot must 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.
(2) Even with a canopy deployed, however, the pilot must remain alert to the danger of power lines, trees, rocks, water, and highways below which may obstruct his/her attempt to safely land.
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1 5/24/95 AC 90-89A Appendix 1 APPENDIX 1. SAMPLE CHECKLIST FOR A CONDITION
INSPECTION AIRCRAFT IDENTIFICATION:
TYPE/SN. /emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln ENGINE MODEL/SN. /emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln N NUMBER /emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln PROPELLER MODEL/SN. /emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln A/F TOTAL TIME /emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln ENGINE TOTAL TIME /emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln OWNER /emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln PROPELLER TOTAL TIME /emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln/emlowln GENERAL:
S = SATISFACTORY U = UNSATISFACTORY (correct all unsatisfactory items prior to flight) Builder/Inspector
S U S U
REGISTRATION/AIRWORTHINESS/OPERATION LIMITATIONS
AIRCRAFT IDENTIFICATION PLATES INSTALLED
EXPERIMENTAL PLACARD INSTALLED
WEIGHT AND BALANCE/EQUIPMENT LIST (updated for each flight)
RADIO LICENSE WINGS:
REMOVE INSPECTION PLATES/FAIRINGS
GENERAL INSPECTION OF THE EXTERIOR/INTERIOR WING
FLIGHT CONTROLS BALANCE WEIGHTS FOR SECURITY
FLIGHT CONTROLS PROPER ATTACHMENT (NO SLOP)
FLIGHT CONTROL HINGES/ROD END BEARINGS SERVICEABILITY
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 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
2 5/24/95 AC 90-89A Appendix 1 APPENDIX 1. SAMPLE CHECKLIST FOR A CONDITION INSPECTION—Continued S = SATISFACTORY U = UNSATISFACTORY (correct all unsatisfactory items prior to flight) Builder/Inspector
S U S U
CORROSION
FOR U/L AIRCRAFT CHECK
FLIGHT CONTROL BOLTS/PINS FOR SAFETY AND CONDITION
WING/STRUT/CABLE ATTACHMENTS AND HARDWARE FOR SAFETY AND
CONDITION 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/GASOLATOR/FLUSH SYSTEM
INSPECT FUEL TANK VENT SYSTEM LANDING GEAR:
INSPECT STRUTS/TORQUE LINKS FOR ATTACHMENT
INSPECT STRUTS FOR PROPER EXTENSION
3 5/24/95 AC 90-89A Appendix 1 APPENDIX 1. SAMPLE CHECKLIST FOR A CONDITION INSPECTION—Continued S = SATISFACTORY U = UNSATISFACTORY (correct all unsatisfactory items prior to flight) Builder/Inspector
S U S U
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
INSPECT FOR CORROSION
INSPECT NOSE GEAR FOR CRACKS AND TRAVEL
INSPECT TAIL WHEEL FOR CRACKS AND TRAVEL
PERFORM GEAR RETRACTION TEST/CK 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:
REMOVE INSPECTION PLATES AND PANELS
INSPECT BULKHEADS AND STRINGERS FOR POPPED RIVETS AND CRACKED SKIN
INSPECT FOR DELAMINATED SKIN/VOIDS (COIN TEST)
INSPECT THE SECURITY OF ALL INTERNAL LINES
INSPECT WINDOWS/CANOPY FOR CRACKS AND FIT
INSPECT DOOR OR CANOPY LATCHING MECHANISM
INSPECT FIRE WALL FOR DISTORTION AND CRACKS
INSPECT RUDDER PEDALS AND BRAKES FOR OPERATION AND SECURITY
INSPECT BEHIND FIREWALL FOR LOOSE WIRES AND CHAFING LINES
4 5/24/95 AC 90-89A Appendix 1 APPENDIX 1. SAMPLE CHECKLIST FOR A CONDITION INSPECTION—Continued S = SATISFACTORY U = UNSATISFACTORY (correct all unsatisfactory items prior to flight) Builder/Inspector
S U S U
CHECK CONTROL STICK/YOKE FOR FREEDOM OF MOVEMENT
CHECK FLAP CONTROL OPERATION
CHECK CABLE AND PULLEYS FOR ATTACHMENT AND OPERATION
PERFORM FLOOD-LIGHT CARBON MONOXIDE TEST
ENSURE THE COCKPIT INSTRUMENTS ARE PROPERLY MARKED
INSPECT INSTRUMENTS, LINES, FOR SECURITY
CHECK/CLEAN/REPLACE INSTRUMENT FILTER
INSPECT COCKPIT FRESH AIR VENTS/HEATER VENTS FOR OPERATION AND
SECURITY
INSPECT SEATS, SEAT BELTS/SHOULDER HARNESS FOR SECURITY AND
ATTACHMENT
CORROSION
CHECK BALLISTIC CHUTE INSTALLATION PER MANUFACTURER
RECOMMENDATIONS
EMPENNAGE/CANARD
REMOVE INSPECTION PLATES AND FAIRINGS
INSPECT CANARD ATTACH POINTS FOR SECURITY
INSPECT VERTICAL FIN ATTACH POINTS
INSPECT ELEVATOR/STABILIZER ATTACH POINTS
INSPECT HINGES/TRIM TABS/ROD ENDS FOR ATTACHMENT AND FREE PLAY (SLOP)
INSPECT EMPENNAGE/CANARD SKIN FOR DAMAGE/CORROSION
INSPECT ALL CONTROL CABLES, HINGES AND PULLEYS
INSPECT ALL CONTROL STOPS FOR U/L: