3-2 characteristics by practicing 90-, 180-, and 360-degree turns and braking action. The pilot should also remember the importance of monitoring the oil pressure, oil temperature, and CHT, and maintaining them within limits, and should not overlook these checks.
Note: Some aircraft brake manufacturers have specific brake lining conditioning procedures (break-in) for metallic and non-asbestos organic linings. You should complete proper brake lining conditioning before starting the low- and high-speed taxi tests. If not properly conditioned, the brake lining will wear quickly and give poor braking action at higher speeds.
3.2.3 I nstrument Check. The pilot should check the flight instruments for operation each time the pilot taxies the aircraft. The compass should match the direction in which the aircraft is pointed, such as the magnetic heading of the runway or taxiway. When making a right hand turn, the turn coordinator/turn and bank should indicate a right turn but the ball should skid to the left. The vertical speed indicator should read zero and the artificial horizon should indicate level.
3.2.4 After Taxi Run. A fter each taxi run, inspect the aircraft for oil and brake fluid leaks. You should not consider a leak as a minor problem, but repair every leak and service the system before the next taxi test.
SECTION 2. HIGH-S PEED TAXI TESTS
3.3 Objective. Determine the aircraft’s high-speed handling and braking parameters.
3.3.1 D irection of Rotation . Propeller rotation will determine which rudder pedal you press to compensate for the asymmetrical thrust of the propeller blades. For example, when viewed from the cockpit, a Volkswagen automotive engine mounted in a tractor configuration will rotate the propeller counterclockwise. In this case, the pilot would use the left rudder pedal for high-speed taxi and takeoff. For a propeller turning clockwise, you would apply right rudder pedal.
3.3.2 Follow the Flight Test Plan. A s with every part of the flight testing program, the high-speed taxi tests should follow the flight test plan. Start slowly and do not progress to the next step until the flight test team is thoroughly satisfied with the aircraft and the team’s performance.
3.3.3 Increasing Taxi Speed. E ach taxi run should be 5 mph faster than the last run until the aircraft is within 80 percent of the predicted stall speed. Prior to reaching the predicted stall speed, the pilot should test aileron effectiveness by attempting to rock the wings slightly. As taxi speeds increase, the rudder becomes more responsive and directional control will improve.
3.3.3.1 I n a nose gear aircraft, the pilot should be able to raise the nose of the aircraft at 80 percent of the predicted stall speed. If the nose cannot be raised at this speed, the W&B and CG range should be rechecked. Most likely, there is a forward CG problem or the main gear is too far aft.
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3.3.3.2 In a tailwheel aircraft at 80 percent of stall speed, the pilot should be able to lift the tail and assume a takeoff position. Again, if the tail cannot be raised, recheck the W&B and CG range. Most likely, there is a rearward CG problem or the main gear is too far forward.
Caution: Heavy braking action at high speeds in tailwheel aircraft may cause directional problems, such as ground loops or nose overs.
3.3.4 T axi with Flaps. If runway conditions permit, duplicate each taxi test with the flaps in the takeoff and landing configuration. Record the flap effects on directional control and insert the information in the draft copy of the AOH.
3.3.5 Lift-O ff Point. Estimate the point on the runway where lift-off will occur and mark it with a green flag if no other existing reference is available.
3.3.6 Braking Distance.
3.3.6.1 Determine how much runway the pilot will need if it becomes necessary to abort the takeoff. This is usually accomplished by accelerating to 80 percent of lift-off speed, bringing the engine back to idle, and applying heavy braking action to bring the aircraft to a full stop. After a takeoff/abort test, give the brakes time to cool down. The brake lining should be examined carefully and replaced if necessary.
3.3.6.2 After determining the distance required to come to a full stop after aborting, add 30 percent to the distance. Measure that distance from the opposite end of the active runway. If no existing reference is available, mark it with a red flag.
The taxi tests are completed when the test pilot is satisfied with both the aircraft’s and the test pilot’s individual performance. Before the first flight, you should thoroughly inspect the aircraft and give special attention to the landing gear, brake system, engine, and propeller.
3.3.7 R epairs. During this inspection, ensure all discrepancies have been corrected. Examine the screens/filters for metal, flush the fuel system, and clean all the screens/filters.
Perform a leak check on the engine and the fuel system by running-up the engine.
Note 1: T he first high -speed taxi tests should be made in a no wind or a light headwind condition. The pilot should ensure that the tests will not interfere with the normal airport operations or create a safety hazard for other aircraft.
Note 2: Pilots of tailwheel aircraft should always be aware that ground loops are possible at any speed. This is true especially if the main landing gear is located too far forward of the aircraft’s CG.
4-1 CHAPTER 4. THE FIRST FLIGHT S ECTION 1. GENERAL
4.1 Objective. Take every precaution to ensure that the first test flight is an uneventful one.
4.2 General.
4.2.1 The first flight is an important event for you. As important as it is, it should not be turned into a social occasion. This puts enormous peer pressure on the pilot to fly an aircraft that may not be airworthy or to conduct the flight in inclement weather.
4.2.2 A professional will avoid this trap by following the flight test plan and inviting only those members of the crew needed to perform specialized tasks when testing the aircraft.
4.2.3 The first flight should be flown a thousand times: the first 500 on paper, the next 499 flights in the test pilot’s mind, and once in actuality. The first flight test should be so well-rehearsed by the test pilot and ground crew that the first flight is a non-event.
4.3 Recommendations.
4.3.1 The best time to test fly an aircraft is usually in the early morning when the winds are calm, and the pilot is well rested.
4.3.2 In addition to a pilot’s kneeboard, a small portable tape recorder or video camera properly mounted to the aircraft is an excellent way to record data.
4.3.3 Good communication with the ground is essential for data exchange and safety.
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4.4 First Flight Inspection. Before the first flight, the test pilot and at least one other experienced person should give the aircraft a good preflight inspection. As part of a thorough aircraft preflight inspection, check that:
4.4.1 Fuel, Weight and Balance (W&B), and Fluids.
4.4.1.1 The fuel on board is four times the amount of usable, clean, and proper octane fuel than is needed for the first flight. If the aircraft has a 2-cycle engine, check that the oil-to-fuel ratio is correct.
4.4.1.2 A current W&B check is completed. The aircraft’s center of gravity (CG) should be in the forward half of the safe CG range. This will reduce the possibility of instability during approach to a stall and enhance recovery from one.
4.4.1.3 Oil, brake, and hydraulic systems are serviced with the correct fluid and quantity.
4.4.1.4 The canopy or cabin door latches lock securely and will not vibrate loose in flight.
4.4.1.5 The fuel valve is in the proper position and vent lines are open.
4.4.1.6 The trim tabs are set in the takeoff position.
4.4.1.7 The altimeter is set to the field elevation and cross-checked with the local altimeter setting.
4.4.1.8 The complete control system functions properly.
4.4.1.9 All ground and air communications frequencies operate properly.
4.4.1.10 Engine cowling and airframe inspection plates/fairings are secured.
4.4.1.11 The airspeed indicator is marked with sticky tape or set electronically on the MFD, if so equipped, at the “predicted” best climb speed, best glide speed, and maneuvering speed (VA). If these speeds are not available from prototype flight test data, the following are conservative guidelines:
1. Best angle of climb speed (VX) = 1.5 times the aircraft’s predicted lift-off speed.
2. Best glide speed = 1.5 times the aircraft’s predicted lift-off speed.
3. Maneuvering speed (VA) = 2 times the aircraft’s predicted stall speed.
4. For applicable aircraft, we advise putting the maximum landing gear operating speed (VLO) and maximum flap-extended speed (VFE) on a piece of masking tape and attaching it to the instrument panel for reference.
4-3 SECTION 2. THE ROLE OF THE CHASE PLANE
4.5 Objective. Determine if you should use a chase plane during the flight test phase.
4.6 General. It should be a test pilot’s decision to use or not to use a chase plane. If you use a chase plane, it should serve specific functions listed in the flight test plan. Its overall purpose is: (1) to contribute to gathering flight test data, and (2) flight safety. The chase plane should not be a distraction to the test pilot nor only serve as a platform for a home camcorder/camera.
4.6.1 The primary functions of the chase plane crew are:
1. To watch the parts/systems of the test aircraft not visible to the test pilot and report any problems.
2. To assist the test pilot in following the flight test plan.
3. Watch for and inform the test pilot of other aircraft.
4. Assist in an emergency situation.
4.6.2 If you use a chase plane, the FAA offers the following suggestions:
4.6.2.1 You should use a single chase plane on the first two flights and the first time the amateur-built aircraft’s landing gear is retracted. The chase plane pilot should be experienced in formation flying and thoroughly briefed before each flight.
4.6.2.2 There should be at least two pilots onboard the chase plane. One pilot’s sole duty is to fly the aircraft and maintain a safe distance from the amateur-built aircraft. The other pilot serves as an observer who: (1) checks for other traffic,
(2) checks the condition of the test aircraft, and (3) communicates with the pilot on the test aircraft on a frequency assigned by air traffic control (ATC) or on the air-to-air communication frequency of 122.75 megahertz (MHz).
4.6.2.3 A good chase plane position is about 100 to 200 feet off the right side and slightly behind and below the test aircraft. Avoid flying directly behind the test aircraft. It is not uncommon that on first flights, fuel and oil leaks develop and small hardware and fasteners could also vibrate off the test aircraft.
Note: Pilots of both aircraft should keep each other informed of their intended actions or maneuvers prior to execution.
4.6.3 In an emergency situation:
4.6.3.1 If the test aircraft’s radio fails, the chase plane should serve as an airborne communication relay with the tower/ATC facility for the test aircraft.
4.6.3.2 For other emergency situations, the chase plane should give the test pilot information or assistance as required. If necessary, the chase plane can guide
4-4 the test pilot to a safe landing at the airport or an emergency field. If the test aircraft makes an off-airport landing, the chase plane can serve as an overhead spotter that can direct emergency personnel to the test aircraft’s location.
SECTION 3. EMERGENCY PROCEDURES
4.7 Objective. Develop a complete set of in-flight emergency procedures for the aircraft that are designed to make unmanageable situations manageable.
4.8 General.
4.8.1 The flight test plan should have a special section on emergency procedures. The responses to each emergency should be based on the aircraft’s predicted flight characteristics, airport location, surrounding terrain, and nearby emergency fields. The following is a partial list of possible emergencies—and suggested responses—that may arise during the flight test phase:
4.8.1.1 Problem: Engine failure on takeoff.
Response: Fly the aircraft. Establish best glide speed. If time permits, try to restart the engine. If altitude is below 800 feet and the engine will not start, land straight ahead or 20 degrees on either side of the runway centerline. We suggest this because, in most cases, the aircraft will lose altitude or airspeed while attempting a 180-degree turn back to the airport. Declare an emergency and shut off the master switch, fuel, and magnetos to reduce the possibility of fire on landing. Above 800 feet, successfully making a 180-degree turn to land downwind on the runway or a nearby emergency field is directly proportional to the wind velocity and the number of practice emergency landings the pilot has made in similar make and model aircraft.
4.8.1.2 Problem: Engine vibration increases with revolutions per minute (rpm).
Response: Fly the aircraft. Adjust power to minimize the effect of vibration, but maintain safe airspeed and altitude. Run through the emergency checklist and land as soon as possible.
4.8.1.3 Problem: Smoke in the cockpit.
Response 1: Fly the aircraft. If the smoke smells like burnt plastic wire installation, shut off the master switch. Put on smoke goggles, open the fresh air vents to clear the cockpit, and land as soon as possible.
Response 2: Fly the aircraft. If the smoke is bluish/grey and has an acrid odor like burning oil, shut off the fresh air/hot air vents and put on the smoke goggles. Monitor oil pressure and temperature. Be prepared to shut the engine down and land as soon as possible.
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4.8.1.4 Problem: Cabin door opening in flight.
Response: Fly the aircraft. A partially open door usually affects the airflow over the tail causing reduced control response and vibration. Reduce speed, maintain level flight, and yaw/slip the aircraft left or right to reduce vibration.
Open the side vent window to reduce air pressure resistance in the cabin and attempt to shut the door. Sometimes, placing the aircraft in a skid will help close a partially open door.
4.8.1.5 Problem: Engine fire.
Response: Fly the aircraft. Shut off the fuel selector, mixture, master switch, and magnetos. Land as soon as possible.
4.8.1.6 Problem: Out of rig condition.
Response: Fly the aircraft. Try to use the appropriate trim to offset adverse control pressures. Maintain altitude with airspeed. Make small control inputs, reduce power slowly to avoid controllability problems, and land as soon as possible.
4.8.2 Other possible emergencies you should plan for include:
1. Canopy opening unexpectedly, if applicable.
2. Loss of communications.
3. Throttle stuck in one position.
4. Oil on the windshield.
5. Separation of a propeller blade.
6. Fire in the cockpit.
SECTION 4. FIRST FLIGHT
4.9 Objective. Determine engine reliability and flight control characteristics.
4.9.1 After completing the preflight inspection, the test pilot should properly fit the seat/shoulder harness, making sure the harness enables easy access to all the cockpit controls. The harness fit should be verified by a flight test crewmember. Following the flight test plan and using the starting checklist, warm up the engine until the engine instruments indicate normal operating temperatures and pressures.
4.9.2 The test pilot should conduct a complete check of each aircraft system, such as carb heat, magnetos, and brakes, and perform a static rpm check.
4.9.3 If the airport does not have a tower/Universal Communications frequency (UNICOM) available, the pilot should transmit over 122.9 MHz the following message: “This is experimental aircraft N___ on the first test flight, departing runway ___ at ___ airport,
4-6 and will remain in the local area for the next hour.” Transmit the aircraft N number, location, and intentions every 10 minutes.
4.9.4 If the airport has a tower, notify tower personnel that an experimental aircraft is on its first test flight and request takeoff instructions.
4.9.5 After the tower clears the test pilot for takeoff, clear the area, line up on the runway centerline, release the brakes, and slowly add power to provide “thinking time.” When the throttle is fully advanced, glance at the oil pressure gauge and tachometer to confirm they are in the green and indicating takeoff rpm. If either oil pressure or tachometer reads low, abort the takeoff. A type certificated (TC) engine of 100 horsepower (hp) will generally produce between 2,100 to 2,300 rpm on the takeoff roll, depending on the propeller installed.
4.9.6 If there is any unusual vibration, if engine rpm exceeds the red line limit, or if the engine hesitates, abort the takeoff!
4.9.7 If the test aircraft has a tailwheel, keep the tail on the runway until the rudder is effective.
This usually happens at approximately 35 mph on most aircraft.
4.9.8 As the aircraft accelerates and approaches the predicted/manufacturer’s lift off speed/point—indicated by the green flag beside the runway—gently ease back on the stick/yoke. The first takeoff should be a gentle and well-controlled maneuver with the aircraft doing all the work.
4.9.9 If the aircraft does not rotate or the test pilot experiences unusual stick forces, abort the takeoff!
4.9.10 If the aircraft has retractable gear, do not raise the gear on the first two to three flights until the aircraft’s stability/control responses have been explored.
4.9.11 The FAA recommends that after establishing a safe climb angle, the pilot not throttle back, switch tanks, or make large inputs into the flight controls for the first 1,000 feet above ground level (AGL). At a preselected altitude, reduce power slowly to avoid a pitch up or pitch down attitude.
Note: Check for any additional aileron or rudder input pressure during the climb.
Try reducing any abnormal stick pressures with trim. Each control input should be small and slow.
4.9.12 If you notice unusual engine vibrations, rapid oil pressure fluctuation, oil temperature or Cylinder Head Temperatures (CHT) approaching red line, or decreasing fuel pressure, refer to the emergency checklist and land as soon as possible.
4-7 SECTION 5. FIRST FLIGHT PROCEDURES
4.10 Objective. Perform a series of tests to develop data that will ensure a safe landing.
4.10.1 T he First Test Flight.
4.10.1.1 After takeoff, climb to 3,000 feet AGL and level off. Reduce power slowly.
Complete the cruise checklist items. Following the flight test plan, circle the airport or emergency field as the engine performance is being monitored.
4.10.1.2 Limit the cruise speed to no more than 1.5 times the predicted stall speed of the aircraft. This will reduce the chances of flutter. If the engine appears to be operating smoothly, try testing the flight controls.
4.10.1.3 With the airspeed being monitored, each control input should be gentle and small. Start with the rudder first. Yaw the nose of the aircraft 5 degrees left and right. Note the response. Raise the aircraft’s nose 3 degrees up, note the response. After the aircraft is stabilized, level off and try 3 degrees nose down, trim, and note the response. Try a gentle bank of no more than 5 degrees to the left, then one to the right. If the aircraft is stable and is operating smoothly, try a few 90-degree clearing turns, followed by two 360-degree turns: one to the left and one to the right, at a bank angle of 10 degrees.
Note: From this point forward, the FAA recommends that all flight test maneuvers be preceded with two 90-degree clearing turns to ensure that the flight test area is free of other aircraft.
4.10.1.4 If the aircraft is responding to the prescribed specifications, increase the bank angle in succeeding turns to 20 degrees bank angle. If you don’t encounter any problems, climb to 5,000 feet AGL using the climb checklist and monitoring engine gauges, level off, fly an imaginary landing pattern, and test the flaps.
Do not forget to announce every 5 to 10 minutes the aircraft’s location, altitude, and intentions. Practice approach to landing by descending to 4,000 feet AGL first, then to 3,000 feet. Remember, use the descent checklist.
4.10.1.5 During these maneuvers, control pressures should increase in proportion to control deflection. If control pressure remains the same as control deflection increases or if stick forces become lighter as control deflection increases, the aircraft may have a stability problem. Avoid large control movements and land as soon as possible.
4.10.1.6 Keep informing the tower/UNICOM/chase plane of what is happening. For every 10 minutes of anticipated flight time, plan a brief rest period for the pilot. Fly straight and level, monitor the gauges, and enjoy the experience.
4.10.1.7 At low cruise power setting, straight and level, observe how the aircraft trims out. Do “fixed” trim tabs on the rudder and aileron need adjustment? Are
4-8 adjustable aileron and elevator trim controls effective? Is the control stick/yoke slightly forward of the middle position in straight and level flight?
4.10.1.8 Climb slowly back up to 5,000 feet. You should answer two questions before landing:
• Is the aircraft controllable at low speeds?
• What is the estimated stall speed?
4.10.1.9 These questions can be answered with an approach to a stall maneuver. Don’t perform a full stall check at this time!
4.10.1.10 An approach to a stall check helps establish a preliminary stall speed (VS1) in mph/knots so you can calculate the approach speed for landing. The pilot will also know the aircraft’s handling characteristics at low speed.
4.10.2 Stall Testing. Suggested procedure below is for the first stall testing.
4.10.2.1 Level off at altitude; make two clearing turns; stabilize airspeed, heading, and altitude; apply carb heat; set the flaps in the landing configuration, reduce power slowly to 900 rpm, trim. If you can’t trim the aircraft properly, you can still proceed with the check as long as control forces are not unusually heavy.
4.10.2.2 With the aircraft airspeed about 1.4 mph/knots times the predicted stall speed, raise the nose slowly. Look for the aircraft to start decelerating slowly, about ½ mph/knot a second. A 30 mph/knot deceleration at ½ mph/knot per second will take about a minute.
4.10.2.3 As the aircraft slows down, note all the things that happen as the speed bleeds off. Observe the changing nose attitude and how the control forces change.
Keep the turn coordinator indication level or the turn and bank “ball” in the middle.
4.10.2.4 Note how much rudder it takes to keep the ball centered. Every few seconds make very small control inputs to check that the aircraft is operating as expected. If the aircraft does not respond to small control inputs—and you should not expect it to respond as quickly as it did at higher speeds—make the inputs a little bit larger. Increase the amount of input progressively. Do not simultaneously put in all three control inputs. Give particular attention to the response to nose-down elevator inputs, which is necessary for recovery.
4.10.2.5 Notice any changes in flight characteristics and the speeds at which they occur. Be especially alert for the onset of pre-stall buffet. Is the buffet felt through the stick? Through the airframe? Through the seat of the pants? Does the nose of the airplane want to rise or drop on its own? How strong is the buffet? Is the buffet continuous? Would it get the pilot’s attention if they were concentrating on something else?
4-9 Note: On some high-performance aircraft or aircraft with unusual wing designs, a pre-stall buffet may not exist, and the stall may be abrupt and violent with a large amount of wing drop.
4.10.2.6 Keep making small control inputs at intervals to check the aircraft’s responses. At approximately 5 mph/knots before the predicted stall speed, or at the first sign of a pre-stall buffet, note the airspeed and stop the test.
Recover and write down the pre-stall indicated airspeed. This airspeed should be the reference stall speed for the first landing.
4.10.2.7 The pre-stall recovery response should be a smooth and quick forward stick movement. This response should be enough to reduce the AOA to the point where the airplane is flying normally again.
4.10.2.8 A wing drop would be unexpected so early in the approach to a stall, but if it becomes necessary to raise a low wing do it with rudder, NOT OPPOSITE AILERON. Use of ailerons at lower speed would increase the chances for a stall or a sudden departure from controlled flight.
4.10.2.9 You don’t need to gain more airspeed than the extra few mph/knots to fly out of a pre-stall condition. After returning to straight and level flight and using the information learned, the pilot can practice a few more recoveries from a pre-stall condition. Remember the aircraft will constantly be losing altitude so you may have to climb back up to 5,000 feet AGL to continue further flight testing. Do not get so involved that the overall objective of the first flight is lost—getting the pilot and aircraft safely back on the ground.
4.10.2.10 The flight test plan for the first flight should call for a maximum of 1 hour of actual flight time. This is to reduce pilot fatigue and the possibility of an engine failure or airframe malfunction occurring due to vibration or construction errors.
Note: The pilot may elect to make several practice approaches to landing at altitude or low approaches to the active runway to get a solid understanding of the lower airspeeds, aircraft attitude, and overall feel of the aircraft in the landing configuration. Before each low approach at the airport, you should advise the tower/UNICOM/chase plane of your intentions. Avoid other traffic in the pattern, and use the landing checklist.
4.10.2.11 When the pilot has completed all the tests called for by the flight test plan, notify the tower/UNICOM/chase plane of your intent to land. Complete the landing checklist before entering downwind. Keep all turns less than 20 degrees of bank, but do not cross-control by using the rudder to move the nose. This will increase the bank angle, which most pilots will correct by using opposite aileron. If allowed to continue, and with backpressure on the
4-10 stick, this will result in a cross-control stall and a roll to a near vertical bank attitude at the beginning of a spin with no altitude left for recovery.
4.10.2.12 On final approach, the aircraft speed should be no less than 1.3 but no more than 1.4 times the recorded first flight pre-stall speed. Homebuilt biplanes— high drag aircraft—should use an approach speed of 1.5 times stall speed on landings.
4.10.2.13 Landings, especially the first one in an amateur-built or kit plane, are always exciting. Proceed slowly and do not over control. If the landing conditions are not ideal, be prepared to go around.
4.10.2.14 The actual touchdown should take place within the first 1,000 feet with braking action being applied before the red (abort) flag marker on the runway.
4.10.2.15 After taxiing in, secure the aircraft, debrief the flight with members of the team, and then together perform a careful post-flight inspection of the aircraft.
Note: Remember to allow enough time to absorb what has been learned about the aircraft’s performance and the pilot’s and ground crew’s responses to it.