(4) Rotate the propeller slowly to see if the next blade ‘‘tracks’’ through the same point (touches the block, see figure 2). Each blade should be within 1⁄16’’ from one another.
b. If the propeller is out of track, it may be due to one or more propeller blades that are bent, a bent propeller flange, or propeller mounting bolts that are over or under torqued. An out-of-track propeller will cause vibration and stress to the engine and airframe and may cause premature propeller failure.
4. METAL PROPELLER INSPECTION Perhaps the two biggest problems affecting the airworthiness of metal propellers are corrosion and nicks on the leading edge.
a. Identifying Corrosion.
(1) Surface corrosion can occur on the surface of metal blades due to a chemical or electrochemical action. The oxidation product usually appears on the surface of the metal as a white powder.
(2) Pitting corrosion causes small cavities or pits extending into the metal surface. This is an advanced form of corrosion, appearing as small dark holes that usually form under decals or blade overlays.
(3) Inter-granular corrosion, rare and difficult to detect in propellers, is the most dangerous form of corrosion. It attacks the boundary layers of the metal, creating patches of lifted metal and white/ gray exfoliation on the surface of the propeller. It is sometimes found in propellers that had a ground strike and have been straightened.
(4) If any of these signs of corrosion are found, do NOT fly the aircraft. Refer to the manufacturer’s maintenance manual for corrosion limits and repairs or AC 43.4, ‘‘Corrosion Control for Aircraft,’’ and AC 20-37D, ‘‘Aircraft, Metal Propeller Maintenance,’’ for additional maintenance information and corrective actions.
b. Nicks and Metal Blades.
(1) Nicks in the leading and trailing edge of a metal blade are usually V-shaped. They are caused by high speed impact between the propeller and a stone or piece of gravel. Properly trained individuals can ‘‘dress out’’ the crack if the nick is not too wide and/or deep. Before each nick is dressed out, each nick and surrounding area should be inspected with a 10-power magnifying glass for cracks. If an area looks suspicious, inspect the area again using the propeller manufacturer’s approved dye penetrant or fluorescent penetrant method.
(2) If the nick is left unattended, the high propeller operational stresses will be concentrated at the bottom of the nick’s V and, in time, will generate a crack. The crack can migrate across the blade until the blade fails, producing a massive imbalance between the propeller and the engine, ultimately causing structural failure. Cracks in metal blades CANNOT be repaired. A cracked propeller must be marked unserviceable and discarded.
c. Warning. Metal propellers are matched/ tuned to the engine and airframe resonant frequency by being manufactured with a particular diameter to minimize vibration. DO NOT SHORTEN METAL BLADES for any reason unless the manufacturer specifically permits this major alteration.
5. PROPELLER INSPECTION.
a. Wood propellers should be inspected before and immediately after a flight. Inspect to ensure the following:
(1) The drain holes are open on metal edged blade tips
(2) The metal/composite leading edge is secured and serviceable
(3) The blades, hub, and leading edge have no scars or bruises
(4) The mounting bolt torque and safety wire or cotter pins are secure
(5) There are no cracks on the propeller spinner (if applicable), and the safety wire is secure
(6) There are no small cracks in the protective coating on the propeller, which are caused by UV radiation
(7) The charring around the mating surface of the prop and the engine flange -- both indications of a loose propeller
b. A word about torque: A new, wooden propeller should have the mounting bolts checked
28 5/24/95AC 90-89A for proper torque within the first hour of flight and every hour for 10 operational hours thereafter.
(1) After 10 hours, check the bolt torque every 5 hours thereafter. The mounting bolt torque also should be checked prior to flight if the aircraft has been in storage for a long period of time (3 to 6 months).
(2) If the bolts need to be torqued, it is suggested all the bolts be loosened for an hour to allow the wood to relax. ‘‘Finger tighten’’ the bolts until snug and tighten the attaching bolts in small increments, moving diagonally across the bolt circle.
It is good practice to check the propeller track (see chapter 1, section 7) as the bolts are torqued down.
The torqued bolts should be safety wired in pairs.
(3) If nylon/fiber insert type nuts are used, they should be changed every time the propeller bolts are re-torqued. They should never be used with a bolt with a cotter key hole in the threaded area because the sharp edges around the hole will cut the nylon/fiber insert and reduce the fastener’s effectiveness. All self-locking nuts should have at least two bolt threads visible pass the nylon/fiber insert after torquing.
(4) If any of the following damage is found, a wood propeller should be removed from the aircraft and sent back to the manufacturer for repair. If the propeller cannot be saved, it should be marked unserviceable.
(i) Any cracks in the blades or hub
(ii) Deep cuts across the wood grain
(iii) Blade track that exceeds 1⁄16’’ limits after attempts to repair
(iv) Any warpage or obvious defect
(v) Extreme wear (leading edge erosion, bolt hole elongation)
(vi) Any separation between lamination NOTE: When parking the aircraft, always leave the wood propeller in the horizontal position. This position will allow the wood to absorb small amounts of moisture evenly across it’s entire span rather than concentrating the moisture (weight) in the low blade and creating a vibration problem.
6. COMPOSITE PROPELLERS INSPECTION.
a. There are generally two types of composite propellers: thermo-plastic injection molded propeller and the carbon/graphite fiber composite propeller.
(1) The thermo-plastic injection molded propeller is a low cost, thin bladed propeller used on engines of 80 horsepower or less. Propeller inspection is straight forward, by examining the blades and hub for cracks and nicks. If a crack is found, do not fly until the propeller is replaced. Small nicks of 3⁄16 of an inch or less can be dressed out and filled using a two-part epoxy.
(2) Carbon/graphite composite propellers are primarily used on engines of 40 horsepower and more. One should inspect for small hair line cracks in the gel coat. These spider cracks are usually caused by vibration generated by a mismatch of the engine and propeller combination. If a crack in the base material of the propeller other than the gel coat is found, do not fly until the manufacturer inspects the propeller.
(i) Nicks of 1⁄2 inch or less in the leading or trailing edges of carbon/graphite propellers can be dressed out and filled using a two-part epoxy. But if the nick has severed the fiberglass roving (looks like a fiberglass wire bundle) that runs hub to tip on the leading and trailing edge, do not fly. The propeller has been severely damaged and must be sent back to the factory for inspection and repair.
(ii) Before making even small repairs on a composite propeller, check with the manufacturer first. Larger nicks must go back to the factory for inspection and repair.
29 CHAPTER 2. TAXI TESTS SECTION 1. LOW SPEED TAXI TESTS ‘‘Yelling ’Clear the Prop!’ before you start an aircraft is the first of a series of well planned, choreographed steps to make you a professional.’’ Jack Crawford, Pilot, Mechanic, Airport Operator (1994)
1. OBJECTIVES. The objectives of the taxi tests are fourfold:
a. To ensure that the aircraft ‘‘tracks’’ straight and there is adequate directional control at 20 percent below the anticipated take-off speed.
b. To determine if the aircraft’s engine cooling and the brake system are adequate.
c. To predict the flight trim of the aircraft and its handling characteristics during take off and landings.
d. To allow the pilot to become proficient with the handling and braking characteristics of the aircraft.
NOTE: All taxi tests, low and high speed, should be made as if it were the first flight.
The pilot should be wearing the proper clothing, seat belt/shoulder harness and helmet and be mentally and physically prepared for the possibility of flight.
2. TAXI TESTS.
a. Prior to beginning taxi tests in a conventional (tail dragger) aircraft, the tail should be raised until the aircraft is in the approximate take-off position. The pilot should spend an hour or more in the cockpit to become accustomed to the aircraft’s takeoff position. This small but important aspect of training will help the pilot avoid overreacting to an unexpected deck angle on the first flight.
NOTE: All taxi tests should always be monitored by a minimum of one other member of the flight test team, who will watch for evidence of fire/smoke or other problems not visible to the pilot.
b. The taxi tests should begin with a taxi speed no faster than a man can walk. The pilot should spend this time getting acquainted with the aircraft’s low speed handling characteristics by practicing 90, 180, and 360 degree turns and braking action. The pilot should also remember that monitoring the oil pressure, oil temperature, cylinder head temperature, and maintaining them within limits is a critical function that must not be overlooked.
30 5/24/95AC 90-89A NOTE: The builder should be aware that some aircraft brake manufacturers have specific brake lining conditioning procedures (break-in) for metallic and non-asbestos organic linings. Proper brake lining conditioning should be completed 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.
c. The pilot should check the flight instruments for operation each time the aircraft is taxied out. The compass should match the magnetic heading of the runway or taxi way the aircraft is on. When making a turn (e.g., right hand turn), the turn coordinator/turn and bank should indicate a right hand turn but the ball should skid to the left. The vertical speed indicator should read zero and the artificial horizon should indicate level.
d. After each taxi run, inspect the aircraft for oil and brake fluid leaks. No leak should be considered a minor problem. Every leak must be repaired and the system serviced prior to the next taxi test.
SECTION 2. HIGH SPEED TAXI TESTS ‘‘First get use to the fact that you are now 30 feet wide and you steer with your feet.’’ Wayne Nutsch
1. OBJECTIVE. To determine the aircraft’s high speed handling and braking parameters.
a. Propeller rotation will determine which rudder pedal is pressed 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 counter-clockwise. In this case, the pilot must use the left rudder pedal for high speed taxi and take-off.
b. As 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 everyone is thoroughly satisfied with the aircraft and his/her own performance.
c. Each 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.
(1) In a nose gear aircraft, the pilot should be able to raise the nose of the aircraft to a take off attitude at 80 percent of the stall speed. If the nose cannot be raised at this speed, the weight and balance and CG range should be rechecked. Most likely there is a forward CG problem or the main gear is too far aft.
(2) In a tail wheel aircraft at 80 percent of stall speed, the pilot should be able to lift the tail and assume a take-off position. Again, if the tail cannot be raised, recheck the weight and balance 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 tail wheel aircraft may cause directional problems (ground loops) or nose overs.
c. If runway conditions permit, duplicate each taxi test with the flaps in the take-off and landing configuration. Record the flap effects on directional control and insert the information in the draft copy of the aircraft’s flight manual.
d. Determine the approximate point on the runway where lift-off will occur and mark it with a green flag if no other existing reference is available.
e. Determine how much runway the pilot will need if it becomes necessary to abort the take-off.
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 each take-off/abort test, the brakes must be allowed to COOL DOWN.
The lining must be examined carefully and replaced if necessary.
f. 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 which will be
31 used. 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 his/her individual performance. Prior to the first flight, the aircraft should be thoroughly inspected with special attention given to the landing gear, brake system, engine, and propeller.
g. During this inspection all discrepancies must be fixed. 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.
h. Notes.
(1) The first high speed taxi tests should be made in a no wind or a light head wind condition.
The pilot should ensure that the tests will not interfere with the normal airport operations or create a safety hazard for other aircraft.
(2) If the aircraft’s engine is not a U.S. type certificated engine, the pilot should determine which way the propeller rotates.
(3) Pilots of tail wheel aircraft must 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.
32 5/24/95AC 90-89A
THIS PAGE INTENTIONALLY LEFT BLANK
33 CHAPTER 3. THE FIRST FLIGHT ‘‘It is critically important that a test pilot never succumb to the temptation to do too much too soon, for that path leads but to the grave.’’ Richard Hallion (1987) SECTION 1. GENERAL
1. OBJECTIVE. To take every precaution to ensure that the first test flight is an ‘‘uneventful’’ one.
2. GENERAL.
a. The first flight is an important event for an amateur-builder. 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.
b. 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.
c. A safe and uneventful first flight begins with verifying all emergency equipment and personnel are standing by, radio communications are functional, members of the crew are briefed, weather is ideal, and the aircraft is airworthy. The pilot must be rested and physically and mentally ready for the first flight and every flight thereafter. The pilot also should review any new data developed for the aircraft’s flight manual.
d. 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.
34 5/24/95AC 90-89A
31. RECOMMENDATIONS.
a. 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.
b. In addition to a pilot’s knee board, a small portable tape recorder or video camera properly mounted to the aircraft is an excellent way to record data.
c. Good communication with the ground is essential for data exchange and safety.
4. FIRST FLIGHT INSPECTION.
a. Prior to the first flight, the aircraft should be given a good pre-flight inspection by the pilot and at least one other experienced individual. A thorough aircraft pre-flight inspection should ensure that:
(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 a 2 cycle engine is used, check that the oil to fuel mix ratio is correct.
(2) A current weight and balance check is completed. The aircraft’s 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.
(3) Check oil, brake fluid, and hydraulic system for the correct fluid and quantity.
(4) Canopy or cabin door latches lock securely and will not vibrate loose in flight.
(5) Fuel valve is in the proper position and vent lines are open.
(6) Trim tabs set in the take-off position.
(7) Altimeter set to the field elevation and cross-checked with the local altimeter setting.
(8) The complete control system has been given a functional check.
(9) Check of all ground and air communications frequencies for proper operation.
(10) Engine cowling and airframe inspection plates/fairings secured.
(11) The airspeed indicator marked with sticky tape at the ‘‘predicted’’ BEST CLIMB speed, BEST GLIDE speed and MANEUVERING speed.
If these speeds are not available from prototype flight test data, the following are conservative guidelines to initially determine the referenced speeds:
(i) BEST ANGLE OF CLIMB (V x) = 1.5 times the aircraft’s predicted lift-off speed.
(ii) BEST GLIDE SPEED = 1.5 times the aircraft’s predicted lift-off speed.
(iii) MANEUVERING SPEED (Va) = 2 times the aircraft’s predicted stall speed.
(iv) For applicable aircraft, it is advisable to put the maximum landing gear operating speed (Vlo) and maximum flap extension speed (Vfe) on a piece of masking tape and attach it to the instrument panel for reference.
SECTION 2. THE ROLE OF THE CHASE PLANE
1. OBJECTIVE. To determine whether a chase plane should be used during the FLIGHT TEST PHASE.
2. GENERAL. To use or not to use a chase plane should be a ‘‘test pilot’s’’ decision. If a chase plane is used, it must serve a specific set of functions identified in the FLIGHT TEST PLAN. Its overall purpose is to contribute to gathering flight test data and flight safety. The chase plane should not serve as a distraction to the test pilot or only as a platform for a home camcorder/camera.
a. The primary functions of the chase plane are as follows:
(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
b. If a chase plane is used , the following suggestions are offered:
(1) A single chase plane should be used on the first two flights and the first time the amateurbuilt aircraft’s landing gear is retracted. The chase plane pilot should be experienced in formation flying and thoroughly briefed prior to each flight.
(2) There should be at least two pilots on board 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 whose duties include checking for other traffic, the condition of the test aircraft, and communicating with the pilot on the frequency assigned by air traffic control (ATC) (e.g., 122.75 megahertz [MHz]).
(3) A good chase plane position is about 100/200 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 vibrate off the aircraft.
NOTE: Pilots of Both Aircraft Must Keep Each Other Informed of Their Intended Action or Maneuver Prior to Execution.
c. In an emergency situation:
(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.
(2) For other emergency situations, the chase plane should provide the test pilot with information or assistance as required. If necessary, the chase plane can guide the test pilot to a safe landing at the airport or an emergency field. If the test aircraft goes down off the airport, the chase plane can serve as an overhead spotter that can direct emergency personnel to the test aircraft location.
SECTION 3. EMERGENCY PROCEDURES ‘‘At the worst possible time, the worst possible thing will happen.’’ Murphy’s Law
1. OBJECTIVE. To develop a complete set of in-flight emergency procedures for the aircraft that are designed to make unmanageable situations manageable.
2. GENERAL. The FLIGHT TEST PLAN should have a special section on emergency procedures. The responses to each emergency should have been developed based on the aircraft’s predicted flight characteristics, airport location, surrounding terrain, and nearby emergency fields.
a. The following is a partial list of possible emergencies that may arise during the flight test phase and includes suggested responses:
(1) PROBLEM: Engine failure on takeoff.
RESPONSE: Fly the aircraft! Establish best glide speed. If time permits, try to restart 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. This is suggested because in most cases the aircraft will run out of altitude or airspeed as the pilot attempts 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, the chances of making a 180 degree turn to land downwind on the runway or another emergency field nearby are directly proportional to the wind velocity and the numbers of practice emergency landings the pilots has made in similar make and model aircraft.
(2) PROBLEM: Engine vibration increases with rpm.
RESPONSE: Fly the aircraft!
Reduce power or increase power to minimize the effect of vibration, but maintain safe airspeed and altitude. Run through the emergency checklist and land as soon as possible.
(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,
36 5/24/95AC 90-89A 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.
(4) PROBLEM: Engine fire.
RESPONSE: Fly the aircraft! Shut off the fuel selector, mixture master switch, and magnetos. Land as soon as possible.
(5) PROBLEM: Out of rig condition.
RESPONSE: Fly the aircraft! Try to use the appropriate trim to offset adverse control pressures. Keep the airspeed high enough to maintain altitude. Make small control inputs, reduce power slowly to avoid controllability problems, and land as soon as practical.
(6) 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 putting the aircraft in a skid will assist in closing a partially open door.
b. Other possible emergencies to plan for include:
(1) Canopy opening unexpectedly
(2) Loss of communications
(3) Throttle stuck in one position
(4) Oil on the windshield
(5) Propeller throws a blade
(6) Fire in the cockpit SECTION 4. FIRST FLIGHT ‘‘Always leave yourself a way out.’’ Chuck Yeager
1. OBJECTIVES. The two objectives of the first flight are to determine engine reliability and flight control characteristics.
a. After completing the pre-flight inspection, the test pilot should ensure that the seat/shoulder harness is properly fitted and allows easy access to all the cockpit controls (verified by a crew member).
Following the FLIGHT TEST PLAN and using the starting checklist, warm up the engine until the engine instruments indicate normal operating temperatures and pressures.
b. A complete check of each aircraft system should be performed (e.g., carb heat, magnetos, static rpm, and brakes).
c. If the airport does not have a tower/unicom available, the pilot should transmit over 122.9 MHz the following message: ‘‘This is experimental aircraft N/emlowln/emlowln/emlowln/wdspc on the first test flight, departing runway /emlowln/emlowln/emlowln/wdspc at /emlowln/emlowln/emlowln/wdspc airport, and will remain in the local area for the next hour.’’ Transmit the aircraft N number, location, and intentions every ten minutes.
d. If the airport is equipped with a tower, notify them that an experimental aircraft is on its first test flight and requests take-off instructions.
e. After being given clearance to take-off, 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 an oil pressure gauge and tachometer to confirm they are in the green and indicating take-off rpm. A type certificated engine of a 100 horsepower will produce between 2100 to 2300 rpm on the take-off roll, depending on the type of propeller installed. If either oil pressure or tachometer is reading low, abort the takeoff!
f. If there is any unusual vibration, rpm exceeding the red line, or engine hesitation, abort the takeoff!
g. If in a tail wheel aircraft, keep the tail on the runway until the rudder is effective. This usually happens at approximately 35 mph on most aircraft.
h. As the aircraft accelerates and approaches the predicted/manufacturer’s lift off speed/point (green flag), gently ease back on the stick. The first take-off should be a gentle and well-controlled maneuver with the aircraft doing all the work.
i. If the aircraft does not want to rotate or unusual stick forces are experienced, abort the takeoff!
j. 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 a little further.
k. It is recommended that after establishing a safe climb angle. the pilot DOES NOT throttle back, switch tanks, or make large inputs into the flight controls for the first 1,000 feet. At the preselected altitude, reduce power slowly to avoid a pitch up or pitch down that might be associated with rapid power reductions.
NOTE: Check if there is any additional stick or rudder input pressure during the climb.
Try reducing any abnormal stick pressures with trim. Each control input should be small and slow.
l. If any unusual engine vibrations, rapid oil pressure fluctuation, oil and cylinder head temperatures approaching red line, or decreasing fuel pressure is experienced, refer to the emergency check list and land as soon as possible.
SECTION 5. FIRST FLIGHT PROCEDURES ‘‘In my opinion, about 90 percent of your risk in a total program comes with a first flight. There is no nice in-between milestone. You have to bite it off in one chunk.’’ Deke Slayton
1. OBJECTIVE. To perform a series of tests to develop data that will ensure a safe landing.
a. The First Test Flight.
(1) After take-off, climb to 3,000 feet above ground level (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.
(2) Limit the cruise speed to no more than
1.5 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.
(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 three 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.
(4) If the aircraft is responding to the prescribed specifications, increase the bank angle in succeeding turns to 20 degrees. If no problems are encountered, 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.
(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.
(6) Remember to keep informing the tower/UNICOM/chase plane of what is happening.
For 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.
38 5/24/95AC 90-89A
(7) At low cruise power setting, straight and level, observe how the aircraft trims out. Do the ‘‘fixed’’ trim tabs on the rudder and aileron need adjustment? Are the adjustable aileron and elevator trim control effective? Is the control stick/yoke slightly forward of the mid-position in straight and level flight?
(8) Climb slowly back up to 5,000 feet.
Two questions must be answered before landing:
(i) Is the aircraft controllable at low speeds?
(ii) What is the approximate stall speed?
(9) These questions can be answered with an approach to a stall maneuver. Do NOT perform a FULL STALL check at this time!
(10) The necessity for an approach to a stall check is because it will help establish a preliminary stall speed (Vsi) in mph/knots so the approach speed for landing can be calculated. Also, the pilot will have knowledge of the aircraft’s handling characteristics at low speed.
b. Suggested Procedure.
(1) Level off at altitude; make two clearing turns; stabilize airspeed, heading, and altitude; apply carb heat; set the flaps in the landing configuration and reduce power slowly to 900 rpm. TRIM. If, as is not uncommon on first flights, the aircraft cannot be trimmed properly, the pilot can still proceed with the check as long as the stick forces are not unusually heavy.
(2) With the aircraft airspeed approximately 1.4 mph/knots times (X) the predicted stall speed, raise the nose slowly. It is desirable for the aircraft to start decelerating slowly, about 1⁄2 mph/ knot a second. A 30 mph/knot deceleration at 1⁄2 mph/knot per second will take only a minute.
(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 stick force changes. Keep the turn coordinator or turn and bank ‘‘ball’’ in the middle.
(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 in the prescribed manner. If the aircraft does not respond to small control inputs -- and it should not be expected 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 nosedown elevator inputs, which is necessary for recovery.
(5) Notice any changes in flight characteristics and the speeds at which they take place. Be especially alert for the onset of pre-stall buffet. Is the buffet felt through the stick? Through the airframe? Though 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 it continuous? Would it get the pilot’s attention if they were concentrating on something else?
NOTE: On some high performance aircraft and aircraft with unusual wing designs, a pre-stall buffet may not exist and the stall may be abrupt and violent with a large degree of wing drop.
(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.
(7) The pre-stall recovery response should be a smooth and quick forward stick movement. This response should be enough to reduce the angle of attack to the point where the airplane is flying normally again.
(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.
(9) There is no need to gain more airspeed than the extra few mph/knots to fly out of a prestall 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