AC 90-89B

Historical

Advisory circular · Amateur-Built Aircraft and Ultralight Flight Testing Handbook

A newer version is currentThis is a historical version. AC 90-89C is the version in force, approved February 14, 2023.
Approved
April 27, 2015
Last reviewed
July 19, 2024
Cancels
AC90-89A
Cancelled by
AC90-89C
Family
AC 90-89 · 3 versions
Revision
B
14 CFR parts
1, 21, 23, 43, 91, 103

Guidance, not mandatory unless a rule or AD requires it. DRS record last changed November 21, 2025.

Show pages 1–12

Par 1-2 Page 5 FIGURE 1. RUNWAY LENGTH CHART

Takeoff Distance in feet A - Distance to takeoff at minimum smooth lift-off speed, fly for 5 seconds at that speed without climbing, land, and stop straight ahead.

B - Distance to reach minimum smooth lift-off speed.

C - Distance covered in 5 seconds of flight at minimum smooth lift-off speed.

D - Distance to stop from minimum smooth lift-off speed (includes air and ground distance).

E - Distance to takeoff at slow approach speed and climb thereafter at an angle of 1 in 20 to 50 ft. altitude, this distance will allow most airplanes to accelerate to normal climb speed before crossing end of runway.

c. Emergency Fields. Identify emergency landing fields located within gliding distance from anywhere in the airport pattern altitude. Since engine failures are second only to pilot error as the major cause of amateur-built aircraft accidents, preparations for this type of emergency should be a mandatory part of the flight-test plan.

d. Communications. You should perform flight tests from an airport with an active Unicom or tower, even if the aircraft either doesn’t have an electrical system or doesn’t have a radio. Even at an uncontrolled field, you should improvise a communications base. For both situations, the FAA recommends a handheld radio with aviation frequencies and a headset with a microphone and a push-to-talk switch. Good radio communications improves the overall level of safety and reduces cockpit workload.

e. Physical Space. The FAA recommends you also consider the availability of hangar space and ramp areas. These facilities will provide protection from inclement weather and vandalism while the aircraft is being tested, maintained, and inspected.

f. Safety. The airport should have a telephone and firefighting equipment complying with relevant municipal codes.

g. Local Management. Explain the flight-test program and emergency plans to the airport manager or owner who may help you obtain temporary hangar space, provide ground/air communications, and supply emergency equipment for use during the flight test.

Par 1-3 Page 6 SECTION 3. EMERGENCY PLANS AND EQUIPMENT “The object of the game, gentlemen, is not to cheat death: the object is not to let him play.”

Patrick Poteen, Sgt. U.S. Army

1-3. OBJECTIVE. To develop a flight-test plan with two sets of emergency plans; one for in-flight emergencies and another for ground emergencies.

a. In-Flight Emergencies. Your in-flight emergency plan should address the following:

(1) Complete or partial engine failure, especially after takeoff.

(2) Flight control problems and severe out-of-rig conditions.

(3) Fire in the engine compartment or cockpit.

b. Ground Emergencies. The ground emergency plan should train the ground crew and/or airport fire department crash crew on:

(1) The airplane canopy or cabin door latching mechanism.

(2) The pilot’s shoulder harness/seat belt release procedure.

(3) The location and operation of the fuel shut-off valve.

(4) The master switch location and its OFF position.

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(5) The magneto switch location and its OFF position.

(6) Engine cowling removal procedures to gain access to the battery location or for firefighting.

(7) The battery location and disconnect procedures.

(8) Fire extinguisher application and use.

(9) How to secure a ballistic parachute system.

c. Ground Crew. A minimum ground crew of two experienced persons should support every test of an amateur built aircraft. Your ground crew’s function is:

(1) To ensure that the aircraft is in airworthy condition for safe operation.

(2) To provide assistance to the test pilot in an emergency.

d. The Airport.

(1) If the airport does not have a fire rescue unit, the FAA suggests the ground crew have a four-wheel-drive vehicle equipped with a portable radio, first aid kit, metal-cutting tools, and a fire extinguisher. At least one person should have completed first aid training.

(2) If the airport provides a fire rescue unit, the test pilot should ensure the rescue unit and the ground crew are trained and competent in performing ground emergency functions as identified in the flight-test plan.

(3) For a small donation, some local volunteer fire and rescue companies may provide standby crew during the initial critical portions of the flight-test phase.

e. Hospital Location. The ground crew should know the location and telephone numbers of the hospitals and fire rescue squads in the vicinity of the airport and the flight-test area. If the test pilot is allergic to specific medications, or has a rare blood type, the test pilot should carry or wear a medical alert bracelet or card to alert medical personnel of the condition.

f. Fire Extinguisher. Fire extinguishers should be available to the ground crew, and a fire extinguisher should be securely mounted in the cockpit within easy reach of the test pilot. A fire axe, or other tool capable of cutting through the canopy, also should be in the cockpit.

g. Fire Protection. There is always danger of a flash fire during test flights. To prevent burns, the pilot should wear an aviation/motorcycle helmet, NOMEX coveralls/gloves, and smoke goggles. If NOMEX clothing is not available, cotton or wool clothing will offer some protection from heat and flames. Pilots should never wear nylon or polyester clothing because synthetic materials melt when exposed to heat and will stick to the skin.

h. Pilot Protection. A modern aviation/motorcycle helmet, a properly installed shoulder harness, a well-designed seat, a clean cockpit design free of protruding components/sharp edges,

Par 1-3 Page 8 NOMEX clothing, smoke goggles, and a memorized emergency plan ensure safety during flight testing.

i. Parachute. The decision to wear a parachute depends on the type of aircraft you are testing. Some aircraft have forward hinged canopies without quick release pins, or have pusher propellers, increasing the chance of injury to the pilot while exiting the aircraft. Other aircraft designs may pose no exit problems. If the pilot decides to wear a parachute, check that a qualified parachute rigger has packed the parachute within 180 days. Ensure that the parachute has not been exposed to rain/moisture and, when worn, does not interfere with cockpit management. The test pilot should be thoroughly trained on how to exit the aircraft and deploy the parachute.

j. Ballistic Parachutes. Ballistic parachutes are the latest development in dealing with in-flight emergencies. A ballistic parachute is attached to the aircraft and when activated, lowers the whole aircraft and the pilot to the ground at the rate of descent of about 20 feet per second or about 1,200 feet per minute.

(1) Deployment Scenarios. You might deploy a ballistic parachute in case of:

(a) Structural failure.

(b) Mid-air collision.

(c) Stall/spin.

(d) Loss of control/icing.

(e) Engine failure over bad terrain.

(f) Pilot incapacitation.

(2) Installation Considerations. You should consider the following when installing a ballistic parachute:

(a) Match the parachute to the aircraft’s size, weight, and Vne speed. Check with the parachute manufacturer.

(b) How to position and mount the parachute.

(c) The parachute’s effect on the aircraft’s weight and balance before deployment and aircraft’s touchdown attitude after deployment.

(d) Compatibility of the opening loads and the aircraft’s structural design limits.

(e) The routing of the bridle and harness.

(f) The routing of the activating housing.

(g) The placement of the activating handle in the cockpit.

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(h) Incorporation of parachute deployment procedures in the in-flight emergency plan and emergency checklist.

(i) The deployment time, from activation to full parachute opening.

(3) Inspection Recommendations. If a ballistic parachute is installed, the builder should add the appropriate ballistic parachute inspection items to the aircraft’s preflight inspection checklist. The builder also should add the ballistic parachute manufacturers repack/refitting schedule and maintenance inspections to the flight manual and the conditional annual inspection checklist.

SECTION 4. TEST PILOT “We are looking for a few good Men and Women!” Marine Corps advertisement (1991)

1-4. OBJECTIVE. Select a qualified individual as the test pilot.

1-5. GENERAL. The test pilot should be competent in an aircraft of similar configuration, size, weight, and performance to the test aircraft.

1-6. TEST PILOT REQUIREMENTS.

a. Minimum Requirements. A test pilot should meet the following minimum qualifications:

(1) Physically fit: Test flying an aircraft is a stressful and strenuous task.

(2) No alcohol or drugs in the last 24 hours.

(3) Rated, current, and competent in the same category and class as the aircraft being tested.

(4) Current medical and biennial or flight review as appropriate, or a current USUA certification and flight review.

b. Suggested Test Pilot Flight Time Requirements. Each test pilot must assess if his or her level of competency is adequate, or if additional flight training is necessary. If you determine you are not qualified to flight test an unproven aircraft, you must find someone who is qualified. The following suggested number of flight hours is only an indication of pilot skill, not an indicator of pilot competence.

(1) One hundred hours solo time before flight testing a kit plane or an aircraft built from a time-proven set of plans.

(2) Two hundred hours solo time before flight testing a unique design or high-performance aircraft.

(3) A minimum of 50 recent takeoffs and landings in a tailwheel aircraft) if the test aircraft is tailwheel equipped.

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c. Pilot Recommendations. The test pilot should:

(1) Be familiar with the airport and the surrounding terrain that could be used for emergency landing fields in the area.

(2) Talk with and, if possible, fly with a pilot in the same kind of aircraft to be tested;

the Experimental Aircraft Association (EAA) maintains a list by state of instructors that hold a Letter of Deviation Authority (LODA). The experimental aircraft model used by the instructor for the purposes of type-specific training is also listed. This list changes often and can be found at: http://www.eaa.org/govt/loda.asp.

(3) Take additional instruction in similar TC’d aircraft, as addressed in AC 90-109, Airmen Transition Experimental or Unfamiliar Airplanes. For example, if the aircraft to be tested is tailwheel equipped, a Bellanca Citabria or Super Cub is appropriate for training. For testing an aircraft with a short wingspan, the Grumman American Yankee or Globe Swift is suitable for training.

(4) For amateur aircraft built from commercial kit manufacturers, consider using an additional pilot, as referenced in AC 90-116, Additional Pilot Program for Phase I Flight Test.

(5) Be considered competent when the test pilot has demonstrated a high level of skill in all planned flight-test maneuvers in aircraft with performance characteristics similar to the test aircraft.

(6) Study the ground and in-flight emergency procedures developed for the aircraft and practice them in aircraft with similar flight characteristics.

(7) Have logged a minimum of 1 hour of training in recovery from unusual attitudes within 45 days of the first test flight.

(8) Have logged a minimum of 10 tailwheel take-off and landings within the past 30 days, if appropriate.

(9) Study the performance characteristics of the aircraft to be tested. Refer to the designer’s or kit manufacturer’s instructions, articles written by builders of the same make and model aircraft, and study actual or video tape demonstrations of the aircraft.

(10) Review the FAA/National Transportation Safety Board (NTSB)/EAA accident reports for the same make and model aircraft to be aware of problems the aircraft has experienced during previous operations (see appendix 2 for the address).

(11) Memorize the cockpit flight controls, switches, valves, and instruments. A thorough knowledge of the cockpit will result in controlled and coordinated mental and physical reactions during emergencies.

(12) Use checklists for both normal and emergency actions and procedures. The Emergency procedures should be also memorized. Add additional notes on the instrument panel to aid in their use if necessary.

Par 1-6 Page 11 NOTE: The EAA has developed a Flight Advisor Program which offers builders/pilots assistance in performing a self-evaluation of the flight-test program and/or selection of the test pilot. To obtain additional information, see the following EAA Web page: http://www.eaa.org/flightadvisors.

SECTION 5. MEDICAL FACTS FOR PILOTS “If the pilot is unairworthy, so is the airplane!” Bill Chana, Aeronautical Engineer

1-7. OBJECTIVE. Identify well-known medical causes for aircraft accidents and stress the importance of a personal pre-flight checklist in addition to an aircraft pre-flight checklist.

a. Alcohol. Test flying an aircraft places additional mental and physical demands on the pilot. In addition to the 8 hour requirement of part 91, § 91.17, General Operating and Flight Rules, the FAA strongly recommends a minimum of 24 hours between the last drink and the test flight. This is because small amounts of alcohol in the blood stream can affect judgment and reaction time, and decrease a pilot’s tolerance to hypoxia.

b. Anesthetics. Local and dental anesthetic can affect a pilot’s performance in many adverse ways. The FAA recommends that a minimum of 48 hours elapse from the time of anesthesia to the time the pilot climbs into the cockpit.

c. Blood Donations. If you donate 1 unit or 500 ml of blood or less, the FAA recommends that you do not pilot an aircraft for 24 hours; if you give more than 1 unit or more than 500 ml, the FAA recommends that you do not pilot an aircraft for 72 hours. Although the physical effects may not be noticeable at sea level, they will become apparent when flying at higher altitudes.

d. Carbon Monoxide (CO). CO is a colorless, odorless, tasteless gas that is always present in engine exhaust fumes. CO prevents oxygen absorption by the blood, and exposure to the gas creates vision problems, headaches, disorientation, and diminished rational thinking. See the current edition of AC 20-23, Carbon Monoxide (CO) Contamination in Aircraft Detection and Prevention.

e. Drugs. Similar to alcohol, illegal drugs will reduce or impair judgment and affect reflexes and hand/eye coordination. Prescription drugs and over-the-counter remedies may be dangerous when combined with flying. The FAA recommends that all pilots who must take medication consult with an aviation medical examiner (AME) to understand the medication’s effects on their ability to think and react while in the cockpit.

f. Ear and Sinus Pain.

(1) Ear and sinus pain is usually caused by the eardrum or sinuses failing to equalize the air pressure during a descent. Blocked ears and sinuses can be caused by a head cold. The pain can be considerable and is most noticeable during descents. For ear blockages try yawning, swallowing, or chewing gum which may give some relief. The Valsalva procedure—pinch the nose, close the mouth, and try to force air through the nostrils— can be effective.

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(2) If ear blockage occurs during flight, try climbing back to a higher altitude—lower air pressure—until the pain lessens. Then begin a gradual rate of descent, giving the ears and sinuses time to adapt to the increasing pressure.

(3) After landing, nasal sprays will give some sinus pain relief. To relieve ear pain, wet paper towels with hot water and place in the bottom of two cups. Hold the cups over the ears—the warmth will help ease the inflamed tissues and reduce the pain. If pain continues, see a doctor.

NOTE: The best way to avoid this problem is not to fly with a head cold, upper respiratory infection, or nasal allergic condition. Be advised that some nasal and oral decongestants could be ineffective at altitude and have side effects such as drowsiness that can significantly impair pilot performance.

Again, consult with an AME to understand the effects of medication before flying.

g. Fatigue. Fly only when healthy, fit, and alert. Mental and physical fatigue will generally slow down a pilot’s reaction time and affect decision-making and attention span. Lack of sleep is the most common cause of fatigue, but family and business problems can create mental fatigue which can have the same effects on the pilot as lack of sleep.

h. Flicker Vertigo. Light, when flashing at a frequency between 4 to 29 cycles per second, can cause a dangerous physiological condition in some people called flicker vertigo.

These conditions range from nausea and dizziness to unconsciousness or even reactions similar to an epileptic episode. When heading into the sun, a propeller cutting the light may produce this flashing effect. Avoid flicker vertigo, especially when the engine is throttled back for landing. To alleviate this when the propeller is causing the problem, frequently change engine revolutions per minute (rpm). When flying at night and the rotating beacon is creating flicker vertigo, turn it off.

i. Underwater Diving. Never fly immediately after scuba diving. Always allow 24 hours to elapse before flying as a pilot or a passenger in order to give the body sufficient time to rid itself of excessive nitrogen absorbed during diving.

j. Stress. Stress from the pressures of a job and everyday living can impair a pilot’s performance, often in subtle ways. A test pilot may further increase the stress level by setting unreasonable test flying schedules in order to meet an arbitrary “done by date.” Stress also may impair judgment, inducing the pilot to take unwarranted risks, such as flying into deteriorating weather conditions or flying when fatigued to meet a self-imposed deadline.

Par 1-8 Page 13 SECTION 6. TRANSPORTING THE AIRCRAFT TO THE AIRPORT “Best laid plans of mice and men are often stuck in traffic.”

Ben Owen, EAA Executive Director (1994)

1-8. OBJECTIVE. Reduce damaging the aircraft in transit.

a. Use a truck or flatbed truck/trailer large enough to carry the aircraft and the additional support equipment.

b. If the aircraft wings are removable, build padded jigs, cradles, or fixtures to hold and support them during the trip to the airport.

c. Secure the fixtures to the truck/trailer, and then secure the wings to the fixture.

d. Use two or more ropes at each tie down point.

e. Use heavy moving pads used for household moves to protect wings and fuselage.

Most rent-a-truck firms offer them for rental.

f. During the planning stage, obtain applicable permits and follow the local ordinances for transporting an oversized load. Ask the local police if they can provide an escort to the airport.

g. Brief the moving crew thoroughly before loading and unloading the aircraft.

h. Ensure the designated driver has recent experience driving a truck/trailer and is familiar with the roads to the airport.

Par 1-9 Page 14 SECTION 7. ASSEMBLY AND AIRWORTHINESS INSPECTION “Complacency is one of the major causes of accidents, no matter how well things are going, something can go wrong” Art Scholl

1-9. OBJECTIVE. To determine the airworthiness of the aircraft and its systems.

1-10. GENERAL.

a. If you must reassemble the aircraft after moving it to the airport—take time to do so carefully. This is a critical event because mistakes can easily occur due to the builder’s preoccupation with the impending first flight of the aircraft. One of the most common and deadly mistakes is to reverse the rigging on the ailerons. To prevent errors in reassembling the aircraft, follow the designer’s or kit manufacturer’s instructions, or use a written checklist specifically designed as part of the flight-test plan. At the completion of each major operation, have another expert check the work.

b. After reassembling the aircraft, perform a pre-flight “fitness inspection.” This inspection should be similar to an annual inspection. You should perform the fitness inspection even if the FAA has just issued a special airworthiness certificate for the aircraft. Even if a builder was 99 percent perfect and performed 10,000 tasks building the aircraft, there would still be a hundred items that would need to be found and corrected before the first flight.

1-11. FITNESS INSPECTION—AIRFRAME. A builder-developed comprehensive post assembly checklist should be used, and the results of that inspection should be recorded on the checklist to provide increased assurance that all items of concern have been addressed and the

Par 1-11 Page 15 results documented. The following additional safety checklist items may not be applicable to all amateur-built make and model aircraft, but the FAA presents them here for consideration and review.

a. Control Stick/Wheel. The control stick/wheel should have a free and smooth operation throughout its full range of travel. There should be no binding or contact with the sides of the fuselage, seat, or instrument panel. There should be no free play (slack) in the controls, nor should the controls be tight as to have stick-slip movement.

b. Rudder Pedals. Move the rudder pedals through the full range of travel. The pedal movement should be smooth, and without any binding. The test pilot’s shoes should not catch on exposed metal lines, fixtures, or electrical wire harness.

c. Brakes. Hand and/or toe brake pressure should be firm with no tendency to bleed down or lock up. Spongy brakes that must be “pumped up,” or that show a drop in the brake fluid reservoir level after a few brake applications, indicates a brake fluid or air leak in the system.

d. Main Landing Gear. Ensure that the gear attach points, shimmy damper, bungees, wheels, brakes, and wheel fairings are airworthy. If applicable, check that the tailwheel pivot point is centered and vertical compared to the longitudinal axis of the aircraft. It is critical that the main landing gear alignment toe in/toe out is zero or matches the specifications for fuselage/landing gear alignment called out in the plans. Even one landing gear wheel out of alignment can cause a ground loop.

e. Control Surfaces. Perform rigging checks to ensure that control input for ailerons, rudder, elevators, and trim tabs results in the correct amount of travel and direction of the control movement and that these control surfaces make contact with their stops. Also, ensure that the flaps, if installed, have the proper travel, operate as a single unit, and cannot be extended beyond the maximum extended position. It is important to ensure that the control cable tension is correct by

(1) checking it with a calibrated tensiometer and (2) confirming that all the attachment hardware is secured and turnbuckles are properly safetied.

(1) If the cable tension is less than required by specifications, in-flight air loads will prevent full travel of the control, even if the control has the right amount of deflection and hits all the stops in the cockpit/wing/tail when tested on the ground. With low cable tension, the slack in the cables will absorb the desired control movement input.

(2) While checking cable tension, make sure there is no “free play” in the flight control hinges and rod ends. Free play and loose cable tension combined with control mass imbalance can bring on control surface “flutter.” Do not, however, rig the controls at too high a cable tension. This will cause high wear rate on the pulleys and prevent good control feel, especially at low airspeeds.

f. Instrument Panel.

(1) All the instruments should be properly secured in the panel and have preliminary markings on them. The airspeed indicator and engine tachometer should be marked with the

Par 1-11 Page 16 expected performance range markings. Oil temperature and oil pressure must have the engine manufacturer’s recommended operating range marked. If the markings are on the instrument glass face, paint a white slippage mark on both the glass and on the instrument case to alert the pilot in case the glass/range marks have moved. Attach a temporary placard to the instrument panel with the expected stall, climb, and glide speeds. It is a handy reference in times of emergency.

(2) Angle of attack systems may require in-flight calibration. Information displayed prior to that calibration may not be accurate.

(3) Electronic data collection systems, when installed, must be checked if possible before flight according to the manufacturer’s instructions. Recording of electronic data through flight and engine instruments can be very useful, but only if it is ensured that accurate information is being collected. Therefore, verification of this data prior to flight is important.

g. Behind the Instrument Panel. Very few amateur-built aircraft of the same make and model have the same instrument panel design. Amateur builders should inspect this area to ensure that all line connections are tight, that nothing interferes with control travel, and there are no loose wires or fuel, oil, or hydraulic leaks.

h. Carbon Monoxide (CO). CO leaks also can be performed. Wait until night or put the aircraft in a dark hangar. Climb into the cockpit and have a friend shine a bright flood light close to the firewall. If light leaks into the cockpit, CO can seep in. Mark it and seal it.

i. Engine and Propeller Controls. All controls should be visually inspected, move in the proper direction, and securely mounted. The friction lock on both controls should be checked for operation. Each control should have full movement with at least a ¼-inch of “cushion” at the full travel position. The control cables should be firmly attached to the fuselage along each 24 inches of their runs to prevent whipping of the cable and loss of cable movement at the other end. Control cables with ball sockets should have large area washers on either end of the bolt connection. This will ensure the control will remain connected, even if the ball socket fails and drops out.

j. Static System. The best procedure to check the altimeter for leaks and accuracy is to have the entire static system checked using 14 CFR part 43, appendix E, at an FAA-approved repair station.

1-12. FIELD CHECK. You need two people to accomplish the following field check by which an amateur-builder can detect if the aircraft’s instrument system is leaking:

NOTE: This field check is not an accuracy check. Additionally, you should check the manufacturer’s manuals for the installed pitot-static instruments to ensure that this test method will not damage any associated electronics.

a. Airspeed Check. Slip a long rubber hose over the pitot mast (The FAA recommends surgical tubing). As one person reads the airspeed, the other should very slowly roll up the other end of the tubing. This will apply pressure to the instrument. When the airspeed indicator needle reaches the aircraft’s approximate recommended cruise speed, pinch the hose shut, and hold that