U.S. Department

of Transportation

Federal Aviation

Administration

 Advisory

 Circular

1

Initiated by: AFS-340

DATE: 5/24/95

AC NO: 90-89A

AMATEUR-BUILT AIRCRAFT AND ULTRALIGHT

FLIGHT TESTING HANDBOOK
U.S. Department

of Transportation

Federal Aviation

Administration

 Advisory

 Circular

i

Subject: AMATEUR-BUILT AIRCRAFT Date: 5/24/95 AC No: 90-89A

& ULTRALIGHT FLIGHT Initiated by: AFS-340 Change:

TESTING HANDBOOK

1. PURPOSE. This advisory circular (AC) sets

forth suggestions and safety related recommendations to assist amateur and ultralight builders in

developing individualized aircraft flight test plans.

2. CANCELLATION. AC 90-89, AmateurBuilt Aircraft Flight Testing Handbook, dated

September 18, 1989, is cancelled.

3. RELATED READING MATERIAL. A list

of selected reading material on amateur-built/

ultralight flight testing and first flight experience

may be found in appendix 3.

4. BACKGROUND.

a. The Federal Aviation Administration

(FAA), the Experimental Aircraft Association

(EAA), and the United States Ultralight Association

(USUA) are concerned and committed to improving

the safety record of amateur-built and ultralight aircraft.

b. The FAA Administrator, T. Allen McArtor,

and EAA President, Paul H. Poberezny, signed a

Memorandum of Agreement on August 1, 1988,

which addressed the need for educational and safety

programs to assist amateur-builders in test flying

their aircraft. In accordance with that agreement, this

AC provides guidelines for flight testing amateurbuilt aircraft.

c. As part of the FAA’s continuing efforts to

improve the safety record of all types of general aviation aircraft, this AC has been revised to include

flight testing recommendations for canard-type and

ultralight aircraft.

5. DEFINITIONS. The following terms are

defined for use in this AC.

a. Amateur-built aircraft means an aircraft

issued an Experimental Airworthiness Certificate

under the provisions of Federal Aviation Regulations

(FAR) § 21.191 (g).

b. The term ultralight means a vehicle that

meets the requirements of FAR § 103.1.

c. The term ultralight in this AC also means

a two-place training vehicle of 496 pounds or less,

operating under an EAA or USUA exemption to

FAR Part 103.

d. For the purpose of this AC, both an amateur-built aircraft and a ultralight vehicle will be

referred to as an ‘‘aircraft.’’

6. DISCUSSION.

a. This AC’s purpose is the following:

(1) To make amateur-built/ultralight aircraft pilots aware that test flying an aircraft is a critical undertaking, which should be approached with

thorough planning, skill, and common sense.

(2) To provide recommendations and

suggestions that can be combined with other sources

on test flying (e.g., the aircraft plan/kit manufacturer’s flight testing instructions, other flight testing

data). This will assist the amateur/ultralight owner

to develop a detailed flight test plan, tailored for their

aircraft and resources.
ii

AC 90-89A 5/24/95

b. The flight test plan is the heart of all professional flight testing. The plan should account for

every hour spent in the flight test phase and should

be adhered to with the same respect for the unknown

that all successful test pilots share. The time allotted

for each phase of a personalized flight test plan may

vary, and each phase may have more events or

checks than suggested in this AC. The goals, however, should be the same.

c. The two goals for an amateur builder/

ultralight owner should be as follows:

(1) At the end of the aircraft’s flight test

phase, the aircraft will have been adequately tested

and found airworthy and safe to operate within its

established operational envelope.

(2) Incorporation of the flight test operational and performance data into the aircraft’s flight

manual so the pilot can reference the data prior to

each flight.

7. REQUEST FOR INFORMATION.

a. This AC is designed as a reference document to assist in preparing a flight test plan for an

amateur-built or ultralight aircraft.

(1) The suggestions and recommendations

in chapters 1 through 6 are for conventionallydesigned aircraft with an air-cooled, 4-cycle, reciprocating engine that develops less than 200 horsepower with a fixed pitch propeller.

(2) Chapter 7 deals with flight testing recommendations for canard aircraft.

(3) Chapters 8 through 10 address flight

testing considerations for ultralight vehicles under

FAR Part 103 and two-seat ultralight training

vehicles of less than 496 pounds empty weight

operating under an exemption to FAR Part 103.

b. Because of the large number of existing

amateur-built/ultralight aircraft designs and new

designs being introduced each year, the FAA encourages public participation in updating this document.

Send comments, suggestions, or information about

this AC to the following address:

U.S. Department of Transportation

Federal Aviation Administration

Flight Standards Service (AFS-340)

800 Independence Ave, SW.

Washington, DC 20591

c. Suggestions also may be sent to AFS-340

by FAX (202) 267-5115.

d. After a review, appropriate comments,

suggestions, and information may be included in the

next revision of this AC.

8. TO OBTAIN COPIES OF THIS AC. Order

AC 90-89A from:

U.S. Department of Transportation

Property Use and Storage

Section, M-45.3

Washington, DC 20590.

William J. White

Deputy Director, Flight Standards Service
iii

5/24/95 AC 90-89A

THIS PAGE IS INTENTIONALLY LEFT BLANK, SO THAT THE TOC CAN BE ON PAGE iii

PER PLACEMENT IN DOCUMENT.
iv

AC 90-89A 5/24/95

THIS PAGE IS INTENTIONALLY LEFT BLANK, SO THAT THE TOC CAN BE ON PAGE iii

PER PLACEMENT IN DOCUMENT.

CONTENTS

Page

CHAPTER 1. PREPARATION

Section 1. Homework ............................................................................................................................... 1

Section 2. Airport Selection ..................................................................................................................... 2

Figure 1 - Runway Length Chart ................................................................................................. 3

Section 3. Emergency Plans and Equipment ........................................................................................... 4

Section 4. Test Pilot ................................................................................................................................. 6

Section 5. Medical Facts For Pilots ......................................................................................................... 7

Section 6. Transporting The Aircraft To the Airport .............................................................................. 9

Section 7. Assembly and Airworthiness Inspection ................................................................................ 10

Section 8. Weight and Balance ................................................................................................................ 14

Figure 2 - Empty Weight CG ....................................................................................................... 15

Figure 3 - Take Off CG ................................................................................................................ 16

Figure 4 - Additional Equipment Added ...................................................................................... 17

Section 9. Paperwork ................................................................................................................................ 18

Section 10. Powerplant Tests ..................................................................................................................... 19

Section 11. Additional Engine Tests ......................................................................................................... 22

Section 12. Propeller Inspection ................................................................................................................ 25

Figure 5 - Propeller Tracking ....................................................................................................... 26

CHAPTER 2. TAXI TESTS

Section 1. Low Speed Taxi Tests ............................................................................................................ 29

Section 2. High Speed Taxi Tests ........................................................................................................... 30

CHAPTER 3. THE FIRST FLIGHT

Section 1. General .................................................................................................................................... 33

Section 2. The Role of the Chase Plane .................................................................................................. 34

Section 3. Emergency Procedures ............................................................................................................ 35

Section 4. First Flight ............................................................................................................................... 36

Section 5. First Flight Procedures ............................................................................................................ 37

CHAPTER 4. THE FIRST 10 HOURS

Section 1. The Second Flight ................................................................................................................... 41

Section 2. The Third Flight ...................................................................................................................... 41

Section 3. Hours 4 through 10 ................................................................................................................. 41

CHAPTER 5. EXPANDING THE ENVELOPE

Section 1. General .................................................................................................................................... 45

Section 2. Hours 11 through 20 ............................................................................................................... 45
v

5/24/95 AC 90-89A

Figure 6 - Climb Airspeed and Altitude Graph ........................................................................... 47

Figure 7 - Best Rate of Climb Speed Graph ............................................................................... 48

Section 3. Hours 21 through 35: Stability and Control Checks ............................................................. 49

Figure 8 - Static Stability .............................................................................................................. 49

Figure 9 - Time ............................................................................................................................. 50

Section 4. A Word or Two About Flutter ............................................................................................... 52
vi

AC 90-89A 5/24/95

CONTENTS—Continued

Page

Section 5. Spins ........................................................................................................................................ 54

Section 6. Accelerated Stalls .................................................................................................................... 56

CHAPTER 6. PUTTING IT ALL TOGETHER: 36 HOURS TO ———?

Section 1. Maximum Gross Weight Tests ............................................................................................... 57

Section 2. Service Ceiling Tests .............................................................................................................. 58

Section 3. Navigation, Fuel Consumption, and Night Flying ................................................................. 59

CHAPTER 7. THOUGHTS ON TESTING CANARD TYPE AMATEUR-BUILT AIRCRAFT

Section 1. Canards .................................................................................................................................... 63

CHAPTER 8. ULTRALIGHT AIRFRAME INSPECTION

Section 1. Differences .............................................................................................................................. 67

Section 2. The Test Pilot .......................................................................................................................... 68

Section 3. Pre-flight Airframe Inspection ................................................................................................ 68

CHAPTER 9. ULTRALIGHT ENGINE/FUEL SYSTEM INSPECTION

Section 1. Engine Inspection .................................................................................................................... 71

Section 2. Fuel Systems ........................................................................................................................... 72

CHAPTER 10. ULTRALIGHT TEST FLYING RECOMMENDATIONS

Section 1. Three Recommendations ......................................................................................................... 75

Section 2. Airport Selection ..................................................................................................................... 75

Section 3. Taxiing ..................................................................................................................................... 76

Section 4. First Flight Differences ........................................................................................................... 76

Section 5. Emergency Procedures ............................................................................................................ 77

Appendix 1. Sample Checklist for a Condition Inspection .................................................................

(7 pages) ........................................................................................................................................................ 1

Appendix 2. Addresses for Accident/Incident Information .................................................................

(1 page) .......................................................................................................................................................... 1

Appendix 3. Additional References on Flight Testing .........................................................................

(4 pages) ........................................................................................................................................................ 1
1

5/24/95 AC 90-89A

CHAPTER 1. PREPARATION

‘‘The Laws of Aerodynamics are unforgiving and the ground is hard.’’ Michael Collins (1987)

SECTION 1. HOMEWORK

‘‘If you have no plan--you have no goal.’’ Harold Little, Aircraft Manufacturer (1994)

1. OBJECTIVE. A planned approach to flight

testing.

a. The most important task for an amateurbuilder is to develop a comprehensive FLIGHT

TEST PLAN. This PLAN should be individually tailored to define the aircraft’s specific level of

performance. It is therefore important that the entire

flight test plan be developed and completed

BEFORE the aircraft’s first flight.

b. The objective of a FLIGHT TEST PLAN

is to determine the aircraft’s controllability throughout all the maneuvers and to detect any hazardous

operating characteristics or design features. This data

should be used in developing a FLIGHT MANUAL

that specifies the aircraft’s performance and defines

its operating envelope.
2

AC 90-89A 5/24/95

SECTION 2. AIRPORT SELECTION

‘‘An airport should be chosen with the same care and consideration as getting a second doctor’s opinion.’’

Fred Wimberly, EAA Flight Test Advisor (1994)

1. OBJECTIVE. To select an airport to test fly

the aircraft.

a. The airport should have one runway

aligned into the prevailing wind with no obstructions

on the approach or departure end. Hard surface runways should be in good repair and well maintained

to avoid foreign object damage (FOD) to the propeller and landing gear. Grass fields should be level

with good drainage. Avoid airports in densely populated or developed areas and those with high rates

of air traffic. The runway should have the proper

markings with a windsock or other wind direction

indicator nearby.

b. To determine an appropriate runway, use

the chart in figure 1 (sea-level elevation), or the following rule-of-thumb:

c. The ideal runway at sea-level elevation

should be at least 4,000 feet long and 100 feet wide.

For each 1,000 feet increase in field elevation, add

500 feet to the runway length. If testing a high

performance aircraft, the airport’s runway at sealevel should be more than 6,000 feet long and 150

feet wide to allow a wider margin of safety. Other

considerations, such as power to weight ratio, wing

design, and density altitude, also should be factored

into the equation for picking the best runway for

the initial flight testing.
3

5/24/95 AC 90-89A

Take-off Distance in Feet

FIGURE 1. Runway Length Chart

d. 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.

e. It is advisable to perform flight tests from

an airport with an active unicom or tower, even if

the aircraft does not have an electrical system or

is not equipped with a radio. Even at an uncontrolled

field, a communications base should be improvised.

For both situations, a hand held radio with aviation

frequencies and a headset with a mike and a pushto-talk switch on the stick/yoke is recommended.

Good radio communications improves the overall

level of safety and reduces cockpit workload.

f. The FAA recommends airport selection criteria include 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.

g. The airport should have a telephone and

fire fighting equipment, the latter being in compliance with relevant municipal codes (e.g., fire codes).

h. Explain the Flight Test Program and

EMERGENCY PLANS to the airport manager or

owner. They may be able to assist the amateurbuilder in obtaining temporary hangar space, providing ground/air communications, and supplying emergency equipment for use during the flight test.
4

AC 90-89A 5/24/95

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. OBJECTIVE. To develop a FLIGHT TEST

PLAN which contain two sets of emergency plans;

one for IN-FLIGHT emergencies and another for

GROUND emergencies.

a. The IN-FLIGHT emergency plan should

address the following:

(1) Complete engine failure or partial failure, especially after take off

(2) Flight control problems and severe outof-rig conditions

(3) Fire in the engine compartment or

cockpit

b. The GROUND EMERGENCY plan should

be developed to train the ground crew and/or the

airport fire department crash crew on the following:

(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 and magneto/ignition switch location and OFF position

(5) Engine cowling removal procedures to

gain access to the battery location or for fire fighting

(6) The battery location and disconnect

procedures

(7) Fire extinguisher application and use

(8) How to secure the ballistic parachute

system

c. Ground Crew. Every test of an amateurbuilt aircraft should be supported by a minimum

ground crew of two experienced individuals. The

ground crew’s function is two-fold:
5

5/24/95 AC 90-89A

(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, it is suggested the ground crew have a four

wheel drive vehicle equipped with a portable radio,

first aid kit, metal-cutting tools, and a fire extinguisher. A minimum of one person should be trained

in first-aid.

(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) Suggestion. For a small donation,

some local volunteer fire and rescue companies will

provide the amateur-builder with a 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, a medical alert bracelet or card should be carried or worn to alert medical personnel of the condition.

f. Fire Extinguisher. Fire extinguisher’s

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 positioned 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, 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 being tested. Some

aircraft have forward hinged canopies that are not

equipped with quick release pins or have pusher

propellers which increase the chance of injury to the

pilot while exiting the aircraft. Other aircraft designs

may pose no exit problems. If the decision is made

to wear a parachute, check that it has been recently

packed (within 120 days) by a qualified parachute

rigger. Ensure that the chute 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 Chutes. Ballistic chutes are the latest development in dealing with in-flight emergencies. A ballistic chute is attached to the aircraft

and when activated, lowers the whole aircraft and

the pilot to the ground at the rate of descent of

approximately 20 feet per second.

(1) Deployment Scenarios:

(i) structural failure

(ii) mid-air collision

(iii) stall/spin

(iv) loss of control/icing

(v) engine failure over bad terrain

(vi) pilot incapacitation

(2) Installation Considerations: The

builder should consider the following when installing

a ballistic chute:

(i) Matching the chute with the aircraft’s size, weight, and Vne speed (check with the

chute manufacturer)

(ii) How the chute will be positioned

and mounted

(iii) The chute’s effect on the aircraft’s weight and balance before deployment and

aircraft’s touchdown attitude after deployment

(iv) Compatibility of the opening

loads and the aircraft’s structural design limits
6

AC 90-89A 5/24/95

(v) The routing of the bridle and

harness

(vi) The routing of the activating

housing

(vii) The placement of the activating

handle in the cockpit

(viii) Incorporation of chute deployment procedures in the in-flight emergency plan and

emergency check list

(ix) The deployment time, from

activation to full chute opening

(3) If a ballistic chute is installed, the

builder should add the appropriate ballistic chute

inspection items to the aircraft’s pre-flight inspection check list. The builder also should add the

ballistic chute manufacturer’s repack/refitting schedule and maintenance inspections to the flight manual

and the conditional annual inspection check list.

SECTION 4. TEST PILOT

‘‘We are looking for a few good Men and Women!’’ Marine Corps advertisement (1991)

1. OBJECTIVE. To select a qualified individual

to be the test pilot.

2. GENERAL. The test pilot should be competent in an aircraft of similar configuration, size,

weight, and performance as the aircraft to be tested.

If the aircraft’s builder is the test pilot, the costs

involved in maintaining pilot competence should be

budgeted with the same level of commitment and

priority that is assigned to plans and materials to

complete the project.

3. TEST PILOT REQUIREMENTS.

a. 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. The following suggested number of flight

hours are only an indication of pilot skill, not an

indicator of pilot competence. Each test pilot must

assess if their level of competence is adequate or

if additional flight training is necessary. If an individual determines they are not qualified to flight test

an unproven aircraft, someone who is qualified must

be found.

(1) 100 hours solo time before flight testing a kit plane or an aircraft built from a time-proven

set of plans

(2) 200 hours solo time before flight testing for a ‘‘one of a kind’’ or a high performance

aircraft

(3) A minimum of 50 recent takeoffs and

landings in a conventional (tail wheel aircraft) if the

aircraft to be tested is a tail dragger

c. The test pilot should:

(1) Be familiar with the airport and the

emergency fields in the area

(2) Talk with and, if possible, fly with a

pilot in the same kind of aircraft to be tested

(3) Take additional instruction in similar

type certificated aircraft. For example, if the aircraft

to be tested is a tail dragger, a Bellanca Citabria

or Super Cub is appropriate for training. For testing

an aircraft with a short wing span, the Grumman

American Yankee or Globe Swift is suitable for

training.

(4) Be considered competent when they

have demonstrated a high level of skill in all planned

flight test maneuvers in an aircraft with performance

characteristics similar to the test aircraft
7

5/24/95 AC 90-89A

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

(6) Have logged a minimum of 1 hour of

training in recovery from unusual attitudes within

45 days of the first test flight

(7) If appropriate, have logged a minimum

of 10 tail wheel take-off and landings within the past

30 days

(8) 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.

(9) 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).

(10) 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.

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, contact a local EAA Chapter

or EAA Headquarters, (414) 426-4800.

SECTION 5. MEDICAL FACTS FOR PILOTS

‘‘If the pilot is unairworthy, so is the airplane!’’ Bill Chana, Aeronautical Engineer

1. OBJECTIVE. To identify some of the well

known medical causes for aircraft accidents and to

stress the importance of a personal pre-flight checklist in addition to an aircraft pre-flight checklist.

a. Alcohol. FAR Part 91, ‘‘General Operating

and Flight Rules,’’ § 91.17 requires that 8 hours

must elapse from the last drink to the first flight.

Test flying an aircraft, however, places additional

mental and physical demands on the pilot. 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 judgement, reaction time, and decrease a

pilot’s tolerance to hypoxia.

b. Anesthetics. Local and dental anesthetic can

affect a pilots performance in many adverse ways.

It is recommended that a minimum of 48 hours

elapse from the time of anesthesia to the time the

pilot climbs into the cockpit.

c. Blood Donations. Do not fly for 3 weeks

after donating blood. The body needs approximately

three weeks for a complete physiological recovery.

Although the physical affects 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. Carbon monoxide prevents

oxygen absorption by the blood, and exposure to the

gas creates vision problems, headaches, disorientation, and blurred thinking (see chapter 1, section 7,

paragraph 3 (g) for testing the aircraft for CO

contamination).

e. Drugs. Similar to alcohol, drugs will reduce

or impair judgement and affect reflexes and hand/

eye coordination. It is a given that the use/abuse of

illegal drugs is dangerous and against the law.

Prescription drugs and over-the-counter remedies,

however, also may be dangerous when combined

with flying. The FAA recommends all pilots who

must take medication consult with an Aviation Medical Examiner (AME) to understand the medication’s

affects 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. The blocked ears and

sinuses can be caused by a head cold. The pain can

be considerable and is most noticeable during
8

AC 90-89A 5/24/95

descents. For ear blockages try yawning, swallowing,

or chewing gum which may give some relief. The

Valsalva procedure can be effective: pinch the nose,

close the mouth, and try to force air through the

nostrils.

(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, allowing 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, try wetting paper towels with hot water, put the towels in

the bottom of a plastic or dixie cup and then 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 Aviation Medical

Examiner to understand the affects 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, 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 fit. 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 ‘‘be

done by date.’’ Stress also may impair judgement,

inducing the pilot to take unwarranted risks, such

as flying into deteriorating weather conditions or flying when fatigued to meet a self imposed deadline.
9

5/24/95 AC 90-89A

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. OBJECTIVE. To reduce damaging the aircraft in transit. The following suggestions may prevent this from happening:

a. Use a truck or flat bed truck/trailer large

enough to accommodate 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, 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-atruck 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.
10

AC 90-89A 5/24/95

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. OBJECTIVE. To determine the airworthiness

of the aircraft and its systems.

2. GENERAL.

a. If the aircraft must be reassembled after

being moved to the airport -- take time to do so

carefully. This is a critical event because mistakes

can easily be made 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

check list specifically designed as part of the

FLIGHT TEST PLAN. At the completion of each

major operation, have another expert check the work.

b. When the aircraft is reassembled, perform

a pre-flight ‘‘fitness inspection.’’ This inspection

should be similar in scope and detail to an annual

inspection. The fitness inspection should be accomplished even if the aircraft has just been issued a

special airworthiness certificate by the FAA. 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.

3. FITNESS INSPECTION - AIRFRAME.

The following additional safety check list items may

not be applicable to all amateur-built make and

model aircraft, but are presented 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 freeplay (slack) in the controls, nor should the controls

be tight as to have stick-slip movement.
11

5/24/95 AC 90-89A

b. Rudder pedals: Move the rudder pedals

through the full range of travel. The pedal movement

should be smooth with no binding. The test pilot

should ensure that their shoes will 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 show a drop in the level of brake fluid in the

reservoir after a few brake applications, indicate a

brake fluid or air leak in the system.

d. Main landing gear: Ensure that the gear

attach points, shimmy dampener, bungees, wheels,

brakes, and wheel fairings are airworthy. If

applicable, check that the tail wheel pivot point is

centered and vertical in relation 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 contact with the stops is made. 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 checking

it with a calibrated tensiometer and confirming that

all the attachment hardware is secured and safetywired.

(1) If the cable tension is less than the

specifications require, the ‘‘in flight’’ air loads during flight 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 desired

control movement input will be absorbed by the slack

in the cables.

(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 sets the

stage for the onset of 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: All the instruments

should be properly secured in the panel and have

preliminary markings on them. Airspeed indicator

and engine tachometer should be marked with the

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.

g. Behind the instrument panel: Very few

amateur-built aircraft of the same make and model

have the same instrument panel design. Each amateur-builder 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: Carbon Monoxide 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

fire-wall. If light leaks into the cockpit, carbon monoxide can seep in. Mark it and seal it.

i. Engine and propeller controls: All controls

should be visually inspected, positive in operation,

and securely mounted. The friction lock on both controls should be checked for operation. Each control

should have full movement with at least a 1⁄4 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 in accordance with FAR

Part 43, appendix E, at an FAA-approved repair station.
12

AC 90-89A 5/24/95

4. FIELD CHECK. Two people are needed to

accomplish the following field check that will enable

an amateur-builder to detect if the aircraft’s

instrument system is leaking: (Note: This field check

is not an accuracy check.)

a. Airspeed check: Slip a long rubber hose

over the pitot mast (surgical tubing is recommended).

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 reading. The airspeed needle should

remain steady for a minute if the system is sound.

A fast drop off will indicate a leak in the instrument,

fittings, lines, or the test hose attachment. NEVER

force air in the pitot tube or orally apply suction

on a static vent. This will cause damage to the

instruments.

b. Altimeter/vertical speed check.

(1) To check the static side, apply low suction at the end of the static vent port. The easiest

way to gain access to the static system is to remove

the static line at the static port. If there are two static

ports, tape the unused port closed. Next, get two feet

of surgical tubing, seal one end, and tightly roll it

up. Attach the open end to the static line and slowly

unroll the tubing. This will apply a suction, or low

pressure, to the static system.

(2) The altimeter should start to show an

increase in altitude. The vertical speed indicator also

should indicate a rate of climb. The airspeed may

show a small positive indication. When the altimeter

reads approximately 2,000 feet, stop and pinch off

the tube. There will be some initial decrease in altitude and the vertical speed will read zero. The altimeter should then hold the indicated altitude for at

least a minute. If altitude is lost, check for leaks.

(3) IMPORTANT: The above airspeed and

altimeter field checks should not be considered the

equivalent of airspeed or static system accuracy tests

as certified by a certificated repair station, but a

check of the system for possible leaks. These checks

do not take into consideration the pitot tube and static

ports located on the airframe. The FAA recommends

the builder not deviate from the designer’s original

plans when installing the pitot and static system.

c. Fuel system: Since 1983, more than 70 percent of the engine failures in amateur-built aircraft

were caused by fuel system problems. Many times

the direct cause of engine failure was dirt and debris

in the fuel tank and lines left behind during the manufacturing process.

(1) Before the aircraft’s fuel tanks are

filled, the amateur-builder should vacuum any manufacturing debris from each tank and wipe them down

with a ‘‘tack’’ cloth (available from a paint supply

store). Next, the system should be flushed with aviation grade gasoline several times in order to remove

any small or hard to reach debris from the tanks

and lines. The fuel filter/gasolator screen/carburetor

finger screen should also be cleaned. The amount

of time spent ‘‘sanitizing’’ the fuel system will provide big safety dividends for the life of the aircraft.

(2) When filling the tanks, place the aircraft in the straight and level cruise position. Add

fuel in measured amounts to calibrate the fuel tank

indicators. While allowing the aircraft to sit for a

short time to observe for possible leaks, inspect the

fuel tank vents to see if they are open and clear.

Check that the fuel tank caps seal properly. If there

are no leaks and the fuel system has an electric boost

pump, pressurize the system and again check for

leaks. The fuel selector, vents and fuel drains should

be properly marked and tested for proper operation.

NOTE: Many amateur-built aircraft take 5

to 8 years to build. During that time, many

rubber-based oil and fuel lines and cork gaskets that were installed early in the building

process may have age hardened, cracked,

and/or turned brittle. The builder should

carefully inspect these components and

replace as necessary to prevent a premature

engine failure.

d. Hydraulic system: The hydraulic system

should function dependably and positively in accordance with the designer’s intent. Retractable landing

gear should be rigorously cycled on the ground,

using both the normal and emergency landing gear

extension system.

e. Safety belt and shoulder harness: These

items should be checked for condition and proper

installation. A review of amateur-built aircraft

accidents has disclosed a significant number of

accidents in which the seat belt mounting hard points
13

5/24/95 AC 90-89A

failed. Each seat belt and shoulder harness mounting

hard point should be built to the designer’s specifications to ensure that it will hold the harness and pilot

in the aircraft at the ultimate design ‘‘G’’ load specification, both positive and negative, for the aircraft.

f. Avionics and electrical checks: Test the avionics systems. Perform an operational check to

ensure the radio(s) transmit and receive on all frequencies. Inspect circuit breakers/fuses, microphones, and antennas for security and operation. Test

the ELT for proper operation and battery life. Electrical systems can be checked for operation of lights,

instruments, and basic nav/comm performance.

Other electrical systems, such as generator/alternator

output can be checked during the engine run-ins, taxi,

and flight tests. Check the battery and the battery

compartment for security and if applicable, ensure

that the battery is properly vented to the outside of

the aircraft. Check the condition of the engine to

airframe bonding (grounding) wire. Ensure that all

electrical instruments operate properly.

g. Cowling and panel checks: Ensure that all

inspection panels are in place, the cowling is secured,

and cowl flap operation is satisfactory. Inspect the

propeller spinner and its backing plate for cracks.

h. Canopy/door locks checks: Ensure the canopy or doors on the aircraft work as advertised. Double check the canopy or door lock(s) so the canopy

and doors will not open in flight and disturb the

airflow over the wings and stall the aircraft. If a

canopy jettison system is installed, check for proper

operation when the aircraft on the ground and when

it is on jacks. (Jacks will simulate flight loads on

the aircraft.)
14

AC 90-89A 5/24/95

SECTION 8. WEIGHT AND BALANCE

‘‘Never argue with your spouse or a mathematician’’ Phil Larsh, Accident Prevention Counselor,

Colfax IN (1994)

1. OBJECTIVE. To discuss the importance of

developing an accurate weight and balance calculations for both test and recreational flights. Additional

information on weight and balance can be found in

AC 91-23A, Pilot’s Weight and Balance Handbook.

a. A good weight and balance calculation is

the keystone of flight testing. Accurately determining

the aircraft’s take-off weight and ensuring that the

center of gravity (CG) is within the aircraft’s design

for each flight is critical to conducting a safe flight

test.

b. An aircraft should be level when weighed,

spanwise and fore and aft in accordance with the

manufacturer’s instructions, and should be in the

level flight position. It is highly recommended that

the weighing be done in an enclosed area, using three

calibrated scales. Bathroom scales are not recommended because they are not always accurate.
15

5/24/95 AC 90-89A

ITEMS WEIGHT (LBS) ARM (INCHES) MOMENT (IN-LBS)

Left Wheel

Right Wheel

Tail Wheel

TOTALS

101

99

42

242

60

60

180

80.8

6060

5940

7560

19560

TOTAL MOMENT = Empty weight CG or 19560 = 80.8

TOTAL WEIGHT 242

FIGURE 2. EMPTY WEIGHT CG

2. DETERMINING EMPTY WEIGHT CG.

a. The sample airplane for determining empty

weight is a single seater, which the kit manufacturer’s design empty weight of 253 pounds and a gross

weight limit of 500 pounds. The datum line is located

at the nose of the aircraft and the CG range is

between 69 to 74 inches from the datum.

b. To work a CG problem, figure the EMPTY

WEIGHT CG first. On a piece of paper draw four

blocks. Title each block from left to right as shown

in figure 3.

(1) Under the block titled item, vertically

list ‘‘left wheel,’’ ‘‘right wheel,’’ and ‘‘nose/tail

wheel.’’

(2) Place a calibrated scale under each

wheel and record the weight on each gear, in pounds,

in the weight block along side the appropriate wheel.

This process is done with an empty fuel tank.

(3) Measure in inches the distance from the

datum line, or imaginary point identified by the

manufacturer (e.g., nose of the aircraft), to the center

line (C/L) of the three wheels. Record the distance

of each wheel and place it in the moment arm block

beside the appropriate wheel (see figure 2).

(4) Multiply the number of inches (arm)

by the weight on each wheel to get the moment (inchpounds) for each wheel. Add the weight on the three

gears and the three moments in inch pounds and

divide the total weight into the total moment. The

sum is the ‘‘EMPTY WEIGHT CENTER OF

GRAVITY’’ in inches. In the sample case, the empty

weight CG is 80.8.

NOTE: All calculations should be carried

out to two decimal places.
16

AC 90-89A 5/24/95

ITEMS WEIGHT (LBS) ARM (INCHES) MOMENT (IN-LBS)

A/C

Pilot

Fuel

TOTALS

242

170

30

442

80.8

65

70

74

19560

11050

2100

32710

TOTAL MOMENT = Takeoff CG or 32710 = 74

TOTAL WEIGHT 442

FIGURE 3. TAKE-OFF CG

3. DETERMINING TAKE-OFF WEIGHT CG.

a. Since the aircraft’s empty weight and empty

weight CG are fixed numbers, the only way an aircraft’s CG can be changed is by adding weight in

other locations.

b. For example, in figure 3, the aircraft’s

empty weight has been written in the appropriate

blocks. The pilot weighs 170 pounds and fuel (5 gallons) weighs 30 pounds.

c. Again, all measurements are made from the

datum to the center line of the object that has been

added. Weight multiplied by inches from the datum

equals moment. Add the weights and moments to

find the take-off CG for that particular flight.

d. Loaded in this configuration, the aircraft

is within the CG flight envelope and is safe to fly.
17

5/24/95 AC 90-89A

ITEMS WEIGHT (LBS) ARM (INCHES) MOMENT (IN-LBS)

A/C

S/B

Pilot

Strobe

Fuel

Fuel

TOTALS

242

15

170

1.5

30

1.5

460

80.8

75

65

179

70

55

74.3

19560

1125

11050

268.5

2100

82.5

34186

TOTAL MOMENT = Alteration Takeoff Weight CG or 34186 = 74.3

TOTAL WEIGHT 460

FIGURE 4. ADDITIONAL EQUIPMENT ADDED

4. ADDING ADDITIONAL EQUIPMENT.

a. During flight testing, a strobe battery and

hand held radio are added. The battery/battery box

weight is 15 pounds and the location is 75 inches

aft of the datum; the strobe assembly weight is 1.5

pounds and is located 179 inches aft of the datum;

the radio’s weight is 1.5 pounds and is located 55

inches aft of the datum (see figure 4).

b. In the sample problem, the previous figures

for take-off weight and moment are still accurate,

hence those numbers have been listed in the appropriate blocks.

(1) Add the battery, strobe, and radio numbers in the appropriate locations and calculate the

totals. At 465 pounds, the aircraft is still 35 pounds

under its design gross weight limit of 500 pounds

but is out of balance because the CG has moved

.3 inches further aft (74.3 inches) than the allowable

rear CG limit of 74 inches.

(2) Since the aircraft is out of balance with

an aft CG, it is no longer 100 percent stable in pitch

and would be dangerous to fly. In most cases, it

is not the amount of weight added to the aircraft

that can cause a major safety problem but its location.

(3) To bring this aircraft back into the safe

CG range, the battery would have to be moved 9

inches forward (66 inches from the datum line).

Another alternative is to install 8 pounds of ballast

in the nose (20 inches from the datum).

(4) If the sample aircraft exceeded the

designer’s gross weight limit (e.g., 300 pound pilot)

instead of the CG limit, its climb, stall, and performance capability would be poor and the possibility

for in-flight structural failure would be high.

NOTE: In the sample weight and balance,

positive numbers were chosen by placing the

datum line on the nose of the aircraft. Some

manufacturers prefer to use a datum located

somewhere between the aircraft’s nose and

the leading edge of the wing.

(5) This kind of datum will set up a system

of positive arms (items located aft of the datum) and

negative arms (items located forward of the datum).

(6) When working a weight and balance

problem with negative and positive moments, subtract the sum of all negative moments from the sum

of all positive moments to reach a ‘‘total moment’’

for the aircraft.
18

AC 90-89A 5/24/95

SECTION 9. PAPERWORK

‘‘It is harder to write a lie in a logbook than tell one, because your eyes see it and your fingers feel

it.’’ Bob Moorman, Ultralight Instructor (1994)

1. OBJECTIVE. To have the proper documentation and paperwork to conduct the flight test.

a. Weight and Balance: The weight and balance for the aircraft should be carefully done. The

gross weight and CG range should be determined

prior to every flight.

b. Airworthiness/Registration/Operating

Limitations/Placards/Weight and Balance: Must be

on board, or the aircraft is not legal to be operated.

c. Checklists: In addition to the assembly/airworthiness checklist previously discussed in section

7, the builder should prepare the following checklists: preflight; take-off/cruise; before starting;

descent/before landing; starting the engine; after

landing; before takeoff; securing the aircraft; and

emergency procedures. A checklist to cover the

above procedures may seem a tedious task, but it

will only be the size of a 5x8 card -- similar to a

checklist for a Cessna 150 or a Piper PA-28-140.

NOTE: The amateur-builder should anticipate several revisions to the checklists.

d. Flight Manual: It is imperative a flight

manual describing the anticipated performance of the

aircraft be written by the aircraft builder/kit manufacturer. The manual will be revised several times during the flight test phase until it accurately reports

the aircraft’s performance.

e. Maintenance Records (logbooks): Operators of amateur-built aircraft are required to only

record the yearly condition inspections in accordance

with the aircraft’s operating limitations. The FAA

recommends, however, that every amateur-built aircraft/ultralight owner record in the aircraft’s

logbooks all inspections and maintenance performed.

This will create an aircraft’s maintenance history and

will be invaluable in spotting trends.
19

5/24/95 AC 90-89A

SECTION 10. POWERPLANT TESTS

‘‘Don’t short-change the engine tests or you won’t be around to give your grandkids a ride.’’ Dick Koehler,

A&P Instructor (1994)

1. OBJECTIVE. To ensure that the engine has

been properly run-in and is safe to operate in all

rpm ranges.

a. An engine pre-oil and cold compression test

can be conducted as follows:

(1) Remove the rocker-box covers and one

spark plug from each cylinder.

(2) Using an external oil pump, or by rotating the propeller in the direction of rotation, pump

a substantial supply of oil up from the sump into

the rocker arms.

(3) When the engine is pre-oiled, run a

cold compression test of each cylinder.

(4) The results will serve only as an initial

bench mark for comparing other compression tests

taken after the engine has been run-up to operating

temperature.

b. New/newly overhauled engine run-in procedures:

(1) Most amateur-builders start with a new

or newly overhauled engine and proceed to ‘‘run it

in’’ on the airframe. This practice is followed due

to lack of access to a test cell or a special ‘‘club’’

propeller that is specifically designed to aid in engine

cooling during run-in. There are pros and cons to

using an airframe to run in an engine, but the best

advice has always been to follow the engine manufacturer’s instructions. These instructions are found

either in the manufacturer’s overhaul manuals, service bulletins, or service letters. Following the manufacturer’s instructions is especially important if the

engine has chrome cylinders which require special

run-in procedures.

(2) Also, before running-up the engine, be

certain that it has the proper grade oil in the sump.

Some new and newly overhauled engines are shipped

with a special preservative oil to prevent corrosion.
20

AC 90-89A 5/24/95

Drain this out and reservice the engine with the correct oil before starting.

c. Used engine run-in procedures: Some amateur-builders install a used engine from a flyable aircraft. The same checks and adjustments used on a

new or newly overhauled engine should be conducted. New and used engines require special

attention to engine cylinder baffling to ensure cylinder cooling is within the engine manufacturer’s

cylinder head temperature specifications.

d. Pre run-in checks:

(1) Before beginning the powerplant tests,

inspect the engine and propeller carefully. All fuel

and oil line connections should be tight. Check the

torque on the engine mount attaching bolts. Be certain that there are no tools, hardware, or rags laying

between the cylinders or under the magnetos.

(2) Check for the proper amount of oil in

the engine and that the dip stick gives an accurate

reading of the oil quantity. Be advised that some

engines were mounted on an angle in type certificated aircraft. These engines have a special part number oil dip stick, which corrects for the different

angle of oil in the crankcase. The same engine,

mounted level in a amateur-built aircraft with the

original dip stick, will not show the correct oil quantity.

e. Test and Support Equipment:

(1) A cylinder head temperature gauge

(CHT) is needed to ensure that all cylinders are

receiving the proper flow of cooling air.

(2) On the newer aircraft engines, the cylinders are drilled and tapped to accept a bayonet

type of CHT thermocouple probes. For older engines,

the thermocouple is designed like a spark plug

washer and fits under a spark plug. It can be installed

in any cylinder, either under the top or bottom spark

plug.

(3) Each type of CHT design can have

multiple thermocouples which are connected to a

selector switch in the cockpit. The pilot then selects

the cylinder he wants to monitor. This also is an

excellent troubleshooting tool for identifying fouled

plugs and bad ignition leads.

(4) If there is only one CHT thermocouple,

attach it to the rearmost cylinder on the right side

of the engine (as viewed from the cockpit) and runup the engine. Run the same test on the opposite

rearmost cylinder to be certain the hottest running

cylinder was selected. Calibrated oil pressure and oil

temperature gauges also are needed to test the

accuracy of the engine instruments installed in the

aircraft.

(5) The following support equipment is

needed: 50 feet or more of tie-down rope, tie-down

stakes, two chocks for each wheel, fire extinguisher,

assorted hand tools, safety-wire, cotter-pins, ear and

eye protection, grease pencils, logbooks, clip board,

pen and paper, a watch to time the tests, rags, and

manufacturer’s instructions.

f. Safety Precautions: Before the first engine

run, ensure the aircraft is tied down, brakes on, and

the wheels are chocked. The builder and flight test

team should wear ear and eye protection. All flight

test participants should be checked out on fire extinguisher use and operation. During engine runs, do

not allow anyone to stand beside the engine, or inline or close to the propeller. Making minor adjustments to a running engine, such as idle and mixture

settings, is a very dangerous procedure and should

be done with great care by experienced individuals.

g. The First Engine Run:

(1) The first start of the engine is always

a critical operation. The engine should be pre-oiled

in accordance with the manufacturer’s instructions.

For aircraft using other than FAA-approved oil pressure and temperature gauges, the FAA recommends

attaching an external calibrated oil temperature and

pressure gauge to the 4 cycle engine in order to calibrate the engine instruments. After priming the

engine and completing the starting engine checklist

items, the first concern is to get an oil pressure reading within the first 20 to 30 seconds. If there is no

oil pressure reading -- shut down.

(2) There are three common problems that

would cause low or fluctuating oil pressure.

(i) Air in the oil pressure gauge line:

This is easily fixed by loosening the line connection

near the oil pressure gauge and squirting oil into

the line until full. Another option is to use a preoiler to provide the pressure and carefully bleed the

air out of the line near the oil gauge by loosening

the B-nut that connects the oil line to the gauge.
21

5/24/95 AC 90-89A

(ii) A misadjusted oil pressure relief

valve: Cleaning the pressure relief ball, checking for

the proper number of washers, correcting spring tension, and re-adjusting the setting could solve the

problem.

(iii) An internal problem within the

engine (most likely the oil pump): An engine tear

down would be required.

(3) With good oil pressure/temperature

readings and the engine running smoothly, ensure

that the engine oil pressure and temperature gauges

in the cockpit match the calibrated oil pressure and

temperature gauges, which were attached to the aircraft for the first run. Do not overlook this test. It

is critical to determine the accuracy of the cockpit

engine gauges not only for the ground engine runin period, but for in-flight engine cooling tests.

(4) Work through the engine manufacturer’s run-in schedule. The majority of the engine

manufacturers recommend a series of engine runs

from low rpm to maximum rpm. Each run usually

incorporates a 200 rpm increase and lasts no longer

than 10 minutes. The secret to a successful engine

run is not to let the engine temperatures exceed

manufacture’s limits during engine runs.

NOTE: Engines with chrome cylinders or

chrome rings require different high power

run-in programs. Follow the manufacturer’s

run-in instructions to ensure the engine will

perform satisfactorily over its lifetime.

h. Engine Cool Down: After a ground-run, the

cooling off period takes approximately an hour. This

is because a newly overhauled engine needs time

for the internal parts (e.g., rings, cylinders, valves,

bearings, and gear faces) to expand and contract several times to obtain a smooth surface that retains

its ‘‘memory.’’ This is a lengthy process even when

done right, but it is important not to skip any of

the recommended runs to save time. To do so is

to risk increasing oil consumption and reducing overall engine performance, reliability, and engine life

span -- which could be costly in the long-term.

i. Record the engine run-in data: During the

engine run, monitor the cylinder head temperatures,

oil temperature, and oil pressure. Record the readings

and adjustments for future reference. If the cylinder

head temperatures are rising close to the red line,

reduce power and stop the test. Some causes of high

cylinder head temperatures include using spark plugs

with the improper heat range; cylinder head temperature gauges installed on the wrong cylinder; missing

or badly designed cylinder head cooling baffles; partially plugged fuel nozzles (applicable to fuel

injected engines); fuel lines of improper internal

diameter (creates lean mixtures); engine improperly

timed either mechanically and/or electrically; and the

carburetor fuel mixture set excessively lean.

j. After shut-down:

(1) After each engine run, check for fuel

and oil leaks, loose connections, and hot spots on

cylinders (burnt paint). The FAA recommends draining the oil and removing the oil screen/filter within

the first 2 hours of running the engine. Check the

screen/filter for ferrous metal with a magnet. Wash

and inspect the screen/filter for non-ferrous metal

like brass, bronze, or aluminum.

(2) A very small quantity of metal in the

screen is not uncommon in a new or newly overhauled engine. It is part of the painful process of

‘‘running-in.’’ If subsequent oil screen checks

(2 hours apart) show the engine is ‘‘making metal,’’

this indicates a problem inside the engine and a tear

down inspection is required.

(3) It also is recommended all fuel sumps,

filters, and gasolators be checked for debris after

each engine run. Special attention should be given

to the fuel system by the builder who constructed

fuel tanks out of composite or fiberglass materials.

Composite and fiberglass strands can be very fine,

making visual detection difficult. Frequent cleaning

of the fuel filters and screens early in the flight testing phase will avoid a gradual build up of loose

composite fibers, which would reduce or stop the

flow of fuel to the engine.
22

AC 90-89A 5/24/95

SECTION 11. ADDITIONAL ENGINE TESTS

‘‘Always go with the best fix not the cheapest fix.’’ Bill Deeth, Master Mechanic (1994)

1. OBJECTIVE. To determine if the engine supply of fuel is adequate at all angles of attack.

a. Mixture and Idle Speed Check: After

completing the initial engine ‘‘run-in’’ tests, check

the idle speed and mixture settings. To determine

if the mixture setting is correct, perform the following:

(1) Warm up the engine until all readings

are normal

(2) Adjust the engine rpm to the recommended idle rpm

(3) Slowly pull the mixture control back

to idle cut-off

(4) Just before the engine quits, the engine

rpm should rise about 50 rpm if the mixture is properly adjusted. If the rpm drops off without any

increase in rpm, the idle mixture is set too lean. If

the rpm increases more than 50 rpm, the idle mixture

is set too rich.

NOTE: Some amateur-builders, after properly setting the idle mixture/rpm to the

manufacturer’s specification, increase the

engine idle rpm by 100 rpm for the first 10

+ hours of flight testing. This is to ensure

that the engine will not quit when the throttle is pulled back too rapidly, or when power

is reduced on the final approach to landing.

b. Magneto Check:

(1) The magneto checks should be smooth

and the difference between both magnetos rpm drops

should average about 50 rpm. The builder also

should perform a ‘‘HOT MAG’’ check, to ensure

against the engine, on its own, deciding when and

where to start. To perform a hot mag check, run

up the aircraft until the engine is warm. At idle rpm

turn the magneto switch off; the engine should stop

running. If the engine continues to run, one or both

of the magnetos is hot (not grounded).

(2) The usual causes for a hot magneto are

a broken ‘‘P’’ lead coming out of the magneto or

a bad magneto switch. THIS IS AN IMMEDIATE
23

5/24/95 AC 90-89A

THREAT TO THE PERSONAL SAFETY OF ANYONE NEAR THE AIRPLANE AND MUST BE

REPAIRED AT ONCE.

c. Cold Cylinder Check:

(1) If the engine is running rough and the

builder determines it may be an ignition problem,

perform the following check:

(i) Run the engine on the bad magneto for about 30 seconds at 1200 rpm. Without

switching the mag switch back to ‘‘both,’’ shut off

the engine.

(ii) One of the test crew should

quickly use a grease pencil to mark an area of the

exhaust stacks approximately an inch from the flange

that attaches the stacks to the cylinders.

(iii) Check the marks on the stacks. If

one or more of the exhaust stacks with a grease mark

has NOT been burned to a grayish-white color and

the mark on the stack still retains most of the original

color of the grease pencil, the ‘‘cold cylinder’’ has

been identified.

(2) Probable causes of the cold cylinder

problem are defective spark plugs, ignition leads, or

a cracked distributor in one of the magnetos. To

detect if the spark plugs are bad, switch both plugs

to another cylinder. If the grease pencil proves the

problem moved to the new cylinder, the spark plugs

are bad. If the problem remains with the original

cylinder, the ignition lead or magneto is bad.

d. Carburetor Heat:

(1) It is strongly recommended that all

amateur-builders install a carburetor heat system that

complies with the engine manufacturer’s recommendation. If no recommendation is available, the

FAA suggests a carburetor heat system for a sealevel engine and a conventional venturi should be

designed so that it will provide a 90 degrees F

increase in the venturi at 75 percent power. For altitude engines using a conventional venturi carburetor,

120 degrees F increase in venturi temperature at 75

percent power will prevent or eliminate icing.

Remember: Too little carburetor heat will have no

effect on carburetor icing, and too much carburetor

heat will cause a overly rich mixture which will

reduce power and may shut down the engine.

(2) During the engine tests, make numerous checks of the carburetor heat system. To avoid

overly rich mixtures from oversized carburetor heat

ducts, ensure that the carburetor heat duct is the same

size as the inlet of the carburetor.

(3) Be certain there is a positive reduction

in rpm each time ‘‘carb heat’’ is applied. If there

is no reduction, or the rpm drop is less than expected,

check the carb heat control in the cockpit and on

the carb heat air box for full travel. Also check for

air leaks in the ‘‘SCAT TUBE’’ that connects the

heat muff to the carburetor air box.

e. Fuel Flow and Unusable Fuel Check: This

is a field test to ensure the aircraft engine will get

enough fuel to run properly, even if the aircraft is

in a steep climb or stall attitude.

(1) First, place the aircraft’s nose at an

angle 5 degrees above the highest anticipated climb

angle. The easiest and safest way to do this with

a conventional gear aircraft is to dig a hole and place

the aircraft’s tail in it. For a nose gear aircraft, build

a ramp to raise the nose gear to the proper angle.

(2) Make sure the aircraft is tied-down and

chocked. With minimum fuel in the tanks, disconnect

the fuel line to carburetor. The fuel flow with a gravity flow system should be 150 percent of the fuel

consumption of the engine at full throttle. With a

fuel system that is pressurized, the fuel flow should

be at least 125 percent. When the fuel stops flowing,

the remaining fuel is the ‘‘unusable fuel’’ quantity.

(3) Since the fuel consumption of most

modern engines is approximately .55 pounds per

brake horsepower per hour for a 100 horsepower

engine, the test fuel flow should be 82.5 pounds (13.7

gallons) per hour for gravity feed, or 68.75 pounds

(11.5 gallons) per hour for a pressurized system. The

pounds per hour divided by 60 equals 1.4 pounds

and 1.15 pounds per minute fuel rate respectively.

NOTE: Formula for fuel flow rate gravity

feed is .55 x engine horsepower x 1.50 =

pounds of fuel per hour divided by 60 to

get pounds per minute, divided by 6 to get

gallons per minute. For a pressurized system, substitute 1.25 for 1.50 to determine

fuel flow rate.

f. Changing Fuel Flow or Pressure: If the

aircraft’s fuel flow rate is less than planned, there
24

AC 90-89A 5/24/95

is a volume or pressure problem. An increase in the

fuel flow volume may necessitate installation of

larger fuel line fittings on the fuel tanks, fuel selector,

and carburetor in addition to larger internal diameter

fuel lines. To increase fuel pressure, install an electrically driven or engine driven mechanical fuel

pump prior to the first flight.

g. Compression Check: When the engine runin procedures have been completed, perform an additional differential compression check on the engine

and record the findings. If a cylinder has less than

60/80 reading on the differential test gauges on a

hot engine, that cylinder is suspect. Have someone

hold the propeller at the weak cylinder’s top dead

center and with compressed air still being applied,

LISTEN. If air is heard coming out of the exhaust

pipe, the exhaust valve is not seating properly. If

air is heard coming out of the air cleaner/carb heat

air box, the intake valve is bad. When the oil dip

stick is removed and air rushes out, the piston rings

are the problem.

h. Last Check: Drain the oil and replace the

oil filter, if applicable. Check the oil and screens

for metal, visually inspect the engine, and do a runup in preparation for the taxi tests. Do not fly the

aircraft if anything is wrong, no matter how small

or how insignificant. The sky, like the sea, is an

unforgiving and uncompromising environment.
25

5/24/95 AC 90-89A

SECTION 12. PROPELLER INSPECTION

‘‘A tough decision is what a man makes when he cannot form a committee to share the blame’’ George

Lutz, Col. U.S. Air Force, Retired (1994)

1. OBJECTIVE. To help the amateur-builder/

ultralight aircraft owner develop an inspection program to maintain his/her propeller.

a. There are three kinds of propeller designs:

metal, wood, and composite.

(1) Because of weight considerations,

metal propellers are used more on amateur-built aircraft than ultralight aircraft. This makes wood and

composite propellers the overwhelming choice for

ultralight aircraft.

(2) Wood propellers are light, reliable, and

inexpensive but require frequent inspections.

(3) Composite carbon-graphite material

props are more expensive than wood, but are stronger

and require less maintenance.

b. All types of propellers have one thing in

common: they are constantly under high levels of

vibration, torque, thrust, bending loads, and rotational stress. Even small nicks in the leading edge

of the blade can very quickly lead to a crack, followed by blade separation. Propeller tip failure and

a subsequent violent, out of balance situation can

cause the propeller, engine, and its mounts to be

pulled from the airframe in less than 5 seconds.

c. It is essential that the make and model

propeller is carefully chosen. Always follow the

manufacturer’s recommendations.

d. Exercise caution if experimenting with different makes and models propellers. A propeller with

the wrong size and pitch will give a poor rate of

climb, cruise, or could cause the engine to ‘‘overrev.’’

2. RECOMMENDATIONS FOR ALL

PROPELLERS.

a. Never use a propeller for a tow bar when

moving the aircraft.

b. Never stand in front of or in-line of a rotating propeller.
26

AC 90-89A 5/24/95

c. Never ‘‘PROP’’ an engine on uneven or

wet/snow covered ground.

d. Always inspect the propeller before and

after a flight.

e. When working on a propeller, make sure

the ignition is off first.

f. Always maintain the propeller to manufacturer’s instructions.

g. To avoid nicks and cuts, do not perform

run-ups near gravel/loose stones.

h. Apply a coat of automotive wax once a

month to protect the finish and keep out moisture.

i. Assume a propeller is unairworthy if it has

suffered any kind of impact or ground strike.

j. After any repair or repainting, or if vibration or roughness is noted, re-balance the propeller.

k. Propeller blades should be balanced within

1 gram of each other to avoid over stressing the gear

reduction system and propeller shaft.

l. Check the bolt torque on all newly installed

propellers every hour of operation for the first 10

hours and once every 5 hours thereafter.

m. After torquing the propeller, track the

blades.

FIGURE 5 - Propeller Tracking

3. PROPELLER TRACKING CHECK.

a. Ensuring good powerplant operation first

starts with a properly installed propeller. Each

propeller should be checked for proper tracking

(blades rotating in the same plane of rotation). The

following procedure is simple and takes less than

30 minutes:

(1) Chock the aircraft so it cannot be

moved. Remove one sparkplug from each cylinder. This will make the propeller easier and safer

to turn.

(2) Rotate the blade so it is pointing

straight down.

(3) Place a solid object (e.g., a heavy

wooden block that is at least a couple inches higher

off the ground than the distance between the propeller tip and the ground) next to the propeller tip so

it just touches.
27

5/24/95 AC 90-89A

(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

AC 90-89A 5/24/95

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

5/24/95 AC 90-89A

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

AC 90-89A 5/24/95

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

5/24/95 AC 90-89A

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

AC 90-89A 5/24/95

THIS PAGE INTENTIONALLY LEFT BLANK
33

5/24/95 AC 90-89A

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

AC 90-89A 5/24/95

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 (Vx)

= 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
35

5/24/95 AC 90-89A

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

AC 90-89A 5/24/95

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 Nlll on the first test flight, departing runway lll at lll 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!
37

5/24/95 AC 90-89A

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

AC 90-89A 5/24/95

(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
39

5/24/95 AC 90-89A

loosing altitude so it is necessary 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 -- which is getting the pilot

and aircraft safely back on the ground.

(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, the tower/

UNICOM/chase plane should be advised of

the pilot’s intentions. Avoid other traffic in

the pattern, and use the landing checklist.

(11) When the pilot has completed all the

tests called for by the FLIGHT TEST PLAN, notify

the tower/UNICOM/chase plane of the 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 back pressure

on the 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.

(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) should use an

approach speed of 1.5 x stall speed on landings.

(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.

(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.

(15) After taxiing in, secure the aircraft,

debrief the flight with members of the team, 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.
40

AC 90-89A 5/24/95

THIS PAGE INTENTIONALLY LEFT BLANK
41

5/24/95 AC 90-89A

CHAPTER 4. THE FIRST 10 HOURS

‘‘One can get a proper insight into the practice of flying only by actual flying experiments.’’

Otto Lilienthal (1896)

SECTION 1. THE SECOND FLIGHT

1. OBJECTIVE. To re-affirm the first flight

findings.

a. Before the second flight, the pilot should

ensure that all discrepancies noted on the first flight

are corrected. It is probable that more ground runups, rigging adjustments, or taxi tests will be

required. Under no circumstances should a pilot takeoff in an aircraft with known airworthiness problems.

The Law of Aerodynamics does not often forgive

these types of mistakes.

b. The pre-flight inspection should be the

same as performed for the first flight, including

draining the oil and inspecting the oil and fuel

screens for contamination.

c. The second flight, again lasting approximately an hour, should be a carbon copy of the first

one, with the exception that all first flight discrepancies are corrected. If problems are not corrected,

all further flight testing should be canceled until solutions are found.

SECTION 2. THE THIRD FLIGHT

‘‘Plan the flight, fly the Plan.’’ Sign on the wall at the Naval Test Pilot School, Patuxent River, MD

1. OBJECTIVE. To validate the engine reliability.

2. GENERAL. The third flight should concentrate on engine performance. Do not forget to

record the engine’s response to any application of

carb heart, leaning of the fuel mixture, changes to

airspeed, and its response to switching fuel tanks.

a. Engine oil pressure, oil temperature, fuel

pressure, and cylinder head temperatures should be

monitored and recorded from 55 percent through 75

percent rpm. At the higher rpm, be sure not to exceed

80 percent of the maximum cruise speed. This is

to avoid the possibility of encountering a flutter

condition. Do not forget to record the engine

responses to any applications of carb heat, leaning

the fuel mixture, changes to the power settings (RPM

and Manifold pressure), changes to airspeed, and its

response to switching fuel tanks.

b. Resist the temptation to explore the more

exciting dimensions of flight. Stick to the FLIGHT

TEST PLAN and perform a conscientious evaluation

of the engine. After landing, review the data with

the crew members. Make adjustments as needed, perform another post-flight inspection of the aircraft,

and record oil and fuel consumption.

c. After three hours of flight testing, the pilot

should be able to make the initial determination that

the aircraft is stable and engine is reliable in cruise

configuration.

SECTION 3. HOURS 4 THROUGH 10

‘‘Keep your brain a couple steps ahead of the airplane.’’ Neil Armstrong

1. OBJECTIVE. To build on the data established by the first three hours and start expanding

on the flight test envelope in a thorough and cautious

manner. This operational data will be added to the

aircraft’s flight manual.

2. GENERAL. These next seven 1-hour test segments should confirm the results of the first 3 hours

and explore the following areas:

a. Gear retraction (if applicable)
42

AC 90-89A 5/24/95

b. Climbs and descents to preselected altitudes.

(monitor engine performance)

c. Airspeed indicator in-flight accuracy check

NOTE: After each test flight, ALL

DISCREPANCIES must be cleared before

the next flight. The aircraft also must be

THOROUGHLY INSPECTED prior to the

next flight.

NOTE: It is recommended 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.

3. GEAR RETRACTION.

a. Before the gear is retracted in flight for the

first time, it is advisable to put the aircraft up on

jacks and perform several gear retraction tests,

including the emergency gear extension test. These

tests will determine if, in the last three hours of flight

testing, any structural deformation or systems malfunctions have occurred. In addition to the gear

retraction test, the pilot/chase pilot/ground crew

should use this time to review the aircraft’s kit/

designer instructions and emergency checklist procedures for malfunctioning gear and plan accordingly.

If at any time the aircraft has suffered a hard landing

or side loading on the gear during flight testing, the

aircraft and its gear should be tested for operation

and condition on the ground.

b. The first gear retraction test should be conducted with the aircraft flying straight and level at

or above 5,000 feet AGL, over an airport or emergency field. The airspeed must be well under the

maximum landing gear retraction airspeed. When the

gear is being retracted, note if there is any tendency

for the aircraft to yaw, pitch, or roll. Record what

changes to the aircraft’s trim are required to maintain

straight and level flight. If there are no adverse flight

reactions or system malfunctions, cycle the gear several times. When satisfied with the straight and level

gear retraction test, try an emergency gear extension

but only if this is practical.

c. With the gear extended, slow the aircraft

to 1.3 times the pre-determined stall speed, stabilize,

lower the flaps to the take-off position, trim, and

maintain straight and level flight.

d. Simulate a normal takeoff by increasing

rpm to full power. Raise the nose 3 degrees, trim,

and then retract the gear. Observe the following: aircraft reaction, such as pitch or roll; length of time

for gear to retract; trim requirements;, and the time

necessary to establish a 1,000-foot climb before

leveling off.

e. Practice a simulated takeoff several times

to ensure that the aircraft’s response is predictable

and the gear retraction system is mechanically reliable.

4. CLIMBS AND DESCENTS. The purpose of

these tests is to monitor engine performance and

reliability. The pilot should start the test only after

the aircraft has been flying straight and level for a

minimum of 10 minutes to stabilize engine oil pressure and temperatures.

a. Engine oil pressure and temperatures must

be kept within the manufacturer’s limits at all times

during these tests. High summer temperatures may

place restrictions on the flight test program because

both oil and cylinder head temperatures will increase

1 degree for each 1 degree increase in outside

temperature.

(1) Climbs. Start the first climb at a 15

degree climb angle, full power, at a predetermined

designated altitude (e.g., 1,000 feet). Maintain the

climb angle for 1 minute. Record the engine temperatures and pressures. Reduce power, stabilize the

engine temperature, and repeat the test. For the second climb test, the Flight Test Plan should call for

increasing the climb time -- record the results. When

satisfied that an engine cooling problem does not

exist at this climb angle, repeat the tests using steeper

climb angles until the pilot has reached 15 degrees

or encountered an engine manufacturer’s limit or a

5-minute climb period at full throttle has been

reached.

(2) Descents. Should begin above 5,000

feet AGL with both the engine temperatures and

pressures stabilized.

(i) The test pilot should use carb

heat and clear the airspace below him before

starting the descent. The first descent should be

at a shallow angle, at low rpm and last for 30 seconds, not exceeding 1.5 times the estimated stall

speed of the aircraft. During long, low power

descents, the pilot must be on the alert for too rapid

cooling of the engine usually identified by a signifi-
43

5/24/95 AC 90-89A

cant drop in oil and CHT temperature. If a noticeable

drop occurs, increase the engine rpm and reduce the

angle of descent. If not corrected, the repeated rapid

cooling of the engine may cause thermal shock to

the engine cylinders and eventually cause cylinder

head cracking or seizure.

(ii) Conduct each test as before, but

increase the time by 30 seconds until limited by the

engine manufacturer’s restrictions or 5-minute

descents are reached. Record temperatures, pressures, altitudes, and airspeeds data for climbs and

descents for addition into the aircraft’s flight manual.

5. AIRSPEED IN-FLIGHT ACCURACY

CHECK. The following procedure for airspeed

calibration is offered for evaluation:

a. A measured course should be chosen with

readily identifiable landmarks at each end. The landmarks should be a known distance apart, and the

length of course should be at least 1 to 2 miles long.

b. The pilot must fly a precision course

maintaining a constant altitude (e.g., 1,000 feet), constant airspeed, constant magnetic heading, and constant engine rpm. The pilot must record the temperature, altitude, indicated airspeed and the time over

each landmark for both directions. The average of

these speeds is the ground speed of the aircraft. An

E6B computer will convert the temperature, altitude,

and ground speed into True Indicated Airspeed for

the tests.

NOTE: The difference between the E6B

computer readings and the aircraft’s ground

speed readings is the error in the instrument

and the error caused by the installation of

the system in the aircraft.

c. The airspeed calibrations runs should be

made several times in opposite headings for each

of the selected airspeeds the pilot wants to check.

Such accuracy test runs should start at the lowest

safe airspeed and work up to cruise speed using 10

mph/knot increments.

d. Most errors will be found at the low end

of the speed range due to the angle of the pitot mast

to the relative wind and/or the location of the static

ports. Recently, amateur-builders have been using

Global Positioning Satellite (GPS) hand held receivers to check airspeed accuracy.

NOTE: Flight testing of all amateur-built

aircraft is restricted to a flight test area. If

a pilot must run additional tests on the aircraft that require more airspace, he should

notify the FAA District Office that issued

the aircraft’s operating limitations and

request a change to those limitations. If a

pilot is found to be operating an EXPERIMENTAL AIRCRAFT in violation of the

aircraft’s Operating Limitations, the FAA

may take certificate action.

e. If the aircraft has retractable gear or flaps,

test the accuracy of the airspeed indicator with the

gear/flaps up and down.

f. Record all the data in order to prepare an

airspeed calibration table for the flight manual.
44

AC 90-89A 5/24/95

THIS PAGE INTENTIONALLY LEFT BLANK
45

5/24/95 AC 90-89A

CHAPTER 5. EXPANDING THE ENVELOPE

‘‘Checklist! Checklist!! Checklist!!!’’ Jim Byers, Flight Instructor/Examiner

SECTION 1. GENERAL

1. OBJECTIVE. To move from a known flight

environment to an unknown flight environment using

a series of planned and carefully executed steps.

a. Before beginning the next series of test

flights, it is highly recommended that the aircraft

undergo a ‘‘Condition Annual’’ inspection as identified in the FAA Operation Limitation the amateurbuilder received with the special airworthiness certificate. It is strongly recommended that the builder

and/or pilot TAKE THE TIME to inspect the aircraft

because within the previous 10 hours, the aircraft

has been subjected to what can be referred to as a

‘‘shakedown cruise.’’

b. During the inspection, check the TORQUE

(paint marks) on the engine mounts, propeller bolts,

and landing gear. Double check the flight control

hinges and rod end bearings for attachment and play.

Check all cable installations, cable tension, and control travel in addition to completing all the standard

inspection and maintenance items. This inspection

also should include checking the oil and fuel filters

for metal or other forms of contamination.

c. Even if there have been no indications of

CO contamination, perform another carbon monoxide (CO) test using the floodlight procedure (see

chapter 1, section 7) or an industrial CO test meter.

There is a strong possibility that operational vibration

and landing stresses may have opened new paths for

CO to enter the cockpit.

SECTION 2. HOURS 11 THROUGH 20

‘‘Fly Scared!’’ Admiral Jack Ready, U.S.N.

1. OBJECTIVE. To focus the next 10 hours of

flight testing on the following: stall speed, best rate

of climb speed, best angle of climb speed, and slow

flight. It is recommended that stall speed tests be

conducted with the aircraft’s fuel tanks full. (CG).

a. As with any unknown, approach slowly,

incrementally, and follow the FLIGHT TEST PLAN.

To improve safety and reduce the possibility of spins,

the aircraft should be tested with a forward CG loading. Start the stall tests at 6,000 AGL. Make clearing

turns and stabilize the airspeed and altitude. The first

full stall should be conducted with power off, no

flaps, and gear-up if applicable. After clearing the

area, reduce the airspeed to 1.3 times the predicted

stall speed and trim. (NOTE: Do not trim within 10

knots of stall.)

NOTE: Some clean, high performance aircraft may not have any noticeable pre-stall

buffet. The actual stall may be abrupt and

violent with a large amount of wing or nose

drop.

b. The preferred pre-stall and stall behavior

is an unmistakable warning buffet starting lightly

about 5 to 10 mph/knots above the eventual stall

speed, growing in intensity as the aircraft slows

down.

c. The desired stall characteristics should be

a straight forward nose drop with no tendency for

roll or pitch-up. This docile and forgiving behavior

implies a stall that has started at the wing root and

progressed smoothly outboard. This gives an early

warning to the pilot in the form of the buffet from

separated airflow over the wings and or tail. The

ailerons will continue to operate in the attached air

flow until the aircraft’s stall speed is reached and

the wing stalls.

d. Begin by using the same procedures

employed on the first flight. Secure cockpit items

and put on carburetor heat. Decelerate slowly at 1⁄2

MPH/knot a second. Make small control inputs, keep

the ball centered, and note the aircraft’s reaction.
46

AC 90-89A 5/24/95

e. Let the aircraft stall and recover immediately, with stick forward and increasing power.

Note the stall speed.

f. Practice the same stall sequence several

times at 1⁄2 mph/knot speed deceleration rate to determine the power-off, one g stall speed. Practice the

same stall series with flaps, starting with the lowest

setting first and working slowly to the full flap

configuration. Record the findings.

g. After exploring the stall and recovery

behavior in a slow deceleration with the ball in the

middle, try a series of stalls with flaps up and then

flaps down with a faster rate of deceleration. Do not

exceed the deceleration rate expected in normal operations.

2. STALLS.

a. Power on Stalls. As before, use the same

procedures moving from the known to the unknown.

Increase power incrementally and run a stall test at

each new power setting until full power is reached.

It is not advisable to jump straight from idle to full

power with the resultant large changes in pitch attitude, torque reaction, and slip stream effect on the

wing and tail.

b. Conducting Power on Stalls. It is recommended that the aircraft be stabilized in level

flight at low cruise power. The power-on stall is

reached by slowly increasing the power to the desired

power setting. The pilot then steadily increases the

pitch attitude until the aircraft experiences the stall

buffet. Remember to keep the ball in the center until

the onset of the stall buffet.

(1) The power on stall may be more likely

to cause a wing drop than one at idle. This is due

to torque reaction and because the propeller slipstream tends to keep the flow of higher velocity air

over the inboard (root) section of the wing despite

the higher angle of attack. This allows the root portion of the wing to continue flying after the wing

tip stalls, dropping a wing.

(2) Tip stalls usually do not give advance

warning and will almost invariably result in some

severe wing drop. These stalls are more likely to

result in a spin, even if the controls are not mishandled. If the spin does not develop, considerably

more height will be lost in the recovery than if the

stall had been straight-ahead nose down.

(3) If the pilot yields to instinct and tries

to correct the wing drop with aileron, it could result

in a spin. Since a sharp wing drop could be regarded

as the onset of spin auto-rotation, the recommended

corrective action is to reduce power, exercise prompt

application of full opposite rudder combined with

lowering the nose to the horizon or below. Take care

to avoid this situation until the aircraft’s spin behavior has been tested.

(4) Perform the same sequence of events

for power on stalls as power-off stalls, unless limited

by the designer’s instructions. Record all findings

for the aircraft’s flight manual.

NOTE: Aircraft with retractable gear will

have to go through a separate series of slow

flight and stall checks with gear extended,

with and without flaps. Record the different

stall speeds for each configuration in the aircraft’s flight manual.
47

5/24/95 AC 90-89A

FIGURE 6. Climb Airspeed and Altitude Graph

c. Best Rate of Climb Speed Tests. To determine the best rate of climb for the aircraft, the following procedures are suggested:

(1) Perform the tests in smooth air, free

from thermal activity. Select an altitude (e.g., 1,000

feet AGL) as a BASE attitude. Use a heading 90

degrees to the wind and for the best results, reverse

the heading 180 degrees after each climb test.

(2) Begin a full throttle climb well below

the predetermined BASE altitude and stabilize at a

preselected airspeed approximately 15 mph/knots

above the predicted best rate of climb speed. As the

aircraft passes through the BASE altitude, begin a

one minute time check. At the end of 1 minute,

record the altitude gained. Descend down below the

BASE altitude. Decrease the airspeed by 5 mph/

knots and run the test again. After each succeeding

test, the pilot should decrease the airspeed by 5 mph/

knots until reaching an airspeed that is 10 mph/knots

higher than the stall speed of the aircraft. Record

the airspeed and altitude gained for each climb on

a graph similar to figure 6.

(3) The airspeed that shows the greatest

gain in altitude is the aircraft’s best rate of climb

speed (Vy).
48

AC 90-89A 5/24/95

FIGURE 7. Best Rate of Climb Speed Graph

d. Best Angle of Climb Speed Tests.

(1) Best angle of climb speed can be found

by using the same chart developed for the best rate

of climb tests. Draw a line (tangent) from the zero

rate of climb feet per minute (see figure 4) outward

to a point, on the rate of climb airspeed curve. Where

both lines touch, draw a line straight down to the

airspeed leg of the chart.

(2) The airspeed that the line intersects is

the best angle of climb airspeed.

e. Slow Flight Test.

(1) For added safety, the slow flight tests

should be performed at 6,000 AGL or higher to allow

room for spin recovery. THE PRIMARY PURPOSE

OF THESE TESTS IS FOR THE PILOT TO

BECOME FAMILIAR WITH THE AIRCRAFT’S

HANDLING QUALITIES AT THE MINIMUM

GEAR UP/DOWN AIRSPEEDS AND POWER

SETTINGS.

(2) The tests should be done with and without flaps. Start the tests at an airspeed of 1.3 times

(X) the stall speed of the aircraft. Once the aircraft

is stabilized and maintaining its altitude, reduce the

airspeed by 5 mph/knots. Maintain the altitude. Keep

reducing the airspeed until approaching a stall.

(3) Maintain 5 mph/knots above the previously determined stall speed. This figure is the initial slow flight airspeed. Practice with each flap setting, noting its affect on the aircraft’s performance.

If the aircraft has retractable gear, test in all gear

and flap combinations. These tests will have to be

run later in the flight test program but with the AIRCRAFT AT GROSS WEIGHT to determine the

actual slow flight airspeed and stall speeds.

(4) Remember, to help reduce the possibility of unplanned stalls in slow flight configurations,

avoid bank angles of more than 5 degrees. When

all the test data has been evaluated, and if the aircraft

is equipped with a stall warning horn or indicator,

set the stall warning at 5 mph/knots above the aircraft’s highest stall speed.
49

5/24/95 AC 90-89A

SECTION 3. HOURS 21 THROUGH 35: STABILITY AND CONTROL CHECKS

‘‘A superior pilot uses his superior judgement to avoid those situations which require the use of superior

skill.’’ Old Aviation Proverb

1. OBJECTIVE. To determine the aircraft’s

stability limits and range of control.

2. GENERAL. Before attempting to satisfy the

requirements of Federal Aviation Regulations

§ 91.319 Aircraft Having Experimental Certificates:

Operating Limitations and declaring that the aircraft

is controllable throughout the normal range of

speeds, two things must be done.

a. Perform another complete inspection of the

aircraft, including oil changes and fuel system filter

checks.

b. Carry out a close examination of the stability and control characteristics of the aircraft. Stability

and control checks will be centered around the three

axes of the aircraft: longitudinal or roll axis (ailerons), the lateral or pitching axis (elevators), and the

vertical or yaw axis (rudder).

c. All tests need a starting point. The starting

point for stability and control checks is called the

state of equilibrium. An aircraft is said to be in a

state of equilibrium when it experiences no acceleration and remains in a steady trimmed condition until

the force or moment balance is disturbed by an

atmospheric irregularity or by pilot input.

FIGURE 8. Static Stability

3. DEFINITIONS.

a. Static Stability: (positive) is when an aircraft tends to return to the state of initial equilibrium

position following a disturbance.

b. Static Stability: (neutral) is when an aircraft

remains in equilibrium in a ‘‘new’’ position, following a disturbance from an initial equilibrium position.

c. Static Stability: (negative) is when an aircraft tends to move further in the same direction as

the disturbance that moved it from the initial equilibrium position (figure 8).
50

AC 90-89A 5/24/95

FIGURE 9. Time

d. Dynamic Stability: is the time history of the

movement of the aircraft in response to its static

stability tendencies following an initial disturbance

from equilibrium (figure 9).

e. Test for Static Longitudinal Stability.

(1) This test should be done first. All tests

should be conducted with the aircraft in the forward

of center CG. Climb to at least 6,000 feet AGL and

trim the aircraft for zero stick force in straight and

level flight at low cruising speed. (Note: Do not

retrim the aircraft once the test has begun.) Apply

a light ‘‘pull’’ force and stabilize at an airspeed about

10 percent less than the trimmed cruise speed. At

this reduced airspeed it should require a ‘‘pull’’ force

to maintain the slower speed.

(i) If it requires a ‘‘pull’’ force, pull

a little further back on the stick and stabilize the

airspeed at approximately 20 percent below the initial cruise trim speed.

(ii) If it requires a still greater ‘‘pull’’

force to maintain this lower airspeed, the aircraft has

POSITIVE STATIC LONGITUDINAL STABILITY.

(iii) If at either test points, no

‘‘pull’’ force is required to maintain the reduced airspeeds, the aircraft has NEUTRAL STATIC

LONGITUDINAL STABILITY.

(iv) If either of these test points

require a ‘‘push’’ force to maintain the reduced airspeed then the aircraft has NEGATIVE STATIC

LONGITUDINAL STABILITY.

(2) Repeat another series of static longitudinal stability tests using a ‘‘push’’ force on the control stick. At an airspeed 10 percent above the trim

cruise speed the control stick should require a

‘‘push’’ force to maintain the airspeed. If a ‘‘pull’’

force is required, the aircraft has NEGATIVE

STATIC LONGITUDINAL STABILITY.

WARNING: If the aircraft exhibits

negative static longitudinal stability,

seek professional advice on correcting the problem before further flight.

(3) After confirming the aircraft has positive STATIC longitudinal stability, the pilot can

check for positive DYNAMIC longitudinal stability

(short period). First, trim the aircraft to fly straight

and level at normal trim cruise speed. With a smooth,

but fairly rapid motion, push the nose down a few

degrees.
51

5/24/95 AC 90-89A

(4) Quickly reverse the input to nose up

to bring the pitch attitude back to trim attitude. As

the pitch attitude reaches trim attitude, release the

stick (but guard it). The aircraft with positive

dynamic longitudinal stability will oscillate briefly

about the trim attitude before stopping at the trim

attitude position.

(5) To test the aircraft for positive

DYNAMIC longitudinal stability (long period),

begin from trimmed, straight and level flight. Without re-trimming, pull (or push) the stick to a speed

about 5 mph/knots off trim and release the stick.

There is no need to stabilize at the new speed. Expect

the aircraft to oscillate slowly about the trim airspeed

a number of times before the motion dampens out.

If there is significant friction in the control system,

the aircraft may settle at a speed somewhat different

from the original trim speed.

(6) If the amplitude increases with time,

the dynamic longitudinal stability is negative or

divergent. This is not necessarily dangerous as long

as the rate of divergence is not too great. It does

mean, however, the aircraft will be difficult to trim

and will require frequent pilot attention.

(7) An aircraft with ‘‘NEUTRAL’’

dynamic longitudinal stability (long period) will continue to oscillate through a series of increasing/

decreasing airspeeds and never return to the original

trim airspeed.

f. Lateral-directional Stability Control Tests.

Lateral (Dihedral Effect) and directional stability

tests are to determine if the aircraft can demonstrate

a tendency to raise the low wing in a sideslip once

the ailerons are freed. They also determine if the

rudder is effective in maintaining directional control.

CAUTION: This test may impose high

flight loads on the aircraft. Do not

exceed the design maneuvering speed

or any other airspeed limitation.

(1) To check lateral and directional stability, the aircraft should be trimmed for level flight

at a low cruise setting and an altitude above 5,000

feet AGL. Slowly enter a sideslip by maintaining

the aircraft’s heading with rudder and ailerons. The

aircraft should be able to hold a heading with rudder

at a bank angle of 10 degrees or the bank angle

appropriate for full rudder deflection. The control

forces and deflection should increase steadily,

although not necessarily in constant proportions with

one another (in some cases, rudder forces may

lighten), until either the rudder or the ailerons reach

full deflection or the maximum sideslip angle is

reached.

(2) At no time should there be a tendency

toward a force reversal, which could lead to an overbalance condition or a rudder lock.

(3) Release the ailerons while still holding

full rudder. When the ailerons are released, the low

wing should return to the level position. Do not assist

the ailerons during this evaluation.

(4) To check static directional stability,

trim the aircraft at a low cruise setting above 5,000

feet AFL. Slowly yaw the aircraft left and right using

the rudder. Simultaneously the wings should be kept

level by using the ailerons. When the rudder is

released, the aircraft should tend to return to straight

flight.

g. Spiral Stability. This is determined by the

aircraft’s tendency to raise the low wing when the

controls are released in a bank. To test for spiral

stability, apply 15 to 20 degrees of bank either to

the left or right, and release the controls. If the bank

angle decreases, the spiral stability is positive. If the

bank angle stays the same, the spiral stability is neutral. If the bank angle increases, the spiral stability

is negative. Negative spiral stability is not necessarily dangerous, but the rate of divergence should

not be too great or the aircraft will require frequent

pilot attention and will be difficult to fly, especially

on instruments.

NOTE: Friction in the aileron control system can completely mask the inherent spiral

characteristics of the airframe.
52

AC 90-89A 5/24/95

SECTION 4. A WORD OR TWO ABOUT FLUTTER

‘‘Stay up on the edge of your seat.’’ Scott Crossfield, Test Pilot

1. OBJECTIVE. To understand the causes and

cures of the condition known as flutter.

2. DESCRIPTION. Flutter in an aircraft structure is the result of an interaction between aerodynamic inputs, the elastic properties of the structure,

the mass or weight distribution of the various elements, and airspeed.

a. To most people, the word ‘‘flutter’’ suggests

a flag’s movement as the wind blows across it. In

a light breeze, the flag waves gently but as the wind

speed increases, the flags motion becomes more and

more excited. It takes little imagination to realize

if something similar happened to an aircraft structure, the effects would be catastrophic. The parallel

to a flag is appropriate.

b. Think of a primary surface with a control

hinged to it (e.g., an aileron). Imagine that the airplane hits a thermal. The initial response of the wing

is to bend upwards relative to the fuselage.

c. If the center of mass of the aileron is not

exactly on the hinge line, it will tend to lag behind

the wing as it bends upwards.

d. In a simple, unbalanced, flap-type hinged

control, the center of mass will be behind the hinge

line and the inertial lag will result in the aileron being

deflected downwards. This will result in the wing

momentarily generating more lift, increasing its

upward bending moment and its velocity relative to

the fuselage. The inertia of the wing will carry it

upwards beyond its equilibrium position to a point

where more energy is stored in the deformed structure than can be opposed by the aerodynamic forces

acting on it.

e. The wing ‘‘bounces back’’ and starts to

move downward but, as before, the aileron lags

behind and is deflected upwards this time. This adds

to the aerodynamic down force on the wing, once

more driving it beyond its equilibrium position and

the cycle repeats.

f. Flutter can happen at any speed, including

take-off speed. At low airspeeds, however, structural
53

5/24/95 AC 90-89A

and aerodynamic damping quickly suppress the flutter motion. But as the airspeed increases, so do the

aerodynamic driving forces generated by the aileron.

When they are large enough to cancel the damping,

the motion becomes continuous.

g. Further SMALL INCREASES will

produce a divergent, or increasing oscillation, which

can quickly exceed the structural limits of the airframe. Even when flutter is on the verge of becoming

catastrophic it can still be very hard to detect. What

causes this is the high frequency of the oscillation,

typically between 5 and 20 Hz (cycles per second).

It will take but a small increase in speed (1⁄4 knot

or less) to remove what little damping remains and

the motion will become divergent rapidly.

h. Flutter also can occur on a smaller scale

if the main control surface has a control tab on it.

The mechanics are the same with the tab taking the

place of the aileron and the aileron taking the place

of the wing. The biggest difference are the masses

involved are much smaller, the frequencies much

higher, and there is less feed-back through the control system. This makes tab flutter more difficult to

detect. The phenomenon known as ‘‘buzz’’ is often

caused by tab flutter. Since flutter is more prevalent

at higher speeds, it is not recommended that the flight

test plan call for high speed runs within 10 percent

of red line.

i. What can be done about it? Having

described how flutter happens, the following suggestions should help reduce the possibility of it happening to the amateur-builder’s aircraft:

(1) Perform a mass balance of all flight

controls in accordance with the designer/kit manufacturer’s instructions.

(2) Eliminate all control ‘‘free play’’ by

reducing slop in rod end bearings, hinges, and every

nut and bolt used in attaching flight controls.

(3) Ensure that all rigging and cable tension is set accurately to the design specifications

using a calibrated cable tensiometer.

(4) Re-balance any flight control if it has

been repaired, repainted, or modified in any way.

NOTE: If the pilot experiences flutter, or

believes he did, reduce power immediately

and land as soon as possible. Do not attempt

further flight until the aircraft has been

thoroughly inspected for flutter induced

damage. This inspection should include all

wing/tail attach points, flight controls, their

attach points/hinges, hardware, control

rods, and control rod bearings for elongated

bolt/rivet holes, cracks, (especially rod end

bearings) and sheared rivets.
54

AC 90-89A 5/24/95

SECTION 5. SPINS

‘‘Go from the known to the unknown -- slowly!’’ Chris Wheal, Military Test Pilot

1. OBJECTIVE. To determine if spin testing is

required.

NOTE: All FAA spin tests for type certification require a spin chute attached to the

aircraft. Even though amateur-built aircraft

have no such certification requirement, use

of a spin chute during testing should be

considered.

2. CAUTION.

a. If the manufacturer/designer of the aircraft

has not demonstrated satisfactory spin characteristics

and safe recovery, avoid all types of high angle of

attack flight testing and placard the aircraft: ‘‘spins

prohibited.’’

b. If the prototype aircraft has satisfactorily

demonstrated spin recovery and the builder’s aircraft

is identical to the prototype aircraft, the pilot may

confirm the aircraft will recover promptly from

inadvertent spin entries. Further tests to prove that

the aircraft will recover from a fully developed spin

(three turns or more) are not necessary unless the

aircraft is designed for, and will be routinely flown

in, aerobatic flight.

c. During all spin tests, it is strongly recommended that the pilot wear a parachute and that

a quick release mechanism to jettison the canopy

or door be installed. If the pilot is unable to exit

the aircraft because of the design restraints, it is recommended that intentional spins not be conducted

even though the design has successfully demonstrated spin recovery.

d. If any modifications or alterations have

been made to the airframe’s original design or

configuration (e.g., adding tip tanks or fairings), it

is not safe to assume that the aircraft still has the

same spin recovery characteristics as the prototype

aircraft. Spins in a modified aircraft should not be

attempted without consulting a qualified test pilot

and/or flight test engineer.

e. The pilot who conducts the spin tests should

have experience in entry into and recovery from fully

developed spins, preferably in makes and models

similar to the aircraft being tested. If the pilot needs
55

5/24/95 AC 90-89A

additional experience, aerobatic training with an

emphasis on spins from a qualified instructor is

highly recommended.

3. PLANNING THE FLIGHT. At this point,

nearly all the preparatory work for spin testing has

been accomplished. Planning the next flight should

be identical to planning for the first flight through

stalls. IT IS EXTREMELY IMPORTANT THAT

THE CENTER OF GRAVITY OF THE AIRCRAFT

IS AT THE FORWARD CG LIMIT AND ANY

BALLAST USED SHOULD BE SECURELY

ATTACHED TO THE AIRCRAFT.

a. The aircraft should be tested with landing

gear (if applicable) and flaps in the up position. The

pilot’s minimum entry altitude for these tests should

be no less than 10,000 feet AGL with the cockpit

secured.

NOTE: The following procedure is one way,

but not the only way, of conducting a spin

test and executing a recovery. Non-conventional aircraft may require significantly different spin recovery control applications.

The pilot should evaluate these procedures

and determine if they are compatible with

the aircraft before attempting any spin testing.

b. The basic technique used to get a clean spin

entry is to continue to reduce airspeed at about a

1 mph/knot a second rate in level flight, carburetor

heat on, and the power at idle.

(1) As the aircraft stalls, APPLY FULL

RUDDER in the desired spin direction, followed

immediately by full aft movement of the control stick

keeping the ailerons neutral.

(2) The transition from a horizontal to a

vertical flight path takes approximately three or four

turns and is referred to as the incipient stage of the

spin.

(3) During the incipient spin, the dynamic

and inertia forces have not achieved equilibrium.

Many aircraft can recover from the incipient spin

phase, but may not be able to recover from a steady

spin.

(4) The normal spin recovery technique is

to apply full rudder opposite to the direction of yaw

(check the turn needle). Move the control stick

smoothly and fairly rapidly forward towards the

instrument panel until the rotation stops.

(5) Quickly center the rudder and ease out

of the dive. Do not attempt to pull up too rapidly

because the structural limits of the aircraft can easily

be exceeded, or the aircraft can stall again. Recover

from the first deliberate spin after a half a turn.

c. If the aircraft is not built for aerobatics,

no further spin testing is required, It is recommended

the instrument panel be placarded ‘‘SPINS PROHIBITED.’’

d. If further spin testing is required, it is

strongly recommended the services of a professional

flight test pilot be used.
56

AC 90-89A 5/24/95

SECTION 6. ACCELERATED STALLS

‘‘Does it pass the Common Sense test?’’ U.S. Air Force, Thunderbird

1. OBJECTIVE. To further explore the stall

characteristics of the aircraft.

a. An accelerated stall is not a stall reached

after a rapid deceleration. It is an in-flight stall at

more than one g, similar to what is experienced in

a steep turn or a pull up.

NOTE: Do not attempt this or any other

extreme maneuver unless the designer or kit

manufacturer has performed similar tests on

a prototype aircraft identical to the amateur-builder’s aircraft.

b. The two standard methods for accelerated

stalls are the constant g (constant bank) and constant

speed (increasing bank). Most preferred of the two

is the constant bank method in which the airspeed

is decreased and the angle of bank is held constant,

until the aircraft stalls. It is the most preferred

because the potential violence of any accelerated stall

is largely governed by the increasing g load and airspeed.

c. As with every test, plan the sequence of

events. Start with small bank angles -- 30 degrees

will produce 1.15 g. Decelerate slowly, ball in the

center, do not over control. Work up incrementally

to a two g, 60 degree bank.

d. The aircraft does not have to develop a deep

stall each time. The pilot needs only to record the

airspeed and bank angle in which the aircraft hits

the pre-stall buffet. Recover by adding power and

reducing the angle of bank.
57

5/24/95 AC 90-89A

CHAPTER 6. PUTTING IT ALL TOGETHER: 36 HOURS TO —————?

‘‘Beware of false knowledge; it is more dangerous than ignorance.’’ George Bernard Shaw

SECTION 1. MAXIMUM GROSS WEIGHT TESTS

1. OBJECTIVE. To develop aircraft performance data across the weight and CG ranges.

a. Up until this point, all tests have been performed well below the test aircraft’s maximum gross

weight, with the possible exception of single seat

aircraft designs. A complete series of flight tests at

maximum gross weight from stalls, rates of climb,

angles of climb, stability, retraction tests, slow flight,

through accelerated stalls should be investigated.

b. These tests should demonstrate that the aircraft has been successfully flown throughout the CG

range, and will operate in and at the full range of

aircraft weights from minimum to full gross weight.

The findings should be documented in the aircraft’s

flight manual.

c. Each phase of the testing should be done

slowly, incrementally, with the same careful attention to detail that should characterize all the flight

testing.

d. Increases in the aircraft weight should be

done in a series of steps. Usually, 20 percent increments of the maximum payload (e.g., sandbags, lead

shot) are added in the aircraft to simulate passengers

or baggage weight. The pilot should carefully weigh

and secure the ballast. A new weight and balance

and CG location must be worked for each new

increase in weight. Stop testing when the aircraft’s

maximum gross weight is reached.

e. The testing up to this point has been done

at, or near, the forward CG limit. During these tests,

the CG should be slowly, but progressively, moved

aft between each test flight. Limit the change to the

CG range to about 20 percent of the range. Again

the pilot should weigh the ballast and work a new

weight and balance for each flight. With each CG

change the aircraft longitudinal static stability and

stall characteristics should be carefully evaluated by

using the same technique discussed earlier. Stop testing when the designer’s or kit manufacturer’s aft CG

limit is reached.

f. If the aircraft develops either a neutral or

negative longitudinal stability problem, or the aircraft displays unsatisfactory stall characteristics at

any CG location being tested, STOP FURTHER

TESTING!!

g. These tests should confirm the designer’s

aft CG limit or establish the last satisfactory aft CG

location. If the aft CG range is not satisfactory, consult with the kit manufacturer, aircraft designer, or

a flight test engineering consultant.

h. The pilot should avoid the temptation to

take a live ballast weight up for a ride for three reasons:

(1) The aircraft has not been proven safe

for the higher gross weights.

(2) The pilot and passenger are at great

risk. It is a sure sign the pilot has become complacent

and sloppy in his flight test program.

(3) The pilot will be breaking a contract

(Operating Limitations) with the U.S. Government,

which is known not to look kindly on such matters.

i. Pilots should ensure that the added ballast

weight in the cockpit is secured. A seat belt over

some sand bags will not stop the weight from shifting

and getting loose in a cockpit. The last thing a test

pilot needs is a 20-pound lead-shot bag free in the

cockpit during a climb test, a landing, or a spin. Tie

each weight down individually, and cover all the

weights with a cargo net.

j. Ensure the ropes/nets and airframe attach

points are strong enough to take the added load.

Make sure the passenger seat can take that much

localized weight safely.

k. The maximum gross weight test results

should be recorded in the flight manual. If there are

any changes to the stall speed initially marked on

the airspeed indicator, it should be changed to reflect

the aircraft stall speed at maximum gross weight.
58

AC 90-89A 5/24/95

SECTION 2. SERVICE CEILING TESTS

‘‘Man is made for error; it enters his mind naturally and he discovers a few truths only with the greatest

effort.’’ Frederick the Great

1. OBJECTIVE. To determine the highest altitude at which an aircraft can continue to climb at

100 feet per minute (Service Ceiling).

a. Pilots who wish to determine the actual

service ceiling of their aircraft are offered the following suggestions:

(1) Ask the local Flight Standards District

Office (FSDO) to amend the Operating Limitations

to permit a climb to the aircraft’s service ceiling,

if that altitude is above 18,000 feet.

(2) Contact the local Flight Service Station

(FSS) or ATC facility, and reserve a time and airspace to make the test.

(3) Install a transponder (reference FAR

§ 91.215) or get a waiver.

(4) Install a portable oxygen bottle, if plans

are to go above 12,000 feet. (Recommend the pilot

becomes familiar with the symptoms and cures of

hypoxia and hyperventilation.)

(5) Review the engine manufacturer’s mixture leaning procedures.

(6) Maintain communications with an air

traffic facility at all times.

b. The climb to the aircraft service ceiling

should be made in a series of step climbs during

which engine performance, temperatures and pressures are recorded. At the slightest indication of

engine performance or aircraft control problems, the

pilot should terminate the test and return to the airport.
59

5/24/95 AC 90-89A

SECTION 3. NAVIGATION, FUEL CONSUMPTION, AND NIGHT FLYING

‘‘That’s one small step for man, one giant leap for mankind.’’ Neil Armstrong

1. OBJECTIVES. To ensure all the small but

important aspects of flight have been tested and

found reliable.

a. The Magnetic Compass. The magnetic

compass should have been checked for accuracy

prior to the first flight. However, the addition and

removal of equipment, changing of wire bundle routing, and other airframe modifications may have

affected the accuracy of the instrument. The following recommendations are offered:

(1) The magnetic compass can be checked

for accuracy by using a compass rose located on

an airport, or using a hand held ‘‘master compass.’’

The master compass is a reverse reading compass

with a gun-sight mounted on the top of it. With the

aircraft facing north and the pilot running the engine

at 1,000 rpm, a second individual standing 30 feet

away facing due south ‘‘shoots,’’ or aligns, the master compass with the aircraft’s centerline. Using hand

signals, the pilot aligns the aircraft with the master

compass. The pilot then runs the aircraft engine up

to approximately 1,700 rpm to duplicate the aircraft’s

magnetic field and reads the compass.

NOTE: Conventional gear aircraft builders

will have to position the magnetic compass

in a straight and level position for this test.

Raise the tail or mount the compass level

with the horizon.

(2) If the aircraft compass is not in alignment with the master compass (start at north), correct

the error by adjusting the north/south brass adjustment screw with a non-metallic screwdriver (can be

made out of stainless steel welding rod, brass stock,

or plastic) until the compass reads correctly. Go to

the reciprocal heading (south) and remove half the

error. On the east/west headings, use the other brass

adjustment screw to make the corrections using the

same procedures that was used to correct the north/

south errors.

(3) Check again for errors at each cardinal

heading. Record the last readings and prepare a compass correction card. The maximum deviation (positive or negative) is 10 degrees on any one heading.
60

AC 90-89A 5/24/95

(4) If the compass cannot be adjusted to

meet this requirement, install another one. If the new

compass is not available, try a different location in

the cockpit, away from all ferrous metals and electrical bundles.

NOTE: A common error that affects the

compass’s accuracy is the mounting of magnetic compass on/in the instrument panel

with steel machine screws and nuts rather

than brass.

(5) If the aircraft has an electrical system

it is recommended that two complete compass checks

be made, one with all electrical accessories on (e.g.,

radios/nav lights), and one with all electrical accessories off. If the deviation in level flight is more

than 10 degrees on any heading with the accessories

on, make up a separate compass correction card that

shows the magnetic heading with the equipment on.

(6) Record the findings in the aircraft’s

flight manual and create a compass correction card,

mounting it near the magnetic compass in the cockpit. Make two cards; one with radios on and one

with radios and non essential electrical accessories

off.

b. Very High Frequency (VHF) Omni-directional Radio Range (VOR) Check. The best guide

to check the accuracy of the VOR on board equipment is the VOR Receiver Check found in the Airman’s Information Manual (AIM), available from the

Superintendent of Documents. The following is an

abbreviated summary of the VOR procedure in the

AIM.

(1) For a ground test of the VOR, a VOR

Test Facility (VOT) must be used. To use the VOT

service, tune in the VOT frequency on the VOR

receiver. It is normally 108 Mhz. With the Course

Deviation Indicator (CDI) centered, the omni-bearing selector should read 0 degrees with the to/from

indicator showing ‘‘from,’’ or the omni-bearing

selector should read 180 degrees with the to/from

indicator showing ‘‘to.’’ The maximum bearing error

should never be more than four degrees.

NOTE: The VOT facilities closest to the

flight test location can be found in the Airport/Facility Directory. It is available by

subscription from NOAA Distribution

Branch N/CG33, National Ocean Service,

Riverdale, MD 20737, or contact the nearest

FAA FSS.

(2) For the airborne test, select a prominent

ground point along the selected radial, preferably

more than 20 miles from the VOR. Maneuver the

aircraft directly over the point at a reasonably low

altitude.

(i) Note the VOR bearing indicated

by the receiver when over the ground point. The

maximum permissible variation between the published radial and the indicated bearing is six degrees.

(ii) If the aircraft has dual VOR’s, the

maximum permissible variation between the two

receivers is 4 degrees.

c. Fuel Consumption: a good indication of

how much the engine is working for each rpm produced. For a new or recently overhauled engine, the

fuel consumption should improve each flight hour

until the engine finishes its ‘‘break in’’ period, i.e.,

after approximately 100 hours of operation.

(1) To determine the aircraft fuel consumption, lay out a race track course with 8 to 10 mile

legs. If the aircraft has one fuel tank or cannot switch

tanks, do the following: Determine the approximate

fuel burn to reach 1,000, 3,000, 5,000, 7,000, and

9,000 feet of altitude. With full tanks, climb to 3,000

feet and run the race track course for half an hour

at 55 percent power.

(2) Land and measure the fuel used by dipping the tanks with a calibrated fuel stick, or by adding measured amounts of fuel to the tank until the

tank is full. Subtract the approximate fuel burn to

altitude, and multiply the remainder by two to get

the fuel burn per hour.

(3) The tests are much easier and the

results more accurate if the aircraft has two

independent fuel tanks. Take-off on one tank and

switch to the opposite tank at the test altitude. At

the completion of the test, switch back to the first

tank; land and measure the amount of fuel added

in both tanks and multiply the quantity by two to

get the amount of fuel used per hour.

(4) Run the same test at 65 percent and

75 percent power at the same altitude, using the same

procedures. Move up to the next altitude and run

the same tests.
61

5/24/95 AC 90-89A

d. Night Operations: should be conducted in

accordance with the aircraft’s FAA Operating

Limitations and limited to normal climbs and

descents (e.g., 500 feet per minute), pitch angles of

less than 5 degrees, straight and level flight, and

coordinated turns of no more than 20 degrees of bank

angle.

(1) The main concern for night testing

should be the availability of a horizonal reference

(e.g., bright moon or artificial horizon).

(2) Prior to every night flight, ensure a reliable flashlight with fresh batteries and a set of

FLIGHT TEST PLAN procedures are on board.

Some night testing requirements should have already

been determined on the ground. For example:

(i) The electrical load review of all

the lights, pumps, instrumentation, and avionics did

not exceed 80 percent of the aircraft’s charging system capacity.

(ii) The cockpit instrumentation lighting is adequate and was tested for reliability of operation during daytime flights.

(iii) The pilot has at least 1⁄2 hour of

night time taxiing the aircraft. This practice is needed

to familiarize the pilot with a different operating

environment. Do not exceed engine operating

temperatures during taxiing.

(iv) The position and brightness of

instrument panel lights, anti-collision strobe lights,

and rotating beacons will not adversely affect the

pilot’s night vision.

(3) A suggested night flight test plan is a

series of takeoffs and landings and traffic pattern

entries and exits. The tests should begin while there

is still enough light to read a newspaper and transition to true night flying. The actual night flight will

consist of an evaluation of the effectiveness of the

taxi/landing light system, during taxi, take-off, and

landing. The pilot should note any glare on the windshield or light flicker on the instrument panel.
62

AC 90-89A 5/24/95

THIS PAGE INTENTIONALLY LEFT BLANK
63

5/24/95 AC 90-89A

CHAPTER 7. THOUGHTS ON TESTING CANARD TYPE AMATEURBUILT AIRCRAFT

‘‘FLY.’’ Jonathan Livingston Seagull

SECTION 1. CANARDS

1. OBJECTIVE. To discuss canard flight

characteristics.

a. Canard configured aircraft generally fall

into 2 categories: the LongEze design (pusher prop,

tandem seats) and the Quickie (Q2) design (tractor

prop, side by side seats). Canard configured aircraft

do not ‘‘stall’’ in the conventional sense. All successful ‘‘loaded canard’’ designs have the angle of

incidence (AOI) of the canard set higher than the

main (rear) wing.

b. As the airplane’s angle of attack (AOA)

increases, the canard should stall first, lowering the

AOA of the main (rear) wing. Since the rear wing

doesn’t stall, a characteristic ‘‘buck’’ or ‘‘nod’’ takes

place. Full aft stick results in the canard alternately

stalling and flying while the rear wing never reaches

it’s critical AOA and continues to fly. This self-limiting stall characteristic makes a properly designed and

built canard aircraft un-spinable. It should be noted,

however, that the accident rate for canard designs

are approximately the same as conventional designed

amateur-built aircraft because of the following:

(1) During take-off, the transition from

ground roll to flight can be a more critical procedure

in some canards as compared to more conventional

designs.

(2) Some canards with combinations of CG

and pitch control sensitivity will be more likely to

over rotate at lift-off.

(3) Some canards have less visible airframe structure in front of the pilot and in his peripheral vision. Others have more than enough. These

differences in design can produce a different reference frame for pilots with many hours of conventional aircraft time and may cause initial errors in

pitch attitude, such as the nose too high on takeoff and landings.

(4) In addition, canard aircraft by design

have very different take-off characteristics than

conventional configured aircraft. Canard aircraft

with pusher propellers need a substantially higher

rotation speed on take-off.

(5) To rotate a conventional design aircraft, all that is required is enough airspeed to provide sufficient control to attain a positive angle of

attack due to the long moment arm from the main

gear (the axis of rotation) to the tail, a relatively

small amount of lift is required. This lift, generated

at a relatively low airspeed, makes it possible to

rotate the aircraft into the take-off position slightly

below flying speed. Allow the aircraft to accelerate

to flying speed and lift off.

(6) In contrast, the canard nose wheel will

stay firmly on the ground until an airspeed is reached

at which the canard, with full up elevator, can generate enough lift to equal the following:

(i) the load carried by the nose

wheel, plus

(ii) the nose down moment caused by

the friction of the nose and main gear tires with the

surface, and the down-thrust vector provided by the

propeller during the take-off roll.

(7) Since the main wing may reach flying

speed before the canard, the nose wheel will stay

firmly on the runway until take-off speed is reached.

Rotation will then occur, and the aircraft will literally

jump off the ground.

(8) Canards with a thrust line above the

CG will have appreciable pitch trim change with

power. Forward stick motion is required when power

is reduced. While this may not be of any consequence

to an experienced pilot, it can be a serious surprise

to an unwary and inexperienced pilot. This unfamiliar flight characteristic might cause pilot-induced

pitch oscillations with disturbing consequences under

some conditions (e.g., an aborted take-off).

(9) Due to its unique design, the canard

aircraft needs a higher nose up attitude when landing

compared to conventional configured aircraft. Many

canard pilots are reluctant to raise the nose high on
64

AC 90-89A 5/24/95

landing due to the limited forward visibility while

the nose is up. Consequently, many canard pilots

tend to make their approach angle shallow. This shallow angle results in approach speeds quite a few

knots faster than what is necessary. For pilots who

prefer visibility to shorter runways, it is recommended that canard designed aircraft be tested

on runways a minimum of 1,000 feet longer than

what would be used for a conventional aircraft of

the same horsepower and performance capability.

Longer runways should be used until the pilot

becomes more experienced with the landing

characteristics of the aircraft.

(10) If the nose is held at a too high an angle

on landing, the canard will stall while the main wing

is still generating lift. The stalled canard will drop

the nose rapidly onto the runway with enough force

to damage the nose gear.

(11) Quickie (tractor engine designs)

configured canard designs have a limited ability to

rotate nose up while on the ground. This tends to

increase takeoff speeds because the canard and the

main wing angle of attack are limited while the aircraft is on the ground. That is why this design

appears to ‘‘levitate’’ off the ground without much

apparent pitch change.

(12) Some canard designs are very sensitive

to rain or other types of contamination on the leading

edge and/or top of the airfoil. Contamination in the

form of water droplets, frost, crushed insects, or even

poorly applied paint will disturb the laminar flow

over the canard and lift is lost. When decreasing lift

over drag (L/D) performance, the chances for an

accident increase.

2. FLIGHT TEST CONSIDERATIONS.

Technically, a canard type aircraft cannot stall, or

at least it will not stall in the normal fashion. A

pilot testing the aircraft for stability characteristics

should approach such testing with caution in mind.

a. Under certain conditions, usually consisting of aft c.g. problems, the main wing may stall

before the canard surface. In this case, extreme pitchup can occur until the canard surface or strakes stall.

The aircraft would then pitch down to a near-level

attitude, however the airspeed would be approaching

zero and the angle of attack could approach or exceed

45 degrees. This condition (high-alpha), could be so

stabilized, with the aircraft in a deep stall, that recovery might not be possible.

b. Testing for pitch stability in a new design

or a just-completed aircraft built from a kit or from

plans is a requirement the pilot needs to consider

prior to carrying passengers. Pitch stability tests are

conducted to ensure that the aircraft does not exhibit

any dangerous flight characteristics but must be

approached and conducted in a logical and sensible

manner.

(i) Positive pitch stability is exhibited when the aircraft trimmed for hands off level

flight, returns to that state when a control force is

applied and released.

(ii) Neutral pitch stability is achieved

when the aircraft remains in the pitch attitude

attained when a control force is applied.

(iii) Negative pitch stability is demonstrated when the aircraft departs from the pitch

attitude attained when a control force is applied and

continues to increase in amplitude.

c. The aircraft should be weighed and the c.g.

carefully calculated. At the same time, determine the

weight needed and the moment calculated to load

the aircraft at the most forward and aft c.g. limits

recommended by the designer. Beginning at the most

forward c.g., trim the aircraft to a hands off condition

and slowly reduce the power, maintaining altitude

by increasing pitch attitude. When the stick reaches

the full aft position, momentarily release the back

pressure followed by full aft stick. The aircraft, in

demonstrating positive stability, should return to its

original pitch attitude and remain there. The aircraft

should display positive stability characteristics.

d. Other tests may be conducted by adjusting

the c.g. further aft and observing the tendency of

the aircraft. At some point near the aft c.g. limit,

you may experience neutral stability, or the point

where the aircraft no longer recovers by itself from

the upset. Moving further aft in the c.g. range from

this point will cause the aircraft to diverge from the

trim path in the direction of the upset (neutral stability).

e. Some designers and builders have installed

adjustable, moveable ballast containers in the aircraft

to allow the c.g. to be adjusted forward or aft during

flight. If testing is to be accomplished outside the
65

5/24/95 AC 90-89A

recommended range, it is advisable to consider the

installation of a ballistic recovery system or spin

chute system. In addition, the pilot should make a

decision about leaving the aircraft if the test becomes

untenable.
66

AC 90-89A 5/24/95

THIS PAGE INTENTIONALLY LEFT BLANK
67

5/24/95 AC 90-89A

CHAPTER 8. ULTRALIGHT AIRFRAME INSPECTION

‘‘You can learn 10 things by learning one.’’ Japanese proverb

SECTION 1. DIFFERENCES

1. OBJECTIVES. To serve as additional

resource for ultralight test pilots and to help the new

owner develop a flight test plan for the ultralight.

2. DEFINITION. The term ‘‘Ultralight’’ means

a fixed wing vehicle that is powered by a conventional 2 or 4 cycle, gasoline powered engine and

is operated under Part 103. It has one seat and does

not exceed 254 pounds, excluding floats and safety

devices. In addition, the ultralight can be unpowered,

in which case the weight is restricted to 155 pounds.

The powered ultralight’s fuel capacity cannot exceed

5 U.S. gallons. The vehicle should not be able to

exceed 55 knots calibrated airspeed at full power

and level flight and cannot exceed a power-off stall

speed of 24 knots calibrated airspeed. The term also

includes two place ultralight training aircraft of 496

pounds or less operated under either the EAA or

USUA exemption to FAR Part 103.

a. Be aware that both single and dual seat

ultralights in this performance class are not restricted

only to FAR Part 103 operation. If they qualify, they

can be operated under FAR Part 91, if they meet

§ 21.191(g) amateur-built category or § 21.191(h)

operating kit built aircraft in primary category. Only

single seat ultralights of less than 254 pounds empty

weight, however, can operate legally under FAR Part

103.

b. Many in the general aviation community

view amateur-built and ultralights as one and the

same design category, therefore all flight testing

procedures should be identical. While in many cases

this assumption is true, there are several major differences between the two designs.

(1) Most ultralights are assembled from

complete kits, unlike amateur-built aircraft of which

the major portion (51 percent) of the aircraft and

its component parts are manufactured by the builder.

Most of the kit/ultralight manufacturer’s pilot operating handbooks/flight manuals are usually accurate

and address the majority of the information covered
68

AC 90-89A 5/24/95

in the first eight chapters of this AC. The FAA recommends the pilot’s operating handbook always be

consulted by the new owner prior to flight.

(2) The changes in ultralight ownership are

more frequent than amateur-built and general aviation aircraft ownership. Although the ultralight is

‘‘used,’’ the new owner is usually unfamiliar with

the its operating characteristics. A comprehensive

flight testing/training program should be a high priority safety consideration of the new owner.

(3) New flying skills should be developed.

Each ultralight pilot/owner should address the effects

smaller size, lighter wing-loading, lower weight, and

higher drag designs have on low-speed flight.

c. Due to these differences, the FAA recommends that each ‘‘new’’ ultralight owner design

a FLIGHT TEST PLAN regardless if the ultralight

was bought, used, and/or the ultralight has a Flight

Manual supplied by the manufacturer. The ultralight

FLIGHT TEST PLAN does not have to be as extensive as the one recommended for amateur-built aircraft but should address all flight conditions and

emergencies called out in the ultralight’s flight manual.

d. With these differences in mind, the next

three chapters will address problems associated with

both NEW and USED ultralight flight testing. Chapter 8 will address pre-test flight inspection, chapter

9 will cover engine and fuel system operation and

inspection, and chapter 10 will cover ultralight flight

testing.

e. In keeping with that professional approach

towards flight testing, it is suggested that a FLIGHT

TEST PLAN and other relevant safety recommendations found in the chapters 1 through 7 be adopted

by the ultralight owner/operator prior to test flying

a new or used ultralight.

SECTION 2. THE TEST PILOT

‘‘There is always a harder way to flight test an aircraft, but that path does not need to be followed. ’’

George Kaseote, FAA Test Pilot

1. GENERAL. Whether the ultralight is brand

new or used, it needs to be properly evaluated. A

new owner should enlist the services of an experienced ultralight flight instructor who is authorized

to give dual instruction under the EAA or the USUA

exemption.

a. The instructor should test fly the ultralight

only after it has been properly assembled, inspected,

engine run-in, and taxi tests have been performed.

It is not recommended that a ‘‘new’’ pilot and a

new/used ultralight ‘‘learn’’ to fly together.

b. The test pilot should be experienced and

competent. He/she should have made a minimum of

100 solo flights in similar make, model, and type

of ultralight and must follow the FLIGHT TEST

PLAN exactly. The FLIGHT TEST PLAN should

examine the ultralight and its performance capability,

beginning with the pre-flight inspection and ending

only after the test pilot has explored the ultralight’s

published flight envelope as described in the flight

manual.

SECTION 3. PRE-FLIGHT AIRFRAME INSPECTION

1. GENERAL.

a. Ultralight owners should remember that the

light-weight, thin wall tubing design of an ultralight

fuselage/wing structure is particularly susceptible to

metal fatigue. When aluminum tubing has been

stressed beyond its elastic limit, it takes on a chalky

white appearance (corrosion) at the point of highest

stress. Warpage and deformation are other signs of

high stress points and once discovered, the ultralight

should be grounded until the damaged is repaired.

b. The tolerance limit of a tube or fitting can

be significantly lowered by over-torquing a bolt. If

a bent or damaged support tube or structure is not

repaired, the bend or dent will become a crack, and

ultimately the crack will become a structural failure.
69

5/24/95 AC 90-89A

NOTE: If a used ultralight has been purchased, it is highly recommended that the

owner perform a detailed acceptance inspection on the aircraft assisted by an experienced individual who is familiar with the

make and model aircraft. It is also recommended that all existing hardware (e.g.,

nuts, bolts, springs) be replaced with new

aviation quality hardware.

c. If possible, remove the fabric envelope and

check the airframe structure underneath for dents,

cracks, and corrosion. Check the top and bottom of

the spars for compression (wrinkled metal) damage.

Double check all wings, landing gear, strut, engine,

and tail surface attach points for wear, elongated

holes, or damage.

d. If any previous repairs are found, check

with the manufacturer to see if damage in that area

can be repaired and if the repair that was made is

airworthy.

2. CHECKLIST. Each ultralight FLIGHT TEST

PLAN should include a pre-flight inspection

CHECKLIST. The CHECKLIST should include a

step-by-step approach to inspection that covers all

the manufacturer inspection items as well as the following suggested items starting at the landing gear.

a. Landing Gear. The landing gear is the last

part of the light-weight aircraft to leave the earth

and the first part to arrive. Since the majority of

these aircraft fly from unimproved strips, the stress

on the gear is high. The checklist should include

inspection items recommended by the manufacturer

and inspection for the following:

(1) The condition of the landing gear attach

points and alignment of the landing gear and wheels

to the longitudinal axis of the fuselage. If the attach

points are mis-aligned, the landing gear will not track

in a straight line and this will affect take-offs and

landings.

(2) Elongated bolt-holes, loose AN hardware, bent tubing, condition and attachment of

wheels, wheel bearings, tire inflation, tire condition

and brakes.

(3) Brake condition and operation, including chafing of brake lines/cables against the gear

struts.

(4) Condition and operation of the steerable nose gear, if applicable.

(5) Condition and attachment of the tail

wheel/skid, if applicable.

b. Wing Assembly. The vast majority of

ultralight aircraft use a man-made sailcloth material

stretched over a tubular frame. This type of fabric

is susceptible to ultra-violet radiation from the sun.

If left unprotected, it can become unairworthy in less

than 6 months. The checklist should include the following inspection items:

(1) Ensure the sailcloth has not suffered

any tears, or abrasion, due to wear or foreign object

damage.

(2) Check the sailcloth for obvious ultraviolet (UV) degrading of fabric strength by examining the condition of the fabric on top of the wing.

Compare it to the fabric on the bottom of the wing.

If the top wing fabric shows a significant difference

in color (faded), the fabric should be tested for

strength with a fabric tester (Maule or Quicksilver)

to see if it tests within the manufacturer’s serviceable

limits. If no minimum service limits are listed, the

fabric should test out at 46 pounds, or 70 percent

or more, of its original tensile strength, whichever

is greater, to be considered airworthy. If the fabric

fails the tests, it must be replaced before further

flight.

(3) Flying and landing support cables

should be checked for tension, routing, attach points,

and condition. Scrutinize the swaged cable ends. It

is recommended that a red reference mark (nail polish works fine) be painted on each of the cables abutting the swaged end. If the cable is growing, i.e.,

a gap forming between the swaged end and the

painted referenced mark, there is an impending failure of the swaged terminal. Do not fly the aircraft

until the cable is replaced.

(4) Flight control cables should be checked

for frayed wires and proper routing. Run a rag over

all of the flying and landing wires and control cables

(wings and tail). If the cloth snags, this may indicate

a frayed wire which demands further inspection. If

possible, bend the cable to form a ‘‘U’’ and inspect

for internal broken wires. Also, check the cable pulleys for wear and operation. Extreme wear patterns
70

AC 90-89A 5/24/95

on pulleys indicate misrouting and must be corrected

prior to flight.

(5) Check wing leading/trailing edge, wing

struts, aileron, flaps, spoiler hinges and attach points

for loose rivets, cracks, elongation and wear. Ensure

that all hardware (nuts and bolts) are of aviation

quality.

(6) Ensure that the bungee, or return

springs for wing spoilers (if applicable), are serviceable and will keep the spoiler down flat against the

top of the wing when not being deployed.

(7) Check the aircraft’s flight controls rigging every time the aircraft is re-assembled. It is

recommended that the cables/rigging for easier

assembly be color coded (e.g., red to red, blue to

blue).

(8) Check for corrosion on all metal surfaces. Corrosion on aluminum usually appears as a

white powder, rough to the touch. On steel parts,

corrosion takes the common form of rust. Dissimilar

metal corrosion occurs when two different types of

metal make surface contact. To obtain additional

information on corrosion and treating it, refer to FAA

AC 43.9, ‘‘Corrosion Control for Aircraft.’’

(9) Make sure the leading edge of the wing

and tail surfaces are clean and free of insects, grass,

or mud prior to flight.

c. Fuselage Assembly. The fuselage is the

backbone of the light-weight aircraft. All the flight

and ground operating stresses encountered by the

wings, tail, landing gear, and engine are transferred

to the fuselage at the attach points. Exercise extra

care when examining these high stress areas because

failure of any of these attach points and associated

hardware will cause catastrophic structural failure.

(1) Flight controls should be checked for

proper operation, travel, and condition of the stops.

There should not be any sharp bends in the flight

control cables.

(2) Check engine controls for proper operation; they should be free of bends and properly

secured. Ensure that all control cables are securely

clamped to the fuselage to prevent the cable from

slipping, hence not transferring the desired movement to the engine control.

(3) Check the instrument panel for security

and instruments for attachment, proper operation,

and range/limit markings.

(4) Inspect for bent or damaged structural

tubing. If a tube is bent, it must be properly repaired

or replaced. Straightening out a bend will only workharden the tube in the damaged area and hasten the

time of failure.

(5) Fiberglass structures should be checked

for cracks, delaminations, and holes -- especially on

the bottom of the fuselage.

(6) Examine the seat, seat brackets, and

seat belt/shoulder harness, attach points, clips/rings,

brackets or tangs and other hardware, for security,

safety (cotter pins or safety wire), and condition.

(7) Check the shoulder/seat belt harness for

condition and proper operation.

(8) Check the ballistic chute hardware and

mounting assembly (review information in chapter

1, section 3).

d. Tail Surfaces. The tail, or empennage

group, contains two of the ultralight’s three primary

control surfaces: the rudder (yaw control) and the

elevator (pitch control). In two-axis ultralights, the

elevators are the only flight controls on the tail. Special attention must be given to the attach points, hardware, and proper operation for both control systems.

(1) Ensure that the primary controls and

trim systems if applicable, have the proper travel,

that control cables are properly tensioned, and that

all turnbuckles are safetied.

(2) Examine the control hinges and attach

points on the elevator and rudder horn for wear,

cracking, and elongation of bolt holes, and security

of the rudder and elevator stops.

(3) Check the leading and trailing edges of

the flight controls for damage.

(4) Check for wear/UV deterioration to the

fabric cover.
71

5/24/95 AC 90-89A

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.
72

AC 90-89A 5/24/95

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.
73

5/24/95 AC 90-89A

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.
74

AC 90-89A 5/24/95

THIS PAGE INTENTIONALLY LEFT BLANK
75

5/24/95 AC 90-89A

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 B747 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

AC 90-89A 5/24/95

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

5/24/95 AC 90-89A

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.
78

AC 90-89A 5/24/95

THIS PAGE INTENTIONALLY LEFT BLANK
1

5/24/95

AC 90-89A

Appendix 1

APPENDIX 1. SAMPLE CHECKLIST FOR A CONDITION

INSPECTION

AIRCRAFT IDENTIFICATION:

TYPE/SN. lllllllllll ENGINE MODEL/SN. lllllllllll

N NUMBER llllllllllll PROPELLER MODEL/SN. llllllllll

A/F TOTAL TIME llllllllll ENGINE TOTAL TIME llllllllll

OWNER llllllllllllll PROPELLER TOTAL TIME lllllllll

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:

CHECK ALL ATTACHMENT POINTS AND CONTROL FOR SAFETY CONDITION
5

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

ENGINE:

PERFORM COMPRESSION TEST #1 lll #2 lll

#3 lll #4 lll #5 lll #6 lll

CHANGE OIL AND FILTER (CHECK FOR METAL)

INSPECT IGNITION HARNESS FOR CONDITION AND CONTINUITY

CHECK IGNITION LEAD CIGARETTES FOR CONDITION/CRACKS

CLEAN AND GAP SPARK PLUGS

CHECK MAGNETO TIMING/POINTS/OIL SEAL/DISTRIBUTOR

INSPECT ENGINE MOUNT/BUSHINGS

INSPECT ENGINE MOUNT ATTACHMENT BOLT TORQUE

INSPECT ALTERNATOR/GENERATOR ATTACHMENT

CHECK ALTERNATOR/GENERATOR BELT CONDITION

INSPECT CYLINDERS FOR CRACKS/BROKEN FINS/ EXHAUST STAINS

INSPECT ENGINE BAFFLES FOR CRACKS/CONDITION

CHECK FOR OIL LEAKS INSPECT VACUUM PUMP AND LINES

INSPECT OIL VENT LINES

INSPECT ALL CABIN HEAT/CARB HEAT/DEFROSTER DUCTS FOR CONDITION

INSPECT CARBURETOR FOR SECURITY & CLEAN INLET SCREEN

INSPECT INTAKE HOSES/SEALS FOR SECURITY/LEAKS

INSPECT THROTTLE/MIXTURE/CARB HEAT/CONTROL FOR

PROPER TRAVEL AND SECURITY

INSPECT CARB HEAT AIR BOX FOR CRACKS/OPERATION

INSPECT CONDITION OF FLEXIBLE FUEL AND OIL LINES

INSPECT OIL COOLER FOR LEAKS AND CONDITION

CHECK EXHAUST SYSTEM FOR ATTACHMENT AND CONDITION

CHECK MUFFLER/INTERNAL BAFFLE/ FOR SECURITY

CHECK EXHAUST PIPES/FLANGES FOR SECURITY & ATTACHMENT

REPACK EXHAUST GASKETS AS REQUIRED

CHECK COWLING FOR CRACKS AND SECURITY
6

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

FOR U/L:

CHECK CARB BOOTS ON 2 CYCLE ENGINES FOR CRACKS

CHECK SAFETIES ON EXHAUST SPRINGS

PERFORM 2 CYCLE COMPRESSION TEST TO CHECK SEALS

ENSURE SPARK PLUG CAPS ARE SAFETIED ON INVERTED ENGINES

PROPELLER:

CHECK SPINNER AND BACK PLATE FOR CRACKS

INSPECT FOR CRACKS/STONE DAMAGE/NICKS

CHECK FOR DELAMINATION (WOOD/COMPOSITE BLADES)

CHECK PROP BOLTS TORQUE/SAFETY WIRE

CHECK FOR OIL LEAKS (CRANKCASE NOSE SEAL)

GREASE LEAKS (CONSTANT SPEED PROP)

CHECK PROPELLER GOVERNOR FOR LEAKS AND OPERATION

CHECK PROP TRACK

CHECK PROP BALANCE (WOOD PROP)

ELECTRICAL

SPARE FUSES AVAILABLE

BATTERY SERVICED AND FREE FROM CORROSION

BATTERY BOX FREE FROM CORROSION

ELT BATTERY FREE FROM CORROSION AND CURRENT BATTERY

CHECK LANDING LIGHT OPERATION

CHECK POSITION LIGHTS OPERATION

CHECK ANTI COLLISION LIGHT FOR OPERATION

INSPECT ALL ANTENNA MOUNTS AND WIRING FOR SECURITY

CHECK ALL GROUNDING WIRES (ENGINE TO AIRFRAME, WING TO AILERON/

FLAP, ETC.)

INSPECT RADIOS/LEADS/WIRES FOR ATTACHMENT & SECURITY

INSPECT CIRCUIT BREAKERS/FUSES PANELS FOR CONDITION
7

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

OPERATIONAL INSPECTION:

VISUAL INSPECTION OF THE ENGINE/PROPELLER

ALL INSPECTION PANELS AND FAIRINGS SECURE

PERSONNEL WITH FIRE BOTTLE STANDING BY

BRAKE SYSTEM CHECK

PROPER FUEL IN TANKS

ENGINE START PROCEDURES

OIL PRESSURE/OIL TEMPERATURE WITHIN LIMITS

VACUUM GAUGE CHECK

MAGNETO CHECK/HOT MAG CHECK

IDLE RPM/MIXTURE CHECK

STATIC RPM CHECK

ELECTRICAL SYSTEM CHECK

COOL DOWN PERIOD/ENGINE SHUT DOWN

PERFORM OIL, HYDRAULIC, AND FUEL LEAK CHECK

PAPERWORK:

AIRWORTHINESS DIRECTIVES

RECORD FINDINGS AND SIGN OFF INSPECTION AND

MAINTENANCE IN AIRCRAFT LOG BOOKS
8

5/24/95

AC 90-89A

Appendix 1

THIS PAGE INTENTIONALLY LEFT BLANK
1

5/24/95

AC 90-89A

Appendix 2

APPENDIX 2. ADDRESSES FOR ACCIDENT/INCIDENT

INFORMATION

Accident/incident reports for all U.S.-registered make and model aircraft are available from the following

sources:

Federal Aviation Administration (FAA)

Information Management Section, AFS-624

P.O. Box 25082

Oklahoma City, OK 73125

FAX: (405) 954-4655

Experimental Aircraft Association (EAA)

P.O. Box 3086

Attention: Information Services

Wittman Airfield

Oshkosh, WI 54903-3086

TEL: (414) 426-4821

National Transportation Safety Board (NTSB)

Public Inquiry Section

RE-51

490 L’Enfant Plaza, SW.

Washington, DC 20594

TEL: (202) 382-6735

Upon writtern request, the FAA will supply summary formatted computer print-outs on all accidents and

incidents concerning all makes and models of general aviation and amateur-built aircraft. Reports for an

individual aircraft accident/incident, or a summary accident/incident report on all aircraft accidents and

incidents for a particular make and model, are also available. Requests must be in writing via mail or FAX.

The FAA, EAA, and the NTSB require the date, location of the accident, and if possible, the ‘‘N’’ number

for a single aircraft accident. Identify the make and model aircraft (e.g., Poteen Rocket, model OB-1) only

if ALL the accidents/incidents for a particular aircraft design are being requested.

A single, computerized report runs approximately 2 pages in length. If the accident is over 18 months old,

the report will list probable causes.

A processing fee may be charged for each request based on the number and length of the reports

requested.

For Ultralight Accident/Incident information, call or write to the following address:

FAA Safety Data Exchange

ACE-103

Attention: Ben Morrow

1201 Walnut Street, Suite 900

Kansas City, MO 64106

TEL: (816) 426-3580

Service reports and service information also are available by computer by dialing the FAA Safety Data

Exchange telephone, (800) 426-3814. The system operates at 1200 thru 9600 Baud rates, and the other parameters are: 8 N 1. It is suggested ANSI or VT100 emulations be used.
2

5/24/95

AC 90-89A

Appendix 2

THIS PAGE INTENTIONALLY LEFT BLANK
1

5/24/95

AC 90-89A

Appendix 3

APPENDIX 3. ADDITIONAL REFERENCES ON FLIGHT

TESTING

The following references comprise selected additional information sources on flight testing and first flight

experiences for amateur-built and ultralight aircraft. This list of informational material may help amateurbuilders in preparing the FLIGHT TEST PLAN for their aircraft.

INDUSTRY PUBLICATIONS: Amateur-Built

Askue, Vaughan, Flight Testing Homebuilt Aircraft, (Ames, IA: State University Press, 1992)

Ariosto, James, ‘‘A Two Minute Test-Hop Reveals All Wrongs,’’ Sport Aviation, (May 1970), pp. 29-30.

Bingelis, Antoni, ‘‘A Report on the 1973 Oshkosh Safety and Courtesy Inspections,’’ Sport Aviation, (November 1973), pp. 35-37.

llll ‘‘After the First Test Flight,’’ Sport Aviation, (April 1988), pp. 27-30.

llll ‘‘Flight Testing Homebuilts-Stage One: Making Preparations for Flight Testing,’’Sport Aviation,

(January 1989), pp. 27-30.

llll ‘‘Flight Testing Homebuilts-Stage Two: Making the Initial Flight Test,’’ Sport Aviation, (February

1989), pp. 27-30.

llll ‘‘Flight Testing Homebuilts-Stage Three: Expanding the Flight Envelope,’’ Sport Aviation, (March

1989), pp. 28-31, 66.

Colby, Doug (1986), ‘‘Into the air, Junior Birdman!’’ Homebuilt Aircraft, V. 13, No ?, pp. 44-47.

Dewey, A. J., and Downie, Don, ‘‘Flight Testing the Deweybird,’’ Air Progress Homebuilt Aircraft, (SpringSummer 1967), pp. 4-9.

Donofrio, P. R., ‘‘Checkmate,’’ Sport Aviation, (June 1978), pp. 30-31.

Dwiggins, Don, ‘‘Flight Testing Your Homebuilt,’’ Homebuilt Aircraft, (July 1985), pp. 40-43.

llll ‘‘Flight Testing Your Homebuilt,’’ Plane and Pilot, (Annual, 1974), pp. 56-61.

Enman, Ann, ‘‘The Moment of Truth! The Test Flight,’’ Air Progress 1989 Guide to Sport Aircraft Kits,

pp. 16-19.

Experimental Aircraft Association, Pilot Reports and Flight Testing, V. 1, pg. 72 (1977). Selected first flight

reports and flight testing procedures.

Friedman, Peter, ‘‘High Tech-First flight,’’ Sport Pilot, (February 1989), pp. 16, 17, 72, 73.

Goyar, Norman, ‘‘Free Insurance and How to Get It,’’ Sport Pilot, j. 5, No. 3 (1989), pp. 44-49.

Hamlin, Benson, Flight Testing Conventional and Jet-Propelled Airplanes, (New York: The MacMillan Company, 1946)

Heintz, Chris, ‘‘The First Flight of Your Aircraft,’’ EAA Light Plane World, (May 1986), pp. 7-9.

llll ‘‘Performance Testing Your Aircraft,’’ EAA Light Plane World, (July 1986), pp. 13-15.

Hurt, H. H., Jr., Aerodynamics for Naval Aviators, (California: University of Southern California, 1960 [revised

1965]). NAVAIR 00-80T-80. Issued by the Office of the Chief of Naval Operations, Aviation Training Division.
2

5/24/95

AC 90-89A

Appendix 3

APPENDIX 3. ADDITIONAL REFERENCES ON FLIGHT

TESTING—Continued

Jacquemin, G., ‘‘Flight-testing for the Amateur,’’ Sport Aviation, (April 1965), pg. 4.

Kerley, Jim, ‘‘Thoughts on Test Flying,’’ Sport Aviation, (March 1970), pp. 34-35.

Ladd, Robert W., ‘‘The Test Flight of Chihuahua,’’Sport Aviation, (February 1968), pg. 4.

Macq, Harvey, ‘‘Test Flight,’’ Sport Aviation, (March 1960), pg. 3.

Mason, Sammy, Stalls, Spins, and Safety, (New York: Macmillan Publishing Company, 1985)

Mitchell, C.G.B., ‘‘Design of the ‘Kittiwake’ Family of Light Aircraft,’’ (Part 2) Sport Aviation, (March

1969), pp. 36-37.

Rhodes, Mike, ‘‘First Flight—Trial by Fire,’’ (Part 1) Sport Aviation, (August 1988), pp. 26, 27, 29.

Smith, Hubert, Performance Flight Testing, (Blue Ridge Summit: Tab Books, Inc. [Modern Aviation Series],

1982), pg. 131.

Sport Aviation, ‘‘Pointers on Test Flying Complied by Chapter 32, St. Louis, MO,’’ Sport Aviation, (December

1960), pg. 3.

Sport Planes, ‘‘The Sacramento Seaplanes,’’ Sport Planes, (Fall 1970), pp. 16-27.

Taylor, M. B., ‘‘Testing your Homebuilt,’’ Sport Aviation, (January 1977), pg. 24-27.

Tausworthe, Jim, ‘‘The Brotherhood of Flight,’’ Sport Aviation, (August 1969), pg. 22.

Thorp, J. W., ‘‘Structural Flight Testing,’’ Sport Aviation, (November 1961), pg. 2.

Wendt, H. O., ‘‘Designing, Building, and Flight Testing of the Wendt Wh-1 Traveler,’’ Sport Aviation,

(March 1973), pg. 10-15.

White, E. J., ‘‘Super Coot—The Fishermans Homebuilt,’’ Homebuilt Aircraft, (September 5, 1981), pg. 18-

21.

Wood, Karl D., Technical Aerodynamics, (New York: McGraw Hill, 1947)

INDUSTRY PUBLICATIONS: Ultralight

Brooke, Rob, ‘‘Greatest Peril,’’ Ultralight Flying, (September 1993), pp. 42-43.

Cannon, Mike, ‘‘Learning to Fly—Again,’’ Ultralight Flying, (June 1988), pp. 5

llll ‘‘Keeping Cool in the Summer Time,’’ Ultralight Flying, (August 1988), pp. 16-17.

Cartier, Kerry, ‘‘Power Failure on Take-off,’’ Ultralight Flying, (January 1988), pp. 25.

Chapman, John, and Smith, Clark, ‘‘Preparing for the In-Flight Emergency,’’ Ultralight Flying, (March 1989),

pp. 32.

Demeter, Dennis, ‘‘Risk Management,’’ Ultralight Flying, (July 1993), pp. 48-49.

llll ‘‘Don’t Forget the Pre-flight,’’ Ultralight Flying, (May 1993), pp. 70-71.

Grunnarson, Tom, ‘‘Getting into Ultralight Float Flying,’’ Ultralight Flying, (April 1989), pp. 27-29.

Johnson, Don, ‘‘Getting the Most out of Flight Reviews,’’ Ultralight Flying, (March 1989), pp. 20-23.

Loveman, Dave, ‘‘Problem-Solving the Cayuna 430R,’’ Ultralight Flying, (June 1988), pp. 24-25.
3

5/24/95

AC 90-89A

Appendix 3

APPENDIX 3. ADDITIONAL REFERENCES ON FLIGHT

TESTING—Continued

Pagen, Dennis, ‘‘‘G’ forces and your Ultralight,’’ Ultralight Flying, (August 1989), pp. 37.

llll ‘‘Weight and Speed,’’ Ultralight Flying, (May 1989), pp. 20-21.

Peghiny, Tom, ‘‘Effects of Sunlight on Polyester Sail Cloth,’’ Ultralight Foundation, Volume 2, Number

1, pp. 49-50, (1986).

GOVERNMENT PUBLICATIONS:

Send a written request for free Advisory Circulars to the FAX or address listed below.

Department of Transportation (DOT)

Property Use and Storage

Section, M-45.3

Washington, DC 20590

FAX: (202) 366-2795

Advisory Circulars (AC) with a stock number and dollar amount can be obtained from:

New Orders

Superintendent of Documents

P.O. Box 371954

Pittsburgh PA 15250-7954

TEL: (202) 783-3238 (Order Desk)

NOTE: Make the check payable to the Superintendent of Documents.

AC 00-2.8 ‘‘Advisory Circular Checklist (and Status of Other FAA Publications)’’

AC 20-27 ‘‘Certification and Operation of Amateur-Built Aircraft’’

AC 20-32 ‘‘Carbon Monoxide (CO) Contamination in Aircraft—Detection and Prevention’’

AC 20-34, ‘‘Prevention of Retractable Landing Gear Failures’’

AC 20-35, ‘‘Tiedown Sense’’

AC 20-37, ‘‘Aircraft Metal Propeller Maintenance’’

AC 20-42, ‘‘Hand Fire Extinguishers for Use in Aircraft’’

AC 20-103, ‘‘Aircraft Engine Crankshaft Failure’’

AC 20-105, ‘‘Engine Power-Loss Accident Prevention’’

AC 20-106, ‘‘Aircraft Inspection for the General Aviation Aircraft Owner’’

AC 20-125, ‘‘Water in Aviation Fuels’’

AC 23-8, ‘‘Flight Test Guide for Certification of Part 23 Airplanes’’ (Available from the Sup. Docs.,

SN 050-007-00817-1, cost $12.00)

AC 23.955-1,‘‘Substantiating Flow Rates and Pressures in Fuel Systems of Small Airplanes’’

AC 23.959-1,‘‘Unusable Fuel Test Procedures for Small Airplanes’’

AC 61-21A, ‘‘Flight Training Handbook’’ (Available from the Sup. Docs., SN 050-007-00504-1, cost $17.00)
4

5/24/95

AC 90-89A

Appendix 3

APPENDIX 3. ADDITIONAL REFERENCES ON FLIGHT

TESTING—Continued

AC 61-23B, ‘‘Pilot’s Handbook of Aeronautical Knowledge’’ (Available from the Sup. Docs., SN 050-011-

00077-1, cost $10.00)

AC 61-107, ‘‘Operations of Aircraft at Altitudes Above 25,000 Feet MSL and/or Mach Numbers (Mmo)

Greater Than .75’’

AC 91-23A, ‘‘Pilot’s Weight and Balance Handbook’’ (Available from the Sup. Docs., SN 050-007-00405-

2, cost $5.00)

AC 91-46, ‘‘Gyroscopic Instruments—Good Operating Practices’’

AC 91-48, ‘‘Acrobatics—Precision Flying With a Purpose’’

AC 91-59, ‘‘Inspection and Care of General Aviation Aircraft Exhaust Systems’’

AC 91-61, ‘‘A Hazard in Aerobatics: Effects or G-Forces of Pilots’’

AC 103-6, ‘‘Ultralight Vehicle Operations-Airports, Air Traffic Control (ATC), and Weather’’

AC 103-7, ‘‘The Ultralight Vehicle’’

Airman’s Information Manual (AIM): Official Guide to Basic Flight Information and ATC Procedures. For

price and availability, call (202) 783-3238.