U.S. Department of Transportation Federal Aviation Administration Advisory Circular Subject: Amateur-Built Aircraft and Ultralight Flight Testing Handbook Date: 4/27/15 Initiated by: AFS-350 AC No: 90-89B Change:
This advisory circular (AC) provides suggestions and safety related recommendations primarily to assist amateur and ultralight builders in developing individualized aircraft flight-test plans. It also provides guidance for experimental light sport aircraft flight testing after modifications to the aircraft. It provides recommendations and suggestions you can combine with other sources on test flying, such as the aircraft plan/kit manufacturer’s flight testing instructions and other flight testing data. This will help you develop a detailed flight-test plan, tailored for your aircraft and resources.
This AC attempts to make you aware that test flying an aircraft is a critical undertaking, which you should approach with thorough planning, skill, and common sense. The flight-test plan is the heart of all professional flight testing. The plan should account for every hour spent in the flighttest phase and you should adhere to it 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, but your goals, should be the same. You should add flight-test operational and performance data to the aircraft’s flight manual so you can reference the data prior to each flight.
This AC is not mandatory and does not constitute a regulation. This AC describes an acceptable means, but not the only means, to develop flight-test plans. However, if you use the means described in the AC, you must follow it in all important respects. This AC applies to amateur and ultralight builders, and individuals involved in flight testing those aircraft.
ORIGINAL SIGNED by /s/ John S. Duncan Director, Flight Standards Service
CONTENTS Paragraph Page
CHAPTER 1. PREPARATION1
Section 1. Homework1
1-1. Objective1
Section 2. Airport Selection4
1-2. Objective4
Section 3. Emergency Plans and Equipment6
1-3. Objective6
Section 4. Test Pilot9
1-4. Objective9
1-5. General9
1-6. Test Pilot Requirements9
Section 5. Medical Facts for Pilots11
1-7. Objective11
Section 6. Transporting the Aircraft to the Airport13
1-8. Objective13
Section 7. Assembly and Airworthiness Inspection14
1-9. Objective14
1-10. General14
1-11. Fitness Inspection—Airframe14
1-12. Field Check16
Section 8. Weight and Balance19
1-13. Objective19
1-14. Determining Empty Weight CG20
1-15. Determining Takeoff Weight CG21
1-16. Adding Additional Equipment22
Section 9. Paperwork24
1-17. Objective24
Section 10. Powerplant Tests26
1-18. Objective26
Section 11. Additional Engine Tests31
1-19. Objective31
Section 12. Propeller Inspection35
1-20. Objective35
1-21. Recommendations for All Propellers35
1-22. Propeller Tracking Check37
1-23. Metal Propeller Inspection37
1-24. Wood Propeller Inspection38
1-25. Composite Propeller Inspection39
CHAPTER 2. TAXI TESTS41
Section 1. Low-Speed Taxi Tests41
2-1. Objectives41
2-2. Taxi Tests41
Section 2. High-Speed Taxi Tests42
2-3. Objective42
CHAPTER 3. THE FIRST FLIGHT45
Section 1. General45
3-1. Objective45
3-2. General45
3-3. Recommendations45
3-4. First Flight Inspection46
Section 2. The Role of the Chase Plane47
3-5. Objective47
3-6. General47
Section 3. Emergency Procedures48
3-7. Objective48
3-8. General48
Section 4. First Flight49
3-9. Objectives49
Section 5. First Flight Procedures51
3-10. Objective51
CHAPTER 4. THE FIRST 10 HOURS55
Section 1. The Second Flight55
4-1. Objective55
Section 2. The Third Flight55
4-2. Objective55
4-3. General55
Section 3. Hours 4 through 1056
4-4. Objective56
4-5. General56
4-6. Gear Retraction56
4-7. Climbs and Descent57
4-8. Airspeed In-Flight Accuracy Check58
CHAPTER 5. EXPANDING THE ENVELOPE61
Section 1. General61
5-1. Objective61
Section 2. Hours 11 through 2061
5-2. Objective61
5-3. Stalls63
Section 3. Hours 21 through 35: Stability and Control Checks66
5-4. Objective66
5-5. General66
5-6. Definitions67
Section 4. A Word or Two about Flutter70
5-7. Objective70
5-8. Description71
Section 5. Spins72
5-9. Objective72
5-10. Caution73
5-11. Planning the Flight73
Section 6. Accelerated Stalls74
5-12. Objective74
CHAPTER 6. PUTTING IT ALL TOGETHER: 36 HOURS TO —————?77
Section 1. Maximum Gross Weight Tests77
6-1. Objective77
Section 2. Service Ceiling Tests78
6-2. Objective78
Section 3. Navigation, Fuel Consumption, and Night Flying79
6-3. Objectives80
CHAPTER 7. THOUGHTS ON TESTING CANARD TYPE AMATEUR-BUILT AIRCRAFT83
Section 1. Canards83
7-1. Objective83
Section 2. Flight Test Considerations84
7-2. General84
CHAPTER 8. ULTRALIGHT AIRFRAME INSPECTION87
Section 1. Differences87
8-1. Objectives87
8-2. Definition87
Section 2. The Test Pilot88
8-3. General88
Section 3. Pre-Flight Airframe Inspection89
8-4. General89
8-5. Checklist89
CHAPTER 9. ULTRALIGHT ENGINE/FUEL SYSTEM INSPECTION93
Section 1. Engine Inspection93
9-1. Objective93
Section 2. Fuel Systems95
9-2. General95
CHAPTER 10. ULTRALIGHT TEST FLYING RECOMMENDATIONS97
Section 1. Three Recommendations97
10-1. Objective97
10-2. Recommendations97
Section 2. Airport Selection98
10-3. Objective98
Section 3. Taxiing98
10-4. General98
Section 4. First Flight Differences98
10-5. Use of Power98
10-6. Control Feel99
10-7. Stalls99
10-8. Steep Turns99
Section 5. Emergency Procedures99
10-9. Engine Failures99
10-10. Loss of Control99
10-11. Catastrophic Failure100
APPENDIX 1. SAMPLE CHECKLIST FOR A CONDITION INSPECTION (9 pages)1
APPENDIX 2. SOURCES FOR ACCIDENT/INCIDENT INFORMATION (1 page)1
APPENDIX 3. ADDITIONAL REFERENCES ON FLIGHT TESTING (4 pages)1
APPENDIX 4. ADMINISTRATIVE INFORMATION (2 pages)1
LIST OF FIGURES
Figure 1. Runway Length Chart5
Figure 2. Empty weight CG20
Figure 3. Takeoff CG21
Figure 4. Additional Equipment Added22
Figure 5. 100 HP Fuel Flow Rate Chart34
Figure 6 Propeller Tracking36
Figure 7. Climb Airspeed and Altitude Graph64
Figure 8. Best Rate of Climb Speed Graph65
Figure 9. Static Stability67
Figure 10. Time68
Par 1-1 Page 1 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)
1-1. OBJECTIVE. A planned approach to flight testing.
a. Develop a Flight-Test Plan. Your most important task is to develop a comprehensive flight-test plan. You should tailor this plan to define the aircraft’s specific level of performance, so it’s important that the entire flight-test plan be developed and completed before the aircraft’s first flight.
NOTE: As part of the comprehensive flight-test plan, the test pilot should read and comprehend this entire AC before proceeding in accomplishing any suggested task.
b. Objective of a Flight-Test Plan. 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. You should use this data to develop a flight manual that specifies the aircraft’s performance and defines its operating envelope. Additionally, the plan should reference the use of checklists to assure that all relevant steps and elements are covered.
c. Time Required for Flight Testing Amateur-Built Aircraft. Your original issued airworthiness certificates should be limited to operation within an assigned flight-test area for a
Par 1-1 Page 2 minimum of 25 hours when a type certificated (TC) engine/propeller combination is installed. A minimum of 40 hours is required when a non TC’d engine, propeller, or engine/propeller combination is installed. Furthermore, if the TC’d engine, propeller, or engine/propeller combination installed has been altered in a way that differs from an approved type design in a Type Certificate Data Sheet (TCDS), a minimum of 40 hours shall be required.
d. Time Required for Flight Testing Experimental Light Sport Aircraft (ELSA). If you own an ELSA experimental aircraft under Title 14 of the Code of Federal Regulations (14 CFR) part 21, § 21.191(i)(2), and it has not been modified, conduct a test flight as per their operations manual in an assigned flight-test area for a minimum of 5 hours. This applies for all classes of light sport aircraft (LSA) to determine aircraft controllability throughout its design limits.
e. Best Practices for Flight Testing After Modifying an Experimental Amateur-Built Aircraft. Before considering any modification to an aircraft previously issued an experimental certificate for the purpose of operating as an amateur-built (E-AB) aircraft, there are two things you need to consider. First is the level of modification; the other is the corresponding flight testing required for the modification. When considering the level of modification, you should first check the E-AB operating limitations. They will detail what, if any, reporting requirements there are for a given modification. This is especially important when the E-AB modification approaches the same level of a major change to TC aircraft as defined in part 21, § 21.93. Usually the owner of the E-AB aircraft is required by the aircraft operating limitations to notify the geographical responsible Flight Standards District Office (FSDO) following a “major change” as defined by § 21.93. This regulation states that a “major change” is any that affects the “weight, balance, structural strength, reliability, operational characteristics, or other characteristics affecting the airworthiness of the product. The corresponding flight testing for a major change will require at least 5 hours minimum of supplemental Phase I flight testing be completed to comply with 14 CFR part 91, § 91.319(b). The aircraft owner must obtain concurrence from the FSDO as to the suitability of the proposed test area.
(1) Flight testing in some form is advisable following any modification to the aircraft. Not only will a structured series of test flights reveal any malfunctions or unintended consequences associated with a modification, but it will also allow the pilot to become familiar with the operation of the aircraft after a given change before returning to “operational” flying.
For example, flight testing a new instrument will verify its proper operation and ensure the pilot understands how to use it. This is important to accomplish before operating the aircraft in a situation where the proper operation of the instrument may affect the safe outcome of the flight.
(2) This sort of flight testing is at the sole discretion of the owner or pilot, so it may or may not be as formal as Phase I. In general, however, the owner or pilot should conduct it in uncongested airspace local to an airport, to keep distractions at a minimum. Passengers flying for the sole purpose of pleasure should be avoided, however, because this is not Phase I testing, a passenger may be carried to monitor aircraft systems or perform other functions relevant to the purpose of the flight, if appropriate. As with any test flight, there should a clear plan with clear objectives.
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(3) It is important to note that, while some modifications are neither mandatory nor necessary to report to the FSDO, you should document all changes appropriately. The aircraft records should be updated with the date the work was completed, the hours in service of the components affected, and the total hours on the aircraft noted in the logbook along with the changes performed and the equipment added or removed. The weight and balance data and the equipment list should also be updated. Note the areas that affect operational differences in the pilot’s operating handbook (POH). In situations where the changes affect installed or needed placards and decals, they should be in place before flying with the new configuration.
(4) If the major change includes installing a different type of engine (reciprocating to turbine) or a change of a fixed-pitch from or to a controllable propeller, the aircraft owner must fill out a revised FAA Form 8130-6 to update the aircraft’s file in the FAA Aircraft Registration Branch (AFS-750). You must conduct all operations under day visual flight rules (VFR) in a sparsely populated area. The aircraft must remain in flight test for a minimum of 5 hours.
(5) At the completion of flight testing, the results should be posted in the aircraft log.
Changes should be incorporated into the POH and other affected records. The statement should, at a minimum, state the scope of the changes, the tests performed along with the results. The total hours as of that date on the aircraft should be included, and the aircraft be declared to be in a condition for safe operation.
f. Modifying ELSAs. All alterations, modifications, and additions or deletions to your ELSA must be approved in writing by the LSA kit manufacturer and recorded in the aircraft records before the original certification in experimental purpose for operation of LSA under § 21.191(i)(2).
(1) Additionally for a major change to your ELSA (such as an alteration, modification, addition, or deletion), the FAA has the authority under part 91 § 91.319(i) to modify your experimental LSA operating limitations with special restrictions for flight testing due to the aircraft modification.
(2) Following any major change, your ELSA must be assigned to a flight-test area for an appropriate time to conduct a flight test and evaluate that your aircraft is in a condition for safe operation. The guidance baseline for this testing is 5 hours of flight time within the flight-test area. The FAA may prescribe any additional limitations and/or flight time within the flight-test area deemed necessary in the interest of safety.
Par 1-2 Page 4 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)
1-2. OBJECTIVE. To select an airport to test fly the aircraft.
a. Runway Alignment. 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. Ideal Runway. The ideal runway at sea-level elevation should be at least 4,000 feet long and 100 feet wide. For each 1,000-foot increase in field elevation, add 500 feet to the runway length. If testing a high-performance aircraft, the airport’s runway at sea level should be more than 6,000 feet long and 150 feet wide for a wider margin of safety. You should factor other considerations, such as power-to-weight ratio, wing design, and density altitude, into the equation for picking the best runway for the initial flight testing. You can also use the chart in Figure 1.