AC 23-15A

27 U.S. Department of Transportation Federal Aviation Administration Subject: SMALL AIRPLANE CERTIFICATION

COMPLIANCE PROGRAM Date: 3/15/05 Initiated by: ACE-100 AC No:

Change:

23-15A 1 _ _____________________________________________

1.

PURPOSE. This change revises existing material in two sentences. The change number and the date of the changed material are shown at t he top of each changed page. Vertical bars in the margin indicate the changed material. Pages havi ng no changes retain the same heading information.

2.

PRINCIPAL CHANGES.

Pa ragraph 5n(2)(e) is revised.

PA

GE CONTROL CHART Remove Pages Dated Insert Pages Dated 27-28 12/30/03 27 -28 3/15/05 S/ Davi d R. Showers Acting Manager, Small Airplane Directorate Aircraft Certification Service

Subject: SMALL AIRPLANE

CERTIFICATION COMPLIANCE

PROGRAM Date: 12/30/03 Initiated By: ACE-100 AC No: AC 23-15A Change:

1. PURPOSE. This advisory circular (AC) provides a compilation of historically acceptable means of compliance to specifically selected sections of 14 CFR part 23 that have become burdensome for small, simple, low performance airplanes (see Applicability section below) to show compliance.

However, applicability of these means of compliance remains the responsibility of the certification manager for each specific project. Utilization of these means of compliance does not affect the applicability of any other certification requirements that fall outside the scope of this AC. This material is neither mandatory nor regulatory in nature and does not constitute a regulation.

a. Applicability: Small, Simple, Low Performance Airplanes – The subject of this AC. The terms “small airplane”, “simple airplanes”, or “small low performance airplanes”, used throughout this AC, are synonymous with “Small, Simple, and Low Performance Airplanes”. This AC is applicable to airplanes with the following characteristics:

• Single reciprocating engine (Part of CLASS 1 definition in AC 23.1309-1C)

• Less than 6,000 pounds (part of CLASS 1 definition in AC 23.1309-1C)

• 4 Seats or le ss including pilot and co-pilot seats

• Unpressurized fuselage

• Normal category maneuvers only (see part 23, §§ 23.3(a)(1) through 23.3(a)(3) for definition of “normal category maneuvers”)

• Conventional materials and techniques – i.e. wood, aluminum monocoque/semimonocoque or tubular steel design, and no composite (i.e. graphite/epoxy), primary structure

• Primary structure (as used above) is that structure which contributes significantly to resisting or transmitting flight or ground loads, or may lead to an unsafe condition if failed. Some examples (not an exhaustive list) of primary structures are:

(1) Fuselage frames, stringers and skins

(2) Wing, horizontal stabilizer and verti cal stabilizer spars, ribs, and skins

(3) Bulkheads

(4) Intercostals

(5) Door and window edge frames, sills, or posts

ii

(6) Landing gear and their attachments

(7) Engine Mounts NOTE There m ay be instances where a portion of structure is not clearly “primary str ucture” and thus will require the judgment of the Aircraft Certification Office (ACO) engineer.

• No unique, un-orthodox, or com plex design features in this context:

(1) A “unique” design feature is somethi ng that the current regulations may not adequately address.

(2) An “un-orthodox” design feature is something that is not typically seen in an airplane of this type, for example, and canard or forward swept wing.

(3) A “complex” design feature is not the same as a complex airplane (defined below).

Precisely what constitutes a complex design feature is a determination that can only be made based on the judgment of the ACO engineer. As a rule of thumb, if a design feature is difficult (from the perspective of an engineer experienced in their field) to understand, analyze, reliably predict the behavior of, or prone to failures (due to complexity), that may create an unsafe condition, then it may be deemed as “complex”

• Engine is 200 Horsepower (HP) or less. NOTE: Airplanes with engines over 200 HP are “h igh-performance” under Title 14 Code of Federal Regulations, part 61, § 61.31 (f).

• The airplane ma y have no more than 2 of the following 3 items. NOTE: An airplane having all 3 of the following items are “complex” under Title 14 Code of Federal Regulations, part 61, § 61.31(e).

(1) Retractable Landing Gear

(2) Flaps

(3) Controllable pitch propeller

• No wing, leading edge, high lift devices.

• For airplanes equipped with trailing edge wing flaps, the design should be a simple, standard design, such as “plain”, “split”, “fowler”, or “single slotted”.

b.

This AC applies only to these types of aircraft. However, certification requirements must always be c oordinated with the local ACO. The ACO will make the determination of the suitability of this AC, based on a review of the aircraft design. It is always within the applicants right to propose the use of this AC to show compliance, and to negotiate this with the ACO.

2. CANCELL ATION. AC 23-15, Small Airplane Certification Compliance Program, dated January 2, 1997, is cancelled.

s/ Jam es E. Jackson Acting Manager, Small Airplane Directorate Aircraft Certification Service

iii CONTE NTS Section Page

1.

Purposei

2.

Cancellationi

3.

Related Regulations And Documents1

4.

Background3

5. Acceptable Method Of Com

pliance4

LIST OF ILLUS

TRATIONS Figure Page

1.

Sighting Bars Spaced Along Runway6

2.

Formula to Determine Height of the Aircraft Above Runway6

3.

Takeoff Data Installation for Swiveling Camera or Recording

Theodolite7

4.

Typical Chart and Takeoff Graph7

5.

Fixed Grid8

6.

Corrected Takeoff Data8

7.

Determination Of Standard S.L. Takeoff Distance Segment Method

(Acceleration Segment)9

8.

Determination of Takeoff Distance to 50 Feet at Given Altitude and

Temperature11

9.

Data Reduction Form Climbs – Equivalent Altitude Method13

10.

Data Reduction Form Climbs-Density Altitude Method15

11.

Data Reduction Form-Correction of Landing Data to Standard

Conditions19

iv LIST OF ILLUSTRATIONS (Continued) Figure Page

12. Normal Category Spin Test Matrix24

13. Performance Content And Format34

3. RELATED REGULATIONS AND DOCUMENTS.

a. Regulations: Title 14, Code of Federal Regulations (CFR), Part 23:

Section 23.45 Perform ance: General.

Section 23.51 Takeoff speeds.

Section 23.65 Clim b: All engines operating.

Section 23.75 Landing distance.

Section 23.77 Balked landing.

Section 23.145 Longitudinal control.

Section 23.161 Trim.

Section 23.175 De monstration of static longitudinal stability.

Section 23.201 W ings level stall.

Section 23.203 Turning flight and accelerated turning stalls.

Section 23.207 Stall warning.

Section 23.221 Spinning.

Section 23.562 Em ergency landing dynamic conditions.

Section 23.605 Fabrication methods.

Section 23.629 Flutter.

Section 23.641 Proof of strength.

Section 23.677 Trim systems.

Section 23.723 Shock absorption tests.

Section 23.725 Lim it drop tests.

Section 23.726 Ground load dynam ic tests.

Section 23.727 Reserve energy absorption drop test.

Section 23.735 Brakes.

Section 23.853 Passenger and cr ew compartment interiors.

Section 23.865 Fire protection of flight controls, engine m ounts, and other flight structure.

Section 23.867 Electrical bonding and protection against lightening and static electricity.

Section 23.954 Fuel system lightning protection.

Section 23.965 Fuel tank tests.

Section 23.1301 Function and installation.

Section 23.1309 Equipment, sy stem s, and installations.

Section 23.1311 Electronic display instrum ent systems.

Section 23.1337 Powerplant instrum ents installation.

Section 23.1431 Electronic equipm ent.

Section 23.1581 Airplane F light Manual and Approved Manual Material- General.

Section 23.1585 Operating procedures.

Section 23.1587 Perform ance information.

b. Advisory Circulars.

AC 20-53A Protection of Aircraft Fuel Systems Against Fuel Vapor

Ignition Due to Lightning

AC 20-115B Radio Technical Commission for Ae ronautics, Inc., Docum ent RTCA/DO-178B

AC 20-121A Airworthiness Approval of Loran-C Navigation Systems for use in the U.S. National & Airspace System (NAS) and Alaska

AC 20-130A Airworthiness Approval of Navigation or Flight Manageme nt Systems Integrating Multiple Navigation Sensors

AC 20-135 Powerplant Installation and Propulsion System Com ponent Fire Protection Test Methods, Standards and Criteria

AC 20-136 Protection of Aircraft Electrical/Electronic Systems against

the Indirect Effects of Lightning

AC 21-22 Injury Criteria for Huma n Exposure to Impact

AC 21-40 Application Guide for Obtaining a Supplem ental Type Certifica te

AC 23-8B Flight Test Guide for Certification of Part 23 Airplanes

AC 23-11A 14 CFR Part 23 Type Certification of an Airplane Originally Certificated to Joint Aviation Regulations - Very light Airplane (JAR-VLA) Standards

AC 23-16 Powerplant Guide for Certification of Part 23 Airplanes

AC 23-17A Systems and Equipm ent Guide for Certification of Part 23 Airplanes

AC 23.562-1 Dynam ic Testing of Part 23 Airplane Seat/Restraint Systems and Occupant Protection

AC 23.629-1A Means of Compliance with Section 23.629, “Flutter”

AC 23.1309-1C Equipment, System s, and Installations in Part 23 Airplanes

AC 23.1311-1A Installation of Electronic Displays in Part 23 Airplanes

3 Airframe and Aircraft Simplified Flutter Prevention Criteria for Personal Type Equipment Engineering Report (AEER) No. 45

FAA Technical Report Aircraft Lightning Protection Handbook DOT/FAA/CT-89/22

(1) The AC's listed above (with the exception of AEER No. 45) can be obtained from the U.S. Department of Transportation, Subsequent Distribution Office, Ardmore East Business Center, 3341 Q 75th Avenue, Landover, MD 20785.

(2) AC's 21-40, 23-17A, and 23-8A are for pur chase and can be obtained from the Superintend ent of Documents, P.O. Box 371954, Pittsburgh, PA 15250-7954, or from any of the Government Printing Office bookstores located in major cities throughout the United States.

(3) All of the above AC's (with the exception of AEER No. 45 and the te chnical report) are also available free of charge in electronic format from the FAA's Aircraft Certification Service web page, located at the following Internet address: http://www.faa.gov/certification/aircraft/.

(4) AEER No. 45 is availa ble from : Manager, Standards Office (ACE-110), Federal Aviation Administration – Small Airplane Directorate, 901 Locust, Room 301, Kansas City, MO 64106 or on the Internet at: http//www.faa.gov/certification/aircraft/aceAEER45-Flutter.pdf.

(5) Technical Report DOT/FAA/CT-89/22 is available by order through the National Technical Infor mation Service, Springfield, Virginia 22161

c. Industry Documents. The Radio Technical Commission for Aeronautics (RTCA) documents listed below are available from the RTCA, Inc., suite 805, 1828 L Street NW, Washington, DC 20036-4001 or at their website at www.rtca.org:

RTCA/DO-160D Environmental Conditions and Test Procedures f or Airborne Equipment

RTCA/DO-178B Software Consideration in Airborne System s and Equipment Certification

4. BACKGROUND. Some industry and aviation organizations expressed concern that the typical means of compliance for some regulations might be more demanding than justified. As a consequence, industry, aviation groups, and the Federal Aviation Administration (FAA) formed a team to study this issue. Historical files, Designated Engineering Representatives (DER's), ACO's, and industry were used to determine target regulations and provide known means of compliance.

This AC is a compilation of the study results, listing the regulations and attendant means of compliance that offer an improvement in certification efficiency. The listed means of compliance have been found acceptable and historically successful, but they are not the only methods, which can be used to show compliance.

5. ACCEPTABLE METHOD OF COMPLIANCE. The selected methods of compliance are organized by affected sections of part 23.

a. Performance - General.

(1) Regulations Reference. Sections 23.45 and 23.1587.

(2) Discussion. Section 23.45(e), requires that performance data for compliance demonstration be based on engine power at 80 percent humidity. The rule also addresses approved power or thrust reduced by maximum installation losses and accessory power extraction. This advisory material is provided for application to small airplanes to address these issues as follows:

(a) Humidity Adjustment.

1. Subsections 23.45(e) requires that perf ormance data for flight requirements compliance demonstration (and for performance information included in the Airplane Flight Manual (AFM) under § 23.1587) be based on engine power at 80 percent relative humidity. Based on AC 23-8B, appendix 1, paragraph 2d(3), no humidity correction is required for sm all airplanes. This paragraph states that, "Experience has shown that conditions such as 80 percent relative humidity on a standard day at sea level has a very sm all effect on engine power...." "Standard" atmospheric conditions referenced in § 23.45 means United States Standard Atmosphere. See AC 23-8B, paragraph 16a(2).

2. The need for detailed and accurate perfo rmance data is closely related to the airplane stall speed. An airplane that has a stall speed of 30 knots and a takeoff roll of 200 feet requires no takeoff performance data because the pilot’s visual judgment is adequate and more convenient. An error of 10 percent is only one fuselage length. For an airplane with a 130-knot stall speed, the ground distances are great enough to be beyond the pilot's visualization and judgment.

The runway length and airplane requirements are closely related. Making a 10 percent error is the difference between a successful rejected takeoff (RTO) and terminating off the airport. Airplanes of this performance level require detailed and accurate data for even routine operation. Small, simple, low performance airplanes do not require that same level of detail and accuracy in order to show compliance to the regulations. Therefore, the small error in performance data based on dry air won’t have a significant affect (for small, simple, low performance airplanes).

(b) Engine Power Losses. The rule contains language regarding "approved power or thrust" reduced by maximum installation losses and accessory power extraction. For small airplanes, the prime losses pertaining here are those associated with induction and exhaust systems;

the typical accessories that extract power are the electrical and vacuum systems. Since all testing is accomplished with the intake and exhaust systems installed on the airplane, no further corrections for losses are applicable. The typical electrical power source, an alternator, on small airplanes (12 volts at a maximum capacity of 60 amps) will consume less than one horsepower maximum.

Testing is normally done with the electrical system on, thereby reducing any potential power correction for the alternator's power extraction to much less than one horsepower. Vacuum pumpsextract approximately one-half horsepower. They typically run all the time and would be expected to be operating during performance testing and, therefore, no correction for vacuum power extraction is warranted. Also, because of the difficulties associated with power determination when

5 using fixed pitch propellers, the best approach is to use full throttle setting for takeoff and clim b performance testing

(c) Test Instrumentation.

1. For measurement of altitude, airspeed, and temperature, a measurement device, such as that developed for the Comparative Aircraft Flight Efficiency, Inc. (CAFE) Triaviathon, will be an acceptable means of generating required data for measuring rate of climb, climb gradient, glide gradient, airspeed, balked landing criteria, etc. (CAFE Foundation, 4370 Raymonde Way, Santa Rosa, CA 95404)

2. This device records indicated airspee d, true airspeed, mean sea level (MSL) altitude, and outside air temperature once per second into a computer memory. It then performs all corrections and calibrations necessary. Video cameras may also be used to record instrument readings and pilot actions to show compliance with flight and performance provisions. Also, the use of traditional equipment such as knee pad, stopwatch, force gauge, etc., is appropriate for many tasks and their use is encouraged.

b. Takeoff.

(1) Regulations Reference. Sections 23.53 and 23.1587.

(2) Discussion.

(a) Measurement Methods. Section 23.51(a) requires the measurement of the distance required to takeoff and climb over a 50-foot obstacle. AC 23-8B, 19.b, describes acceptable methods of compliance. To avoid any inference that expensive test equipment is required, this advisory material provides additional guidance specifically applicable to small airplanes.

(b) Distance and Height Measurements and Equipment. Measurements should be taken to determine the distance from the takeoff starting point to the place where the aircraft leaves the ground and to the point where the airplane reaches the height of 50 feet. These measurements may be made in various ways. A few of the acceptable methods in general use follow:

1. When space-positioning equipment is not available, either of the following systems may be used. The first consists of several theodolites (sighting bars) spaced along the runway so as to cover the distance and time from takeoff point to the simulated 50-foot obstacle.

The distance and time from takeoff point to each sighting station will give an approximation of the aircraft speed and takeoff distance. This method is shown schematically in figure 1.

Figure 1 – SIGHTING BARS SPACED ALONG RUNWAY

(aa) It is good practice to station two or three observers at the edge of the runway in the vicinity of the takeoff point to mark the exact point of takeoff. The data obtained by such observers are always a good check on ground roll distance regardless of the method used for obtaining data. Additionally, the error in visually determining the takeoff point may be minimized by making a series of lime lines on the runway at 5 to 10-foot intervals in the expected takeoff zone.

The transit should be tilted so that the plane of rotation of the sight intersects the vertical plane of the runway centerline at 50 feet. (The height of the aircraft above the runway may be obtained by a formula determined from figure 2.) During a takeoff run, the airplane is tracked by the transit. As the airplane passes up through the horizontal cross hairs of the transit sight, the transit is stopped. A ground observer may be waved into position on the runway below the cross hairs to note the distance; or a calibration of distance as a function of transit azimuth may be made, and the distance at 50 feet read directly. Using this method the height of the aircraft above the runway may be obtained by a formula determined from figure 2.

Figure 2 – FORMULA TO DETERMINE HEIGHT OF THE AIRCRAFT ABOVE RUNWAY

(bb) A more accurate field method of obt aining takeoff data consists of a theodolite pivoted so it may track the aircraft during the takeoff run. See figure 3.

Figure 3 – TAKEOFF DATA INSTALLATION FOR

SWIVELING CAMERA OR RECORDING THEODOLITE

(cc) The theodolite is constructed in su ch a way that, by keeping cross hairs on the aircraft, a pencil trace of the aircraft position is placed on a chart fastened rigidly to the theodolite supports, or alternately, an electronic trace could be fed directly to a laptop computer.

The swiveling theodolite is set up at a known distance from the runway and so aligned as to encompass only as much of the runway as will be necessary for the tests of the particular aircraft under consideration. This is done to obtain the greatest accuracy from the instrument.

(dd) Various standard distances fr om the runway may be arbitrarily determined and charts prepared in advance for use on this theodolite. A timing mechanism built into the sighting bar marks every second on the chart. Ground observers are used to mark the exact point of takeoff, and this information may be placed on the chart at the end of each test. A typical chart and takeoff graph is illustrated in figure 4.

Figure 4 – TYPICAL CHART AND TAKEOFF GRAPH

2. A fixed grid may also be used to phot ographically record the tests. In this method, a grid consisting of a network of calibrated wires is placed in front of a video camera in the manner shown in figure 3, and at such a distance that it will remain in focus along with the airplane being tested. A timing device may be mounted on either the grid or camera to give a time history of the takeoff or landing. A typical frame taken through this type of grid is shown in figure 5.