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.
Distance Wires - Height Wires 75 Ft.
50 Ft.
25 Ft.
2000 1900 1800 Runway Timing Light Figure 5 - FIXED GRID From information obtained by any of the above methods in the previous section, the observed data may be plotted as in figure 6. This figure is usually included in the final report as is the corrected takeoff data.
35 T
OBSERVED TAKE OFF DATA 30 _Type Aircraft & No.
Gross Weight (Seconda) 25 20 Power Settings Configuration IAS at 50' TAS at 50° 100 HEIGHT ABOVE RUNWAY (It) Las at TAS at 1 5 TIME Wind Component 10 Along Runway Temperature Baron. Press.
5 Type Runvay 500 1000 1500 DISTANCE ALONG BUNWAI, (It) Figure 6 - CORRECTED TAKEOFF DATA
4. All takeoff performance data are corrected to sea level standard conditions and zero wind unless otherwise specified. A minimum of six takeoffs should be made and measured. Each test may be made using the appropriate speed over the obstacle.
(c) For simple airplanes equipped with reciprocating sea level engines, an acceptable data correction process to produce the takeoff distance for standard sea level no wind conditions is presented in figure 7.
TAKEOFF DISTANCE - SEGMENT METHOD (ACCELERATION SEGMENT) Target Speed at 50 ft. Vsa KCAS 75 Indicated Pressure Altitude, ft. 3750 (recorded] Calibrated Pressure altitude, ft. 3750 [this example assumes that there is no difference between ind. And cal.] Obs. OAT, deg F [recorded] Std lamp @ Alt,, teg F (line 2) 46 [59 - 00356616 * line 2] Density Altitude @ line 2 and line 3, It. 5187 I((1-6.87535 * 10* * line2$361 × (518.688 / (line 3 + 459.7)) 0335 - 11/(6.87535 * 105) Density @ line 5 0.00212126 10.0023769 * 1-(6.87535 * 10** line 2) *2565 Density Ratio 0.89241259 [line 6/0.002377] Sq root of density ratio in line 7 0.9447 (line 7) "3g 9 Obs. Comp. WindVelocity (+ head - tail), knots 3.00 [record] 10 Accelerate Airspeed for Test Cond. (TA5) 79.39 [V50/line 7] 50° speed corrected for alt Accelerate Ground Spd. for Test Cond. (TAS) 76.39 [line 10-Line 9] 50' speed corrected for alt. And wind Equivalent Altitude @ line 2 and line 3, ft 4267 (line 2-(0.36* (line 2-line 8)| 13 R/C @ Vse @ line 12, ft/min 450 [look up on equivalent alt, climb performance chart] 14 R/C@ Ya @S.. It/min 495 [look up on equivalent alt. climb performance chart] 15 Accelerate Run Power Corr. 0.91 [line 13/ine 14] 16 VSE AIR/V50 GND 1,04 [line 10/ine 11] 17 Accelerate Run Wind Corr. 1.07 [line 16) 83 18 Accelerate Run Density Corr. = line 7 0.89 [just the density ratio from line 7] 19 Observed Accelerate Dist. to Speed @ line 11, ft. 820 frecord) 20 Corr. S.L.. Accelerate Dist. to Vso, ft 714 [line 19 * line 18 * line 17 * line 15] 31 Average S.L. Accelerate Distance, ft 755 [average from total runs] climb segment 22 Via Speed @ 50 ft. std. S..., knots 97 [look up on climb chart!
23 R/C @ Vso and std. S.., ft/min 495 | [line 14] 24 Horizontal Distance from Lift-off to 50 ft 789 [¡50 it (line 22 * 1.69 * 60)/line 23)| S.L. Total Distance from Start to 50 ft, ft 1544 [line 21 + line 24] ground distance to 50' speed + horizontal component (distance) to climb 50' taken from climb chart Notes:
This chart is for sea level, std. Day takeoff distance to 50° Aircraft configuration, flaps and weight, should be specified
3. Landing gear is assumed down until after 50' point - if its determined that retracting the gear would significantly increase drag and therefore takeoff distance - a caution should be included in the handbook.
Figure 7 - DETERMINATION OF STANDARD S.L. TAKEOFF DISTANCE SEGMENT
METHOD (ACCELERATION SEGMENT) 9
1. The Takeoff Distance Segment Method (figure 7) is a simplified method to collect takeoff distance data to a 50-foot obstacle clearance height. This method is appropriate for simple airplanes because it is conservative and it does not require any elevation instrumentation to determine the 50-foot point. This method sums the ground acceleration, without any climb, to the point where the target obstacle cl earance speed is achieved, with the horizontal distance to climb 50 feet.
2. A simple way to understand the takeoff distance segment method is to understand it in terms of work/energy. The total distance is the sum of the work/energy required to accelerate to the obstacle clearance speed without any climb and the work/energy required for a steady climb of 50 feet (out of ground effect). The data for the climb segment should be based on the data reduction used for climb testing. Airplanes with fixed pitch props should use the equivalent altitude method, whereas airplanes with constant speed propellers should use the density altitude method. Radio calls can allow ground observers to mark distances to planned liftoff and obstacle clearance speeds. This figure presumes the test to have been conducted within the +5/-1 percent weight tolerance of § 23.21, and that correction of off-standard weight is not necessary. For the same type of airplane, an acceptable method of determining the approximate effects of altitude and temperature upon takeoff distance is presented in figure 8.
-6.87535 * 10* Determination of Takeoff Distance to 50 ft at Given Altitude and Temperature [recorded [ this example assumes that there is no difference between ind. and cal. ] recorded 00356616 * line 21 59 - I (1 - 6.87535 * 10* • line 2) 52881 * (518.688 / ( line 3 + 459.7 )) 6235 - 11/ I 0.0023769 * ( 1- ((6.87535 * 10* ) * line 2) I line 6 / 0.002377 1 I (line 7) 0.5 g line 2 - (0.36 * ( line 2 - line 5)) 1 indicated corrected for instrument error ] [ look up on equivalent alt. climb performance chart ] [ line 13 / line 14] [ from the chart shown in fig. 71 [ line 14 / ( line 13 * line 7)] • (50 * 60 * line 10) / ( line 13 * line 7 * line 12)) [ line 15 + line 16] 3750 3750 68 46 5187 0.002121 0.892413 0.9447 4267 76 450 495 0.91 755 931 568 1498 calibrate Pressure Artude f Temperature, deg F St'd temp @ Altp, deg F (line 2) Density Altitude @ line 2 and line 3, ft Density @ line 5 Density Ratio Sq. root of density ratio in line 7 Equivalent Altitude @ line 2 and line 3, ft Vso- Calibrated Airspeed, knots R/C @ Vso @ line 9, ft/min R/C @ Vso @ S.L., ft/min Accelerate Run Power Corr. Distance to accelerate to Vso @ S.L.Std Distance to Accelerate to Vso at line 1 and line Distance to Climb to 50 ft Total Distance from Start to 50 ft.
10 11 12 Figure 8 - DETERMINATION OF TAKEOFF DISTANCE TO 50 FEET AT GIVEN ALTITUDE
AND TEMPERATURE 11
3. The correction process of figures 7 and 8 presume the acceleration distance to vary inversely as the excess thrust that exists at the 50-foot speed, rather than inversely with the “effective acceleration” which generally corresponds with a speed approximately 30 percent lower.
This simplifying assumption enables use of the airplane's climb performance ratio as an approximate correction factor for the effect of altitude and temperature upon acceleration distance, and thereby avoids the need for thrust computations. However, the process is not considered to be valid for extrapolating performance to gross weights or wind conditions, which differ significantly from those of the test.
4. This method calculates total takeoff di stance and not a ground run distance.
Part 23 does not require any ground distance data for small airplanes; however, it would be helpful to the pilot to include the ground distance numbers that are determined using this method. The ground distance for sea level, standard day conditions at gross weight could be provided with correction factors for increasing altitude and temperature.
(d) Glossary of Terms :
H p - Pressure Altitude OAT - Outside Air Temperature H D - Density Altitude σ - (sigma) Density Ratio H e - Equivalent Altitude α - Runway Slope, in Degrees R/C GU - Rate of Climb, Gear Up b - Wingspan E - Oswald Efficiency Factor g - Gravitational Constant (.6 may be assumed in the absence of analysis or test)
c. Climb .
(1) Regulations Reference . Sections 23.65 and 23.1587.
(2) Discussion . Section 23.65 requires the determination of climb performance, which exceeds a minimum standard. When AC 23-8B was published, it no longer included the previously longstanding equivalent altitude method of reducing climb data for fixed pitch propeller airplanes.
The elimination of the equivalent altitude method of reducing climb data leaves no practical method for simple airplanes with fixed pitch propellers to reduce climb data.
• The density altitude m ethod of climb data reduction for constant speed propeller airplanes is still embodied in AC 23-8B.
• For sm all airplanes, simplified me thods are acceptable as follows:
(a) Equivalent Altitude .
1. Data reduction procedures using the equivalent altitude method are an acceptable means of compliance for small airplanes with fixed pitch propellers. This method is described in National Advisory Committee for Aeronautics (NACA) Report 297. The data reduction form shown in figure 9 may be employed. This method is applicable to both saw tooth and continuous climb data sets. Full throttle operation is required for valid results.