AC 29.63. § 29.63 (Amendment. 29-12) TAKEOFF: CATEGORY B.
a. Explanation.
(1) Takeoff distance is the horizontal distance measured from an initial position to a point 50 feet above the takeoff surface with all engines operating within approved limits.
(2) The height-velocity diagram is normally developed and accepted prior to conducting takeoff distance tests. Takeoff distance tests are conducted avoiding the critical areas of the diagram. The amount of power utilized in determining takeoff distance may not be greater than that used in constructing the takeoff corridor and “knee” portions of the height-velocity diagram. Power might also have to be constrained, depending upon the amount of excess power available, so that a “reasonable” nose down pitch attitude is not exceeded during the initial portion of the takeoff run. Acceptable values used during past programs include:
limits)
(i) Hover power + 10 percent (not to exceed rated engine takeoff power
(ii) A percent transmission limiting torque (not to exceed rated engine takeoff power limits), and
(iii) Engine (or transmission) limiting power for the particular ambient conditions.
(3) The critical center of gravity should be used for takeoff distance tests.
Critical center of gravity should be established analytically or from previous testing and may be forward or aft depending on the type of rotorcraft. Items that should be considered in determining the critical center of gravity are climb performance and cockpit visibility. At least two gross weights should be flown at each test altitude, if weight accountability is desired, in order to validate the manufacturers prediction of weight effects.
(4) The speed utilized at the 50-foot point in the takeoff profile (V50 speed) may be largely determined by the ability to obtain reliable, repeatable airspeed indications which can also comply with § 29.1323. Section 29.1323 ties the airspeed system accuracy requirements to the climbout speed. The climbout speed should be that speed attained at 50 feet in complying with § 29.63.
b. Procedures.
(1) Instrumentation. A ground station will measure ambient temperature, humidity (if applicable), and wind. For allowable wind conditions and engine power considerations refer to paragraph AC 29.45. A photo panel or hand recording method Page B - 57
may be utilized, as necessary, to record engine and flight parameters. A phototheodolite, takeoff and landing camera, or other approved instrumentation is utilized to measure distance, heights, speed, and time.
(2) Conduct of the Test. If the applicant elects to show weight effects on distance, at least two weights should be flown and, depending on the range of takeoff and landing altitudes to be approved, at least two test altitudes should be flown.
Altitudes should be sufficiently far apart to include a major portion of the approved takeoff and landing altitude range. Takeoff profiles should be started from an initial condition. For takeoffs from a hover, the hover height should be determined by performing fixed collective takeoffs as described in paragraph AC 29.51. “Takeoff” power should be smoothly applied and the aircraft nose lowered as necessary to accelerate without gaining excessive altitude. It must be possible to conduct a consistent takeoff profile clear of the height-velocity diagram with normal pilot effort and skill. A minimum of five good runs should be flown by the FAA/AUTHORITY pilot at each altitude and weight. Runs by the company and FAA/AUTHORITY pilot may be averaged. Effects of missing the V 50 speed by some amount (± 5 knots, for example) or other small changes in profile should be evaluated to determine if gross performance changes result from small piloting errors. Engine failures should be conducted along the takeoff profile to assure safe landing capability. Past programs have shown the low speed point immediately after addition of power to be particularly critical. Night takeoffs should at least be qualitatively evaluated to assure the takeoff procedures are compatible for night operation.
(3) Test Results. Test results are utilized in constructing the flight manual takeoff distance charts required by § 29.1587. The takeoff surface utilized in conducting these takeoff distance and engine failure tests should be included in the flight manual.
The “climbout speed” should also be defined and included in the flight manual. The airspeed utilized at the 50-foot point in the conduct of these tests must be clearly defined to allow compliance with § 29.1323. Test results may be extrapolated in accordance with guidance contained in paragraph AC 29.45.
(4) Test Techniques. For the FAA/AUTHORITY test data runs which will result in rotorcraft flight manual (RFM) performance, only the operational cockpit instrumentation as shown on the minimum equipment list and the piloting procedures from the RFM should be used. A useful technique is to “lead” the targeted V 50 speed by a fixed amount, so that a smooth, consistent, and operationally realistic transition may be made between the acceleration and climbout phases; e.g., begin rotation at 35 knots to achieve 46 knots passing 50 feet. This and other pertinent information defining the takeoff flight path are required flight manual entries per § 29.1587(b).
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TAKEOFF PROFILE
HEIGHT ABOVE GROUND (FEET) AVOID
• 5 KTS MINIMUM MARGIN AVOID
VELOCITY (KNOTS) FIGURE AC 29.63-1 CONVENTIONAL TAKEOFF PROFILE CATEGORY B Page B - 59
AC 29.65. § 29.65 (Amendment 29-15) CLIMB: (ALL ENGINES OPERATING).
a. Explanation.
(1) Section 29.65 requires in part that the steady rate of climb be determined for each Category B rotorcraft with maximum continuous power on each engine for the range of weights, altitudes, and temperatures for which certification is requested. The climb airspeed should be the best rate-of-climb (VY) for standard day sea level conditions at maximum weight and at a speed(s) selected by the applicant for other conditions not to exceed VNE. The applicant can either publish a climb schedule in accordance with the above or utilize a constant climb airspeed for all conditions.
Equivalent levels of safety have been found wherein the applicant was allowed to select a climb airspeed that was not the actual VY. The selected airspeed must be consistent with the speed used to show compliance with such items as cooling, stability, etc. The rate-of-climb resulting from the selected climb airspeed versus that from the actual VY shall not differ to an extent that a pilot will be encouraged, by appreciable increases in climb performance to fly a climb airspeed different from that published in the Flight Manual.
(2) For Category A rotorcraft, if VNE at any altitude is less than the maximum gross weight sea level standard day condition VY, the steady rate-of-climb must be determined at the climb speed(s) selected by the applicant not to exceed VNE. The climb performance must be determined from 2,000 feet below the altitude from where VNE intersects VY up to the maximum altitude for which certification is requested. This should be done utilizing maximum continuous power on each engine with the landing gear retracted.
b. Procedure to Determine VY.
(1) Sawtooth climbs may be used to determine the best rate-of-climb airspeed VY. If such a technique is used, climbs should be flown in pairs on opposite headings 90° to the winds at the test altitude. This procedure will minimize any windshear effects.
All testing should be done in smooth air. Windshear is usually an indication of unstable air or a temperature inversion and should be avoided. The climbs are flown on reciprocal headings for approximately 5 minutes through a 1,000-foot band, or a comparable time/altitude band, using maximum continuous power at a constant airspeed. Periodic power adjustments may be necessary. Additional reciprocal heading climbs must also be conducted at different airspeeds sufficient to bracket the lowest point of the power required versus airspeed curve. This technique can be repeated at different altitudes to obtain VY throughout the altitude range.
(2) Level flight performance (speed power) may also be used to determine the best rate-of-climb airspeed (VY). The testing should be done in smooth air. The advantage of this method is that less time is required, and the accuracy is equivalent to the sawtooth climb method. The test can be repeated at various altitudes to determine the VY throughout the altitude range desired for the rotorcraft. The test at each altitude Page B - 60
should be conducted at a constant weight over sigma (W/σ). The test is normally started at the desired W/σ with maximum continuous power, or at VNE, in level flight. A series of points should be taken, reducing airspeed 10 to 15 knots between points, with the lowest speed point at approximately 20 to 30 knots. Weight should be computed for each point and the test altitude adjusted to maintain a constant W/σ. After the data are reduced to standard day conditions, the minimum power required airspeed will be the VY speed.
(3) Prior to the flight test, the rotorcraft should be ballasted to the desired gross weight and the critical center of gravity. The airspeed should be stabilized prior to data acquisition. Data to be recorded includes time, altitude, airspeed, ambient temperature, engine parameters, torque(s), rotor RPM, fuel reading, aircraft heading, external configuration, etc. Power setting, weight, and climb airspeed should be planned prior to flight. For some turboshaft engines, temperature and/or engine speed limits may be reached prior to a limiting torque. The test team should verify that the resulting power utilized in these tests closely approximates the power producing capabilities of installed minimum specification engine.
c. Procedure to Determine all Engine Operating Climb Performance.
(1) Background. Continuous climbs are conducted at the appropriate climb airspeeds as outlined above in order to obtain the rotorcraft’s climb performance for the flight manual. By -products are a qualitative evaluation of the rotorcraft handling characteristics in a climb and engine data to assist in the determination of installed power available.
(2) Techniques. The techniques used to determine this performance may be the same as those used in the VY determination. The climbs are conducted on reciprocal headings at the established airspeed(s) through the target altitude range.
The same parameters are recorded. The rotorcraft will usually climb very rapidly during the first few thousand feet; therefore, the data acquisition method must be timely if accurate results are expected. This procedure is usually repeated at weight extremes.
The resulting data must then be corrected for power and weight. Power and weight corrections are satisfactory, provided the test powers and weights closely approximate the target values to make the weight and power corrections accurate. Once this data is finalized and corrected for all the flight test variables, interpolation for intermediate weights can be made with a high degree of reliability. If the rotorcraft has any stability augmentation system, vent systems, etc., which may influence the climb performance, then it must be accounted for. Caution should be taken that anti -ice, air-conditioning, etc., are not on unless the performance is being established specifically for those conditions.
AC 29.65A (AC 29.64) §§ 29.64 and 29.65 (Amendment 29-39) CLIMB (GENERAL AND ALL ENGINES OPERATING).
a. Explanation.
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(1) Amendment 29-39 relocated and clarified the general climb requirements into a new § 29.64 and added requirements to determine Category A climb performance in § 29.65. The guidance material presented in paragraph AC 29.67 does not apply to rotorcraft certified with Amendment 29-39 or later. Sections 29.64 and 29.65 require that the steady rate of climb be determined with maximum continuous power on each engine for the range of weights, altitudes, and temperatures for which certification is requested. The climb airspeed should be the best rate-of-climb (VY) for standard day sea level conditions at maximum weight and at a speed(s) selected by the applicant for other conditions not to exceed VNE. The applicant can either publish a climb schedule in accordance with the above or utilize a constant climb airspeed for all conditions.
Equivalent levels of safety have been found wherein the applicant was allowed to select a climb airspeed that was not the actual VY. The selected airspeed should be consistent with the speed used to show compliance with such items as cooling, stability, etc. The rate- of-climb resulting from the selected climb airspeed versus that from the actual VY shall not differ to an extent that a pilot will be encouraged by appreciable increases in climb performance to fly a climb airspeed different from that published in the Flight Manual.
(2) If VNE at any altitude is less than the maximum gross weight sea level standard day condition VY, the steady rate-of-climb should be determined at the climb speed(s) selected by the applicant not to exceed VNE. The climb performance should be determined from 2,000 feet below the altitude from where VNE intersects VY up to the maximum altitude for which certification is requested. This should be done utilizing maximum continuous power on each engine with the landing gear retracted.
b. Procedure to Determine VY.
(1) Sawtooth climbs may be used to determine the best rate-of-climb airspeed VY. If such a technique is used, climbs should be flown in pairs on opposite headings 90° to the winds at the test altitude. This procedure will minimize any windshear effects.
All testing should be done in smooth air. Windshear is usually an indication of unstable air or a temperature inversion and should be avoided. The climbs are flown on reciprocal headings for approximately 5 minutes through a 1,000-foot band, or a comparable time/altitude band, using maximum continuous power at a constant airspeed. Periodic power adjustments may be necessary. Additional reciprocal heading climbs should also be conducted at different airspeeds sufficient to bracket the lowest point of the power required versus airspeed curve. This technique can be repeated at different altitudes to obtain VY throughout the altitude range.
(2) Level flight performance (speed power) may also be used to determine the best rate-of-climb airspeed (VY). The testing should be done in smooth air. The advantage of this method is that less time is required, and the accuracy is equivalent to the sawtooth climb method. The test can be repeated at various altitudes to determine the VY throughout the altitude range desired for the rotorcraft. The test at each altitude should be conducted at a constant weight over sigma (W/σ). The test is normally Page B - 62
started at the desired W/σ with maximum continuos power, or at VNE, in level flight. A series of points should be taken, reducing airspeed 10 to 15 knots between points, with the lowest speed point at approximately 20 to 30 knots. Weight should be computed for each point and the test altitude adjusted to maintain a constant W/σ. After the data are reduced to standard day conditions, the minimum power required airspeed will result in the airspeed for maximum rate of climb. However, aircraft stability may suggest that a higher climb speed may be used for VY.
(3) Prior to the flight test, the rotorcraft should be ballasted to the desired gross weight and the critical center of gravity. The airspeed should be stabilized prior to data acquisition. Data to be recorded includes time, altitude, airspeed, ambient temperature, engine parameters, torque(s), rotor RPM, fuel reading, aircraft heading, external configuration, etc. Power setting, weight, and climb airspeed should be planned prior to flight. For some turboshaft engines, temperature and/or engine speed limits may be reached prior to a limiting torque. The test team should verify that the resulting power utilized in these tests closely approximates the power producing capabilities of installed minimum specification engine.
c. Procedure to Determine all Engine Operating Climb Performance.
(1) Background. Continuous climbs are conducted at the appropriate climb airspeeds as outlined above in order to obtain the rotorcraft’s climb performance for the flight manual. By -products are a qualitative evaluation of the rotorcraft handling characteristics in a climb and engine data to assist in the determination of installed power available.
(2) Techniques. The techniques used to determine this performance may be the same as those used in the VY determination. The climbs are conducted on reciprocal headings at the established airspeed(s) through the target altitude range.
The same parameters are recorded. The rotorcraft will usually climb very rapidly during the first few thousand feet; therefore, the data acquisition method should be timely if accurate results are expected. This procedure is usually repeated at weight extremes.
The resulting data should then be corrected for power and weight. Power and weight corrections are satisfactory, provided the test powers and weights closely approximate the target values to make the weight and power corrections accurate. Once this data is finalized and corrected for all the flight test variables, interpolation for intermediate weights can be made with a high degree of reliability. If the rotorcraft has any stability augmentation system, vent systems, etc., which may influence the climb performance, then it should be accounted for. Caution should be taken that anti -ice, air-conditioning, etc., are not on unless the performance is being established specifically for those conditions.
AC 29.67. § 29.67 (Amendment 29-34) CLIMB: ONE ENGINE INOPERATIVE.
a. Explanation.
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(1) Section 29.67 requires that Category A rotorcraft must be capable of a steady rate-of-climb without ground effect, of at least 100 feet per minute for all combinations of weight, altitude, temperature, and center of gravity for which takeoffs are to be scheduled. The rate- of-climb is determined with the critical engine inoperative and the remaining engine(s) operating within approved operating limits. The landing gear is extended and the airspeed is the takeoff safety speed (VTOSS) selected by the applicant.
(2) In addition, the steady rate-of-climb must be at least 150 feet per minute at 1,000 feet above the takeoff surface for which takeoffs are to be scheduled. The rate-of-climb will be determined with the critical engine inoperative and the remaining engine(s) at maximum continuous or the 30-minute minimum specification installed power available values. The landing gear is retracted and the airspeed is that selected by the applicant.
b. Procedures.
(1) One of the acceptable procedures used to obtain the required climb performance is similar to the all engine climb performance determination (paragraph AC 29.65) except that the VTOSS and the Category A climb speed may be selected by the applicant for different weights and ambient conditions. The Category A climb speed could be a single speed, vary as VY does, or actually be VY. Making a Category A climbout speed equal to VY should be encouraged to simplify cockpit procedures. The required results are the allowable weight, altitude, and temperature combinations wherein the rotorcraft is capable of demonstrating 100 feet per minute rate-of-climb at VTOSS and 150 feet per minute rate-of-climb at 1,000 feet above the takeoff surface. Either of these two climb requirements may establish the maximum allowable takeoff weight.
(2) For multiengine Category B rotorcraft with engine isolation, the steady rate of climb or descent must be determined at VY, using maximum continuous power and 30-minute power if that rating is approved. Appropriate performance data must be included in the Rotorcraft Flight Manual to cover variations in gross weight, altitude, and temperature.
(3) Since climb performance testing is normally conducted separately from Category A and B takeoff performance testing, it is imperative the engine power(s), rotor RPM, and aircraft configuration be the same as those used during the takeoff testing to ensure the climb performance demonstrated will be that attainable immediately after an engine failure during takeoff. The allowable pilot/crew actions during the Category A takeoff and climbout maneuver must be thoroughly evaluated. The pilot’s full attention is required to control the rotorcraft during this phase of flight. Permitting the pilot to readjust (beep) the rotor RPM during this phase of flight should be considered only if such adjustment can be accomplished without a significant increase in pilot workload.
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(4) A typical sequence for selecting the various speeds to comply with this requirement is as follows:
(i) Conduct sawtooth climbs at the various airspeeds (VY and below) up to the proposed takeoff and landing altitudes. From this a determination can be made regarding the maximum allowable weight that will result in a rate of climb of 150 feet per minute at the selected VY for the proposed ambient conditions.
(ii) At the same time determine the minimum value of VTOSS that will result in 100 feet per minute rate of climb at the maximum weight determined in (b)(4)(i).
AC 29.67A. § 29.67 (Amendment 29-39) CLIMB: ONE ENGINE INOPERATIVE.
a. Explanation.
(1) Amendment 29-39 expanded the OEI rate of climb requirements. The guidance material presented in paragraph AC 29.67 does not apply to rotorcraft certified with Amendment 29-39 or later. Section 29.67 requires that Category A rotorcraft should be capable of a steady rate-of-climb without ground effect 200 feet above the takeoff surface, of at least 100 feet per minute for all combinations of weight, altitude, temperature, and center of gravity for which takeoffs are to be scheduled. The rate-of-climb is determined with the critical engine inoperative and the remaining engine(s) operating within approved operating limits. The landing gear is extended and the airspeed is the takeoff safety speed (VTOSS) selected by the applicant.
(2) The steady rate-of-climb should be at least 150 feet per minute at 1,000 feet above the takeoff surface for which takeoffs are to be scheduled. The rate- of-climb will be determined with the critical engine inoperative and the remaining engine(s) at maximum continuous or the 30-minute minimum specification installed power available values. The landing gear is retracted and the airspeed is that selected by the applicant.
(3) Additionally, the steady state rate of climb or descent must be determined with the critical engine inoperative and the remaining engines at OEI maximum continuous power and at 30-minute OEI power if applicable. This performance must be scheduled throughout the ranges of weight, altitude and temperatures for which certification is requested with the landing gear retracted, at an airspeed selected by the applicant.
b. Procedures.
(1) One of the acceptable procedures used to obtain the required climb performance is similar to the all engine climb performance determination (paragraph AC 29.65) except that the VTOSS and the Category A climb speed may be selected by the applicant for different weights and ambient conditions. The Category A climb speed could be a single speed, vary as VY does, or actually be VY. Making a Category A climbout speed equal to VY should be encouraged to simplify cockpit Page B - 65
procedures. The required results are the allowable weight, altitude, and temperature combinations wherein the rotorcraft is capable of demonstrating 100 feet per minute rate-of-climb at VTOSS at a height of 200 feet above the takeoff surface and 150 feet per minute rate-of-climb at 1,000 feet above the takeoff surface. Either of these two climb requirements may establish the maximum allowable takeoff weight.
(2) For multiengine Category B rotorcraft with engine isolation, the steady rate of climb or descent should be determined at VY, using maximum continuous power, maximum continuous OEI power, and 30-minute power if that rating is approved.
Appropriate performance data should be included in the Rotorcraft Flight Manual to cover variations in gross weight, altitude, and temperature.
(3) Since climb performance testing is normally conducted separately from Category A and B takeoff performance testing, it is imperative the engine power(s), rotor RPM, and aircraft configuration be the same as those used during the takeoff testing to ensure the climb performance demonstrated will be that attainable immediately after an engine failure during takeoff. The allowable pilot/crew actions during the Category A takeoff and climbout maneuver should be thoroughly evaluated. The pilot’s full attention is required to control the rotorcraft during this phase of flight. Permitting the pilot to readjust (beep) the rotor RPM during this phase of flight should be considered only if such adjustment can be accomplished without a significant increase in pilot workload.
(4) A typical sequence for selecting the various speeds to comply with this requirement is as follows:
(i) Conduct sawtooth climbs at the various airspeeds (VY and below) up to the proposed takeoff and landing altitudes. From this, a determination can be made regarding the maximum allowable weight that will result in a rate of climb of 150 feet per minute at the selected VY for the proposed ambient conditions.
(ii) At the same time, determine the minimum value of VTOSS that will result in 100 feet per minute rate of climb at the maximum weight determined in b(4)i.
AC 29.71. § 29.71 (Amendment 29-12) ROTORCRAFT ANGLE OF GLIDE:
CATEGORY B.
a. Explanation.
(1) Performance capabilities during stabilized autorotative descent are useful pilot tools to assist in the management of a Category B rotorcraft when all engines fail.
This information is also useful in determining the suitability of available landing areas along a given route segment.
(2) Two speeds are of particular importance, the speed for minimum rate of descent and the speed for best angle of glide. These speeds are required as flight manual entries per § 29.1587. The speed for minimum rate of descent is useful for Page B - 66
engine failure conditions at higher altitudes and the pilot is required to perform some time-related task, engine restart, float inflation, radio calls, etc. The speed for best angle of glide is a somewhat higher speed that is of particular use when it is necessary to reach a distant landing area. This speed, with appropriate rotor RPM, provides the maximum horizontal distance available from a particular altitude assuming zero wind conditions.
(3) A third speed, recommended autorotation speed, may be provided in addition to minimum rate of descent speed and maximum glide angle speed. The recommended speed for autorotation is usually optimized to assure an effective flare capability and yet be slow enough to allow a controlled, relatively slow touchdown condition. Recommended autorotation speed is ordinarily between the minimum rate of descent and maximum glide angle speeds. The recommended autorotation speed may be provided in the Rotorcraft Flight Manual. The relationship between minimum rate of descent, best glide angle, and recommended autorotation speed is shown in figure AC 29.71-1.
(4) Forward center of gravity is usually critical, however, center of gravity effects should be spot-checked to confirm this for a given design.
b. Procedures.
(1) Tests are conducted at speeds which bracket the anticipated speeds for minimum rate of descent and best glide angle. On a power required plot, the speed for minimum power required approximates the speed for minimum rate of descent. The speed for maximum range glide may be estimated by drawing a tangent from the origin to the power required curve.
(2) Autorotative performance tests may be conducted in conjunction with the climb performance tests. The required data are similar for both tests and it is sometimes convenient and efficient to run alternating climbs and descents through a desired altitude band. Descents should be conducted on reciprocal headings and results averaged in the same manner as climb performance tests.
(3) A reduction in rotor RPM from the normal power-on value may enhance autorotative performance. If the applicant wishes to develop autorotative performance at RPM values significantly below the governing or power-on range, the practicality of reducing and controlling RPM at the lower value and of then increasing RPM as a landing is approached, must be considered. At low weights and low density altitudes, full down collective may automatically produce lower RPM values and this condition is, of course, acceptable provided the approved power-off RPM range is not exceeded.
(4) Care must be taken to make certain that no engine power is delivered to the rotor drive system since a very small amount of power can have a large effect on descent performance.
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RATE OF
DESCENT RECOMMENDED
AUTOROTATIONAL SPEED
BEST GLIDE ANGLE
MINIMUM
RATE OF DESCENT
AIRSPEED FIGURE AC 29.71-1 AUTOROTATIONAL CHARACTERISTICS - TYPICAL Page B - 68