Page B - 20 exercised and/or the operator has demonstrated his ability to operate safely with deteriorated engines.
AC 29.45A. § 29.45 (Amendment 29-24) PERFORMANCE - GENERAL.
a. Explanation . Amendment 29-24 adds § 29.45(f) to the regulation. This section establishes the requirement for furnishing power assurance information for turbine powered aircraft. This information is to provide the pilot a means of determining, prior to takeoff, that each engine will produce the power necessary to achieve the performance presented in the rotorcraft flight manual (RFM).
b. Procedures . All of the policy material pertaining to this section remains in effect. In addition, the power assurance information included in the RFM should be verified. Although this requirement is normally met with a power assurance curve, other methods of compliance may be proposed.
AC 29.45B. § 29.45 (Amendment 29-24) PERFORMANCE - GENERAL.
a. Explanation . Amendment 29-34 added the requirements for certification of 30-second/2-minute One Engine Inoperative (OEI) power ratings. For rotorcraft approved for the use of 30-second/2-minute OEI, partial power checks currently accomplished with approved power assurance procedures for lower power levels may not be sufficient to guarantee the ability to achieve the 30-second power level.
b. Procedures . Information provided in paragraph AC 29 MG 9 includes guidance material on power assurance procedures to ensure that the OEI power level can be achieved. The guidance material presented in paragraphs AC 29.45 and AC 29.45A continue to apply.
Page B - 21
CERTIFICATION BASIS
FAR 29 CAR 7 Requirement s 29-Amdt. 21 29-Amdt. 1 Original Original H-V Ref.
29.25
29.87
29.1517
29.1581
29.1583
7.11
7.715
7.741 CAT A TEST
CONDITIONS Cat A & B (>9 pax seats):
1. W.A.T. for which
t.o. and ldg. are approved.
2. Failure of critical engine.
Cat A:
1. MGW Sea Level
2. Max. IGE wt.
Max.
alt. capability.
3. Failure of critical engine.
Cat A:
1. MGW Sea Level
2. Max. IGE wt.
Max.
alt. capability.
3. Failure of critical engine.
Cat. A:
1. MGW Sea Level
2. Max. IGE wt.
Max.
alt. Capability.
3. Failure of critical engine.
AC 29-2C paras AC
29.45 & AC
29.79 CAT A RFM
3. H-V is limitation.
4. Type of ldg.
surface.
4. H-V is limitation.
5. Type of ldg.
Surface.
4. H-V is limitation.
5. Type of ldg.
surface.
4. H-V is limitation.
5. Type of ldg.
surface.
CAT B TEST
CONDITIONS Cat B (</=9 pax seats):
1. MGW Sea Level
2. Max. OGE wt.
Max.
alt. Capability
3. Complete power failure, or failure of critical engine (w/eng isolation).
Cat B:
1. MGW Sea Level
2. Max. IGE wt.
Max.
alt. Capability
3. Complete power failure, or failure of critical engine (w/eng isolation).
Cat B:
1. MGW Sea Level
2. Max. IGE wt.
Max.
alt. Capability
3. Complete power failure, or failure of critical engine (w/eng isolation.)
Cat B:
1. MGW Sea Level
2. Max. IGE wt.
Max.
alt. Capability
3. Complete power failure, or failure of critical engine (w/eng isolation.)
CAT B RFM
4. H-V is perf. Info.
5. Type of ldg.
surface.
4. H-V is limitation info.
5. Type of ldg.
Surface.
4. H-V is limitation info.
5. Type of ldg.
surface.
4. H-V is limitation info.
5. Type of ldg.
surface.
FIGURE AC 29.45-1. H-V REQUIREMENTS
Page B - 22
CERTIFICATION BASIS
FAR 29 CAR 7 Requirement s 29-Amdt. 24 29-Amdt. 3 Original Original IGE
CONTROL Ref. 29.25
29.1583
7.121
7.743
CAT A TEST
CONDITIONS Cat A
1. W.A.T. for which
t.o. and ldg. are approved.
2. Critical wt.
Critical CG Critical Nr
3. Wind not less than 17 kts.
1. Conditions selected by the applicant.
2. Critical CG Critical Nr
3. Wind not less than 17 kts.
1. Conditions selected by the applicant.
2. Critical CG Critical Nr
3. Wind not less than 20 mph.
1. Conditions selected by the applicant.
2. Critical CG Critical NR
3. Wind not less than 20 mph.
AC 29-2C paras AC
29.45 and AC 29.143 CAT A RFM
4. Max.
allowable wind is limitation.
4. Max safe wind above max.
alt. For which 17 kt. Wind envelope is established is perf. info.
4. Max safe wind above alt. for which 17 kt. wind envelope is established is perf. info.
4. Max.
allowable wind above the altitude for which 20 mph wind envelope is est. is perf.
info.
CAT B TEST
CONDITIONS Cat B:
1. W.A.T. for which
t.o. and ldg. are approved.
2. Critical wt.
Critical CG Critical Nr
3. Wind speed & quad selected by the applicant.
CAT B RFM
4. Max. safe wind is perf.
info.
FIGURE AC 29.45-2 IGE CONTROLLABILITY REQUIREMENTS
600 500 CORRECTED SHAFT HORSEPOWER ENG S/N 12345
MIN CERTIFIED
SPECIFICATION ENGINE 100 1000 1100 1200 1300 1400 1500 CORRECTED TOT °F FIGURE AC 29.45-3 SHAFT HORSEPOWER VS TURBINE OUTLET
TEMPERATURE - SEA LEVEL STANDARD DAY Page B - 23
20 16 PRESSURE ALTITUDE - FEET (X 1000) 200 ЗАМІ 500
SHAFT HORSEPOWER AVAILABLE FIGURE AC 29.45-4 UNINSTALLED TAKEOFF POWER AVAILABLE Page B - 24
20 18 70= 10-501 C 14 TRANSMISSION LIMIT PRESSURE ALTITUDE - FEET (X 1000) 200 300 400
SHAFT HORSEPOWER AVAILABLE FIGURE AC 29.45-5 INSTALLED TAKEOFF POWER AVAILABLE, ANTI-ICE OFF, 400 RPM Page B - 25
120 EXAMPLE: OAT = 17.5°C TOT = 760° C Hp = 4000 FT REQUIRED TORQUE = 70% 80 100 PERCENT TORQUE FIGURE 29.45-6 POWER ASSURANCE CHECK CHART GENERATOR LOAD 100 AMPS 60 OUTSIDE AIR TEMPERATURE - °C CONDITIONS: ZERO AIRSPEED RPM 100% ANTI-ICE OFF 20 30 0 10 800°C 780°C 760°C 740°C 720°C 700°C 680°C 660°C Page B - 26
Page B - 27 AC 29.49. § 29.49 (Amendm ent 29-39) PERFORMANCE AT MINIMUM OPERATING SPEED. HOVER PERFORMANCE FOR ROTORCRAFT.
(For performance at minimum operating speed and for hover performance prior to Amendment 39, see § 29.73 and paragraph AC 29.73.)
a. Explanation .
(1) Amendment 29-39 redesignated § 29.73 as § 29.49 to relocate the requirements for rotorcraft hover performance. For the purpose of this manual, the word “hover” applies to a rotorcraft that is airborne at a given altitude over a fixed geographical point regardless of wind. Pure hover is accomplished only in still air.
(2) Under § 29.49, hover perform ance should be determined at a height consistent with the takeoff procedure for Category A rotorcraft and IGE for Category B rotorcraft. Additionally, OGE hover performance should be determined for both Category A and B rotorcraft. Hover OGE is that condition, where an increase in height above the ground will not require additional power to hover. Hover OGE is the absence of measurable ground effect. It can be less than one rotor diameter at low gross weight increasing significantly at high gross weights. The lowest OGE hover height at gross weight may be approximated by placing the lowest part of the vehicle 1 ½ rotor diameters above the surface.
(3) The objective of hover performance tests is to determine the power required to hover at different gross weights, ambient temperatures, and pressure altitudes.
Using nondimensional power coefficients (Cp) and thrust coefficients (Ct) for normalizing and presenting test results, a minimum amount of data are required to cover the rotorcraft’s performance operating envelope.
(4) Hover performance tests must be conducted over a sufficient range of pressure altitudes and weights to cover the approved ranges of those variables for takeoff and landings. Additional data should be acquired during cold ambient temperatures, especially at high altitudes, to account for possible Mach effects.
(5) The minimum hover height for which data should be obtained and subsequently presented in the flight manual should be the same height consistent with the minimum hover height demonstrated during the takeoff tests. Refer to paragraph AC 29.51 for the procedure to determine the minimum allowable hover height.
b. Procedures .
(1) Two methods of acquiring hover per formance data are the tethered and free flight techniques. The tethered technique is accomplished by tethering the rotorcraft to the ground using a cable and load cell. The load cell and cable are attached to the ground tie-down and to the rotorcraft cargo hook. The load cell is used to measure the
Page B - 28 rotorcraft’s pull on the cable. Hover heights are based on skid or wheel height above the ground. During tethered hover tests, the rotorcraft should be at light gross weight.
The rotorcraft will be stabilized at a fixed power setting and rotor speed at the appropriate skid or wheel height. Once the required data are obtained, power should be varied from the minimum to the maximum allowed at various rotor RPM. This technique will produce a large Ct/Cp spread. The load cell reading is recorded for each stabilized point. The total thrust the rotor produces is the rotorcraft’s gross weight, weight of the cables and load cell plus cable tension. Care must be taken that the cable tension does not exceed the cargo hook limit or load capacity of the tie-down. For some rotorcraft, it may be necessary to ballast the rotorcraft to a heavy weight in order to record high power hover data.
(2) The pilot maintains the rotorcraft in position so that the cable and load cell are perpendicular to the ground. To insure the cable is vertical, two outside observers, one forward of the rotorcraft and one to one side, can be used. Either hand signals or radio can be used to direct the pilot. The observers should be provided with protective equipment. This can also be accomplished by attaching two accelerometers to the load cell which sense movement along the longitudinal and lateral axes. Any displacement of the load cell will be reflected on instrumentation in the cockpit and by reference to this instrumentation, the rotorcraft can be maintained in the correct position. Accurate load cell values may also be obtained by measuring cable angles and, through geometry, determining a corrected load cell value. Increased caution should be utilized as tethered hover heights are decreased because the rotorcraft may become more difficult to control precisely. The tethered hover technique is especially useful for OGE hover performance data because the rotorcraft’s internal weight is low and the cable and load cell can be jettisoned in the event of an engine failure or other emergency.
(3) To obtain consistent data, the wi nd velocity should be 3 knots or less.
Large rotorcraft with high downwash velocities may tolerate higher wind velocities. The parameters usually recorded at each stabilized condition are:
(i) Engine torques.
(ii) Rotor speed.
(iii) Ambient temperatures.
(iv) Pressure altitude.
(v) Fuel used (or remaining).
(vi) Load cell reading.
(vii) Generator(s) load.
Page B - 29 As a technique, it is recommended the rotorcraft be loaded to a center of gravity near the hook to minimize fuselage angle changes with varying powers. All tethered hover data should be verified by a limited spotcheck using the free flight technique. The free flight technique as contained in paragraph b(4) below will determine if any problems, such as load cell malfunctions have occurred. The free flight hover data must fall within the allowable scatter of the tethered data.
(4) If there are no provis ions or equipment to conduct tethered hover tests, the free flight technique is also a valid method. The disadvantage of this technique as the primary source of data acquisition is that it is very time consuming. In addition a certain element of safety is lost OGE in the event of emergency. The rotorcraft must be reballasted to different weights to allow the maximum Ct/Cp spread. When using the free flight technique, either as a primary data source or to substantiate the tethered technique, the same considerations for wind, recorded parameters, etc., as used in the tethered technique apply. Free flight hover tests should be conducted at CG extremes to verify any CG effects. If the rotorcraft has any stability augmentation system which may influence hover performance, it must be accounted for.
(5) It is extremely difficult to determi ne when a rotorcraft is hovering OGE at high altitudes above ground level since there is no ground reference. In a true hover, the rotorcraft will drift with the wind. Numerous techniques have been tried to allow OGE hover data acquisition at high altitudes, all of which have resulted in much data scatter. Until a method is proposed and found acceptable to the FAA/AUTHORITY, OGE hover data must be obtained at the various altitude sites where IGE hover data is obtained. Hover performance can usually be extrapolated up to a maximum of 4,000 feet.
AC 29.51. § 29.51 TAKEOFF DATA - GENERAL .
a. Explanation . Section 29.51 details the conditions under which takeoff performance data can be obtained and presented in the FAA/AUTHORITY approved flight manual. The flight manual must also contain the technique(s) to be used to obtain the published flight manual takeoff performance. Technique should not be confused with exceptional pilot skill and/or alertness as mentioned in § 29.51. Rotorcraft are different from one another and due to this, different pilot techniques are sometimes required to achieve the safest and most optimum takeoff performance. The recommended technique that is published in the flight manual and used to achieve the performance must be determined to be one that the operational pilot can duplicate using the minimum amount of type design cockpit instrumentation and the minimum crew.
b. Background .
(1) Certain special takeoff techniques ar e necessary when a rotorcraft is unable to takeoff vertically because of altitude, weight, power effects, or operational limitations.
The recommended technique used to take off under such conditions is to accelerate the rotorcraft in-ground-effect (IGE) to a predetermined airspeed prior to climbout. Takeoff
Page B - 30 tests are performed to determine the best repeatable technique(s) for a particular rotorcraft over the range of weight, altitude, and temperature for which certification is requested.
(2) The primary factor which determines the rotorcraft’s takeoff performance is the amount of excess power available. Excess power available is the difference between the power required to hover at the reference height above the ground and the takeoff power available from a minimum installed specification engine. Utilizing the total power available to execute a takeoff may not be operationally feasible due to such items as HV constraints. In such situations, hover power required plus some power increment may be the maximum that can be used and the resulting performance determined accordingly.
(3) Landing gear height above the ground should not be greater than that demonstrated satisfactorily for HV, rejected takeoff, and that height for which IGE hover performance data is presented in the RFM, or less than that height below which ground contact may occur when accomplishing takeoff procedures. For rotorcraft fitted with wheels, a running takeoff procedure may be accepted. The hover reference height is established as the minimum landing gear height above the takeoff surface, from which a takeoff can be accomplished consistently in zero wind without contacting the runway.
Category B takeoff must be accomplished with power fixed at the power required to hover at the reference height (not greater than the height for which IGE performance data is presented).
c. Procedure . There are different techniques which may be used in order to determine which method is best for a particular rotorcraft. The most commonly accepted method is the hover and level acceleration technique. In this technique, the rotorcraft is stabilized in a hover at the reference height. From the stabilized hover, the rotorcraft is accelerated to the climbout airspeed using the predetermined takeoff power.
When the desired climbout airspeed is achieved, the rotorcraft is rotated and the climbout is accomplished at the schedule airspeed(s) and constant rotor RPM. Power adjustments may be accomplished to maintain targeted power except where procedure requires high workload outside cockpit (i.e., that portion of takeoff where horizontal acceleration close to the ground has pilot scan outside the cockpit and adjustment of engine torque or temperature would require an undue increase in workload).
AC 29.51A. § 29.51 (Amendment 29- 39) TAKEOFF DATA - GENERAL.
a. Explanation . Amendment 39 added takeoff requirements in new §§ 29.55,
29.60, 29.61 and 29.62.
b. Procedures . The guidance material presented in paragraph AC 29.51 continues to apply.
Page B - 31 AC 29.53. § 29.53 TAKEOFF: CATEGORY A .
a. Explanation .
(1) A Category A takeoff typically begins with an acceleration and/or climb from a hover to a critical decision point. The rule requires that the critical decision point (CDP) be defined for the pilot in terms of an indicated altitude and airspeed combination. However, other parameters to define the CDP have been accepted by the FAA/AUTHORITY on an equivalent safety basis. A regulatory project has been established to change the rule permitting other parameters to be used for CDP definition.
(2) The requirement to define CDP as a combination of both airspeed and height above the takeoff surface is based on a minimum required total energy concept.
A specific minimum combination of kinetic energy (airspeed) and potential energy (height) must be attained at the CDP to be assured that a continued takeoff can be accomplished following the complete failure of one engine. In § 29.53(b), CDP is required to be “…a combination of height and speed selected by the applicant…” Any other method proposed to define CDP must provide the same level of safety as would be obtained using an airspeed-height combination. When using “time,” “height,” or “airspeed” only as alternative methods of identifying the CDP, they must be combined with a precisely defined takeoff path and crew procedure in order to provide the required equivalent level of safety. In addition, it must be demonstrated that the pilot technique used during the takeoff sequence is easily repeatable and consistently produces the required energy (i.e., airspeed and altitude combination) when the CDP “time,” “height,” or “airspeed” is attained. This condition should be verified during the flight test program.
(3) If an engine fails at the CDP or at any point in the takeoff profile prior to attaining CDP, the rotorcraft must be able to land safely within the established rejected takeoff distance. Flight testing to determine the Category A rejected takeoff distance is very similar to height-velocity testing and should be approached with caution. The initial Category A takeoff profiles should be outside of the Category B height-velocity envelope. Previous programs have shown the low speed point immediately after application of power to be particularly critical.
(4) If an engine fails at the CDP or at any subsequent point in the Category A takeoff profile, a continued safe climb-out capability is assured. The continued takeoff for conventional Category A runway profiles is designed to allow acquisition of the takeoff safety speed (VTOSS), at a minimum of 35 feet above the takeoff surface and a positive rate of climb. During the continued takeoff profile, the pilot is assumed to be flying the rotorcraft via the primary flight controls (cyclic stick, collective, and directional pedals). Manipulation of the throttle controls or beep switches may be permitted as long as such manipulation can be accomplished readily by the pilot flying the rotorcraft without removing his hands from the cyclic and collective flight controls. These manipulations of engine controls should not make major adjustments in power, and