c.g. limit, and present the resulting AFM performance for that same extreme forward c.g. limit. However, no corresponding requirement exists for presentation of AFM data in § 25.1583 (Operating Limitations) or § 25.1587 (Performance Information) that would limit the performance information to being presented for only the most extreme unfavorable center of gravity obtainable for a particular airplane. In the context of the part 25 airworthiness requirements, it would be acceptable to specify alternate forward c.g. limits as operating limitations, and provide takeoff performance that represents the capability of the airplane at those c.g. limits.
(5) The primary concern in granting pe rformance credit for forward c.g. limits, aft of the extreme forward limit, relates to the diminishment of the conservative performance margin that resulted from generally operating with the c.g. some measurable increment aft of the extreme forward limit, upon which the takeoff performance is based. With the availability of alternate forward c.g. limits, this intrinsic performance margin will be decreased, and on a statistical basis, completely eliminated more often. Consequently, emphasis must be put on maintaining accurate weight and balance records, implementing accurate loading plans, and providing the necessary training and operating procedures for ground and dispatch personnel.
(6) Flight crew training is also a concern for alternate forward c.g. limit operations. With many of today's transport category airplanes incorporating high levels of cockpit automation (e.g., Flight Management Systems), it is imperative that the flightcrew be aware of when an alternate forward c.g. limit is being used as the basis for computing takeoff performance data. This is of critical import when an alternate forward c.g. limit is used in conducting a performance-limited takeoff. Since the aforementioned automated onboard systems may or may not be reprogrammed to accommodate the necessary performance data, it should be emphasized that the forward c.g.
limit provided by the ground operations and dispatch personnel takes precedence over that shown by any onboard systems.
c. Procedures . Approval may be granted for as many as two alternate forward c.g. limits (for a total of three), with associated takeoff performance credit, provided the following certification and operational criteria are complied with:
(1) Certification Criteria .
(i) No more than two alternat e forward c.g. limits (three total) may be approved per operatorspecific variant of a particular airplane type and model. "Airplane type" refers to those airplanes of similar design as identified on the Type Certificate; “airplane model” refers to different versions of an airplane type as reflected on the Type Certificate. An "operator specific variant" is an airplane type and model outfitted to a particular customer's requirements (e.g., engine type, seat pitch, galley locations, etc.). For control purposes, airplanes that are classified as an "operator specific variant" must be clearly identifiable as such; this can be accomplished by definitive AFM document numbering systems and AFM's tied to specific airplane serial numbers.
(ii) The alternate fo rward c.g. limits should be sufficiently different that they will be treated as discrete limits and not result in confusion when determining takeoff performance adjustments.
(iii) The c.g. range that results from the use of an alternate forward c.g. limit must be of sufficient magnitude to be practical and allow for expected variations in operational loading.
(iv) The alternate forward c.g. limits must be identified as such and presented on the Weight and Center of Gravity chart in the limitations section of the basic AFM. That chart should also provide a reference to a separate appendix to the AFM that contains the related airplane performance adjustments.
(v) To minimize the impact on crew training and standardization of cockpit procedures, it is preferable that onboard Flight Management Systems (FMS) be modified to include the performance and fuel management data associated with the alternate forward c.g. limits. If the FMS is not modified in such a manner, a limitation must be added to the AFM that prohibits the use of the FMS when using an alternate forward c.g. limit.
(vi) The AFM performance associated with alternate forward c.g. limit operations must be substantiated by flight test data. This does not mean that flight test data needs to be obtained at every alternate forward c.g. limit; the intent is for the applicant to verify the analytical predictions of c.g. effect with flight test data collected at different c.g.’s.
(vii) All affected cockpit placards and displays must be rev ised to reflect the alternate forward c.g.
limits.
(2) Operational Criteria .
(i) Training and operational procedures, emphasizing the need for accurate weight and balance control, should be implemented. These procedures should address weight and balance knowledge of any given airplane, loading plans and procedures, dispatch responsibilities and procedures, and flightcrew awareness.
(ii) Before an operator implements alternate forward c.g. limit operations, each airplane that will be used in those operations should be weighed and its Operating Empty Weight (OEW) and center of gravity location determined. This process should be repeated on an annual basis to assure accurate knowledge of the empty airplanes’ c.g. positions.
(iii) Operators seek ing takeoff performance credit for alternate forward c.g. limits should provide evidence that their loading plans and procedures result in the c.g. location of any affected airplane being known to within 1 percent mean aerodynamic chord (MAC).
(iv) Operators with mixed fleets of a particular airplane type (i.e., more than one "operator specific variant" of a type) should provide evidence of having an accurate control system to eliminate the potential for loading errors.
(v) If the Flight Management System (FMS) databases have not been modified to reflect the effect of the alternate forward c.g. limits on performance (e.g., takeoff speeds) and fuel consumption, a limitation must be placed in the appropriate operating manuals that prohibits the use of the FMS when operating with an alternate forward c.g. limit.
(vi) All affected documents (Weight and Balance manuals, Flight Crew Operating Manual, etc.)
should be revised to reflect the alternate forward c.g. limits. These documents should also note any restrictions associated with their use.
241. PERFORMANCE CREDIT FOR AUTOMATIC PROPELLER DRAG REDUCTION DEVICES .
a. Explanation. In the description of takeoff path requirements, § 25.111(c)(4) states, in part, that "no change in power or thrust that requires action by the pilot may be made, until the airplane is 400 feet above the takeoff surface." This can result in significant takeoff performance penalties for propeller driven airplanes if the propeller on the critical inoperative engine remains in takeoff pitch, or assumes some other high drag windmilling pitch. Devices that automatically reposition an engine's propeller to a blade angle that reduces its drag contribution
(e.g., autofeather systems), upon failure of the engine, can provide significant takeoff performance gains.
Performance credit has been approved for the operation of these automatic propeller drag reduction devices, below 400 feet above the takeoff surface, when compliance with the criteria described below has been shown.
b. Procedures .
(1) Propeller pitch setting generally has a significant effect on minimum control speeds and airplane drag. The magnitude of these effects is such that continued safe flight may not be possible should a combined failure of an engine and its automatic propeller drag reduction system occur at a takeoff speed based on operation of that system. Consequently, in accord with the stipulations of § 25.1309(b)(1), the probability of this combined failure must be shown to be extremely improbable (on the order of 10 -9 per flight hour).
(2) In determining the combined engine and automatic propeller drag reduction system failure rate of paragraph (1) above, the engine failure rate should be substantiated. Notwithstanding the in-service engine failure rate, the failure of the automatic propeller drag reduction system should be shown not to exceed 10 -4 per flight hour.
(3) The automatic propeller drag reduction system should be designed so that it will automatically be disabled on the operating engine(s) following operation on the failed engine. The probability of an unwanted
operation of the automatic propeller drag reduction system on an operating engine, following its operation on the failed engine, should be shown to be extremely improbable (on the order of 10 -9 per flight hour).
(4) If performance credit is given for operation of the automatic propeller drag reduction system in determining the accelerate-go takeoff distances, the propeller of the failed engine must also remain in the reduced drag position in determining the accelerate-stop distances.
(5) In determining the brake application speed for the maximum energy rejected takeoff demonstration of § 25.109(g), consideration should be given to the accelerate-stop configuration (all-engines-operating vs. engine failure with automatic propeller drag reduction system operation) that will produce the greatest brake energy absorption requirement.
(6) The limitations section of the Airplane Flight Manual should contain a requirement for a flight crew functional check of the automatic propeller drag reduction system. The frequency with which flight crew functional checks and ground maintenance checks of the automatic propeller drag reduction system are required will be considered in the evaluation of the system reliability.
(7) Clear annunciations should be provided to the flight crew for the following:
(i) The automatic propeller drag reduction system is "ARMED."
(ii) A malfunction exists in the automatic propeller drag reductio n system.
242. AIRPLANE BACKING USING REVERSE THRUST .
a. Explanation. Where compliance with applicable airworthiness requirements has been demonstrated, operational approval has been granted for the use of reverse thrust to back airplanes away from airport gates in lieu of a tug pushback. The applicable airworthiness requirements are prescribed in paragraph b, below. Note that compliance with these requirements only demonstrates the capability of the airplane, and does not constitute operational approval; operational approval should be coordinated with the applicable FAA Flight Standards office.
b. Procedures . To obtain airworthiness approval for reverse thrust backing, compliance should be demonstrated with the criteria prescribed below. Since operational approvals for reverse thrust backing specify the applicable airplanes, airports, and gates, some of these tests will be "site" specific and should be coordinated with the applicable FAA Flight Standards office.
(1) Both the airplane and engine manufacturer should determine the applicability of the maneuver and provide appropriate limitations for the procedure. These limitations should include:
(i) Engine power setting and operating parameter limits;
(ii) Minimum and maximum allowable w eights;
(iii) Center of gravity (c.g.) limits;
(iv) Ramp slope limits;
(v) Use of wheel brakes;
(vi) Atmospheric conditions (see NOTE, below); and
(vii) Any other factor unique to the proposed operation.
NOTE: The use of reverse thrust backing with snow, ice, or slush on the ramp, or during periods of heavy rain, is not considered good operating practice.
(2) All limitations, and any normal or abnormal operating procedures, associated with reverse thrust backing should be included in the Airplane Flight Manual (AFM). Any procedures related to ground crew functions should also be included in the AFM.
(3) Testing should be conducted to verify that the reverser efflux does not have a detrimental effect on the powerplant installations. Items to be considered include:
(i) Foreign object damage (FOD);
(ii) Effects on engine cooling;
(iii) Inlet flow distortion;
(iv) Reingestion of exhaust gases; and
(v) Any effects on engine mounted accessories.
(4) Testing shou ld be conducted to verify that the reverser efflux does not have a detrimental effect on other airplane systems such as air conditioning system inlets, APU inlets and exhausts, overboard drains, etc.
(5) It should be verified that cockpit and cabin air will not be contaminated.
NOTE: It is acceptable to have a limitation prohibiting the operation of the air conditioning packs during reverse thrust backing to avoid cockpit and cabin air contamination.
(6) Reverse thrust backing demonstrations should be conducted to evaluate the associated procedures.
These demonstrations should be conducted at:
(i) Maximum ramp weight with the c.g. at the aft limit, and
(ii) Any other weight that may be critical with the c.g. at the aft limit.
(7) The reverse thrust backing demonstrations of paragraph (6), above, should be evaluated to determine:
(i) The degree of aft pitching moment, including its effect on nose wheel steering;
(ii) The effect of inadvertent heavy/emergency braking action;
(iii) Adequate cockpit visibility and ground crew function;
(iv) The adequacy of procedures for transitioning from reverse to forward thrust;
(v) The effect of thrust asymmetry due to failure of an engine to enter reverse, or recover forward thrust mode;
(vi) The effects of low tire pressures;
(vii) The effect of ramp slope and surface condition;
(viii) The effects of ambient atmospheric temperature; and
(ix) The effect of flap/slat configuration.
APPENDIX 1
HISTORY OF JET TRANSPORT PERFORMANCE STANDARDS When the first jet transport airplanes were certificated in the late 1950s, the applicable transport category airworthiness regulations were contained in Part 4b of the Civil Air Regulations (CAR 4b). The airworthiness requirements of CAR 4b were developed from years of experience with propeller-driven airplanes powered by reciprocating engines. The different powerplant operating principles, and expanded speed and altitude envelopes of the first generation jet-powered airplanes required comprehensive changes to the performance requirements of CAR 4b. Special Civil Air Regulation No. SR-422 was adopted in July 1957 as a supplement to CAR 4b, containing airworthiness and operational requirements that were applicable to transport category airplanes powered by turbine engines (turbojet and turbopropeller). As experience was gained, SR-422 was amended in July 1958 (SR-422A) and July 1959 (SR-422B) to better reflect the operating environment of these new airplane designs.
These Special Civil Air Regulations, presented in this appendix, formed the basis for the current transport category airworthiness and operating performance regulations of 14 CFR parts 25, 121, and 135. Though the number of operational airplanes that were certificated to these requirements is continually decreasing, these Special Civil Air Regulations, and the related preamble material, still provide a worthwhile perspective on many of the issues behind the development of today ’s regulations, and are therefore preserved for future reference in this appendix.
SPECIAL CIVIL AIR REGULATION NO. SR-422 Effective: August 27, 1957 Adopted: July 23, 1957 Turbine-Powered Transport Category Airplanes of Current Design Part 4b of the Civil Air Regulations contains rules governing the design of transport category airplanes. For a number of years, this part has established airworthiness requirements for this category of airplanes by prescribing detailed provisions to be met for the issuance of a type certificate. However, the advent of turbine-powered airplanes (jets, turbo-props, etc.) has brought about operations at considerably higher speeds and altitudes than those involving reciprocating engine airplanes. These higher speeds and altitudes as well as certain inherent characteristics of turbine engines have introduced numerous new technical and design problems and have necessitated re-evaluation and amendment of many provisions in Part 4b.
In recent years the Board has amended Part 4b by introducing numerous technical provisions more specifically applicable to turbine-powered airplanes. These were included in amendments pertaining to structural, flight characteristic, powerplant installation, and other provisions. It is believed that Part 4b as now written is applicable to turbine-powered airplanes with but one exception; namely, airplane performance. In the future, further amendments to this part, other than those relating to performance, will be comparatively minor in nature mainly reflecting the latest experience in the certification and operation of these airplanes.
The performance requirements presently in Part 4b were first promulgated almost twelve years ago. They are now considered by the Board to be in a form not suitable for direct application to turbine-powered airplanes.
The administrator of Civil Aeronautics is in receipt of a large number of applications for type certification of turbine-powered airplanes. However, the so-called "non-retroactive" clause of section 4b.11(a) of Part 4b does not make applicable to a particular airplane type any amendment which is adopted after an application is filed by the manufacturer for type certification of that airplane. Thus, most of these airplanes are not now required to meet some of the latest effective provisions of Part 4b unless the Board prescribes otherwise. With so many applications for type certificates pending, it is essential that the Board establish adequate requirements which will effectively apply to the type certification of turbine-powered transport category airplanes. This Special Civil Air Regulation is being promulgated for that purpose.
This Special Civil Air Regulation is being made effective with respect to all turbinepowered transport category airplanes not yet certificated. In essence, it prescribes a revised set of performance requirements for turbine-powered airplanes and incorporates such of the recent amendments to Part 4b as the Administrator finds necessary to insure that the level of safety of turbine-powered airplanes is equivalent to that generally intended by Part 4b.
The performance requirements contained herein include not only the performance requirements necessary for the certification of an airplane, but also the complementary performance operating limitations as applicable under Parts 40, 41, and 42 of the Civil Air Regulations. In promulgating this new performance code, the Board intends that the resulting level of safety will be generally similar to the level of safety established by the performance code as expressed by the provisions now contained in Parts 4b and 40 (or 41 or 42 as appropriate) for reciprocating engine airplanes. To attain this, many of the performance provisions have been modified for better applicability to turbine-powered airplanes, some in the direction of liberalization, others in the direction of improvement in the required performance.
A significant change being made is the introduction of full temperature accountability in all stages of performance, except the landing distances required. The introduction of full temperature accountability will insure that the airplane's performance is satisfactory irrespective of the existing atmospheric temperature. The performance requirements heretofore applicable did not give sufficient assurance in this respect.
The reason for omitting the direct application of temperature accountability in the requirement for landing distances is that this stage of performance always has been treated in a highly empirical fashion whereby temperature effects are taken into account indirectly together with the effects of other operational factors. Long range studies on rationalization of airplane performance so far have not yielded a satisfactory solution to the landing stage of performance.
The Board hopes, however, that continued studies will result in a solution of this problem in the near future.
The introduction of full temperature accountability has necessitated a complete reevaluation of the minimum climb requirements. Since the prescribed climb must now be met at all temperatures rather than to be associated with standard temperature, the specific values of climb have been altered. In each instance, the change has been in the downward direction because, although the previous values were related to standard temperature, a satisfactory resultant climb performance was attained at temperatures substantially above standard. While values of minimum climb performance specified in the new code will tend to increase the maximum certificated weights of the airplane for the lower range of temperatures, they will limit these weights for the upper range of temperatures, giving adequate assurance of satisfactory climb performance at all temperatures.
In considering the various stages of flight where minimum values of climb have been heretofore established, the Board finds that in two of the stages (all-engines-operating en route and one-engine-inoperative en route) the establishment of minimum values of climb is unnecessary because, in the case of the all-engines-operating stage, it has been found not to be critical and the case of the one-engine-inoperative stage is now more effectively covered by the en route performance operating limitations.
Considering that the minimum climbs being prescribed affect mainly the maximum certificated weights of the airplane but not the maximum operating weights, the Board, in adopting the new performance code, places considerable emphasis on the ability of the airplane to clear obstacles on take-off and during flight. To this end, criteria for the take-off path, the en route flight paths, and the transition from take-off to the en route stage of flight have been prescribed to reflect realistic operating procedures. Temperature is fully accounted for in establishing all flight paths and an expanding clearance between the take-off path and the terrain or obstacles is required until the en route stage of flight is reached.
In order to insure that the objectives of the prescribed performance are in fact realized in actual operations, the manufacturer is required to establish procedures to be followed in the operation of the airplane in the various conditions specified in the regulation. These procedures, each designed for a specific airplane, will permit the operator to utilize the full performance capabilities of the airplane more readily than if the regulations prescribed all-inclusive procedures. The use of these procedures in determining compliance with the requirements governing take-off, en route, and landing stages, will also add considerable flexibility to the regulation.
The new performance requirements established more clearly than heretofore which of the performance limitations are conditions on the airworthiness certificate of the airplane. In addition to the maximum certificated take-off and landing weights, there are included limitations on the take-off distances and on the use of the airplane within the ranges of operational variables,
such as altitude, temperature, and wind. Since these limitations are in the airworthiness certificate, they are applicable to all type operations conducted with the airplane.
The new performance code contains values for minimum climb expressed as gradients of climb, in percent, rather than as rates of climb, in feet per minute, as has been the case heretofore. The Board believes that the gradient of climb is more direct in expressing the performance margins of the airplane. Use of the gradient eliminates the influence of the stalling speed on the required climb. Heretofore, higher rates of climb were required for airplanes with higher stalling speeds. The only differentiation in the new code with respect to the required climb is between two and four-engine airplanes. This type of differentiation is of long standing in the regulations, being applicable to the one-engine-inoperative stage of flight. It is now being expanded to the take-off and approach stages.
The new performance requirements contained herein are based on the best information presently available to the Board. It is realized, however, that due to the present limited operating experience with turbine-powered transport airplanes, improvement in the requirements can be expected as a result of the direct application of the code to specific designs of new airplanes.
There are certain areas in the new requirements where additional refinement of details might be advisable. This is so particularly in the case of the requirements pertaining to the landing stage of flight. It is anticipated that, after further study of the regulation and especially after its application in the design, certification, and operation of forthcoming turbine-powered airplanes, the desirability of changes may become more apparent. It is the intent of the Board to consider without delay such changes as might be found necessary. Only after the provisions of this Special Civil Air Regulation are reasonably verified by practical application will the Board consider incorporating them on a more permanent basis into Parts 4b, 40, 41, and 42 of the Civil Air Regulations.
This Special Civil Air Regulation is not intended to compromise the authority of the Administrator under section 4b.10 to impose such special conditions as he finds necessary in any particular case to avoid unsafe design features and otherwise to insure equivalent safety.
Interested persons have been afforded an opportunity to participate in the making of this regulation (21 F.R. 6091), and due consideration has been given to all relevant matter presented.
In consideration of the foregoing, the Civil Aeronautics Board hereby makes and promulgates the following Special Civil Air Regulation, effective August 27,1957.
Contrary provisions of the Civil Air Regulations notwithstanding, all turbine-powered transport category airplanes for which a type certificate is issued after the effective date of this Special Civil Air Regulation shall comply with the following:
1. The provisions of Part 4b of the Civil Air Regulations, effective on the date of application for type certificate; and such of the provisions of all subsequent amendments to Part 4b, in effect prior to the effective date of this special regulation, as the Administrator finds necessary to insure that the level of safety of turbine-powered airplanes is equivalent to that generally intended by Part 4b.
2. In lieu of sections 4b.110 through 4b.125, and 4b.743 of Part 4b of the Civil Air Regulations, the following shall be applicable:
PERFORMANCE 4T.110 General.
(a) The performance of the airplane shall be determined and scheduled in accordance with, and shall meet the minima prescribed by, the provisions of sections 4T.110 through 4T.123. The performance limitations, information, and other data shall be given in accordance with section 4T.743.
(b) Unless otherwise specifically prescribed, the performance shall correspond with ambient atmospheric conditions and still air. Humidity shall be accounted for as specified in paragraph (c) of this section.
(c) The performance as affected by engine power and/or thrust shall be based on a relative humidity of 80 percent at and below standard temperatures and on 34 percent at and above standard temperatures plus 50°F. Between these two temperatures the relative humidity shall vary linearly.
(d) The performance shall correspond with the propulsive thrust available under the particular ambient atmospheric conditions, the particular flight conditions, and the relative humidity specified in paragraph (c) of this section. The available propulsive thrust shall correspond with engine power and/or thrust not exceeding the approved power and/or thrust less the installational losses and less the power and/or equivalent thrust absorbed by the accessories and services appropriate to the particular ambient atmospheric conditions and the particular flight condition.
4T.111 Airplane configuration, speed, power, and/or thrust; general.
(a) The airplane configuration (setting of wing and cowl flaps, air brakes, landing gear, propeller, etc.), denoted respectively as the take-off, en route, approach, and landing configurations, shall be selected by the applicant except as otherwise prescribed.
(b) It shall be acceptable to make the airplane configurations variable with weight, altitude, and temperature, to an extent found by the Administrator to be compatible with operating procedures required in accordance with paragraph (c) of this section.
(c) In determining the accelerate-stop distances, take-off flight paths, take-off distances, and landing distances, changes in the airplane’s configuration and speed, and in the power and/or thrust shall be in accordance with procedures established by the applicant for the operation of the airplane in service, except as otherwise prescribed. The procedures shall comply with the provisions of subparagraphs (1) through (3) of this paragraph.
(1) The Administrator shall find that the procedures can be consistently executed in service by crews of average skill.
(2) The procedures shall not involve methods or the use of devices which have not been proven to be safe and reliable.
(3) Allowance shall be made for such time delays in the execution of the procedures as may be reasonably expected to occur during service.
4T.112 Stalling speeds.
The minimum steady flight speed at which the airplane is controllable, in
(a) The speed VS0 shall denote the calibrated stalling speed, or knots, with:
(1) Zero thrust at the stalling speed, or engines idling and throttles closed if it is shown that the resultant thrust has no appreciable effect on the stalling speed;
(2) If applicable, propeller pitch controls in the position necessary for compliance with subparagraph (1) of this paragraph;
(3) The airplane in the landing configuration;
(4) The center of gravity in the most unfavorable position within the allowable landing range;
(5) The weight of the airplane equal to the weight in connection with which V S is being used to determine compliance with a particular requirement.
(b) The speed V S1 shall denote the calibrated stalling speed, or the minimum steady flight speed at which the airplane is controllable, in knots, with:
(1) Zero thrust at the stalling speed, or engines idling and throttles closed if it is shown that the resultant thrust has no appreciable effect on the stalling speed;
(2) If applicable, propeller pitch controls in the position necessary for compliance with subparagraph (1) of this paragraph; the airplane in all other respects (flaps, landing gear, etc.) in the particular configuration corresponding with that in connection with which VS1 is being used;
(3) The weight of the airplane equal to the weight in connection with which V S1 is being used to determine compliance with a particular requirement.
(c) The stall speeds defined in this section shall be the minimum speeds obtained in flight tests conducted in accordance with the procedure of subparagraphs (1) and (2) of this paragraph.
(1) With the airplane trimmed for straight flight at a speed of 1.4 V S and from a speed sufficiently above the stalling speed to insure steady conditions, the elevator control shall be applied at a rate such that the airplane speed reduction does not exceed one knot per second.
(2) During the test prescribed in subparagraph (1) of this paragraph, the flight characteristics provisions of section 4b.160 of Part 4b of the Civil Air Regulations shall be complied with.
4T.113 Take-off; general
(a) The take-off data in sections 4T.114 through 4T.117 shall be determined under the conditions of subparagraphs (1) and (2) of this paragraph.
(1) At all weights, altitudes, and ambient temperatures within the operational limits established by the applicant for the airplane.
(2) In the configuration for take-off (see sec. 4T.111).
(b) Take-off data shall be based on a smooth, dry, hard-surfaced runway, and shall be determined in such a manner that reproduction of the performance does not require exceptional skill or alertness on the part of the pilot. In the case of seaplanes or float planes, the take-off surface shall be smooth water, while for skiplanes it shall be smooth dry snow. In addition, the take-off data shall be corrected in accordance with subparagraphs (1) and (2) of this paragraph for wind and for runway gradients within the operational limits established by the applicant for the airplane.
(1) Not more than 50 percent of nominal wind components along the take-off path opposite to the direction of take-off, and not less than 150 percent of nominal wind components along the take-off path in the direction of take-off.
(2) Effective runway gradients.
4T.114 Take-off speeds.
(a) The critical-engine-failure speed V1, in terms of calibrated air speed, shall be selected by the applicant, but shall not be less than the minimum speed at which controllability by primary aerodynamic controls alone is demonstrated during the take-off run to be adequate to permit proceeding safely with the take-off using average piloting skill, when the critical engine is suddenly made inoperative.
(b) The minimum take-off safety speed V 2, in terms of calibrated air speed, shall be selected by the applicant so as to permit the gradient of climb required in section 4T.120 (a) and
(b), but it shall not be less than:
(1) 1.2 VS1 for two-engine propeller-driven airplanes and for airplanes without propellers which have no provisions for obtaining a significant reduction in the one-engine-inoperative power-on stalling speed.
(2) 1.15 V S1 for propeller-driven airplanes having more than two engines and for airplanes without propellers which have provisions for obtaining a significant reduction in the one-engine-inoperative power-on stalling speed;
(3) 1.10 times the minimum control speed V MC , established in accordance with section 4b.133 of Part 4b of the Civil Air Regulations.
(c) If engine failure is assumed to occur at or after the attainment of V 2, the demonstration in which the take-off run is continued to include the take-off climb, as provided in paragraph (a) of this section, shall not be required.
4T.115 Accelerate-stop distance.
(a) The accelerate-stop distance shall be the sum of the following:
(1) The distance required to accelerate the airplane from a standing start to the speed V1;
(2) Assuming the critical engine to fail at the speed V1, the distance required to bring the airplane to a full stop from the point corresponding with the speed V1.
(b) In addition to, or in lieu of, wheel brakes, the use of other braking means shall be acceptable in determining the accelerate-stop distance, provided that such braking means shall have been proven to be safe and reliable, that the manner of their employment is such that consistent results can be expected in service, and that exceptional skill is not required to control the airplane.
(c) The landing gear shall remain extended throughout the accelerate-stop distance.
4T.116 Take-off path. The take-off path shall be considered to extend from the standing start to a point in the take-off where a height of 1,000 feet above the take-off surface is reached or to a point in the take-off where the transition from the take-off to the en route configuration is completed and a speed is reached at which compliance with section 4T.120(c) is shown, whichever point is at a higher altitude. The conditions of paragraphs (a) through (i) of this section shall apply in determining the take-off path.
(a) The take-off path shall be based upon procedures prescribed in accordance with section 4T.111(c).
(b) The airplane shall be accelerated on or near the ground to the speed V 2 during which time the critical engine shall be made inoperative at speed V1 and shall remain inoperative during the remainder of the take-off.
(c) Landing gear retraction shall not be initiated prior to reaching the speed V2
(d) The slope of the airborne portion of the take-off path shall be positive at all points.
(e) After the V2 speed is reached, the speed throughout the take-off path shall not be less than V2 and shall be constant from the point where the landing gear is completely retracted until a height of 400 feet above the take-off surface is reached.
(f) Except for gear retraction and propeller feathering, the airplane configuration shall not be changed before reaching a height of 400 feet above the take-off surface.
(g) At all points along the take-off path starting at the point where the airplane first reaches a height of 400 feet above the take-off surface, the available gradient of climb shall not be less than 1.4 percent for two-engine airplanes and 1.8 percent for four-engine airplanes.
(h) The take-off path shall be determined either by a continuous demonstration take-off, or alternatively, by synthesizing from segments the complete take-off path.
(i) If the take-off path is determined by the segmental method, the provisions of subparagraphs (1) through (4) of this paragraph shall be specifically applicable.
(1) The segments of a segmental take-off path shall be clearly defined and shall be related to the distinct changes in the configuration of the airplane, in power and/or thrust, and in speed.
(2) The weight of the airplane, the configuration, and the power and/or thrust shall be constant throughout each segment and shall correspond with the most critical condition prevailing in the particular segment.
(3) The segmental flight path shall be based on the airplane’s performance without ground effect
(4) Segmental take-off path data shall be checked by continuous demonstrated take-offs to insure that the segmental path is conservative relative to the continuous path.
4T.117 Take-off distance. The take-off distance shall be the horizontal distance along the take-off path from the start of the take-off to the point where the airplane attains a height of 35 feet above the take-off surface as determined in accordance with 4T.116.
4T.118 Climb; general. Compliance shall be shown with the climb requirements of sections 4T.119 and 4T.120 at all weights, altitudes, and ambient temperatures, within the operational limits established by the applicant for the airplane. The airplane’s center of gravity shall be in the most unfavorable position corresponding with the applicable configuration.
4T.119 All-engine-operating landing climb. In the landing configuration, the steady gradient of climb shall not be less than 4.0 per cent, with:
(a) All engines operating at the available take-off power and/or thrust;
(b) A climb speed not in excess of 1.4 VS0.
4T.120 One-engine-inoperative climb.