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AC 25-7D Appendix D point where a height of 35 feet is reached. The required runway length must not be less than the take-off run nor less than the accelerate stop distance.
According to the definition given, a clearway is subjected to the control of the airport authorities. It is not intended, however, that there be ownership by the airport authorities of the area in which the clearway lies. The objective for requiring control by the airport authorities is to insure that no flight will be initiated using a clearway unless it is determined with certainty that no movable obstacle will exist within the clearway when the airplane flies over.
It is anticipated that the introduction of clearways will offer further possibilities of increasing the utility of existing airport facilities in this country. When such areas can be integrated into existing facilities, economical benefits will accrue to the community and the operators. In addition, since clearways are presently available at some of the airports in other countries, United States operators will have the opportunity of taking advantage of such facilities.
There are included changes with respect to the prescribed minimum altitude of 1,000 feet relative to the take-off path and to the one-engine-inoperative and two-engine-inoperative requirements applicable to the vicinity of the airport. Heretofore, the Civil Air Regulations have incorporated the reference altitude of 1,000 feet in respect of performance criteria over the airport. Obscure as is the significance of this altitude operationally, the altitude of 1,500 feet has worldwide precedent of being used as the altitude above the airport at which, generally, IFR approaches are initiated and go-around procedures executed. For this reason, the changes made extend the take-off path to a minimum altitude of 1,500 feet and make this altitude applicable to the prescribed performance criteria above the airport for the one- and two-engine-inoperative en route requirements. It is not anticipated that these changes will create any problems with respect to the en route stages of flight; however, it is realized that a further extension of the takeoff path might add to the problem of obtaining accurate data on obstacles relatively distant from the airport. The Board finds that the extension of the flight path to 1,500 feet is warranted in light of the operational significance of this altitude and because the extended flight paths will provide more fully for adequate terrain clearance at the end of the take-off path.
There is included a change with respect to the take-off path whereby the take-off flight path is established as starting from a 35-foot height at the end of the take-off distance and a net take-off flight is prescribed for operational use. This latter change is for consistency with the specification of net flight paths for the en route stages of flight and to simplify determination of obstacle clearances operationally. The net flight path is specified to be the actual flight path diminished by a gradient of 1.0 percent. It is intended that the net flight path be obtained from the gross flight path by simple geometric means.
The change in the altitude from 1,000 to 1,500 feet previously mentioned, as well as a reevaluation in other respects of some of the climb gradients in SR-422, justify certain changes.
The gradients of 1.4 and 1.8 applicable to the take-off path and the final take-off climb are being reduced to 1.2 and 1.7 for two-engine and four-engine airplanes, respectively. In addition, the gradients 1.4 and 1.8 in the one-engine-inoperative en route case are being reduced to 1.1 and
1.6, respectively.
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AC 25-7D Appendix D Changes are made with respect to the one-engine-inoperative take-off climb by interrelating more realistically the prescribed airplane configuration, weight, and power. These changes, in effect, permit meeting the prescribed gradients of climb at slightly higher airplane weights than would be possible under the presently effective provisions.
There is included a change to the provisions applicable to the one-engine-inoperative take-off climb with landing gear extended which increases the prescribed minimum gradient from substantially zero to 0.5 percent for four-engine airplanes. This change is made to attain consistency in the difference between gradients applicable to twins and fours.
Changes are incorporated in connection with the two-engine-inoperative en route requirement. Representations have been made that the gradient of 0.6 percent now prescribed is unduly conservative. On the other hand, it has been pointed out that the fuel requirements for this case are not realistically covered. Both of these contentions warrant consideration and changes are included which reduce the margin gradient from 0.6 to 0.5 percent, reduce the prescribed altitude from 5,000 to 2,000 feet, and require scheduling the flight so that there is sufficient fuel on board to reach the airport and subsequently to fly for 15 minutes at cruise power or thrust.
Changes are also made relative to the approach and landing stages of flight. There is a new provision which requires the establishment of procedures for the execution of missed approaches and balked landings. A question has been raised as to whether the speed limitation of
1.5 VS applicable to the approach condition is realistically related to the normal day-in and day-out landing procedures. To insure that it will be so related, it is required that the speed used for demonstrating the approach climb be established consistent with the landing procedures, but that it not exceed 1.5 VS. In addition, the approach gradient of 2.8 percent prescribed for four-engine airplanes is being reduced to 2.7 percent to obtain consistency in the differences between gradients applicable to twins and fours.
A change is made to the “all-engines-operating landing climb” provisions which now require a 4.0 percent gradient of climb in the landing configuration. On the premise that requiring the landing configuration during the climb after a balk is unduly conservative, consideration was given to a proposal to permit showing of compliance with the 4.0 percent gradient of climb in the configuration which would exist 5 seconds after the initiation of the climb. Further study of this proposal indicated that such a rule would tend to introduce complications in design and lead to less favorable operating procedures which ultimately would not contribute to safety. One of the most important factors in connection with this configuration is the response of the engines to throttle movement. Therefore, there is a provision which requires that the power used in showing compliance with the climb gradient be that power or thrust attained 8 seconds after initiation of movement of the power controls to the take-off position from the minimum flight idle position. In addition, for consistency with the procedures used for determining the landing distance, the speed limitation of 1.4 VS is reduced to 1.3 VS.
Concern has been indicated to the effect that any reduction in the prescribed gradient of
1.0 percent might not insure in all cases the ability of the airplane to continue a safe climb after a balk. To provide a further safeguard, the take-off weight-altitude-temperature limitations (WAT limitations stemming from the application of the one-engine-inoperative take-off climb requirements) are being made applicable to the maximum landing weight at the airport of D-20
Appendix D landing. In the past, the landing weight limitations were applicable to the airport of destination but not to the weather alternates. This regulation makes both the take-off weight and landing weight limitations equally applicable to the airport of destination and the weather alternates. In view of the aforementioned changes, a reduction of the required climb gradient from 4.0 to 3.2 percent is justified and included in this regulation.
In addition to the substantive changes which have been discussed, there are three significant changes of a clarifying nature. The first deals with the determination of the landing distance as affected by devices or means other than wheel brakes. There is included a provision similar to the one applicable to the accelerate-stop distance for application to the landing distance. This provision permits the use of means other than wheel brakes in the determination of the landing distance. Additionally, there is a change to the provision which requires in some cases the determination of the landing distance with one engine inoperative. It is believed that the new requirement expresses the intent more clearly. One of the more obvious applications of this provision is in respect of turbo-propeller airplanes. Such airplanes usually are landed with the propellers in a relatively high drag position. If one of the engines becomes inoperative, its propeller would be expected to be in a relatively low drag position with the consequence of a longer landing distance than with all engines operating. In such a case it is required that the landing distance be determined with one engine inoperative unless use could be made by the crew of other means (e.g., reverse thrust not otherwise considered in determining the landing distance) which would reduce the landing distance at least to that determined for all-engine operation. The second clarification being included deals with the provision setting forth the procedures which must be included in the AFM. This provision in SR-422 does not make clear what procedures are involved and whether the procedures are considered to be limitations on the operation of the airplane. The clarification in language specifies that the procedures which are included with the performance limitations shall be considered only as guidance material.
The third clarification concerns the applicability of the performance limitations prescribed in SR-422. These consist of the “certificate limitations” and the “operating limitations.” The former relate to maximum take-off and landing weights, minimum take-off distances, accelerate-stop distances, and the operational limits imposed upon the airplane. These limitations, being part of the conditions of the type and airworthiness certificates, must be complied with at all times irrespective of the type of operation being conducted (e.g., air carrier, private, cargo). The “operating limitations,” distinct from the “certificate limitations,” are only applicable when required by the operating parts of the regulations (Parts 40, 41, and 42 require compliance for passenger operations). Although it appeared that previous Board pronouncements regarding this general principle as well as the explanation contained in the preamble to SR-422 would make the issue quite clear, it has come to the Board’s attention that there is still some misunderstanding of this matter. Apparently, this misunderstanding stems from the fact that SR-422 prescribes operating rules for air carrier operations which contain both the “certificate limitations” and the “operating limitations” while no prescription is given to non-air-carrier operations; thus giving an impression that not even the “certificate limitations” are applicable to non-air-carriers. The inclusion of “certificate limitations” for air carrier operations with the “operating limitations” was meant only to provide the operators with the convenience of having together the complete prescription of the applicable performance limitations, notwithstanding that such an inclusion, in fact, duplicates the general requirement of compliance with the “certificate limitations” contained in the AFM. In view of the possible misunderstanding which D-21
Appendix D might exist from the aforementioned inclusion, there are included in this regulation the same “certificate limitations” for application to all operations under the provisions of part 43 of the Civil Air Regulations.
In addition, other changes of a minor nature are included herein, the most significant of which is the generalization of the stall speed VS, eliminating reference to VS0 and VS1.
Of the changes to SR-422 made in this regulation, there are a number which might require further consideration as studies continue and as additional experience is gained with the application of these new rules. Several of these involve new concepts with which U.S. operators have had little or no experience. These entail the requirements relative to unbalanced field lengths with respect to clearways, to the rotational speed, and to the all-engine take-off distance.
Strong representation has been made to the Board to the effect that the numerical factors applicable to the aforementioned rules are too high and should be reduced pending further experience. The Board considers that it would not be in the public interest to reduce any of these factors until such time as further experience indicates that they are in fact overly conservative.
Realizing, however, that these issues are of considerable importance in prescribing a practicable level of performance, the Board stands ready to reconsider the relevant provisions of this regulation at such time as substantiating information is received.
There are areas other than those previously mentioned where additional refinement of details may be advisable. This is so particularly in the case of the requirements pertaining to the landing stage of flight, to the take-off lateral clearances, and to the two-engine inoperative en route gradient margin. 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, 42, and 43 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 ensure equivalent safety.
Interested persons have been afforded an opportunity to participate in the making of this regulation (23 F.R.2139), 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 July 2, 1958:
Contrary provisions of the Civil Air Regulations notwithstanding, all turbine-powered transport category airplanes for which a type certificate is issued after August 27, 1957, shall comply with Special Civil Air Regulation No. SR-422 or, alternatively, with the following provisions, except that those airplanes for which a type certificate is issued after September 30,1958, shall comply with the following provisions:
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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 August 27, 1957, as the Administrator finds necessary to ensure 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 prescribe d, 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 condition, 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 wi ng 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 accelerat e-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 D-23
Appendix D airplane in service, except as otherwise prescribed. In addition, procedures shall be established for the execution of balked landings and missed approaches associated with the conditions prescribed in section 4T.119 and 4T.120(d), respectively. All 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.
(a) The speed V S, 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 p itch 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 VS is being used;
(3) The weight of the airplane equal to the weight in connection with which VS is being used to determine compliance with a particular requirement; and
(4) The c.g. in the most unfavorable position within the allowable range.
(b) The stall speed defined in this section shall be the minimum speed obtained in flight tests conducted in accordance with the procedure of subparagraphs (1) and (2) of this paragraph.
(1) With the airplane trimmed for st raight flight at a speed of 1.4 VS and from a speed sufficiently above the stalling speed to ensure 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 subpara graph (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.
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(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 smoot h, 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 runw ay gradients.
4T.114 Take-off speeds.
(a) The critical-engine-failure speed V 1, 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 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 V S 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 S 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;
(4) The rotation speed VR plus the increment in speed attained in compliance with section 4T.116(e).
(c) The minimum rotation speed V R, in terms of calibrated air speed, shall be selected by the applicant, except that it shall not be less than:
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AC 25-7D Appendix D
(1) The speed V 1;
(2) A speed equal to 95 percent of the hi ghest speed obtained in compliance with subparagraph (1) or (2), whichever is applicable, and with subparagraph (3) of paragraph (b) of this section;
(3) A speed which permits the attainment of the Speed V 2 prior to reaching a height of 35 feet above the take-off surface as determined in accordance with section 4T.116(e);
(4) A speed equal to 110 percent of the minimum speed above which the airplane, with all engines operating, can be made to lift off the ground and to continue the take-off without displaying any hazardous characteristics.
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 engi ne 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 brak es, 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 1,500 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 acceler ated on the ground to the speed V1 at which point the critical engine shall be made inoperative and shall remain inoperative during the remainder of the take-off. Subsequent to attaining speed V1, the airplane shall be accelerated to speed V2, during which time it shall be permissible to initiate raising the nose gear off the ground at a speed not less than the rotation speed VR.
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(c) Landing gear retraction shall not be initi ated until the airplane becomes airborne.
(d) The slope of the airborne portion of the take-off path shall be positive at all points.
(e) The airplane shall attain the speed V 2 prior to reaching a height of 35 feet above the take-off surface and shall continue at a speed as close as practical to, but not less than, V2 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 star ting 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 1.2 percent for two-engine airplanes and 1.7 percent for four-engine airplanes.
(h) The take-off path shall be determined either by a continuous demonstrated 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 pa th 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 confi guration, 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 ba sed on the airplane’s performance without ground effect.
(4) Segmental take-off path data shall be checked by continuous demonstrated takeoffs to ensure that the segmental path is conservative relative to the continuous path.
4T.117 Take-off distances and take-off run.
(a) Take-off distance. The take-off distance shall be the greater of the distances established in accordance with subparagraphs (1) and (2) of this paragraph.
(1) The horizontal distance along the take-off path from th e 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 section 4T.116.
(2) A distance equal to 115 percent of th e horizontal distance along the take-off path, with all engines operating, 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 by a procedure consistent with that established in accordance with section 4T.116.
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(b) Take-off run. If the take-off distance is intended to include a clearway (see item 5 of this regulation), the take-off run shall be determined and shall be the greater of the distances established in accordance with subparagraphs (1) and (2) of this paragraph.
(1) The horizontal distance along the take-off path from the start of the take-off to a point equidistant between the point where the airplane first becomes airborne and the point where it attains a height of 35 feet above the take-off surface, as determined in accordance with section 4T.116.
(2) A distance equal to 115 percent of th e horizontal distance along the take-off path, with all engines operating, from the start of the take-off to a point equidistant between the point where the airplane first becomes airborne and the point where it attains a height of 35 feet above the take-off surface, as determined by a procedure consistent with that established in accordance with section 4T.116.
4T.117a Take-off flight path.
(a) The take-off flight path shall be considered to begin at a height of 35 feet above the take-off surface at the end of the take-off distance as determined in accordance with section 4T.117(a).
(b) The net take-off flight path data shall be determined in such a manner that they represent the airplane’s actual take-off flight paths, determined in accordance with paragraph (a) of this section, diminished by a gradient of climb equal to 1.0 percent.
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 c.g. 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 3.2 percent, with:
(a) All engines operating at th e power and/or thrust which is available 8 seconds after initiation of movement of the power and/or thrust controls from the minimum flight idle to the take-off position;
(b) A climb speed not in excess of 1.3 V S.
4T.120 One engine-inoperative climb.
(a) Take-off; landing gear extended. In the take-off configuration existing at the point of the flight path where the airplane first becomes airborne, in accordance with section 4T.116 but without ground effect, the steady gradient of climb shall be positive for two-engine airplanes and shall not be less than 0.5 percent for four-engine airplanes, with:
(1) The critical engine inoperative, the remaining engine(s) operating at the available take-off power and/or thrust existing in accordance with section 4T.116 at the time D-28
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AC 25-7D Appendix D retraction of the airplane’s landing gear is initiated, unless subsequently a more critical power operating condition exists along the flight path prior to the point where the landing gear is fully retracted;
(2) The weight equal to the airplane’s weight existing in accordance with section 4T.116 at the time retraction of the airplane’s landing gear is initiated;
(3) The speed equal to the speed V 2.
(b) Take-off; landing gear retracted. In the take-off configuration existing at the point of the flight path where the airplane’s landing gear is fully retracted, in accordance with section 4T.116 but without ground effect, the steady gradient of climb shall not be less than 2.5 percent for two-engine airplanes and not less than 3.0 percent for four-engine airplanes, with:
(1) The critical engine inoperative, the remaining engine(s) operating at the available take-off power and/or thrust existing in accordance with section 4T.116 at the time the landing gear is fully retracted, unless subsequently a more critical power operating condition exists along the flight path prior to the point where a height of 400 feet above the take-off surface is reached;
(2) The weight equal to the airplane’s weight existing in accordance with section 4T.116 at the time the airplane’s landing gear is fully retracted.
(3) The speed equal to the speed V 2.
(c) Final take-off. In the en route configuration, the steady gradient of climb shall not be less than 1.2 percent for two-engine airplanes and not less than 1.7 percent for four-engine airplanes, at the end of the take-off path as determined by section 4T.116, with:
(1) The critical engine inoperative, the remaining engine(s) operating at the available maximum continuous power and/or thrust;
(2) The weight equal to the airplane’s weight existing in accordance with section 4T.116 at the end of the take-off path;
(3) The speed equal to not less than 1.25 V S.
(d) Approach. In the approach configuration such that the corresponding VS for this configuration does not exceed 110 percent of the VS, corresponding with the related landing configuration, the steady gradient of climb shall not be less than 2.2 percent for two-engine airplanes and not less than 2.7 percent for four-engine airplanes with:
(1) The critical engine inoperative, the remaining engine(s) operating at the available take-off power and/or thrust;
(2) The weight equal to the maximum landing weight;
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(3) A climb speed established by the applicant in connection with normal landing procedures, except that it shall not exceed 1.5 VS (see sec. 4T.111(c)).
4T.121 En route flight paths. With the airplane in the en route configuration, the flight paths prescribed in paragraphs (a) and (b) of this section shall be determined at all weights, altitudes, and ambient temperatures within the limits established by the applicant for the airplane.
(a) One engine inoperative. The one-engine-inoperative net flight path data shall be determined in such a manner that they represent the airplane’s actual climb performance diminished by a gradient of climb equal to 1.1 percent for two-engine airplanes and 1.6 percent for four-engine airplanes. It shall be acceptable to include in these data the variation of the airplane’s weight along the flight path to take into account the progressive consumption of fuel and oil by the operating engine(s).
(b) Two engines inoperative. For airplanes with four engines, the two-engineinoperative net flight path data shall be determined in such a manner that they represent the airplane’s actual climb performance diminished by a gradient of climb equal to 0.5 percent. It shall be acceptable to include in these data the variation of the airplane’s weight along the flight path to take into account the progressive consumption of fuel and oil by the operating engines.
(c) Conditions. In determining the flight paths prescribed in paragraphs (a) and (b) of this section, the conditions of subparagraphs (1) through (4) of this paragraph shall apply.
(1) The airplane’s c.g. shall be in the most unfavorable position.
(2) The critical engine(s) sh all be inoperative, the remaining engine(s) operating at the available maximum continuous power and/or thrust.
(3) Means for controlling th e engine cooling air supply shall be in the position which provides adequate cooling in the hot-day condition.
(4) The speed shall be selected by the applicant.
4T.122 Landing distance. The landing distance shall be the horizontal distance required to land and to come to a complete stop (to a speed of approximately 3 knots in the case of seaplanes or float planes) from a point at a height of 50 feet above the landing surface. Landing distances shall be determined for standard temperatures at all weights, altitudes, and winds within the operational limits established by the applicant for the airplane. The conditions of paragraphs (a) through (g) of this section shall apply.
(a) The airplane shall be in the landing conf iguration. During the landing, changes in the airplane’s configuration, in power and/or thrust, and in speed shall be in accordance with procedures established by the applicant for the operation of the airplane in service. The procedures shall comply with the provisions of section 4T.111(c).
(b) The landing shall be preceded by a steady gliding approach down to the 50-foot height with a calibrated air speed of not less than 1.3 VS.
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