CFR NPRM

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[Federal Register: January 18, 1996 (Volume 61, Number 12)]
[Page 1259-1268]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Parts 1, 25, 36, and 97
[Docket No. 28404; Notice No. 95-17]

RIN 2120-AD40
1-g Stall Speed as the Basis for Compliance With Part 25 of the Federal Aviation Regulations

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The Proposed Amendments

Accordingly, the Federal Aviation Administration (FAA) proposes to amend 14 CFR parts 1, 25, 36, and 97 of the Federal Aviation Regulations (FAR) as follows:

PART 1--DEFINITIONS AND ABBREVIATIONS

1. The authority citation for part 1 is revised to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.

2. Section 1.1 is amended by adding new definitions in alphabetical order to read as follows:

Sec. 1.1 General definitions.

* * * * *

Final takeoff speed means the speed of the airplane that exists at the end of the takeoff path in the en route configuration with one engine inoperative.
* * * * *

Reference landing speed means the speed of the airplane, in a specified landing configuration, at the point where it descends through the landing screen height in the determination of the land distance for manual landings.
* * * * *

3. Section 1.2 is amended by adding new terms in alphabetical order to read as follows:

Sec. 1.2 Abbreviations and symbols.

* * * * *
VFTO means final takeoff speed.
* * * * *
VREF means reference landing speed.
* * * * *
VSR means reference stall speed.
VSR0 means reference stall speed in the landing configuration.
VSR1 means reference stall speed in a specific configuration.
VSW means speed at which onset of natural or artificial stall warning occurs.
* * * * *

PART 25--AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES

4. The authority citation for part 25 is revised to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 22704.

5. Section 25.103 is revised to read as follows:

Sec. 25.103 Stall speed.

(a) The reference stall speed, VSR, is a calibrated airspeed as defined in paragraph (c) of this section. VSR is determined with--
(1) Engines idling, or, if that resultant thrust causes an appreciable decrease in stall speed, not more than zero thrust at the stall speed;
(2) Propeller pitch controls (if applicable) in the takeoff position;
(3) The airplane in other respects (such as flaps and landing gear) in the condition existing in the test in which VSR is being used;
(4) The weight used when VSR is being used as a factor to determine compliance with a required performance standard;
(5) The center of gravity position that results in the highest value of reference stall speed; and
(6) The airplane trimmed for straight flight at a speed selected by the applicant, but not less than 1.13 VSR and not greater than 1.3 VSR.
(b) Starting from the stabilized trim condition, apply elevator control to decelerate the airplane so that the speed reduction does not exceed one knot per second.
(c) The reference stall speed, VSR, is a calibrated airspeed determined in the stalling maneuver. VSR may not be less than a 1- g stall speed. VSR is expressed as:



where--

VCLMAX = Speed occurring when lift coefficient is first a maximum. In addition, if the stalling maneuver is limited by a device that commands an abrupt nose down pitch (e.g., a stick pusher), VCLMAX may not be less than the speed existing at the instant the device operates; and nZW = Flight patch normal load factor (not greater than 1.0) at VCLMAX.


6. Section 25.107 is amended by revising paragraphs (b)(1) introductory text, (b)(2) introductory text, (c)(1) and (c)(2), and by adding new paragraphs (c)(3) and (g) to read as follows:



Sec. 25.107 Takeoff speeds.


* * * * *

(b) * * *
(1) 1.13 VSR for--
* * * * *

(2) 1.08 VSR for--
* * * * *

(c) * * *
(1) V2MIN;
(2) VR plus the speed increment attained (in accordance with Sec. 25.111(c)(2)) before reaching a height of 35 feet above the takeoff surface; and

(3) A speed that provides the maneuvering capability specified in Sec. 25.143(g).
* * * * *

(g) VFTO, in terms of calibrated airspeed, must be selected by the applicant to provide at least the gradient of climb required by Sec. 25.121(c), but may not be less than--
(1) 1.18 VSR; and
(2) A speed that provides the maneuvering capability specified in Sec. 25.143(g).
7. Section 25.111 is amended by revising paragraph (a) introductory text to read as follows:

Sec. 25.111 Takeoff path.

(a) The takeoff path extends from a standing start to a point in the takeoff at which the airplane is 1,500 feet above the takeoff surface, or at which the transition from the takeoff to the en route configuration is completed and VFTO is reached, whichever point is higher. In addition--
* * * * *

8. Section 25.119 is amended by revising the section heading and paragraph (b) to read as follows:

Sec. 25.119 Landing climb: All-engines-operating.

* * * * *

(b) A climb speed of not more than VREF.
9. Section 25.121 is amended by revising paragraphs (c) introductory text, (d) introductory text, (d)(2) and (d)(3), and by adding paragraph (d)(4) to read as follows:

Sec. 25.121 Climb: One-engine-inoperative.

* * * * *

(c) Final takeoff. In the en route configuration at the end of the takeoff path determined in accordance with Sec. 25.111, the steady gradient of climb may not be less than 1.2 percent for two-engine airplanes, 1.5 percent for three-engine airplanes and 1.7 percent for four-engine airplanes, at VFTO and with--
* * * * *

(d) Approach. In a configuration corresponding to the normal all- engines-operating procedure in which VSR for this configuration does not exceed 110 percent of the VSR for the related all- engines-operating landing configuration, the steady gradient of climb may not be less than 2.1 percent for two-engine airplanes, 2.4 percent for three-engine airplanes, and 2.7 percent for four engine airplanes, with--
(1) * * *
(2) The maximum landing weight;
(3) A climb speed established in connection with normal landing procedures, but not more than 1.4 VSR; and
(4) Landing gear retracted.
10. Section 25.125 is amended by revising paragraph (a)(2) to read as follows:

Sec. 25.125 Landing.

(a) * * *
(2) A stabilized approach, with a calibrated airspeed of VREF, must be maintained down to the 50 foot height. VREF may not be less than--
(i) 1.23 VSR0,
(ii) VMCL established under Sec. 25.149(f); and
(ii) A speed that provides the maneuvering capability specified in Sec. 25.143(g).
* * * * *

11. Section 25.143 is amended by adding a new paragraph (g) to read as follows:

Sec. 25.143 General.

* * * * *

(g) The maneuvering capabilities in a constant speed coordinated turn at forward center of gravity, as specified in the following table, must be free of stall warning or other characteristics that might interfere with normal maneuvering:

Configuration
Speed
Maneuvering bank
angle in a coordinated turn
Thrust/power setting
TakeoffV230 deg. Asymmetric WAT-limited.1
TakeoffV2+XX 240 deg.All-engines-operating
climb.3
En route VFTO40 deg. Asymmetric WAT-limited.1
LandingVREF40 deg.Symmetric for -3 deg. flight
path angle.

1 A combination of weight, altitude, and temperature (WAT) such that the thrust or power setting produces the minimum climb gradient specified in Sec. 25.121 for the flight condition.
2 Airspeed approved for all-engines-operating initial climb.
3 That thrust or power setting which, in the event of failure of the critical engine and without any crew action to adjust the thrust or power of the remaining engines, would result in the thrust or power specified for the takeoff condition at V2, or any lesser thrust or power setting that is used for all engines-operating initial climb procedures.

12. Section 25.145 is amended by revising paragraphs (a) introductory text, (a)(1), (b)(1), (b)(4), (b)(6), and (c) introductory text to read as follows:

Sec. 25.145 Longitudinal control.

(a) It must be possible, at any point between the trim speed prescribed in Sec. 25.103(a)(6) and the stall, to pitch the nose downward so that the acceleration to this selected trim speed is prompt with--
(1) The airplane trimmed at the trim speed prescribed in Sec. 25.103(a)(6);
* * * * *
(b) * * *
(1) With power off, flaps retracted, and the airplane trimmed at 1.3 VSR1, extend the flaps as rapidly as possible while maintaining the airspeed at approximately 30 percent above the reference stall speed existing at each instant throughout the maneuver.
* * * * *
(4) With power off, flaps retracted, and the airplane trimmed at 1.3 VSR1, rapidly set go-around power or thrust while maintaining the same airspeed.
* * * * *
(6) With power off, flaps extended, and the airplane trimmed at 1.3 VSR1, obtain and maintain airspeeds between VSW and either 1.6 VSR1 or VFE, whichever is lower.
(c) It must be possible, without exceptional piloting skill, to prevent loss of altitude when complete retraction of the high lift devices from any position is begun during steady, straight, level flight at 1.08 VSR1 for propeller powered airplanes, or 1.13 VSR1 for turbojet powered airplanes, with--
* * * * *
Sec. 25.147 [Amended]

13. Section 25.147 is amended in paragraphs (a) introductory text, (a)(2), (c) introductory text, and (d) by revising the expression "1.4 VS1" to read "1.3 VSR1".

Sec. 25.149 [Amended]

14. Section 25.149 is amended in paragraph (c) introductory text by revising the expression "1.2 VS" to read "1.13 VSR."

Sec. 25.161 [Amended]

15. Section 25.161 is amended in paragraphs (b), (c)(1), (c)(2), (c)(3) and (d) introductory text by revising the expression "1.4 VS1" to read "1.3 VSR1"; and in paragraph (e)(3) by revising the expression "0.013 VS02" to read "0.013VSR02".

Sec. 25.175 [Amended]

16. Section 25.175 is amended in paragraphs (a)(2), (b)(1) introductory text, (b)(2) introductory text, (b)(3)

introductory text and (c)(4) by revising the expression "1.4 VS1" to read "1.3 VSR1", in paragraph (b)(2)(ii) by revising the expression "VMO+1.4 VS1/2" to read "(VMO+1.3 VSR1)/2", in paragraph (c) introductory text by revising the expressions "1.1 VS1" to read "VSW" and "1.8 VS1" to read "1.7 VSR1", in paragraph (d) introductory text by revising the expressions "1.1 VS0" to read "VSW" and "1.3 VS0" to read "1.7 VSR0", and in paragraph (d)(5) by revising the expression "1.4 VSO" to read "1.3 VSR0".

Sec. 25.177 [Amended]

17. Section 25.177 is amended in paragraph (c) by revising the expression "1.2 VS1" to read "1.13 VSR1".

Sec. 25.181 [Amended]

18. Section 25.181 is amended in paragraphs (a) introductory text and (b) by revising the reference "1.2 VS" to read "1.13 VSR".

19. Section 25.201 is amended by revising paragraphs (a)(2) and (b)(4) to read as follows:

Sec. 25.201 Stall demonstration.

(a) * * *
(2) The power necessary to maintain level flight at 1.5 V<INF>SR1 (where V<INF>SR1 corresponds to the reference stall speed with flaps in the approach position, the landing gear retracted, and the maximum landing weight).
(b) * * *
(4) The airplane trimmed for straight flight at the speed prescribed in Sec. 25.103(a)(6).
* * * * *

20. Section 25.207 is amended by revising paragraphs (b) and (c), and by adding new paragraphs (d), (e), and (f) to read as follows:

Sec. 25.207 Stall warning.

* * * * *

(b) The warning must be furnished either through the inherent aerodynamic qualities of the airplane or by a device that will give clearly distinguishable indications under expected conditions of flight. However, a visual stall warning device that requires the attention of the crew within the cockpit is not acceptable by itself. If a warning device is used, it must provide a warning in each of the airplane configurations prescribed in paragraph (a) of this section at the speed prescribed in paragraphs (c) and (d) of this section.
(c) When the speed is reduced at rates not exceeding one knot per second, with engines idling and throttles closed, stall warning must begin, in each normal configuration, at a speed, VSW, exceeding the reference stall speed by not less than three knots or three percent, whichever is greater. For the purposes of this paragraph, the reference stall speed is as defined in Sec. 25.103, except that Sec. 25.103(a)(5) does not apply. Stall warning must continue throughout the demonstration, until the angle of attack is reduced to approximately that at which stall warning is initiated.
(d) In addition to the requirements of paragraph (c) of this section, when devices that abruptly push the nose down at a selected angle of attack (e.g., stick pushers) are installed, the stall warning must occur at a speed not less than five knots or five percent, whichever is greater, above the speed at which the device activates.
(e) In slow-down turns up to 1.5g at entry rates up to 3 knots per second, with the flaps and landing gear in any normal position, the stall warning margin must be sufficient to allow the pilot to prevent stalling when recovery is initiated not less than one second after the onset of stall warning.
(f) Stall warning must also be provided in each abnormal configuration of the high lift devices that is likely to be used in flight following system failures (including all configurations covered by Airplane Flight Manual procedures).

Sec. 25.231 [Amended]

21. Section 25.231 is amended in paragraph (a)(2) by revising the word "altitude" to read "attitude" and by revising the expression "80 percent of VS1" to read "75 percent of VSR1".

Sec. 25.233 [Amended]

22. Section 25.233 is amended in paragraph (a) by revising the reference "0.2 VS0" to read "0.2 VSR0".

Sec. 25.237 [Amended]

23. Section 25.237 is amended in paragraphs (a), (b)(1), and (b)(2) by revising the reference "0.2 VS0" to read "0.2 VSR0".
24. Action 25.735 is amended by revising paragraphs (f)(2) and (g) to read as follows:

Sec. 25.735 Brakes.

* * * * *
(f) * * *
(2) Instead of a rational analysis, the kinetic energy absorption requirements for each main wheel brake assembly may be derived from the following formula, which must be modified in the case of unequal braking distribution, which assumes an equal distribution of braking between main wheels:

KE=0.0443 (WV2/N) where--

KE=Kinetic energy per wheel (ft.-lb.); W=Design landing weight (lb.); V=VREF/1.3 VREF=Airplane steady landing approach speed, in knots, at the maximum design landing weight and in the landing configuration at sea level; and N=Number of main wheels with brakes.

(g) The minimum speed rating of each main wheel-brake assembly (that is, the initial speed used in the dynamometer tests) may not be more than the V used in the determination of kinetic energy in accordance with paragraph (f) of this section, assuming that the test procedures for wheel-brake assemblies involve a specified rate of deceleration, and, therefore, for the same amount of kinetic energy, the rate of energy absorption (the power absorbing ability of the brake) varies inversely with the initial speed.

Sec. 25.773 [Amended]

25. Section 25.773 is amended in paragraph (b)(1)(i) by revising the expression "1.6 VS1" to read "1.5 VSR1".

Sec. 25.1001 [Amended]

26. Section 25.1001 is amended in paragraphs (c)(1) and (c)(3) by revising the expression "1.4 VS1" to read "1.3 VSR1".

Sec. 25.1323 [Amended]

27. Section 25.1323 is amended in paragraph (c)(1) by revising the expression "1.3 VS1" to read "1.23 VSR1" and in paragraph (c)(2) by revising the expression "1.3 VS0" to read "1.23 VSR0".

Sec. 25.1325 [Amended]

28. Section 25.1325 is amended in paragraph (e) by revising the expressions "1.3 VS0" and "1.8 VS1" to read "1.23 VSR0" and "1.7 VSR1", respectively.

Sec. 25.1587 [Amended]

29. Section 25.1587 is amended in paragraph (b)(2) by revising the expression "VS" to read "VSR".

PART 36--NOISE STANDARDS: AIRCRAFT TYPE AND AIRWORTHINESS CERTIFICATION

30. The authority citation for part 36 continues to read as follows:

Authority: 42 U.S.C. 4321 et seq., 49 U.S.C. 106(g), 40113, 44701-44702, 44704, 44715; sec. 305, Pub. L. 96-193, 94 Stat. 50, 57; E.O. 11514, 35 FR 4247, 3 CFR, 1966-1970 comp., p. 902.

31. Appendix C to part 36, Section C36.9 is amended by revising paragraph (e)(1) to read as follows:

Appendix C to Part 36--Noise Levels for Transport Category and Turbojet Powered Airplanes Under Sec. 36.201

* * * * *

Sec. C36.9 Approach Reference and Test Limitations

* * * * *

(e) * * *
(1) For subsonic airplanes a steady approach speed of V<INF>REF + 10 knots must be established and maintained over the approach measuring point.
* * * * *

PART 97--STANDARD INSTRUMENT APPROACH PROCEDURES

32. The authority citation for part 97 is revised to read as follows:

Authority: 49 U.S.C. 106(g), 40103, 40106, 40113, 40114, 40120, 44502, 44514, 44701, 44719, 44721-44722.

33. Section 97.3 is amended by revising the first two sentences of paragraph (b) introductory text to read as follows:

Sec. 97.3 Symbols and terms used in procedures.

* * * * *
(b) Aircraft approach category means a grouping of aircraft based on a speed of VREF at the maximum certificated landing weight. VREF and the maximum certificated landing weight are those values as established for the aircraft by the certification authority of the country of registry. * * *
* * * * *



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Issued in Washington, DC on November 29, 1995.
Thomas E. McSweeny,
Director, Aircraft Certification Service.
[FR Doc. 96-415 Filed 1-17-96; 8:45 am]
BILLING CODE 4910-13-M



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Other Notice of Proposed Rulemaking Actions:
Not Applicable.

Final Rule Actions:
Final Rule. Docket No. 18404; Issued on 11/14/2002.