background image

208 

14 CFR Ch. I (1–1–24 Edition) 

§ 25.31 

§ 25.31

Removable ballast. 

Removable ballast may be used on 

showing compliance with the flight re-
quirements of this subpart. 

§ 25.33

Propeller speed and pitch lim-

its. 

(a) The propeller speed and pitch 

must be limited to values that will en-
sure— 

(1) Safe operation under normal oper-

ating conditions; and 

(2) Compliance with the performance 

requirements of §§ 25.101 through 25.125. 

(b) There must be a propeller speed 

limiting means at the governor. It 
must limit the maximum possible gov-
erned engine speed to a value not ex-
ceeding the maximum allowable r.p.m. 

(c) The means used to limit the low 

pitch position of the propeller blades 
must be set so that the engine does not 
exceed 103 percent of the maximum al-
lowable engine rpm or 99 percent of an 
approved maximum overspeed, which-
ever is greater, with— 

(1) The propeller blades at the low 

pitch limit and governor inoperative; 

(2) The airplane stationary under 

standard atmospheric conditions with 
no wind; and 

(3) The engines operating at the take-

off manifold pressure limit for recipro-
cating engine powered airplanes or the 
maximum takeoff torque limit for tur-
bopropeller engine-powered airplanes. 

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as 
amended by Amdt. 25–57, 49 FR 6848, Feb. 23, 
1984; Amdt. 25–72, 55 FR 29774, July 20, 1990] 

P

ERFORMANCE

 

§ 25.101

General. 

(a) Unless otherwise prescribed, air-

planes must meet the applicable per-
formance requirements of this subpart 
for ambient atmospheric conditions 
and still air. 

(b) The performance, as affected by 

engine power or thrust, must be based 
on the following relative humidities; 

(1) For turbine engine powered air-

planes, a relative humidity of— 

(i) 80 percent, at and below standard 

temperatures; and 

(ii) 34 percent, at and above standard 

temperatures plus 50 

°

F. 

Between these two temperatures, the 
relative humidity must vary linearly. 

(2) For reciprocating engine powered 

airplanes, a relative humidity of 80 per-
cent in a standard atmosphere. Engine 
power corrections for vapor pressure 
must be made in accordance with the 
following table: 

Altitude 

(ft.

Vapor 

pressure 

(In. Hg.) 

Specific humidity 

(Lb. moisture 

per lb. dry air) 

Density ratio 

0.0023769 

0 0.403  0.00849  0.99508 

1,000 .354  .00773  .96672 
2,000 .311  .00703  .93895 
3,000 .272  .00638  .91178 
4,000 .238  .00578  .88514 
5,000 .207  .00523  .85910 
6,000 .1805 

.00472 

.83361 

7,000 .1566 

.00425 

.80870 

8,000 .1356 

.00382 

.78434 

9,000 .1172 

.00343 

.76053 

10,000 .1010 

.00307 

.73722 

15,000 .0463  .001710 

.62868 

20,000 .01978 

.000896 

.53263 

25,000 .00778 

.000436 

.44806 

(c) The performance must correspond 

to the propulsive thrust available 
under the particular ambient atmos-
pheric conditions, the particular flight 
condition, and the relative humidity 
specified in paragraph (b) of this sec-
tion. The available propulsive thrust 
must correspond to engine power or 
thrust, not exceeding the approved 
power or thrust less— 

(1) Installation losses; and 
(2) The power or equivalent thrust 

absorbed by the accessories and serv-
ices appropriate to the particular am-
bient atmospheric conditions and the 
particular flight condition. 

(d) Unless otherwise prescribed, the 

applicant must select the takeoff, en 
route, approach, and landing configura-
tions for the airplane. 

(e) The airplane configurations may 

vary with weight, altitude, and tem-
perature, to the extent they are com-
patible with the operating procedures 
required by paragraph (f) of this sec-
tion. 

(f) Unless otherwise prescribed, in de-

termining the accelerate-stop dis-
tances, takeoff flight paths, takeoff 
distances, and landing distances, 
changes in the airplane’s configura-
tion, speed, power, and thrust, must be 
made in accordance with procedures es-
tablished by the applicant for oper-
ation in service. 

(g) Procedures for the execution of 

balked landings and missed approaches 

VerDate Sep<11>2014 

09:06 Jun 28, 2024

Jkt 262046

PO 00000

Frm 00218

Fmt 8010

Sfmt 8010

Y:\SGML\262046.XXX

262046

jspears on DSK121TN23PROD with CFR