356 

14 CFR Ch. I (1–1–14 Edition) 

Pt. 23, App. H 

H23.3, 

Reliability and performance require-

ments. 

(a) It must be shown that, during the crit-

ical time interval, an APR failure that in-
creases or does not affect power on either en-
gine will not create a hazard to the airplane, 
or it must be shown that such failures are 
improbable. 

(b) It must be shown that, during the crit-

ical time interval, there are no failure modes 
of the APR system that would result in a 
failure that will decrease the power on either 
engine or it must be shown that such failures 
are extremely improbable. 

(c) It must be shown that, during the crit-

ical time interval, there will be no failure of 
the APR system in combination with an en-
gine failure or it must be shown that such 
failures are extremely improbable. 

(d) All applicable performance require-

ments must be met with an engine failure 
occurring at the most critical point during 
takeoff with the APR system functioning 
normally. 

H23.4, 

Power setting. 

The selected takeoff power set on each en-

gine at the beginning of the takeoff roll may 
not be less than— 

(a) The power necessary to attain, at V

1

, 90 

percent of the maximum takeoff power ap-
proved for the airplane for the existing con-
ditions; 

(b) That required to permit normal oper-

ation of all safety-related systems and equip-
ment that are dependent upon engine power 
or power lever position; and 

(c) That shown to be free of hazardous en-

gine response characteristics when power is 
advanced from the selected takeoff power 
level to the maximum approved takeoff 
power. 

H23.5, 

Powerplant controls—general. 

(a) In addition to the requirements of 

§ 23.1141, no single failure or malfunction (or 
probable combination thereof) of the APR, 
including associated systems, may cause the 
failure of any powerplant function necessary 
for safety. 

(b) The APR must be designed to— 
(1) Provide a means to verify to the flight 

crew before takeoff that the APR is in an op-
erating condition to perform its intended 
function; 

(2) Automatically advance power on the 

operating engines following an engine failure 
during takeoff to achieve the maximum at-
tainable takeoff power without exceeding en-
gine operating limits; 

(3) Prevent deactivation of the APR by 

manual adjustment of the power levers fol-
lowing an engine failure; 

(4) Provide a means for the flight crew to 

deactivate the automatic function. This 
means must be designed to prevent inad-
vertent deactivation; and 

(5) Allow normal manual decrease or in-

crease in power up to the maximum takeoff 
power approved for the airplane under the 
existing conditions through the use of power 
levers, as stated in § 23.1141(c), except as pro-
vided under paragraph (c) of H23.5 of this ap-
pendix. 

(c) For airplanes equipped with limiters 

that automatically prevent engine operating 
limits from being exceeded, other means 
may be used to increase the maximum level 
of power controlled by the power levers in 
the event of an APR failure. The means must 
be located on or forward of the power levers, 
must be easily identified and operated under 
all operating conditions by a single action of 
any pilot with the hand that is normally 

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