181 

Federal Aviation Administration, DOT 

§ 23.2150 

strength, within the operating enve-
lope— 

(1) At all loading conditions for 

which certification is requested; 

(2) During all phases of flight; 
(3) With likely reversible flight con-

trol or propulsion system failure; and 

(4) During configuration changes. 
(b) The airplane must be able to com-

plete a landing without causing sub-
stantial damage or serious injury using 
the steepest approved approach gra-
dient procedures and providing a rea-
sonable margin below V

ref

or above ap-

proach angle of attack. 

(c) V

MC

is the calibrated airspeed at 

which, following the sudden critical 
loss of thrust, it is possible to maintain 
control of the airplane. For multien-
gine airplanes, the applicant must de-
termine V

MC,

if applicable, for the most 

critical configurations used in takeoff 
and landing operations. 

(d) If the applicant requests certifi-

cation of an airplane for aerobatics, 
the applicant must demonstrate those 
aerobatic maneuvers for which certifi-
cation is requested and determine 
entry speeds. 

§ 23.2140

Trim. 

(a) The airplane must maintain lat-

eral and directional trim without fur-
ther force upon, or movement of, the 
primary flight controls or cor-
responding trim controls by the pilot, 
or the flight control system, under the 
following conditions: 

(1) For levels 1, 2, and 3 airplanes in 

cruise. 

(2) For level 4 airplanes in normal op-

erations. 

(b) The airplane must maintain lon-

gitudinal trim without further force 
upon, or movement of, the primary 
flight controls or corresponding trim 
controls by the pilot, or the flight con-
trol system, under the following condi-
tions: 

(1) Climb. 
(2) Level flight. 
(3) Descent. 
(4) Approach. 
(c) Residual control forces must not 

fatigue or distract the pilot during nor-
mal operations of the airplane and 
likely abnormal or emergency oper-
ations, including a critical loss of 
thrust on multiengine airplanes. 

§ 23.2145

Stability. 

(a) Airplanes not certified for aero-

batics must— 

(1) Have static longitudinal, lateral, 

and directional stability in normal op-
erations; 

(2) Have dynamic short period and 

Dutch roll stability in normal oper-
ations; and 

(3) Provide stable control force feed-

back throughout the operating enve-
lope. 

(b) No airplane may exhibit any di-

vergent longitudinal stability char-
acteristic so unstable as to increase 
the pilot’s workload or otherwise en-
danger the airplane and its occupants. 

§ 23.2150

Stall characteristics, stall 

warning, and spins. 

(a) The airplane must have control-

lable stall characteristics in straight 
flight, turning flight, and accelerated 
turning flight with a clear and distinc-
tive stall warning that provides suffi-
cient margin to prevent inadvertent 
stalling. 

(b) Single-engine airplanes, not cer-

tified for aerobatics, must not have a 
tendency to inadvertently depart con-
trolled flight. 

(c) Levels 1 and 2 multiengine air-

planes, not certified for aerobatics, 
must not have a tendency to inadvert-
ently depart controlled flight from 
thrust asymmetry after a critical loss 
of thrust. 

(d) Airplanes certified for aerobatics 

that include spins must have control-
lable stall characteristics and the abil-
ity to recover within one and one-half 
additional turns after initiation of the 
first control action from any point in a 
spin, not exceeding six turns or any 
greater number of turns for which cer-
tification is requested, while remaining 
within the operating limitations of the 
airplane. 

(e) Spin characteristics in airplanes 

certified for aerobatics that includes 
spins must recover without exceeding 
limitations and may not result in unre-
coverable spins— 

(1) With any typical use of the flight 

or engine power controls; or 

(2) Due to pilot disorientation or in-

capacitation. 

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