449 

Federal Aviation Administration, DOT 

Pt. 60, App. D 

2.c.2. ......................

Static 

Stability ................

Longitudinal Control Position: 

±

10% of change from trim or 

±

0.25 in. (6.3 mm) or Longitu-

dinal Control Force: 

±

0.5 lb. 

(0.223 daN) or 

±

10%.

Cruise or Climb. 

Autorotation. Aug-
mentation On and 
Off.

Record results for a minimum of 

two speeds on each side of the 
trim speed. May be a series of 
snapshot tests.

X X X 

2.c.3. ......................

Dynamic Stability. 

2.c.3.a. ...................

Long Term Response ...

±

10% of calculated period. 

±

10% 

of time to 

1

⁄

2

or double ampli-

tude, or 

±

0.02 of damping ratio. 

For non-periodic responses, the 
time history must be matched 
within 

±

3

° 

pitch; and 

±

5 kts air-

speed over a 20 sec period fol-
lowing release of the controls.

Cruise Augmentation 

On and Off.

Record results for three full cy-

cles (6 overshoots after input 
completed) or that sufficient to 
determine time to 

1

⁄

2

or double 

amplitude, whichever is less. 
For non-periodic responses, the 
test may be terminated prior to 
20 sec if the test pilot deter-
mines that the results are be-
coming uncontrollably diver-
gent. Displace the cyclic for 
one second or less to excite 
the test. The result will be ei-
ther convergent or divergent 
and must be recorded. If this 
method fails to excite the test, 
displace the cyclic to the pre-
determined maximum desired 
pitch attitude and return to the 
original position. If this method 
is used, record the results.

X 

X 

X  The response for certain 

helicopters may be 
unrepeatable throughout 
the stated time. In these 
cases, the test should 
show at least that a di-
vergence is identifiable. 
For example: Displacing 
the cyclic for a given time 
normally excites this test 
or until a given pitch atti-
tude is achieved and 
then return the cyclic to 
the original position. For 
non-periodic responses, 
results should show the 
same convergent or di-
vergent character as the 
flight test data. 

2.c.3.b. ...................

Short Term Response ...

±

1.5

° 

Pitch or 

±

2

°

/sec. Pitch 

Rate. 

±

0.1 g Normal Accelera-

tion.

Cruise or Climb. Aug-

mentation On and 
Off.

Record results for at least two air-

speeds.

X 

X  A control doublet inserted 

at the natural frequency 
of the aircraft normally 
excites this test. How-
ever, while input doublets 
are preferred over pulse 
inputs for Augmentation- 
Off tests, for Augmenta-
tion-On cases, when the 
short term response ex-
hibits 1st-order or dead-
beat characteristics, lon-
gitudinal pulse inputs 
may produce a more co-
herent response. 

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