337
Federal Aviation Administration, DOT
Pt. 60, App. D
the helicopter data. The procedure for evalu-
ating the response is illustrated in Figure 1
of this attachment.
(c) Critically Damped and Overdamped Re-
sponse. Due to the nature of critically
damped responses (no overshoots), the time
to reach 90 percent of the steady state (neu-
tral point) value must be the same as the
helicopter within
±
10 percent. The simulator
response must be critically damped also.
Figure 2 of this attachment illustrates the
procedure.
(d) Special considerations. Control systems
that exhibit characteristics other than clas-
sical overdamped or underdamped responses
should meet specified tolerances. In addi-
tion, special consideration should be given to
ensure that significant trends are main-
tained.
(2) Tolerances.
(a) The following summarizes the toler-
ances, ‘‘T’’ for underdamped systems, and
‘‘n’’ is the sequential period of a full cycle of
oscillation. See Figure D2A of this attach-
ment for an illustration of the referenced
measurements.
T(P
0
)
±
10% of P
0
T(P
1
)
±
20% of P
1
T(P
2
)
±
30% of P
2
T(P
n
)
±
10(n+1)% of P
n
T(A
n
)
±
10% of A
1
T(A
d
)
±
5% of A
d
= residual band
Significant overshoots First overshoot and
±
1 subsequent overshoots
(b) The following tolerance applies to criti-
cally damped and overdamped systems only.
See Figure D2B for an illustration of the ref-
erence measurements:
T(P
0
)
±
10% of P
0
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