Pt. 60, App. A

14 CFR Ch. I (1-1-19 Edition)

overshoots since the significance of such
overshoots becomes questionable. Only those
overshoots larger than 5 per cent of the total
initial displacement should be considered.
The residual band, labeled T(Ad) on Figure
A2A is Section5 percent of the initial displacement
amplitude Ad from the steady state value of
the oscillation. Only oscillations outside the
residual band are considered significant.
When comparing FFS data to airplane data,
the process should begin by overlaying or
aligning the FFS and airplane steady state
values and then comparing amplitudes of oscillation peaks, the time of the first zero
crossing and individual periods of oscillation. The FFS should show the same number
of significant overshoots to within one when
compared against the airplane data. The procedure for evaluating the response is illustrated in Figure A2A.
(b) Critically damped and overdamped response. Due to the nature of critically
damped and overdamped responses (no overshoots), the time to reach 90 percent of the
steady state (neutral point) value should be
the same as the airplane within Section10 percent.
Figure A2B illustrates the procedure.
(c) Special considerations. Control systems
that exhibit characteristics other than classical overdamped or underdamped responses
should meet specified tolerances. In addition, special consideration should be given to
ensure that significant trends are maintained.
(2) Tolerances.
(a) The following table summarizes the tolerances, T, for underdamped systems, and
 - n -  is the sequential period of a full cycle of
oscillation. See Figure A2A of this attachment for an illustration of the referenced
measurements.

T(P0)
T(P1)
T(P2)
T(Pn)
T(An)
T(Ad)

..........
..........
..........
..........
..........
..........

Section10% of P0.
Section20% of P1.
Section30% of P2.
Section10(n + 1)% of Pn.
Section10% of A1.
Section5% of Ad = residual
band.

Section10% of P0

END INFORMATION
lllllllllllllllllllllll
BEGIN QPS REQUIREMENT
c. Alternative method for control dynamics evaluation.
(1) An alternative means for validating
control dynamics for aircraft with hydraulically powered flight controls and artificial
feel systems is by the measurement of control force and rate of movement. For each
axis of pitch, roll, and yaw, the control must
be forced to its maximum extreme position
for the following distinct rates. These tests
are conducted under normal flight and
ground conditions.
(a) Static test - Slowly move the control so
that a full sweep is achieved within 95 to 105
seconds. A full sweep is defined as movement
of the controller from neutral to the stop,
usually aft or right stop, then to the opposite stop, then to the neutral position.
(b) Slow dynamic test - Achieve a full
sweep within 8-12 seconds.
(c) Fast dynamic test - Achieve a full
sweep within 3-5 seconds.
NOTE: Dynamic sweeps may be limited to
forces not exceeding 100 lbs. (44.5 daN).
(d) Tolerances
(i) Static test; see Table A2A, FFS Objective Tests, Entries 2.a.1., 2.a.2., and 2.a.3.
(ii) Dynamic test - Section2 lbs (0.9 daN) or Section10%
on dynamic increment above static test.
END QPS REQUIREMENT
lllllllllllllllllllllll
BEGIN INFORMATION

Significant overshoots, First overshoot
and Section1 subsequent overshoots.
(b) The following tolerance applies to critically damped and overdamped systems only.
See Figure A2B for an illustration of the reference measurements:

kpayne on VMOFRWIN702 with $$_JOB

T(P0) ..........

d. The FAA is open to alternative means
such as the one described above. The alternatives should be justified and appropriate
to the application. For example, the method
described here may not apply to all manufacturers- systems and certainly not to aircraft
with reversible control systems. Each case is
considered on its own merit on an ad hoc
basis. If the FAA finds that alternative
methods do not result in satisfactory performance, more conventionally accepted
methods will have to be used.

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