105 

Federal Aviation Administration, DOT 

Pt. 60, App. A 

lllllllllllllllllllllll

B

EGIN

I

NFORMATION

 

3. G

ENERAL

 

a. If relevant winds are present in the ob-

jective data, the wind vector should be clear-
ly noted as part of the data presentation, ex-
pressed in conventional terminology, and re-
lated to the runway being used for test near 
the ground. 

b. The reader is encouraged to review the 

Airplane Flight Simulator Evaluation Hand-
book, Volumes I and II, published by the 
Royal Aeronautical Society, London, UK, 
and AC 25–7, as amended, Flight Test Guide 
for Certification of Transport Category Air-
planes, and AC 23–8, as amended, Flight Test 
Guide for Certification of Part 23 Airplanes, 
for references and examples regarding flight 
testing requirements and techniques. 

4. C

ONTROL

D

YNAMICS

 

a. General. The characteristics of an air-

plane flight control system have a major ef-
fect on handling qualities. A significant con-
sideration in pilot acceptability of an air-
plane is the ‘‘feel’’ provided through the 
flight controls. Considerable effort is ex-
pended on airplane feel system design so that 
pilots will be comfortable and will consider 
the airplane desirable to fly. In order for an 
FFS to be representative, it should ‘‘feel’’ 
like the airplane being simulated. Compli-
ance with this requirement is determined by 
comparing a recording of the control feel dy-
namics of the FFS to actual airplane meas-
urements in the takeoff, cruise and landing 
configurations. 

(1) Recordings such as free response to an 

impulse or step function are classically used 
to estimate the dynamic properties of 
electromechanical systems. In any case, it is 
only possible to estimate the dynamic prop-
erties as a result of being able to estimate 
true inputs and responses. Therefore, it is 
imperative that the best possible data be col-
lected since close matching of the FFS con-
trol loading system to the airplane system is 
essential. The required dynamic control 
tests are described in Table A2A of this at-
tachment. 

(2) For initial and upgrade evaluations, the 

QPS requires that control dynamics charac-
teristics be measured and recorded directly 
from the flight controls (Handling Quali-
ties—Table A2A). This procedure is usually 
accomplished by measuring the free response 
of the controls using a step or impulse input 
to excite the system. The procedure should 
be accomplished in the takeoff, cruise and 
landing flight conditions and configurations. 

(3) For airplanes with irreversible control 

systems, measurements may be obtained on 
the ground if proper pitot-static inputs are 
provided to represent airspeeds typical of 
those encountered in flight. Likewise, it may 

be shown that for some airplanes, takeoff, 
cruise, and landing configurations have like 
effects. Thus, one may suffice for another. In 
either case, engineering validation or air-
plane manufacturer rationale should be sub-
mitted as justification for ground tests or for 
eliminating a configuration. For FFSs re-
quiring static and dynamic tests at the con-
trols, special test fixtures will not be re-
quired during initial and upgrade evalua-
tions if the QTG shows both test fixture re-
sults and the results of an alternate ap-
proach (e.g., computer plots that were pro-
duced concurrently and show satisfactory 
agreement). Repeat of the alternate method 
during the initial evaluation satisfies this 
test requirement. 

b. Control Dynamics Evaluation. The dy-

namic properties of control systems are 
often stated in terms of frequency, damping 
and a number of other classical measure-
ments. In order to establish a consistent 
means of validating test results for FFS con-
trol loading, criteria are needed that will 
clearly define the measurement interpreta-
tion and the applied tolerances. Criteria are 
needed for underdamped, critically damped 
and overdamped systems. In the case of an 
underdamped system with very light damp-
ing, the system may be quantified in terms 
of frequency and damping. In critically 
damped or overdamped systems, the fre-
quency and damping are not readily meas-
ured from a response time history. There-
fore, the following suggested measurements 
may be used: 

(1) For Level C and D simulators. Tests to 

verify that control feel dynamics represent 
the airplane should show that the dynamic 
damping cycles (free response of the con-
trols) match those of the airplane within 
specified tolerances. The NSPM recognizes 
that several different testing methods may 
be used to verify the control feel dynamic re-
sponse. The NSPM will consider the merits 
of testing methods based on reliability and 
consistency. One acceptable method of eval-
uating the response and the tolerance to be 
applied is described below for the under-
damped and critically damped cases. A spon-
sor using this method to comply with the 
QPS requirements should perform the tests 
as follows: 

(a) Underdamped response. Two measure-

ments are required for the period, the time 
to first zero crossing (in case a rate limit is 
present) and the subsequent frequency of os-
cillation. It is necessary to measure cycles 
on an individual basis in case there are non- 
uniform periods in the response. Each period 
will be independently compared to the re-
spective period of the airplane control sys-
tem and, consequently, will enjoy the full 
tolerance specified for that period. The 
damping tolerance will be applied to over-
shoots on an individual basis. Care should be 
taken when applying the tolerance to small 

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