MIL-PRF-27197E
TABLE II. Scale error tolerance. - Continued.
IAS (knots)
Differential pressure (inches Hg)
Tolerance (±knots)
600*
21.075
10.0
650
25.589
10.0
700*
30.764
10.0
750
36.566
10.0
800*
49.938
10.0
850*
49.842
10.0
4.6.3.2 Mach number scale error. For qualification and sampling tests, the indicator shall be
tested at each of the mach number settings in Table II. For individual tests, the indicator shall be
tested at only those test points marked with an asterisk. The specified altitude shall be established
and the IAS pointer set on the mach number graduation at each of the specified test points. The
error shall be determined by reading the airspeed value indicated by the airspeed.
4.6.3.3 MAEAS pointer scale error. For the qualification and sampling tests, the MAEAS
pointer shall be tested at each point in Table IV. For the individual tests, the MAEAS pointer
shall be tested at only those test pints marked with an asterisk. At each test point, the error shall
be within the tolerance specified in Table IV.
4.6.4 Friction error.
4.6.4.1 IAS pointer friction error. The IAS pointer shall be tested for friction error at the first
and then every other asterisked test point in Table II. The pressure shall be increased to bring the
pointer to the approximate desired reading and held constant while two readings are taken, the
first before the indicator is tapped, the second after the indicator is tapped. The difference
between any two readings shall be within 3 knots for an IAS of 80 to 200 knots, and within 5
knots for an IAS greater than 200 knots.
4.6.4.2 MAEAS pointer friction error. The MAEAS pointer shall be tested for friction error at
the first and then every other asterisked test point in Table IV. The pressure shall be held
constant while the two readings are taken, the first before the indicator is tapped and the second
after the indicator is tapped. The difference between any two readings shall be less than 10 knots.
4.6.4.3 Friction error mach number scale. The mach number scale shall be tested for friction
error at the first and then every other asterisked test point in Table III. Pressure shall be
decreased to bring the mach number position to the desired test point and the position held
constant while two readings are taken, the first before the indicator is tapped and the second after
the indicator is tapped. The difference between any two readings shall be within 5 knots.
4.6.5 Position error.
4.6.5.1 IAS pointer position error. The difference between the IAS scale reading taken while
the indicator is held in any position and is being tapped and when the indicator is held in the
normal position shall be within 3 knots for airspeeds between 80 and 200 knots, and 5 knots for
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