Document ID: chunk:federal_register_of_legislation:F2021C01280:reg:5:p25
Version: federal_register_of_legislation:F2021C01280
Segment Type: reg
Provision Reference: reg 5 (pt 25/26)
Character Range: 69144–71902

in paragraph (g) or (h) (as the case requires).
(g) For unpressurised airplanes — evacuate the static pressure system to a pressure differential of approximately 33 hPa or to a reading on the altimeter that is 1 000 feet above the aircraft's elevation at the time of the test. Without additional pumping for a period of 1 minute, the loss of indicated altitude must not exceed 100 feet on the altimeter.
(h) For pressurised airplanes — evacuate the static pressure system until a pressure differential equivalent to the maximum cabin pressure differential for which the airplane is type certificated is achieved. Without additional pumping for a period of 1 minute, the loss of indicated altitude must not exceed 2 per cent of the equivalent altitude of the maximum cabin differential pressure or 100 feet, whichever is greater.
(i) On completion of the static pressure system test, ensure that all static port seals are removed.

       (2)Pitot-systems

(a) The pitot system is tested for leaks by applying a pressure at the pitot head sufficient to cause the airspeed indicator to read 120 knots, or the maximum indicated speed, whichever is the greater.
(b) There must be no discernible lag in the movement of the airspeed indicator pointer with the application of the pressure, as such a lag indicates restrictions in the piping.
(c) There must be no decrease in the reading when the system is sealed for at least 10 seconds.

Clause 2 Tests for altimeters and air data computers
Note   For testing of air data computers, see subclause 2 (8) below.

       (1)Environmental conditions test

(a) Vibration (intended to minimise the effects of friction). If suitable test equipment is available, each test for performance may be conducted with the instrument installed in the aircraft. If suitable test equipment for an installed test is not available, or if the instrument fails the installed test, the instrument must be removed from the aircraft and tested or retested with vibration applied.

(b) Temperature. When tests are conducted with the temperature substantially different from ambient temperature of approximately 25°C, allowance must be made for that temperature difference.

       (2)Scale error test
(a) With the barometric pressure scale at 1 013 hPa, the altimeter must be successively subjected to pressures corresponding to the altitude specified in Table 1 up to the maximum, normally expected, operating altitude of the aircraft in which the altimeter is, or is to be, installed.
(b) The reduction in pressure must be made at a rate not in excess of 20 000 feet per minute to within approximately 2 000 feet of the test point.
(c) The test point must be approached at a rate compatible with the test equipment.
(d) The altimeter must