Document ID: chunk:federal_register_of_legislation:F2021C01280:reg:500:p2
Version: federal_register_of_legislation:F2021C01280
Segment Type: reg
Provision Reference: reg 500 (pt 2/2)
Character Range: 75089–76834

point (50 per cent of maximum altitude)   75
Second test point (40 per cent of maximum altitude)  75
After effect test                                    30

       (5)Friction test
(a) The altimeter is to be subjected to a steady rate of decrease of pressure approximating 750 feet per minute.
(b) At each altitude listed in Table 3, the change in reading of the pointers after vibration (using a light tapping of the instrument panel adjacent to the altimeter if the altimeter does not have an integral vibrator) must not exceed the corresponding tolerance listed in Table 3.
(c) If the altimeter fails the friction test while installed on the aircraft, the altimeter must be removed and retested.
Table 3 Friction

Altitude (feet)  Tolerance
                 (feet)
1 000 -          ±70
2 000 -          70
3 000            70
5 000            70
10 000           80
15 000           90
20 000           100
25 000           120
30 000           140
35 000           160
40 000           180
50 000           250

       (6)Case leak test
       The leakage of the altimeter case, when the pressure within it corresponds to an altitude of 18 000 feet, must not change the altimeter reading by more than the tolerance shown in Table 2 in subclause 2 (4) during an interval of 1 minute.

       (7)Barometric scale error test
       At constant atmospheric pressure, the barometric pressure scale must be set at each of the pressures (falling within its range of adjustment) that are listed in Table 4, and this must cause the pointer to indicate the equivalent altitude difference shown in Table 4 within a tolerance of plus or minus 25 feet.

Table 4 Pressure-altitude difference

Pressure       Altitude difference
(hectopascal)  (feet)