Appendix E to Part 43 - Altimeter System Test and Inspection
14:1.0.1.3.22.0.283.14.49 : Appendix E
Appendix E to Part 43 - Altimeter System Test and Inspection
Each person performing the altimeter system tests and
inspections required by § 91.411 of this chapter must comply with
the following:
(a) Static pressure system:
(1) Ensure freedom from entrapped moisture and restrictions.
(2) Perform a proof test to demonstrate the integrity of the
static pressure system in a manner acceptable to the Administrator.
For airplanes certificated under part 25 of this chapter, determine
that leakage is within the tolerances established by § 25.1325.
(3) Determine that the static port heater, if installed, is
operative.
(4) Ensure that no alterations or deformations of the airframe
surface have been made that would affect the relationship between
air pressure in the static pressure system and true ambient static
air pressure for any flight condition.
(b) Altimeter:
(1) Test by an appropriately rated repair facility in accordance
with the following subparagraphs. Unless otherwise specified, each
test for performance may be conducted with the instrument subjected
to vibration. When tests are conducted with the temperature
substantially different from ambient temperature of approximately
25 degrees C., allowance shall be made for the variation from the
specified condition.
(i) Scale error. With the barometric pressure scale at
29.92 inches of mercury, the altimeter shall be subjected
successively to pressures corresponding to the altitude specified
in Table I up to the maximum normally expected operating altitude
of the airplane in which the altimeter is to be installed. The
reduction in pressure shall be made at a rate not in excess of
20,000 feet per minute to within approximately 2,000 feet of the
test point. The test point shall be approached at a rate compatible
with the test equipment. The altimeter shall be kept at the
pressure corresponding to each test point for at least 1 minute,
but not more than 10 minutes, before a reading is taken. The error
at all test points must not exceed the tolerances specified in
Table I.
(ii) Hysteresis. The hysteresis test shall begin not more
than 15 minutes after the altimeter's initial exposure to the
pressure corresponding to the upper limit of the scale error test
prescribed in subparagraph (i); and while the altimeter is at this
pressure, the hysteresis test shall commence. Pressure shall be
increased at a rate simulating a descent in altitude at the rate of
5,000 to 20,000 feet per minute until within 3,000 feet of the
first test point (50 percent of maximum altitude). The test point
shall then be approached at a rate of approximately 3,000 feet per
minute. The altimeter shall be kept at this pressure for at least 5
minutes, but not more than 15 minutes, before the test reading is
taken. After the reading has been taken, the pressure shall be
increased further, in the same manner as before, until the pressure
corresponding to the second test point (40 percent of maximum
altitude) is reached. The altimeter shall be kept at this pressure
for at least 1 minute, but not more than 10 minutes, before the
test reading is taken. After the reading has been taken, the
pressure shall be increased further, in the same manner as before,
until atmospheric pressure is reached. The reading of the altimeter
at either of the two test points shall not differ by more than the
tolerance specified in Table II from the reading of the altimeter
for the corresponding altitude recorded during the scale error test
prescribed in paragraph (b)(i).
(iii) After effect. Not more than 5 minutes after the
completion of the hysteresis test prescribed in paragraph (b)(ii),
the reading of the altimeter (corrected for any change in
atmospheric pressure) shall not differ from the original
atmospheric pressure reading by more than the tolerance specified
in Table II.
(iv) Friction. The altimeter shall be subjected to a
steady rate of decrease of pressure approximating 750 feet per
minute. At each altitude listed in Table III, the change in reading
of the pointers after vibration shall not exceed the corresponding
tolerance listed in Table III.
(v) Case leak. The leakage of the altimeter case, when
the pressure within it corresponds to an altitude of 18,000 feet,
shall not change the altimeter reading by more than the tolerance
shown in Table II during an interval of 1 minute.
(vi) Barometric scale error. At constant atmospheric
pressure, the barometric pressure scale shall be set at each of the
pressures (falling within its range of adjustment) that are listed
in Table IV, and shall cause the pointer to indicate the equivalent
altitude difference shown in Table IV with a tolerance of 25
feet.
(2) Altimeters which are the air data computer type with
associated computing systems, or which incorporate air data
correction internally, may be tested in a manner and to
specifications developed by the manufacturer which are acceptable
to the Administrator.
(c) Automatic Pressure Altitude Reporting Equipment and ATC
Transponder System Integration Test. The test must be conducted by
an appropriately rated person under the conditions specified in
paragraph (a). Measure the automatic pressure altitude at the
output of the installed ATC transponder when interrogated on Mode C
at a sufficient number of test points to ensure that the altitude
reporting equipment, altimeters, and ATC transponders perform their
intended functions as installed in the aircraft. The difference
between the automatic reporting output and the altitude displayed
at the altimeter shall not exceed 125 feet.
(d) Records: Comply with the provisions of § 43.9 of this
chapter as to content, form, and disposition of the records. The
person performing the altimeter tests shall record on the altimeter
the date and maximum altitude to which the altimeter has been
tested and the persons approving the airplane for return to service
shall enter that data in the airplane log or other permanent
record.
Altitude |
Equivalent pressure (inches
of mercury) |
Tolerance ±(feet) |
−1,000 |
31.018 |
20 |
0 |
29.921 |
20 |
500 |
29.385 |
20 |
1,000 |
28.856 |
20 |
1,500 |
28.335 |
25 |
2,000 |
27.821 |
30 |
3,000 |
26.817 |
30 |
4,000 |
25.842 |
35 |
6,000 |
23.978 |
40 |
8,000 |
22.225 |
60 |
10,000 |
20.577 |
80 |
12,000 |
19.029 |
90 |
14,000 |
17.577 |
100 |
16,000 |
16.216 |
110 |
18,000 |
14.942 |
120 |
20,000 |
13.750 |
130 |
22,000 |
12.636 |
140 |
25,000 |
11.104 |
155 |
30,000 |
8.885 |
180 |
35,000 |
7.041 |
205 |
40,000 |
5.538 |
230 |
45,000 |
4.355 |
255 |
50,000 |
3.425 |
280 |
Table II - Test Tolerances
Test |
Tolerance (feet) |
Case Leak
Test |
±100 |
Hysteresis
Test: |
|
First Test
Point (50 percent of maximum altitude) |
75 |
Second Test
Point (40 percent of maximum altitude) |
75 |
After Effect
Test |
30 |
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 |
Table IV - Pressure-Altitude Difference
Pressure (inches of Hg) |
Altitude difference
(feet) |
28.10 |
−1,727 |
28.50 |
−1,340 |
29.00 |
−863 |
29.50 |
−392 |
29.92 |
0 |
30.50 |
+ 531 |
30.90 |
+ 893 |
30.99 |
+ 974 |
(Secs. 313, 314, and 601 through 610 of the Federal Aviation Act of
1958 (49 U.S.C. 1354, 1355, and 1421 through 1430) and sec. 6(c),
Dept. of Transportation Act (49 U.S.C. 1655(c))) [Amdt. 43-2, 30 FR
8262, June 29, 1965, as amended by Amdt. 43-7, 32 FR 7587, May 24,
1967; Amdt. 43-19, 43 FR 22639, May 25, 1978; Amdt. 43-23, 47 FR
41086, Sept. 16, 1982; Amdt. 43-31, 54 FR 34330, Aug. 18, 1989;
Doc. No. FAA-2015-1621, Amdt. 43-49, 81 FR 96700, Dec. 30, 2016]