858
14 CFR Ch. I (1–1–19 Edition)
Pt. 43, App. E
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 fur-
ther, 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 al-
timeter at either of the two test points shall
not differ by more than the tolerance speci-
fied in Table II from the reading of the al-
timeter for the corresponding altitude re-
corded 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 sub-
jected to a steady rate of decrease of pres-
sure 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 cor-
responds 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 at-
mospheric 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 toler-
ance of 25 feet.
(2) Altimeters which are the air data com-
puter type with associated computing sys-
tems, or which incorporate air data correc-
tion internally, may be tested in a manner
and to specifications developed by the manu-
facturer which are acceptable to the Admin-
istrator.
(c) Automatic Pressure Altitude Reporting
Equipment and ATC Transponder System In-
tegration Test. The test must be conducted
by an appropriately rated person under the
conditions specified in paragraph (a). Meas-
ure 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 alti-
tude 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 al-
timeter 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 per-
forming the altimeter tests shall record on
the altimeter the date and maximum alti-
tude 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.
T
ABLE
I
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
T
ABLE
II—T
EST
T
OLERANCES
Test
Tolerance
(feet)
Case Leak Test ...............................................
±
100
Hysteresis Test:
First Test Point (50 percent of maximum
altitude) .................................................
75
Second Test Point (40 percent of max-
imum altitude) .......................................
75
After Effect Test ...............................................
30
T
ABLE
III—F
RICTION
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
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