Compare and highlight differences

Compare / EASA/ Incorporated Amendments/ Compare & Highlight Differences

Appendix 1 to ETSO-C46a - Federal Aviation Administration Standard, Maximum Allowable Airspeed Indicator Systems

Available versions for ERULES-1963177438-7731

ED Decision 2003/10/RM found in: CS-ETSO Amdt 17 - European Technical Standard Orders (Oct 2026)

Version

Show details Hide details

###### Appendix 1 to ETSO-C46a – Federal Aviation Administration Standard, Maximum Allowable Airspeed Indicator Systems

*ED
Decision
2003/10/RM*

1. Purpose.

This document specifies minimum performance standards for
pitot-static type, maximum allowable airspeed indicator systems which
indicate continuously both indicated airspeed and maximum allowable
airspeed.

2. Performance Requirements.

2.1 General

(a) Materials. Materials must be of a quality demonstrated to be
suitable and dependable for use in aircraft instruments.

(b) Environmental conditions. The instrument must be capable of
performing its intended function and not be adversely affected during
or following prolonged exposure to the environmental conditions
stated under section 3. Where optional environments conditions are
set forth, the conditions selected must be declared as equipment
limitations.

2.2 Detail requirements.

(a) Indicating means. Indicated airspeed and maximum allowable
airspeed must be displayed in such a manner that the numerical values
on the scale increase in a clockwise, left to right, or bottom to top
direction.

(b) Case markings. The outlets in the case must be marked with „P“
for the pitot pressure connection, and with „S“ for the static
pressure connection.

2.3 Design requirements.

(a) Adjustable settings.

(1) Maximum allowable airspeed pointer. An adjustable stop may be
provided in the instrument for limiting the movement of the maximum
allowable airspeed pointer. If included, the design of this
adjustment must be such that it will not affect the indication of the
pointer when the altitude pressure conditions and Mach Number setting
are such that the limiting speed will be lower than that set by the
adjustable stop.

(2) Mach Number. If a readily accessible means is provided for
setting the instrument to any desired Mach Number, the value of the
setting must be visible from the front of the instrument. When the
instrument does not contain an external Mach Number setting
adjustment, the value of the permanent Mach Number setting need not
be visible from the front of the instrument.

(b) Visibility. The indicating means and all markings must be visible
from any point within the frustum of a cone, the side of which makes
an angle of at least 30° with the perpendicular to the dial and the
small diameter of which is the aperture of the instrument case. The
distance between the dial and the cover glass must be a practical
minimum.

(1) Indicated air-speed pointer. The indicated airspeed pointer must
indicate airspeed in accordance with the values contained in Table I.

(2) Maximum allowable airspeed pointer. The maximum allowable
airspeed pointer must indicate maximum allowable airspeed values in
the Vmo and Mmo limit ranges which -

(i) Follow the standard fundamental relationships of subsonic
compressible flow gas dynamics which are stated in appendix A; or

(ii) Are adjusted to account for design factors that are
characteristic of a particular aircraft type design such as, but not
limited to, static source pressure error variations and variable
speed limitations with altitude.

(d) Scale error.

(1) Instruments with permanent Mach Number setting. The indicated
airspeed scale error and the maximum allowable airspeed scale error
must not exceed the tolerances specified in Tables I and II,
respectively, with the instrument set at its permanent Mach Number.

(2) Instruments with means for external Each Number setting
adjustment.

(i) The indicated airspeed scale error must not exceed the tolerances
specified in Table I with the instrument set at the lowest Mach
number.

(ii) The maximum allowable airspeed scale error must not exceed the
tolerances specified in Table II with the instrument set at the
lowest Mach Number and at increasing Mach Number setting of not more
than 0.10 to and including the maximum Mach Number.

(e) Hysteresis. The reading of the maximum allowable airspeed pointer
first at 30,000 feet altitude and then at 10,000 feet altitude must
not differ by more then 2 knots from the corresponding readings
obtained for increasing altitudes during tests to assure the
instrument complies with the scale error requirements of section
2.3(d)(2)(ii) of this TSO.

(f) After effect. To assure the instrument complies with the scale
error requirements of section 2.3 (d) (2) (ii) of this TSO, the
maximum allowable airspeed pointer must return to its original
readings, corrected for any change in atmospheric pressure, within 3
knots, after not less than 1 or more than 5 minutes have elapsed
following completion of performance tests.

(g) Friction.

(1) Maximum allowable airspeed pointer. The friction of the pointer
must not produce an error exceeding 4 knots at each point indicated
by an asterisk in Table II.

(2) Indicated airspeed pointer. The friction on the pointer must not
produce an error exceeding 3 knots at each point indicated by an
asterisk in Table I.

(h) Leak.

(1) Case leak. When subjected to a static pressure differential of 15
inches of mercury between the inside and outside of the case, the
internal pressure must not increase because of case leaks more than
0.05 inches of mercury at the end of 1 minute time following first
application of the differential pressure.

(2) Airspeed diaphragm leak. There must not be any apparent movement
of the indicated airspeed pointer for 1 minute after a sequence of
events in which pressure sufficient to produce full scale deflection
of the indicated airspeed pointer is applied to the pitot connection
(static pressure connection open to atmosphere), the pressure source
is stopped, and the connection tubing pinched.

3. Environmental Conditions.

3.1 Temperature. The instrument must perform its intended function
over the range of ambient temperature from -30° to 50° C. With the
instrument temperature stabilized at the limits of the range, the
scale error must not exceed by more than 4.5 knots the tolerances
specified in Tables I and II at the points marked with an asterisk.
The instrument must not be adversely affected by exposure to the
range of ambient temperature from -65° to 70° C.

3.2 Altitude. The instrument must perform its intended function and
must not be adversely affected when operating in the pressure range
from -1,000 feet and the maximum altitude of intended operation. The
instrument must withstand an external case pressure of 50“ Hg.
absolute when installed properly and vented to an atmospheric
pressure of approximately 29.92“ Hg. absolute.

3.3 Vibration. The instrument must perform its intended function and
must not be adversely affected when subjected to vibrations of the
following characteristics:

<table bgcolor="#d9d9d9" cellpadding="7" cellspacing="0">
<col/>
<col/>
<col/>
<col/>
<tr valign="top">
<td bgcolor="#808080">
Instrument
					panel mounted (vibration isolated)
</td>
<td bgcolor="#808080">
Frequency
cycles
					per second
</td>
<td bgcolor="#808080">
Maximum
					double
amplitude
					(inches)
</td>
<td bgcolor="#808080">
Maximum
					acceleration
</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9" rowspan="2">
Reciprocating
					engine
powered
					aircraft – –
</td>
<td bgcolor="#d9d9d9">
5-50
</td>
<td bgcolor="#d9d9d9">
0.020
</td>
<td bgcolor="#d9d9d9">
1.5
</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
 

</td>
<td bgcolor="#d9d9d9">
 

</td>
<td bgcolor="#d9d9d9">
 

</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9" rowspan="2">
Turbine
					engine
powered
					aircraft – –
</td>
<td bgcolor="#d9d9d9">
5-55
</td>
<td bgcolor="#d9d9d9">
0.020
</td>
<td bgcolor="#d9d9d9">
					– – – – –
</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
55-1000
</td>
<td bgcolor="#d9d9d9">
					– – – – –
</td>
<td bgcolor="#d9d9d9">
0.25g
</td>
</tr>
</table>

3.4 Humidity. The instrument must perform its intended function and
must not be adversely affected following exposure to the extreme
condition of relative humidity in the range from 0 to 95 percent at a
temperature of approximately 70° C. for a period of 10 hours.

4. Compliance Tests.

As evidence of compliance with this standard, the manufacturer must
perform evaluation tests on proto- type instruments to demonstrate
proper design, reliability in performance of its intended functions,
and conformity with the performance standards of section 2. Tests
must also be performed to demonstrate compliance with the
environmental condition requirements specified in section 3.

5. Individual Performance Tests.

The manufacturer must conduct such tests as may be necessary on each
instrument to assure that it will meet the minimum performance
requirements of sections 2.3 (b) through 2.3 (h).

***TABLE
I***

<table bgcolor="#d9d9d9" cellpadding="7" cellspacing="0">
<col/>
<col/>
<col/>
<thead>
<tr valign="top">
<td bgcolor="#808080">
Speed
				knots
</td>
<td bgcolor="#808080">
Impact
				pressure (qc) inches Hg at 25°C
</td>
<td bgcolor="#808080">
Tolerance
				knots
</td>
</tr>
</thead>
<tbody>
<tr valign="top">
<td bgcolor="#d9d9d9">
50
</td>
<td bgcolor="#d9d9d9">
0.1198
</td>
<td bgcolor="#d9d9d9">
±4.0
</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
*60
</td>
<td bgcolor="#d9d9d9">
.1727
</td>
<td bgcolor="#d9d9d9">
2.0
</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
80
</td>
<td bgcolor="#d9d9d9">
.3075
</td>
<td bgcolor="#d9d9d9">
2.0
</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
*100
</td>
<td bgcolor="#d9d9d9">
.4814
</td>
<td bgcolor="#d9d9d9">
2.0
</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
120
</td>
<td bgcolor="#d9d9d9">
.6950
</td>
<td bgcolor="#d9d9d9">
2.0
</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
*150
</td>
<td bgcolor="#d9d9d9">
1.091
</td>
<td bgcolor="#d9d9d9">
2.5
</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
180
</td>
<td bgcolor="#d9d9d9">
1.580
</td>
<td bgcolor="#d9d9d9">
3.0
</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
*200
</td>
<td bgcolor="#d9d9d9">
1.959
</td>
<td bgcolor="#d9d9d9">
3.0
</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
230
</td>
<td bgcolor="#d9d9d9">
2.610
</td>
<td bgcolor="#d9d9d9">
3.0
</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
*250
</td>
<td bgcolor="#d9d9d9">
3.100
</td>
<td bgcolor="#d9d9d9">
3.0
</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
280
</td>
<td bgcolor="#d9d9d9">
3.924
</td>
<td bgcolor="#d9d9d9">
3.5
</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
*300
</td>
<td bgcolor="#d9d9d9">
4.534
</td>
<td bgcolor="#d9d9d9">
3.5
</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
320
</td>
<td bgcolor="#d9d9d9">
5.195
</td>
<td bgcolor="#d9d9d9">
3.5
</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
*350
</td>
<td bgcolor="#d9d9d9">
6.286
</td>
<td bgcolor="#d9d9d9">
4.0
</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
370
</td>
<td bgcolor="#d9d9d9">
7.082
</td>
<td bgcolor="#d9d9d9">
4.5
</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
*400
</td>
<td bgcolor="#d9d9d9">
8.385
</td>
<td bgcolor="#d9d9d9">
5.0
</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
430
</td>
<td bgcolor="#d9d9d9">
9.826
</td>
<td bgcolor="#d9d9d9">
5.5
</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
*450
</td>
<td bgcolor="#d9d9d9">
10.87
</td>
<td bgcolor="#d9d9d9">
6.0
</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
480
</td>
<td bgcolor="#d9d9d9">
12.56
</td>
<td bgcolor="#d9d9d9">
7.0
</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
*500
</td>
<td bgcolor="#d9d9d9">
13.78
</td>
<td bgcolor="#d9d9d9">
7.0
</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
520
</td>
<td bgcolor="#d9d9d9">
15.07
</td>
<td bgcolor="#d9d9d9">
7.0
</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
*550
</td>
<td bgcolor="#d9d9d9">
17.16
</td>
<td bgcolor="#d9d9d9">
8.5
</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
570
</td>
<td bgcolor="#d9d9d9">
18.66
</td>
<td bgcolor="#d9d9d9">
8.5
</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
*600
</td>
<td bgcolor="#d9d9d9">
21.07
</td>
<td bgcolor="#d9d9d9">
9.0
</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
630
</td>
<td bgcolor="#d9d9d9">
23.71
</td>
<td bgcolor="#d9d9d9">
9.5
</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
*650
</td>
<td bgcolor="#d9d9d9">
25.59
</td>
<td bgcolor="#d9d9d9">
10.0
</td>
</tr>
</tbody>
</table>

***TABLE
II***

<table bgcolor="#d9d9d9" cellpadding="7" cellspacing="0">
<col/>
<col/>
<col/>
<tr valign="top">
<td bgcolor="#808080">
Altitude
			feet mercury
</td>
<td bgcolor="#808080">
Pressure
			inches ± knots
</td>
<td bgcolor="#808080">
Maximum
			speed pointer tolerance
</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
0
</td>
<td bgcolor="#d9d9d9">
29.921
</td>
<td bgcolor="#d9d9d9">
**4
</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
*5,000
</td>
<td bgcolor="#d9d9d9">
24.896
</td>
<td bgcolor="#d9d9d9">
 

</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
10,000
</td>
<td bgcolor="#d9d9d9">
20.577
</td>
<td bgcolor="#d9d9d9">
 

</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
*15,000
</td>
<td bgcolor="#d9d9d9">
16.886
</td>
<td bgcolor="#d9d9d9">
 

</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
20,000
</td>
<td bgcolor="#d9d9d9">
13.750
</td>
<td bgcolor="#d9d9d9">
 

</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
*25,000
</td>
<td bgcolor="#d9d9d9">
11.104
</td>
<td bgcolor="#d9d9d9">
 

</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
30,000
</td>
<td bgcolor="#d9d9d9">
8.885
</td>
<td bgcolor="#d9d9d9">
 

</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
*35,000
</td>
<td bgcolor="#d9d9d9">
7.041
</td>
<td bgcolor="#d9d9d9">
 

</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
40,000
</td>
<td bgcolor="#d9d9d9">
5.538
</td>
<td bgcolor="#d9d9d9">
 

</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
*45,000
</td>
<td bgcolor="#d9d9d9">
4.355
</td>
<td bgcolor="#d9d9d9">
 

</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
50,000
</td>
<td bgcolor="#d9d9d9">
3.425
</td>
<td bgcolor="#d9d9d9">
**4
</td>
</tr>
</table>

\*\*From indicated airspeed corresponding to maximum equivalent
airspeed or maximum mach whichever is the limiting factor.

**APPENDIX
A**

**Relationships
For Calibrating Maximum Allowable Airspeed Pointer**

(1) For altitudes from sea level to altitude where

![](/static/files/file_jytjXw2lpRK/image003.png)

(2) For altitudes where MMO is limited factor:

![](/static/files/file_jytjXw2lpRK/image004.png)

Where:

Vmo = Maximum allowable indicated airspeed in knots.

Mmo = Maximum allowable mach.

K = Ratio of specific heats=1.40 for air.

Po = Pressure at sea level in inches of Hg.

P = Ambient static pressure in inches of Hg.

Cso = Speed of sound at sea level=661.48 knots.

a = Density ratio at altitude.

Vm = Maximum equivalent airspeed in knots