The following requirements apply to both TYPE A & B unless otherwise stated.
1 Performance Standard a. The Instrument shall trigger visual and aural alarm when CO is detected.
b. The concentration against time characteristic of the alarm activation shall meet the requirements of Table 1 below:
c. The instrument may provide a readout of actual detected CO concentration level in parts per million (ppm) by volume.
d. The probability of false alarms should be shown by the manufacturer to be sufficiently remote so as not to encourage the flight crew to distrust the instrument.
e. The warm-up time of the instrument should not exceed 5 minutes.
| CONCENTRATION
(ppm by volume) | NO ALARM BEFORE
(minutes) | ALARM BEFORE
(minutes) |
|---|
| Less than or equal to 30 | DO NOT ALARM | DO NOT ALARM |
| More than 30 | 120 | 180 |
| More that 50 | 60 | 90 |
| More than 100 | 10 | 40 |
| More than 300 | No delay | 3 |
Table 1: Alarm Activation Concentration
2 Alarm Operation a. There shall be a flashing AMBER indication, visible within the angle shown in Figure 1 below, whenever any of the criteria, described in Table 1, are met.
[Figure or form omitted from this preview — available in the Avioverse workspace library.]
Figure 1 Plan View of Instrument showing Minimum Viewing Angle
b. The flashing visual caution light shall be accompanied by an intermittent aural alarm of a distinctive characteristic that cannot be confused with other aural alarms or indications that are typically found in the aircraft.
c. The aural alarm shall be of such a characteristic that the attenuation by an Automatic Noise Reduction Headset will be kept to a minimum.
d. In order to mitigate any distraction at critical stages of the flight, the aural alarm should initially alarm at a low intensity. At each cycle of the alarm the intensity should be increased until it is at least 85dBA at a range of 3 metres.
e. It shall be possible for the pilot to cancel the alarms. Once cancelled the instrument should re-set within 2 minutes. At this point, the instrument should continue to monitor the air and re-warn if the criteria of paragraph 1b are met.
3 Function/Power Indications a. Self test:
Both types of unit should have a function indicator which illuminates showing that a self test of the instrument has been successfully completed. The test should confirm as many of the functions as possible.
b. Battery Power test. TYPE A only
The TYPE A unit shall provide the pilot with a steady visual indication that there is 5 hours or less of useful battery power remaining. If there is less than 2 hours left, the visual indication should be made to flash.
4 Standard Performance Test
The following is a detailed test requirement to be carried out when specified. During all tests the detector should be mounted in its normal operating orientation.
a. Test gases for Alarm Operation: the following concentrations should be used to check the alarm operation.
| REF | CO TEST GAS
(ppm by volume) | NO ALARM BEFORE
(minutes) | ALARM BEFORE
(minutes) |
|---|
| A | 20-25 | 240 | - |
| B | 31-37 | 120 | 180 |
| C | 51-61 | 60 | 90 |
| D | 101-121 | 10 | 40 |
| E | 301-361 | - | 3 |
| F | 5000-5500 | - | 3 |
b. The test conditions for the standard test are:
Temperature: 15 to 25°C
Humidity: Between 30% and 70% Relative humidity.
Pressure: 980 to 1050 hPa c. Standard Test procedure: the following is required:
Switch on instrument and allow to warm up for 5 minutes
Purge with clean air for 15 minutes
Test Gas B and check alarm between 120 to 180 minutes
Purge with clean air for 15 minutes
Test Gas C and check alarm between 60 to 90 minutes
Purge with clean air for 15 minutes
Test Gas D and check alarm between 10 to 40 minutes
Purge with clean air for 15 minutes
Test Gas E and check alarm before 3 minutes d. Digital Display
If a digital display is featured on the equipment then it should be checked that it reads in the band ± 10% of the actual value for each of the conditions above.
5 Low CO concentration test.
To ensure that nuisance warnings do not occur at low concentrations, carry out the following test exposing the instrument to the following gases:
Clean air for 15 min
Test gas A for 240 min or more
Check that the alarm is not triggered
Test gas B and ensure that alarm is triggered between 120 and 180 min
6 High CO concentration test.
To ensure that the instrument is capable of reacting to extremely high concentrations, carry out the following test exposing the instrument to the following gases:
Pass clean air for 15 min
Pass test gas F.
Check that the alarm is triggered within 3 min.
Pass clean air for 10 min
Pass test gas B.
Check that the alarm triggers between 120 and 180 min.
7 Documentation
The supplier shall provide written guidance in the following areas:
7.1 Operation
General description including the principle of operation including;
Details of and interpretation of warnings.
Details of and interpretation of test indications.
Limitations.
Battery changing procedure if applicable.
Action in the event of receiving a warning
Suggest generic actions helping the installer defining appropriate AFM procedures.
7.2 Installation
The installation instruction must make it clear which categories of aircraft the instrument is suitable for and any restrictions in its use must also be clearly stated.
A general description of the optimum position for the instrument in different aircraft types and the positions to be avoided to ensure reliable air sampling and to avoid compass interference.
7.3 Continued Airworthiness
Cleaning and other instructions as required.
[Amdt ETSO/6]