Type Approval and Type Certification - Decreasing Fuel Consumption and Exhaust Gas Emissions in Transportation - page 175

exhaust
nozzle

sampling

nozzle center line

sample
transfer
line

minimum of 4
mozzle diameters

18-25 nozzle diametres

nozzle
exit

sampling
point

Fig. 12.6 Sampling at the test bench

12.2.2 Sampling, Sample Transfer, Instrumentation
and Measurement Technology

The instrumentation and measurement technology requirements of jet engines are
regulated in Appendix E of JAR-34, Section 1 of ICAO (Appendix 5 of Annex 16,
Volume II) [ 23 ].
The test must be done at the required thrust setting on a properly equipped test
bench. The engine must be stabilized at each setting and the probe must be made
of stainless steel. If a mixing probe is used, all sampling orifices must be of equal
diameter. The proposed design and position is shown in Fig. 12.6 .
The sample must be transferred from the probe to the analyzers via a tube with
an internal diameter of 4.0-8.5 mm (0.157-0.334 in), taking the shortest practical
route and having a flow rate of less than 10 s. The tube must be heated to
160C ± 5C (320F ± 41F).
The branch tube must be maintained at a temperature of 65C ± 15C
(149F ± 59F). When sampling to measure unburned hydrocarbons, CO, CO 2 , NO,
and NO 2 , the tube must be made of stainless steel or carbon-loaded grounded Teflon.
Basically, the analyzers for testing the engines of vehicles, airplanes, and ships are
the same. The total amount of hydrocarbons can be analyzed with a heated FID, CO,
and CO 2 concentrations can be determined with a non-dispersible infra-red (IR)
analyzer and NO x concentrations can be measured by CLD (see Fig. 12.7 ).

12.2.3 JAR-E and CS-E for the Certification of Engines

JAR-E is based on European Civil Aviation Requirements (ECAR) Section C and
is termed JAR for engines. It contains the airworthiness requirements of all aircraft
engines [ 24 , 25 ]. The relevant EASA, Subpart A-General regulations are contained
in Table 12.2 [ 26 ].