Every carbon fuel powered engine has a carburettor usually mounted on top of the cylinder. Inside the carburettor is where the fuel-air mixture happens before it is pumped into the cylinder. The fuel-air mixture has to be precisely both in terms of fuel-to-air ratio and as to the temperature of the mixture.

1. All aircraft have a whole bunch of probes connecting various parts of the aircraft
engine to the cockpit. The probes (or sensors), pickup the information it is supposed
to pickup and transmits it in real time to the cockpit where it is connected to the
appropriate indicator or engine data managers (EDM).
CRB probe and CHT gasket probes are two
such probes. The Carburettor Temperature
Probe (CRB) probe transmits carburettor
temperature while the Cylinder Head
Temperature (CHT) gasket probes transmits
the cylinder head temperature to the
appropriate Aircraft Fuel Flow Indicator
/ EDM in the cockpits.
As youmight guess, irrespective ofthe weather
or temperature outside the aircraft, the engine
and every other vital parts of the aircraft, has
to function at a temperature that is conducive
to its smooth functioning. Overheating can
lead tofuel ignition and fire whereas,a drop in
temperature can lead to the engine stalling
and dying out in flight due to fuel starvation.
Every pilot therefore keeps a wary eye on the CRB and CHT indicators. If the cockpit
sports an EDM than the pilot’s task is made simpler as the EDM can be pilot-
programmed to raise and alarm in the event of any abnormalities in the CRB and
CHT readings. The pilot is therefore free to pursue higher cognitive functions.
CRB probe explained:
Every carbon fuel powered engine has a carburettor usually mounted on top of the
cylinder. Inside the carburettor is where the fuel-air mixture happens before it is
pumped into the cylinder. The fuel-air mixture has to be precisely both in terms of
fuel-to-air ratio and as to the temperature of the mixture. Any deviation will lead to

2. serious consequences inside the cylinder and for the aircraft itself hence the need to
monitor the carburettor temperature.
J.P. Instruments manufacturers CRB probes that are immune to humidity or
presence of oil and gasoline. J.P.I CRB probes are also engineered to withstand
temperature fluctuations.
CHT probes explained:
Although there are three basic types of CHT probes, the one that we are concerned
with, is the “J-type” CHT Probes; also known as CHT gasket probe because it
replaces the gasket on 18mm spark plugs.
You buy a CHT gasket probe if your aircraft engine does not have a threaded
thermowell receptor. If you have difficulty adopting the CHT probe to your cylinder,
you might want to look at the ‘CHT adapter probe’.
The CHT adapter probe is used in conjunction with the OEM CHT probe. The CHT
adapter probe is a threaded probe that fits into the cylinder head thermo well and is
available as a bayonet type or threaded type. So, you might want to take a look at
the existing CHT probe and cylinder before buying the replacement CHT probe or
CHT gasket probe.
JPI Sales:
1-800-345-4574
714-557-3805
FAX: 714-557-9840
sales@jpinstruments.com
JPI Technical Support:
1-800-345-4574
714-557-3805
support@jpinstruments.com
J.P. InstrumentsInc:
3185-B AirwayAve
Costa Mesa, CA 92626