rating/identification plug provides the EEC with engine configuration
information for proper engine operation.
It is plugged into
connector P11 and attached to the fan case by a metal strap. It remains with
the engine even after EEC replacement.
The plug includes a
coding circuit, soldered to the plug connector pins. It is equipped with fuse
links and push- pull links, which either ensure, or prohibit connections
between the different plug connector pins.
The EEC stores
schedules, in its Non-Volatile Memory (NVM), for all available engine
configurations. During initialization, it reads the plug by looking for
voltages on certain pins. Depending on the location and voltage present at
specific pins, the EEC will select a specific schedule.
In the case of a
missing, or invalid ID plug, the EEC uses the value stored in the NVM for the
previous plug configuration.
(ID) plug supplies configuration data codes to the EEC as follows:
1.Engine family and
2. N1 trim modifier
3. Thrust rating
4. Bump option for
the -7B22 B1, -7B24 B1, -7B27 B1
5. Engine condition
monitoring (PMUX optional)
6. Engine combustor
configuration (SAC or DAC)
Push-pull links provide the EEC with configuration information. They
consist of switch mechanisms located between 2 contacts and can be manually
opened, or closed, according to customer requests.
This N1 Trim
modifier is a measure of how a given engine performed in a test cell. When
engines are moved between aircraft and may require a different thrust
installation this N1 modifier is used in calculations to uprate or derate a
given engine at an appropriate level.
level of an engine is changed (perhaps more accurately "programmed")
by installing a "ID plug" that screws onto the EEC and conveys
program information that sets the engine thrust output to the level desired by
will calculate thrust margin with formula : (see engine shop manual testing
NOTE: You must run all of the acceptance steady state
test points with a fan speed modifier level (N1 Trim Level) of zero.
and then find a fan speed modifier (FMN1) based on the
takeoff thrust margin of the engine model, see table below ;
the 'N1 Modifier Level' , Set the ID Plug according to CFM56-7B S/B 72-0106.