EFFECTIVITY
ALL CFM56 ENGINES
CFMI PROPRIETARY INFORMATION
CFM56-ALL
TRAINING MANUAL
INTRODUCTION
BORESCOPE INSPECTION
Page 18
Sep 03
ON CONDITION MAINTENANCE
CFM56 engines use a maintenance concept called ‘On
Condition Maintenance’. This means that engines have
no periodic overhaul schedules and can remain installed
under the wing until something important occurs, or when
lifetime limits of parts are reached.
For this reason, to monitor and maintain the health of an
engine, different tools are available.
Engine performance trend monitoring.
To evaluate engine deterioration over a period of time,
certain engine parameters, such as gas temperature,
are recorded and compared to those initially observed
at engine installation on the aircraft. Any abnormalities
can be immediately identified and further investigation
initiated.
For troubleshooting, record and report the following
engine and aircraft data as soon as engine and records
are available for initial inspection.
- Hours since engine last used.
- Flight data prior to, during, and after the event.
- Hours since last shop visit.
- Service Bulletin compliance.
- Pilots report of the event.
- Condition of engine inlet.
- Any obvious incidents that may have contributed to,
or immediately preceded, an event.
Lubrication particles analysis.
Lubrication oil circulating in the engine is filtered, and
large, visible-to-the-eye particles (larger than 10 microns)
are collected in filters and magnetic chip detectors, for
visual inspection. Analysis of these particles, that usually
indicate worn or broken engine parts, may show that the
internal parts of the engine have to be inspected in detail.
Engine vibration monitoring system.
Sensors located in various positions in the engine, send
vibration values to the on-board monitoring system. When
vibration values are excessive, the data recorded can be
used to take remedial balancing action.
Borescope inspection.
To visually check the condition of engine internal parts
that are not easily accessible, borescope probes can be
inserted through various ports that are located on the
engine outer casing.
TOC
