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ENGINE DETERIORATION
EGT MARGIN
OAT LIMITE
New Engine EGT
Red Line
EGT
OAT
OATL
EGTMARGIN
CP
Engine deterioration
EGTMARGIN < 0
OATL < CP
If OATL < CP
EGT exceedances may occur
during a Full Power Takeoff
1°C OAT or Flex Temperature = 3,3°C EGT
EGTTMaarrggiinn & OATTLL
The OATL calculation for the CFM56-5B:(see
Commercial Engine Service Memorandum)
OATL = CP + EGTM / 3,3
CFM56-5C Corner Point is ISA+15°C
e.g.: At Sea Level the OATL = 30 + EGTM / 3,3
950°C
78
Flight Operations Support
10 September 2005
CFM PROPRIETARY INFORMATION
Subject to restrictions on the cover or first pa ge
EGT Transcient
allowance to -5B EGT limits
Area A
•If engine warm-up not sufficient
No troubleshooting. 20 overtemp permitted.
•If EGT exceedance condition identified
No troubleshooting. 10 overtemp permitted.
•If EGT exceedance condition can ’t be identified
Troubleshooting. 10 exceedances permetted in
area A & B combined before engine removal.
Area B
Troubleshooting. 10 exceedances permetted in
area A & B combined before engine removal
Area C
The enginemust be removed to examine
damage. One nonrevenue flight permitted if
damage within boroscope inspection.
EGTTMaarrggiinn & OATTLL
79
Flight Operations Support
10 September 2005
CFM PROPRIETARY INFORMATION
Subject to restrictions on the cover or first pa ge
• Temperature inversion
• Warm-up time
• Dirty compressor airfoils
• Engine deterioration
• Too much bleed air on the engine
• FOD
• Engine system malfunction
(e.g. VBV actuation)
• Engine hardware malfunction
Causes of EGT exceedances
Temperature invertion
EGT
N1
FLAT RATED THRUST
Thrust
(TOGA)
OAT
CP*
* CP: Corner Point or Flat Rated Temperature
EGT Red line
EGTTMaarrggiinn & OATTLL
FADEC will control the engine according to the above charts.
Below FRT, thrust would be maintained but N1 and EGT would be
higher versus no inversion. Above FRT, some loss of thrust would
occur (not deemed significant by the aircraft manufacturers in
terms of aircraft performance).
80
Flight Operations Support
10 September 2005
CFM PROPRIETARY INFORMATION
Subject to restrictions on the cover or first pa ge
KEEP IN MIND
•Stick to your Flight Manual Procedures
• Certified thrust will indeed remain available even in case of EGT
Exceedance
• At TOGA, ENG OVERTEMPERATURE may occur when:
OAT ³ OATL and the OATL £ CP (ISA+15°C)
• No EGT exceedances for performance deterioration as long as the OATL > CP
(ISA+15°C)
• 1°C OAT or Flex Temperature = 3,3°C EGT
• OATL data:
- helps the crew to assess potential EGT exceedances
- is the primary basis for the scheduling of engine removal
EGTTMaarrggiinn & OATTLL
81
Flight Operations Support
10 September 2005
CFM PROPRIETARY INFORMATION
Subject to restrictions on the cover or first pa ge
?
When EGTMargin decrease,
Fuel Burn increase.
+ 10°EGT = + 0.7% SFC
ENGINES contribute...
…
Peerrffoorrmaannccee Deetteerriiaattiioonn
… to AIRCRAFT performance deterioration
~ 66 %
82
Flight Operations Support
10 September 2005
CFM PROPRIETARY INFORMATION
Subject to restrictions on the cover or first pa ge
THERMAL Loads
PRESSURE & AERODYNAMIC Loads
CENTRIFUGAL Loads
ENGINE
performance
deterioration
Peerrffoorrmaannccee Deetteerriiaattiioonn
83
Flight Operations Support
10 September 2005
CFM PROPRIETARY INFORMATION
Subject to restrictions on the cover or first pa ge
FATIGUES
High Load Value
Cycle Frequency
Time
Load
Cycle
Time
Load
Time At a Given Load
Steady
Fix parts
• Combustion Chamber
• Nozzles, Vanes, Valves
Performance Deetteerriiaattiioonn
ROTATING PARTS
• HPT Blades and Disks
• LPT Blades and Disks
84
Flight Operations Support
10 September 2005
CFM PROPRIETARY INFORMATION
Subject to restrictions on the cover or first pa ge
ENGINE
performance
deterioration
BLADES / CASING
CLEARANCES
ENGINE WEAR
LEADS TO A DETERIORATION OF THE
ENGINE EFFICIENCY
Fuel
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CFFM556 Flight Operations Support(11)
