Presentation on Failure Of Second Stage Compressor Blade In An Aircraft Engine (case study)

1. Presentation on Case Study
“Failure Of Second Stage Compressor Blad
In An Aircraft Engine”
By : Kunal Chauhan
Production And Industrial Engineering

2. CONTENT
 Introduction
 Common Causes Of Failure
 Failure Analysis Methodology
 Background Information
 Location Of Failure
 Visual Examination Of General Physical Features
 Testing Procedure
 Metallography And Hardness
 Results

3. Introduction
SERVICE FAILURES of components and structures have been
increasingly experienced in several industries, quite often without
any warning. Some failures may be trivial, while others may have
serious consequences.
Service failures may result in:
 Injuries to personnel
 Damage to property
 Shutdown of an entire plant
 Loss of production
 Ecological problems such as release of hazardous materials
 Expensive and prolonged litigations affecting the credibility of the
manufacturers and the reliability of their products
Fig1: failure of wind turbine [instant]

4. Common Causes of Failure
Improper Design
Abnormalities, and Abuses
Defective Manufacture
Improper Inspection
Environmental Effects
Operation, Service
Failures Due To Materials
Failures Due To Processing
Failure causes

5. Failure Analysis Methodology
Background
information
Location of failed
component
Specimen collection &
Preliminary examination
Microscopic examination
Chemical analysis Mechanical properties
Non destructive
evaluation
Simulation studies
Analysis of data Prepartion of report

6. Background Information
 A blade of the second-stage compressor in an engine fractured in service.
 The fracture was in brittle mode, with intergranular facets.
 The blade also had cracks in other regions.
 The blade had unusually high hardness, and the fracture was attributed to SCC.
Location of Failure
 A blade of the second-stage compressor blade of an
aircraft engine fractured after 21 hours and 19
minutes of service.
 The failed blade and its adjacent blades were
examined
 The failed blade and its adjacent blades, two on
either side, are shown in Fig2
Fig2:Second-stage compressor blade failed in an engine,
along with the adjacent blades

7. Visual Examination of General Physical Features
 A close-up view of the fracture surface is shown
in fig3
 The fracture surface was generally light gray in
color except for a flat region at the mid chord of
the blade, where it was dark brown.
 Macroscopically, the fracture was brittle
 Cracks were observed at the leading edge and the
root of the blade fig4
Fig3: Close-up view of the discolored area on the fracture
surface of the failed blade

8. Visual Examination of General Physical Features
Fig4: Cracks in other areas of the failed blade. Insets show
enlarged areas of some of these cracks. Fig5:Crack shown in Fig4. opened up. The discoloration is
similar to that noticed on the fracture surface of the failed
blade.
 The longest crack was opened, and the resulting
fracture surface also exhibited a dark brown color
(fig5) similar to that on the fracture surface,
suggesting that all the cracks could be of similar
nature.

9. Testing Procedure And Results
SCANNING ELECTRON
FRACTORAPHY
 Under the SEM, intergranular facets were observed
on the dark brown region of the failed blade (Fig6.)
 Careful examination of the transition zone did not
reveal the presence of fatigue striations.
 Intergranular cracking was observed on the freshly
opened up surface near the blade root area, further
confirming that all the cracks were similar in nature.
Fig6: SEM fractograph showing the intergranular
cracking in the dark brown region in the failed blade

10. Metallography And Hardness
 The Microstructure Of The Failed Blade Was
Tempered Martensite.
 The Hardness Was 510 Hv, Which Is Unusually High
Compared With The Specified Value Of 350 To 380
Hv.
 The Blades Adjacent To The Failed Blade Had A Fully
Tempered Martensite Structure, With A Hardness In
The Specified Range.
 The Crack On The Surface With Extensive Branching
Is Shown In Fig7.
Fig7: Optical micrograph of the cracks noticed on the
blade surface

11. RESULTS
DISCUSSION
 The intergranular mode of fracture and the
branching of cracks are typical of SCC.
 The high hardness due to inadequate
tempering was conducive to such
cracking.
 The other adjoining blades that showed
hardness within the specified range
showed no such cracking
CONCLUSION
 The blade failed due to SCC at the mid-chord region.
RECOMMENDATION
 Care should be exercised to follow strickly the heat
treatment schedule specified

12. Thankyou