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Cases › ENG14IA001 · Part 121 airline

AIRBUS A319 132Spirit Airlines

Greenville, TX, USA · 2013-10-15·N516NK

0
fatal
0
serious
No injury
highest injury
Minor
damage
AnalyseThe analystOne timeline · precedents · ask the docket · what the record saysGenerateInvestigation briefFacts, cause, recorder extremes, sequence, sourcesSourceNTSB docket10 documents on data.ntsb.gov

What happened

NTSB summary, verbatim

Based on metallurgical analysis, a No. 1 engine high pressure turbine (HPT) 2nd stage blade separated below the blade platform due to stress corrosion cracking in the blade J-channel cooling air cavity. The liberated blade entered the gas path and caused extensive damage to the HPT and low pressure turbine (LPT) hardware and cases. The damaged engine was left at a high power setting for about four minutes until the crew received a No. 1 engine fire warning. During this time the turbine was exposed to temperatures that exceeded the material annealing temperature and resulted in failure and separation of multiple components including the LPT 3rd and 4th stage disks, turbine exhaust case center body, and the No. 5 bearing housing. The engine nacelle was not breached and all separated engine components traveled out the back of the engine.  

Photographs

37the aircraft, and what the investigators found
The aircraft before the accident
LAS AIRPORT FROM FLIGHT LAS-LAX N516NK A319 (10509733653)
Eric Salard · CC BY-SA 2.0 · Wikimedia Commons
Wreckage and site documentation · 36 photographs from the docket

Photographs are NTSB docket attachments — works of the US government, in the public domain. Captions are the Board’s own.

Probable cause

the Board's determination
A high pressure turbine 2nd stage blade separation due to stress corrosion cracking in the J channel cooling cavity. The failed blade entered the gas path and caused substantial damage to the low pressure turbine. The engine was subsequently left at a high power setting for approximately four minutes, exposing the turbine hardware to temperatures that exceeded the material annealing temperature and resulted in in failure and separation of multiple engine components.

Occurrence sequence

1 stepsNTSB coding · CICTT taxonomy
  1. 1 · Enroute-climb to cruise
    Powerplant sys/comp malf/fail
    defining event

Findings

1 causal · 0 contributing
  • CAUSE
    Aircraft › Aircraft power plant › Engine (turbine/turboprop) › Turbine section — Fatigue/wear/corrosion

Sequence of events

18 timed eventsfrom the FDR factual report · claude-sonnet-5
  1. 13:36:22 CDTtakeoffp.3
    Aircraft took off
  2. 13:47:18 CDTclimbp.3
    Engine 1 N1 began to reduce and engine 1 oil pressure increased
  3. 13:47:18 CDTclimbp.3
    For 1 second, engine 1 EPR increased and then began to decrease
  4. 13:47:21 CDTclimbp.3
    Engine 1's N1 vibration increased from a prior steady-state value of 1.1 to 7.2; engine 1's N2 vibration increased from a prior steady-state value of 0.3 to 2.1
  5. 13:47:22 CDTclimbp.3
    Engine 1 EGT Overlimit was activated, aircraft climbing through 19,588 feet pressure altitude
  6. 13:47:27 CDT to 13:51:30 CDTclimb/responsep.3
    Thrust Lever Angle on both engines increased by about 10 degrees
  7. 13:47:33 CDTclimbp.3
    Engine 1 oil temperature began to increase
  8. 13:47:40 CDTclimbp.3
    Engine 1 EGT data became invalid (fluctuating between recorded values of 0°C and 2,560°C)
  9. 13:48:00 CDTclimbp.3
    Master warning occurred
  10. 13:49:46 CDTclimbp.3
    Engine 1 switched from EPR to N1 mode
  11. 13:50:28 CDTclimbp.3
    Engine 1 oil quantity began to decrease
  12. 13:50:33 CDTclimbp.3
    Engine 1 oil pressure began to decrease
  13. 13:50:34 CDTclimbp.3
    Engine 1's N2 vibration increased to 9.9, as engine 1's N1 vibration fluctuated and decreased to between 2.2 and 4.5
  14. 13:51:14 CDTclimbp.3
    Engine 1 fire warning began
  15. 13:51:50 CDTclimbp.3
    Engine 1 fuel fire valve moved out of the 'not fully closed' position as the avionics smoke warning began
  16. 13:51:54 CDTclimbp.3
    Engine 1 low oil pressure warning began
  17. 13:51:54 to ~13:54:24 CDTclimbp.3
    Over the next 2.5 minutes, the following warnings occurred: lavatory smoke, cargo smoke, forward lower cargo 1 smoke, forward lower cargo 2 smoke, aft lower cargo 1 smoke, and aft lower cargo 2 smoke
  18. around 13:47:22 CDTclimbp.3
    Autopilot was disengaged, re-engaged momentarily, then remained off for the rest of the flight

NTSB analysis

from the final report

Based on metallurgical analysis, a No. 1 engine high pressure turbine (HPT) 2nd stage blade separated below the blade platform due to stress corrosion cracking in the blade J-channel cooling air cavity. The liberated blade entered the gas path and caused extensive damage to the HPT and low pressure turbine (LPT) hardware and cases. The damaged engine was left at a high power setting for about four minutes until the crew received a No. 1 engine fire warning. During this time the turbine was exposed to temperatures that exceeded the material annealing temperature and resulted in failure and separation of multiple components including the LPT 3rd and 4th stage disks, turbine exhaust case center body, and the No. 5 bearing housing. The engine nacelle was not breached and all separated engine components traveled out the back of the engine.