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.
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.
| Time | Event | Page |
|---|---|---|
| 13:36:22 CDT | Aircraft took off | 3 |
| 13:47:18 CDT | Engine 1 N1 began to reduce and engine 1 oil pressure increased | 3 |
| 13:47:18 CDT | For 1 second, engine 1 EPR increased and then began to decrease | 3 |
| 13:47:21 CDT | 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 | 3 |
| 13:47:22 CDT | Engine 1 EGT Overlimit was activated, aircraft climbing through 19,588 feet pressure altitude | 3 |
| 13:47:27 CDT to 13:51:30 CDT | Thrust Lever Angle on both engines increased by about 10 degrees | 3 |
| 13:47:33 CDT | Engine 1 oil temperature began to increase | 3 |
| 13:47:40 CDT | Engine 1 EGT data became invalid (fluctuating between recorded values of 0°C and 2,560°C) | 3 |
| 13:48:00 CDT | Master warning occurred | 3 |
| 13:49:46 CDT | Engine 1 switched from EPR to N1 mode | 3 |
| 13:50:28 CDT | Engine 1 oil quantity began to decrease | 3 |
| 13:50:33 CDT | Engine 1 oil pressure began to decrease | 3 |
| 13:50:34 CDT | 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 | 3 |
| 13:51:14 CDT | Engine 1 fire warning began | 3 |
| 13:51:50 CDT | Engine 1 fuel fire valve moved out of the 'not fully closed' position as the avionics smoke warning began | 3 |
| 13:51:54 CDT | Engine 1 low oil pressure warning began | 3 |
| 13:51:54 to ~13:54:24 CDT | 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 | 3 |
| around 13:47:22 CDT | Autopilot was disengaged, re-engaged momentarily, then remained off for the rest of the flight | 3 |
Docket: data.ntsb.gov/Docket/?NTSBNumber=ENG14IA001. This brief is an analytical aid assembled from public records; it is not an investigative finding.