ASN Wikibase Occurrence # 310039
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| Date: | Tuesday 6 November 2012 |
| Time: | 19:00 LT |
| Type: |  McDonnell Douglas MD-88 |
| Owner/operator: | Delta Air Lines |
| Registration: | N908DE |
| MSN: | 53417/2032 |
| Year of manufacture: | 1992 |
| Engine model: | P & W JT8D SERIES |
| Fatalities: | Fatalities: 0 / Occupants: 147 |
| Aircraft damage: | None |
| Category: | Serious incident |
| Location: | Atlanta Hartsfield-Jackson International Airport, GA (ATL/KATL) -
 United States of America
|
| Phase: | Initial climb |
| Nature: | Passenger - Scheduled |
| Departure airport: | Atlanta Hartsfield-Jackson International Airport, GA (ATL/KATL) |
| Miami International Airport, FL (MIA/KMIA) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
A Delta Air Lines Boeing (previously McDonnell Douglas) MD-88 airplane, N908DE, experienced an uncontained 4th stage turbine blade separation and loss of power from the No. 1 (left) engine, a Pratt & Whitney JT8D-219, as the airplane was climbing through FL 240 after departing from the Hartsfield-Jackson Atlanta International Airport, Atlanta (ATL), Georgia. The pilots reported hearing a loud bang and the indications on the No. 1 engine's rpm and engine pressure ratio gages dropped while the indication on the exhaust gas temperature gage increased. The pilots retarded the No. 1 engine's power lever to idle and noted that the engine continued to run. The pilots declared an emergency and requested to return to ATL. While enroute back to ATL, the pilots shut down the No. 1 engine after the oil quantity had decreased to near zero and the oil pressure was less than 10 pounds per square inch. The airplane returned to ATL for a single-engine landing without further incident. The examination of the airplane revealed a large hole in the bottom of the No. 1 engine's cowl coincident with where the engine's fan duct was ruptured. The disassembly and examination of the No. 1 engine revealed all of the 4th stage turbine blades were fractured transversely across the airfoil adjacent to the blade root platform. There was one 4th stage turbine blade that had a flat, blue-colored, elliptical-shaped area on the fracture surface on the convex (suction) side of the airfoil that was identified by the NTSB's Materials Laboratory as a high-cycle fatigue (HCF) fracture. HCF fractures at that location on JT8D- 219 4th stage turbine blades are consistent with wear on the blade tip shroud notches that cause an increase in the stresses in the airfoil. There is an airworthiness directive that requires an inspection of JT8D-219 4th stage turbine blades for shroud notch wear, however the incident occurred prior to the blades having accumulated enough time in service to have required the blades to be inspected. All of the 4th stage turbine blades had the tip shroud notches repaired at Delta's turbine blade shop prior to installation in the engine. Delta reported that they had seen an increase in the number of JT8D-219 4th stage turbine blade fracture incidents, almost all that involved blades that had been repaired in their blade repair shop. As a result of the number of JT8D-219 4th stage turbine blade fracture incidents that had occurred, Delta had discontinued repairing those turbine blades in their shop and were using either new blades or blades that were repaired at a turbine blade repair facility. Although a special dimensional inspection to measure the turbine blade's shroud notches was developed, there were no Delta-repaired 4th stage turbine blades available to measure
Probable Cause and Findings
The 4th stage turbine blade separation that resulted in an uncontained release of low pressure turbine blade material was Delta Air Lines' repair process for the turbine blades' tip shrouds. It was not possible to identify the part of the repair process that led to the premature wear of the blade's tip shoud and
subsequent separation.
Accident investigation:
 |
|
Sources:
NTSB ENG13IA005
History of this aircraft
Other occurrences involving this aircraft
| 24 January 2016 | N908DE | Delta Air Lines | 0 | Newark Liberty International Airport, NJ (ERW/KEWR) | |
sub |
| Collision with other aircraft on apron | ||||||
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 02-Apr-2023 17:53 | ASN Update Bot | Added |
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