McDonnell Douglas MD-10-30F N304FE

Summary

On 13 February 2012 at about 20:00 local time, a McDonnell Douglas MD-10-30F registered N304FE, operated by Federal Express Corporation, was involved in an incident near Portland, Oregon, United States. The number of people on board was not recorded. The aircraft was slightly damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

13 February 2012 at 20:00

Classification

Incident

Location

Portland, Oregon, United States

Nearest airport

Portland Intl Jetport (PWM)

Coordinates

45.5892, -122.6056

Aircraft

McDonnell Douglas MD-10-30F

Registration

N304FE

Category

Airplane

Engines

3

Operator

Federal Express Corporation

Operating rule

Part 121: Air Carrier

Phase of flight

Not recorded

Route

Portland → Oakland

Aircraft damage

Minor

Weather

Unk

Light

Not Reported

NTSB number

ENG12IA012

Injuries not recorded.

The fracture of the fan mid shaft due to a stress corrosion cracking initiated by local regions of corrosion pitting, which resulted from oil migration within the shaft and its subsequent degradation.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

On February 13, 2012, a FedEx McDonnell Douglas (Boeing) MD10-30, registration number N304FE, equipped with three General Electric (GE) CF6-50 turbofans engines, performed a rejected take-off due to a failure of the No. 1 (left) engine. No injuries were reported. The incident flight was a regularly scheduled domestic cargo flight, operated under the provisions of Title 14 CFR Part 121, from Portland to Oakland, California. Examination of the airplane revealed no damage or penetration of the cowlings and no damage to the airplane; however, examination of the engine revealed three penetration holes and tears in low pressure turbine case and a single hole located in the turbine rear frame. Disassembly of the incident engine found that the fan mid shaft had fractured and the aft section of the fan mid shaft exhibited a spiral crack angled 45° to the longitudinal axis that measured about 69.5-inches in total length (about 3½ revolutions around the shaft) and extended about 20.5-inches axially in length. Metallurgical examination of the fan mid shaft found that it had fractured entirely in an intergranular mode. The initiation of the spiral fracture was comprised of numerous discolored, thumbnail shaped cracks initiating from the inner diameter surface of the fan mid shaft, some of which had progressed through the fan mid shaft thickness. The morphology of the cracks was consistent with a stress corrosion cracking mechanisms typical of high strength steel such as the fan mid shaft parent material. Localized areas of corrosion pitting, scaling, and loss of the anti-corrosion coating were observed throughout the inner diameter of the fan mid shaft. Examination of the debris within the shaft identified it as an ester based engine oil residue, typical of the kind of oil used in turbine engines. The stress corrosion cracking observed on the fan mid shaft was caused primarily due to the breakdown of a synthetic oil product inside the FMS during both storage and engine operation. The exact source or mechanism by which the oil entered the dry cavity between the fan mid shaft and the center vent tube is unknown.

Quoted verbatim from the NTSB record.