Boeing 747 B18701

Summary

On 25 February 2013, a Boeing 747 registered B18701, operated by China Airlines, was involved in an incident near Dallas, Texas, United States. 3 people were on board and nobody was injured. The aircraft was slightly damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

25 February 2013

Classification

Incident

Location

Dallas, Texas, United States

Coordinates

32.9019, -97.0419

Aircraft

Boeing 747

Registration

B18701

Category

Airplane

Engines

4

Operator

China Airlines

Operating rule

Part 129: Foreign

Phase of flight

Not recorded

Route

Altanta → Dallas

Aircraft damage

Minor

Weather

Unk

Light

Not Reported

NTSB number

ENG13IA016

Nobody was injured.

Fuel leaking from a fractured fuel manifold feeder line that ignited on contact with the engine’s hot compressor rear frame, which resulted in an engine undercowl fire. The fuel manifold feeder line failed due to high amplitude fatigue because the fuel manifold resonance frequencies were within the engine operation range. Contributing to the incident was that the engine was overhauled about the same time as the most current fuel manifold configuration that addressed the high amplitude fatigue failure mode was introduced, thus it was not installed on the engine.

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

Read the full NTSB narrative

On February 25, 2013, a Boeing B747-409F freighter, B-18701, powered by four General Electric CF6-80C2B1F turbofan engines, experienced a No. 2 (left inboard) engine undercowl fire while taxiing after landing at Dallas/Fort Worth International Airport, Dallas Texas. After receiving the fire warning, the pilots discharged a fire suppression bottle and the fire ceased. There were no injuries to the three crewmembers on board and no airplane damage was reported. The incident flight was a regularly scheduled cargo flight, operated by China Airlines under provisions of 14 Code of Federal Regulations Part 129, from Taipei, Taiwan, to Dallas with stops in Anchorage, Alaska, and Atlanta, Georgia. Initial visual examination of the engine found that at the No. 2 fuel nozzle position, the right fuel manifold feeder tube aft o-ring support was displaced rearward against the snap ring. When the No. 2 fuel nozzle feeder tube shroud was removed, the feeder tube was found fractured and separated between the feeder tube-to-ferrule weld joint and the aft o-ring, which is one of the features that prevents a fuel leak when the feeder tube fractures. Metallurgical examination revealed that the feeder tube fractured due to lower alternating stress high-cycle fatigue cracking that transitioned to increasing alternating stress fatigue cracking before ultimately failing in overload. Further, the o-ring had sustained a spiral-like separation. Additional examination confirmed that no inclusions or any material anomalies at the feeder tube crack initiation sites and that the material properties of the feeder tube and o-ring and the weld quality met their required specifications. The fracture mode of the feeder tube is well-documented and GE issued Service Bulletin (SB) 73-0371 to introduce a redesigned fuel manifold and bracket to address this issue. Service Bulletin 73-0371 also introduced changes to the manifold feeder tube configuration and orientation (to avoid resonance frequencies of the manifold that were within the engine operating range) to prevent fuel manifold fractures and wear-through of the tube thickness that had resulted in previous fuel leaks and undercowl fires. The SB was issued just 7 days before the installation of the incident fuel manifold on the incident engine; therefore the operator was unable to install the most current fuel manifold design.

Quoted verbatim from the NTSB record.