Boeing 767-322 N644UA

Summary

On 4 August 2010 at about 20:47 local time, a Boeing 767-322 registered N644UA, operated by United, was involved in an incident near Chicago, Illinois, United States. 190 people were on board and 6 had minor injuries. The aircraft was slightly damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

4 August 2010 at 20:47

Classification

Incident

Location

Chicago, Illinois, United States

Nearest airport

Chicago O'hare Intl (ORD)

Coordinates

41.5853, -87.5425

Aircraft

Boeing 767-322

Registration

N644UA

Category

Airplane

Engines

2

Operator

United

Operating rule

Part 121: Air Carrier

Phase of flight

Not recorded

Route

London → Chicago

Aircraft damage

Minor

Weather

VMC

Light

Day

NTSB number

DCA10IA082

6 people had minor injuries.

the brake fire after landing was caused by hydraulic fluid leaking on to hot brakes.

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

Read the full NTSB narrative

Flight 949 conducted a normal landing under maximum landing weight and the crew did not receive any warnings or cautions. There were no system anomalies found except for the damaged left-hand brake assembly. Examination of the left brake assembly found that it caught fire due to catalytic oxidation, most likely as a result of the carbon disk being exposed to deicing fluid.  The catalytic oxidation allowed the pistons from the brake housing to punch through the softened pressure plate and contact the rotor resulting in piston displacement, possible piston bushing damage and hydraulic fluid leakage.    When the 2R slide was unpacked at the manufacturer to determine why it did not fully inflate during the evacuation, the aspirator was found unattached. This was likely removed when the slide was packed for shipping because the slide would not have even partially inflated if it was not installed during the evacuation. When the slide was laid out, the two missing portions of the aspirator spider arms were found within the slide. Analysis of the fracture surfaces on both spider arms found that each had preexisting cracks.  These preexisting cracks were stress risers that reduced the strength of the arms.  Since the fracture faces contained no evidence of fatigue, the two arms fractured during slide inflation sequence which caused the slide to not properly inflate during the evacuation. The preexisting cracks most likely occurred during the manufacturing process.

Quoted verbatim from the NTSB record.