ASN Wikibase Occurrence # 314604
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| Date: | Wednesday 4 August 2010 |
| Time: | 14:47 LT |
| Type: |  Boeing 767-322 |
| Owner/operator: | United Airlines |
| Registration: | N644UA |
| MSN: | 25094/369 |
| Year of manufacture: | 1991 |
| Total airframe hrs: | 82012 hours |
| Engine model: | P&W PW4000 SER |
| Fatalities: | Fatalities: 0 / Occupants: 190 |
| Aircraft damage: | Minor |
| Category: | Serious incident |
| Location: | Chicago-O'Hare International Airport, IL (ORD/KORD) -
 United States of America
|
| Phase: | Landing |
| Nature: | Passenger - Scheduled |
| Departure airport: | London (LHR) |
| Chicago-O'Hare International Airport, IL (ORD/KORD) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
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.
Probable Cause: the brake fire after landing was caused by hydraulic fluid leaking on to hot brakes.
Accident investigation:
 |
|
Sources:
NTSB DCA10IA082
History of this aircraft
Other occurrences involving this aircraft
| 19 January 2018 | N644UA | United Airlines | 0 | Amsterdam-Schiphol International Airport (AMS/EHAM) |  |
min |
| Loss of pressurization | ||||||
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 02-Jun-2023 18:51 | ASN Update Bot | Added |
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