Boeing 757-225 N919UW

Summary

On 28 October 2007 at about 13:48 local time, a Boeing 757-225 registered N919UW, operated by US Airways Inc, was involved in an incident near Charlotte, North Carolina, United States. 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

28 October 2007 at 13:48

Classification

Incident

Location

Charlotte, North Carolina, United States

Nearest airport

Charlotte/Douglas Intl (CLT)

Coordinates

35.2090, -80.9526

Aircraft

Boeing 757-225

Registration

N919UW

Category

Airplane

Engines

2

Operator

US Airways Inc

Operating rule

Part 121: Air Carrier

Phase of flight

Not recorded

Aircraft damage

Minor

Weather

Unk

Light

Not Reported

NTSB number

ENG08IA001

Nobody was injured.

The truck beam fracture initiated by fatigue and stress corrosion cracking from pits that were present on the ID surface of the truck beam, under the protective finishes. Crack propagation occurred by alternating modes of stress corrosion cracking and fatigue until final fracture occurred by ultimate ductile separation. The condition of the surface finishes and base metal at the fracture initiation area indicated that the pitting was present before the last application of cadmium plating and primer, rather than the result of corrosion since the last overhaul. The observed pitting appeared to be remnants of incomplete corrosion removal during the last overhaul.

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

Read the full NTSB narrative

On October 28, 2007, a US Airways Boeing 757-200, N919UW, experienced a fracture of the truck beam on the left hand (LH) main landing gear (MLG) while preparing for departure from Charlotte/Douglas International Airport (CLT). The airplane was loaded with flight crew, cabin crew, passengers and cargo at the time of the truck beam failure. There was no other damage to the airplane and there were no injuries to any of the occupants or the ground personnel. The truck beam had accumulated 24,025 cycles since new and 2,707 cycles since its last overhaul which occurred in May, 2005. The truck beam fracture initiated by fatigue and stress corrosion cracking from pits that were present on the ID surface of the truck beam, under the protective finishes. Crack propagation occurred by alternating modes of stress corrosion cracking and fatigue until final fracture occurred by ultimate ductile separation. The condition of the surface finishes and base metal at the fracture initiation area indicated that the pitting was present before the last application of cadmium plating and primer, rather than the result of corrosion since the last overhaul. The observed pitting appeared to be remnants of incomplete corrosion removal during the last overhaul. Residual stress analysis of the ID surface in the fracture initiation region suggested that the blended area did not receive adequate peening to restore typical residual compressive stresses. The observed reduction in residual compressive stresses likely contributed to the fracture initiation. The wall thickness at the area of fracture initiation measured 0.29” and was within drawing dimensional tolerances. Chemical analysis and hardness testing verified that the truck beam was fabricated from the required material in the specified heat treated condition. Evaluation of the protective finishes on the truck beam indicated that the cadmium plating on the ID surface did not meet the minimum thickness requirements.

Quoted verbatim from the NTSB record.