IAD97IA048

The crew experienced an unsafe nose gear light on approach to landing. After recycling the gear, all indications were that the gear was down and locked. The airplane landed on runway 4R during which the nose gear collapsed; the airplane skidded to a stop. Examination of the airplane revealed the nose landing gear upper lock link had fractured. The lock link had accumulated 28,978 service hours and 24,511 cycles since original manufacture. The lock link was overhauled 13,515 and 6,317 hours prior to the failure. A metallurgical examination revealed the upper lock link was fractured through the 'I' beam section near its lower end about 3 inches from the overcenter pivot with the lower lock link. The fracture features were typical of fatigue which progressed over a large portion of the fracture. No mechanical, corrosion, or manufacturing discontinuities were visible at the fatigue origin. At the time of the failure, there was an Airworthiness Directive AD-97-02-10 about the upper lock link. It required inspections of assemblies prior to 10,000 total cycles or within 90 days of its issue, February 11, 1997, whichever came later. Continental Airlines was in the process of inspecting its entire fleet of affected aircraft when this incident occurred.

On February 17, 1997, at about 1259 eastern standard time, a McDonnell Douglas MD-82, N34838, operated by Continental Airlines as Flight 134, experienced an unsafe nose gear light while on approach to Newark International Airport, Newark, New Jersey. The flight crew recycled the landing gear and all indications were that the gear was down and locked. After landing on runway 4R, and during the roll out, the nose gear collapsed and the aircraft skidded to a stop. The two flight crewmembers, three flight attendants, one jumpseat rider and 141 passengers reported no injuries. Passengers and crew disembarked the aircraft through the aft galley door (L4) using mobile stairs and were bussed to the terminal. The flight originated from Denver, Colorado, exact time unknown. Instrument meteorological conditions prevailed, and an instrument flight rules (IFR) flight plan had been filed. The flight was conducted under the provisions of Title 14 Code of Federal Regulations (CFR) Part 121 as a domestic, scheduled passenger/cargo flight.

After an inspection, it was determined that the nose landing gear upper lock link had fractured. This component and the lower lock link were sent to the National Transportation Safety Board's Materials Laboratory for examination.

According to the Materials Laboratory Factual Report, the upper lock link had accumulated 28,978 service hours and 24,511 cycles since original manufacture. The lock link was overhauled 13,515 and 6,317 hours prior to the failure. The upper lock link was fractured through the "I" beam section near its lower end about 3 inches from the overcenter pivot with the lower lock link. According to the report, the fracture features were typical of fatigue which progressed over a large portion of the fracture. No mechanical, corrosion, or manufacturing discontinuities were visible at the fatigue origin. The material met of the hardness specifications.

At the time of the failure, there was an Airworthiness Directive AD-97-02-10 about the upper lock link. It required inspections of assemblies prior to 10,000 total cycles or within 90 days of its issue, February 11, 1997, whichever came later. Continental Airlines was in the process of inspecting its entire fleet of affected aircraft when this incident occurred.