Narrative
During landing, the airplane sustained damage when the nose landing gear remained in the up position. According to flight crew statements and communications transcripts, the crew attempted to lower the landing gear but did not receive a nose gear down indication. They performed a low approach, and air traffic control tower personnel confirmed that the nose landing gear was not extended. The crew then climbed to 6,000 feet and contacted American Airlines maintenance to troubleshoot. After executing the appropriate emergency checklists, including an attempted manual extension of the nose landing gear, the procedures proved unsuccessful. The crew subsequently executed a landing on runway 14R with the main landing gear extended and the nose gear retracted.
Examination
Post-accident examination revealed that the nose landing gear spray deflector center link had fractured, and the right-hand urethane deflector was displaced. The deflector had rotated aft and was not in its track within the wheel well. When the crew attempted to lower the nose landing gear, the deflector impinged on the wheel well structure, preventing the gear from extending. The spray deflector components were sent to the NTSB Materials Laboratory for analysis.
Metallurgical Analysis
The center deflector assembly exhibited fractures along three separate lines where the right side deflector attaches. The aft right side of the center deflector was fractured through the bolt holes and both vertical and horizontal plate members. Magnified optical examinations of the three fracture faces revealed rough, crystalline matte gray surfaces, consistent with overstress separations in cast aluminum alloys. No evidence of porosity, corrosion, or preexisting cracking was observed on any fracture face. The engineering drawing specified the center deflector (part number 5952241) as cast aluminum alloy C355 per federal specification QQ-A-596, solution heat treated and aged to T61 temper. A Brinell hardness test on a piece of the center deflector measured 101 HB, consistent with the specified alloy and heat treatment.