Cessna 402C N769EA incident near Nantucket, Massachusetts

Probable cause

Company maintenance personnel’s failure to comply with the airplane manufacturer’s service instructions by not removing the cracked drag brace from service nor inspecting the repaired drag brace at the appropriate interval, which resulted in the failure of the nose landing gear drag brace due to fatigue cracking and collapse of the nose landing gear during the landing roll. Contributing to the failure of the nose landing gear drag brace was the failure of the repair station to detect a remaining portion of a crack following repair.

NTSB analysis

While on approach for a full-stop landing, the pilot extended the landing gear and performed the Before Landing checklist. The airplane landed on its main landing gear, and then, as the pilot lowered the nose, it continued to lower until it contacted the runway.

Postincident examination of the airplane revealed that the nose landing gear drag brace failed near the nose landing gear actuator attachment lug due to a fatigue crack. A review of maintenance records revealed that a crack in the nose landing gear drag brace was repaired in June 2011 and that, following the repair, the drag brace had been installed on two other company airplanes. In July 2012, the nose landing gear drag brace was removed from the second airplane for inspection, during which, a 1/8-inch-long shallow crack was found near the actuator attachment lugs. The crack was blended in accordance with Cessna Service Bulletin MEB91-11, Revision 1, and then a fluorescent dye penetrant inspection of the area was performed. The inspection did not detect any further cracks; however, it is likely that, at this time, some portion of the crack remained. After the drag brace was returned to service, it was installed on the incident airplane on August 3, 2012. Subsequently, the nose landing gear drag brace was visually inspected in-situ twice; however, neither inspection identified the fatigue crack.

At the time of the incident, the airplane had been operated for about 286 cycles since the crack repair in July 2012, which exceeded the 250-cycle inspection interval specified by MEB91-11R1. It is likely that, if the nose landing gear drag brace had been inspected after 250 landings in accordance with the manufacturer's service instructions, the crack would have been detected at that time. Additionally, if the operator had incorporated into its maintenance program Supplemental Inspection 32-20-00, which stated, in part, that the nose landing gear drag braces should be inspected using visual and eddy current inspections and that repair or modification of cracked nose landing gear drag braces was not allowed, it is likely that the nose landing gear drag brace would have been removed from service in July 2012.

Text from the NTSB. Open the NTSB docket for ERA12IA550 for the full record.