N544KCDiamond Aircraft Ind DA20-C1 · 2009

The flight instructor and pilot-receiving-instruction were conducting an instructional flight when the nosewheel separated from the nose landing gear strut during takeoff. The flightcrew reported that the takeoff was normal and that there was no indication that the nosewheel had separated from the airplane. However, after the nosewheel was located on the runway, the flight instructor received a phone call from the airplane operator and then via subsequent radio calls over the operator dispatch frequency it was determined that the separated nosewheel was likely from their airplane. Then the airplane operator and airport tower controller each visually confirmed that the nosewheel was indeed missing from the airplane. During the subsequent landing, the nose landing gear strut collapsed aft when it contacted the runway. The composite fuselage structure sustained multiple cracks, the nose landing gear box delaminated, and the firewall delaminated from the fuselage during the landing.

The lower portion of the nose landing gear strut welded assembly terminates with a threaded stud where a castellated nut and cotter pin secure the nosewheel fork assembly to the strut pivot. A postaccident examination determined that the threaded stud fractured which allowed the nosewheel fork to separate from the strut pivot. The castellated nut and cotter pin remained installed to the threaded portion of the fractured stud.

In January 2023, the airplane manufacturer issued Service Information Letter (SIL) No. SIL20C1-014 to address cracks at the top of the nose landing gear strut pivot and/or at the top of the threaded stud. Additionally, the airplane manufacturer cautioned that a single hard landing may severely reduce the service life of the nose landing gear strut, and that improper assembly of the nose landing gear could result in cracking at the threaded stud which may result in the separation of the nosewheel fork assembly. The airplane manufacturer recommended a thorough examination of the nose landing gear strut pivot and threaded stud every 100 hours in accordance with the airframe maintenance manual instructions. The airplane manufacturer further stipulated that it was imperative that “all suspected hard landings are reported and the airplane inspected.”

According to a postaccident review of maintenance documentation, there were no cracks observed on the nose landing gear strut when it was last examined during a 100-hour examination completed about 30.7 flight hours before the accident flight.