Honda Aircraft Co Llc HA-420 N10XN accident near Kennesaw, Georgia

Probable cause

The mechanic’s improper installation of the left main wheel assembly.

NTSB analysis

The accident flight and approach to the airport were normal. After the airplane touched down on the runway, the pilot applied the brakes; however, there was no braking action. The pilot called out that they had “no brakes” and elected to pull the emergency brake. The airplane began to skid, continued off the left side of the runway, completed a 180° turn, and came to rest in the grass. During the accident sequence, the right main landing gear collapsed, which resulted in substantial damage to the right wing.

The left main landing gear wheel was located about 225 ft from the main wreckage. Examination of the axle revealed that there was damage to the bottom threads of the axle and partial thread damage on the nut that secured the wheel to the axle. The individual parts of the left wheel retention stack (axle nut, retention key, and hubcap) were found intact inside the wheel hubcap. The retention key, which contained the locking tabs, was still safety wired to the axle nut. The airplane discrepancy log indicated that the left main landing gear wheel assembly was replaced the morning of the accident due to a discrepancy the pilot wrote up the day before the accident.

The mechanic who performed the work reported that during the installation of the left wheel assembly, the locking tab did not engage into the axle, so he removed and reinstalled the wheel assembly, which then “slid into place much easier.” In addition, the mechanic reported the jack he used to perform the maintenance was not the jack specified in the maintenance manual for the procedure. Although the mechanic stated the left main wheel assembly was installed correctly, it likely was not installed properly as indicated by the minimal damage to the securing nut and to the axle, which likely occurred when the axle contacted the runway surface after the wheel departed the airplane. Additionally, a study performed comparing the jack the mechanic used to the jack specified in the maintenance procedure indicated that it was possible for the unapproved jack to interfere with the proper reseating of the wheel assembly on the axle during installation. Further, the mechanic who performed the maintenance had not received specific training on the airframe. In summary, given the limited damage to the wheel assembly, the mechanic’s lack of airplane specific maintenance training, and his use of an improper jack for the maintenance, it is likely the mechanic installed the wheel assembly improperly, which resulted in the wheel separating from the airplane.

Text from the NTSB. Open the NTSB docket for ERA21LA246 for the full record.