On June 4, 2021, about 1550 eastern daylight time, a Honda Aircraft HA-420, N10XN, was substantially damaged when it was involved in an accident at Cobb County International Airport-McCollum Field (RYY), Atlanta, Georgia. Both airline transport pilots were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 positioning flight.
According to the pilot in command, the flight and approach to the airport were normal. After the airplane touched down on the runway, he applied the brakes; however, there was no braking action from the airplane, and there was no compression of the brake pedals. The pilot called out that they had “no brakes” and elected to pull the emergency brake. The airplane began to skid, and the pilot released the emergency brake and noted that the airplane was about 45° off centerline and turning to the left. The airplane struck the grass apron next to the runway, completed a 180° turn, and came to rest heading in the opposite direction of travel in the grass to the left side of the runway.
Examination of the wreckage by a Federal Aviation Administration inspector revealed that the right main landing gear collapsed, which resulted in substantial damage to the right wing. The left main landing gear wheel assembly was located about 225 ft from the main wreckage. Examination of runway skid marks indicated that their orientation were consistent with a separation of the left wheel while the airplane was still on the runway and skidding to the left. 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.
Examination of the airplane discrepancy log revealed that the accident flight was the first flight after maintenance. 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, which stated the left main landing gear tire was “worn beyond [the] thread cords.”
According to the mechanic who installed the wheel assembly, he used a TRONAIR 02-7813C0100 jack to perform the wheel change. Once he received the airplane maintenance manual excerpts to perform the maintenance, he began to install the overhauled main wheel assembly. After “installing the wheel and torquing it the locking plate would not engage into the axle.” He removed and reinstalled the wheel assembly. It seemed to “slide into place much easier this time,” and the locking plate did engage “this time.” The mechanic then completed the maintenance paperwork and returned the airplane to service. The maintenance logbook entry indicated that all maintenance was performed in accordance with the HA-420 Maintenance Manual.
In a follow-up interview with an FAA inspector, the mechanic stated that he was positive that the locking tabs were engaged to secure the left main landing wheel onto the axle.
A review of the maintenance paperwork revealed that the mechanic signed off the maintenance rather than the repair station signing it off as the Honda HA-420 was not on the repair station’s certificate. Further, the mechanic indicated that the operator needed to send the maintenance manual excerpts since he “did not have access” to the HA-420 maintenance manuals.
Honda Aircraft Company searched their database of mechanics who received HA-420 specific maintenance training, and the mechanic who performed the maintenance on the airplane had not received the approved Flight Safety International maintenance training. Section 32-441-11-401 of the Honda HA-420 Maintenance Manual described the procedure for the removal and installation of the main landing gear tire and wheel assembly. This procedure referenced another procedure (AMM 07-11-10-201), which was “Lifting the Airplane with One Jack.” Under “Special Tools and Materials,” the lifting procedure specified item number 07-10-06 as the axle jack required. The specific TRONAIR part number (02-7924C0100) for the approved jack was in the HA-420 Tool and Equipment Manual.
Honda Aircraft Company performed a study comparing the jack the mechanic used (TRONAIR 02-7813C0100) and the Honda specific jack listed in the maintenance manual (TRONAIR 02-7924C0100). The results of the study indicated that it was possible for the jack used in the maintenance procedure on the accident airplane to interfere with the proper reseating of the wheel assembly on the axle during installation.