Accident Overview
On June 4, 2021, at approximately 1550 eastern daylight time, a Honda Aircraft HA-420, registration N10XN, was substantially damaged during landing at Cobb County International Airport-McCollum Field (RYY) in Atlanta, Georgia. The two airline transport pilots were not injured. The flight was conducted as a positioning flight under 14 Code of Federal Regulations Part 91.
Sequence of Events
The pilot in command reported that the flight and approach were normal. After touchdown, he applied the brakes but felt no braking action and no compression of the brake pedals. The pilot announced “no brakes” and deployed the emergency brake. The airplane began to skid; he released the emergency brake and observed the airplane about 45° off the centerline, turning left. The airplane struck the grass apron adjacent to the runway, completed a 180° turn, and came to rest heading opposite the direction of travel in the grass on the left side of the runway.
Damage and Component Examination
A Federal Aviation Administration inspector examined the wreckage. The right main landing gear had collapsed, resulting in substantial damage to the right wing. The left main landing gear wheel assembly was located about 225 ft from the main wreckage. Runway skid marks indicated that the left wheel separated while the airplane was still on the runway and skidding left. The axle showed damage to the bottom threads and the nut securing the wheel had partial thread damage. The left wheel retention stack components (axle nut, retention key, and hubcap) were found intact inside the wheel hubcap. The retention key, with its locking tabs, remained safety-wired to the axle nut.
Maintenance Background
According to the airplane discrepancy log, the accident flight was the first flight after maintenance. The left main landing gear wheel assembly had been replaced the morning of the accident due to a pilot write-up the previous day noting the tire was “worn beyond [the] thread cords.”
The mechanic who installed the wheel assembly stated he used a TRONAIR 02-7813C0100 jack to perform the wheel change. After receiving maintenance manual excerpts, he began installing an overhauled main wheel assembly. After torquing the wheel, the locking plate would not engage into the axle. He removed and reinstalled the assembly; this time it slid into place more easily and the locking plate engaged. He completed the maintenance paperwork and returned the airplane to service. The logbook entry indicated all maintenance was performed per the HA-420 Maintenance Manual.
In a follow-up interview, the mechanic expressed certainty that the locking tabs were engaged to secure the left main landing wheel onto the axle.
Maintenance Documentation and Training
A review of the maintenance paperwork showed that the mechanic signed off the work rather than the repair station, as the HA-420 was not on the repair station’s certificate. The mechanic indicated the operator needed to provide the maintenance manual excerpts because he “did not have access” to the HA-420 manuals.
Honda Aircraft Company searched their database of mechanics who received HA-420 specific maintenance training; the mechanic who performed the work had not completed the approved Flight Safety International maintenance training.
Relevant Maintenance Procedures
The HA-420 Maintenance Manual section 32-441-11-401 describes removal and installation of the main landing gear tire and wheel assembly. This procedure references another procedure (AMM 07-11-10-201) for “Lifting the Airplane with One Jack.” Under “Special Tools and Materials,” the lifting procedure specifies item number 07-10-06 as the required axle jack. The HA-420 Tool and Equipment Manual lists the specifically approved jack as TRONAIR part number 02-7924C0100.
Post-Accident Study
Honda Aircraft Company performed a study comparing the jack used by the mechanic (TRONAIR 02-7813C0100) with the Honda-specific jack (TRONAIR 02-7924C0100). The study indicated that it was possible for the jack used in the accident airplane’s maintenance to interfere with the proper reseating of the wheel assembly on the axle during installation.