What happened
On 12 August 2023, a Piper PA-22-150 Tri-pacer, registration ZU-AKE, was performing circuit-and-landing exercises at Vereeniging Airfield (FAVV) in Gauteng. During a "wheeler landing" (a three-point touchdown), the pilot heard an unusual noise from beneath the aircraft, followed by the right wing sinking toward the ground. Suspecting a gear issue, the pilot immediately initiated a go-around.
After a brief period, the pilot requested a visual inspection of the landing gear from the aircraft owner on the ground. Despite the owner finding no visible damage during a low fly-pass, a subsequent landing attempt resulted in the right wing sinking again. The pilot performed another go-around and eventually landed the aircraft on the grass adjacent to the runway at approximately 50 mph. The impact caused the right landing gear to fail, resulting in a 90-degree yaw to the right. As the gear collapsed, the tail lifted and the fuselage leaned, causing the left wing tip to strike the ground. The aircraft sustained substantial damage, including a bent propeller, buckled struts, and a dented wing, though the pilot escaped without injury.
The investigation
SACAA AIID investigators examined the wreckage and the aircraft's maintenance history. The inspection of the right-side landing gear revealed that the Hydrasorb shock absorber had failed at the mounting boss. Evidence of rust, pitting corrosion, and dirt indicated that a crack had existed in the boss for an extended period, leaving only a tiny fraction of the original diameter intact.
Records showed the aircraft had undergone its most recent annual inspection in May 2023, with the airframe having flown roughly 38 hours since that service. While the aircraft's maintenance logs indicated that periodic inspections were being performed, the specific fatigue crack in the mounting boss had gone undetected.
Findings
- The primary cause of the accident was the failure of the right-side mounting boss due to an undetected fatigue crack.
- The failure of this component caused the right main landing gear to disconnect from the suspension, leading to its total collapse under load.
- Inadequate maintenance inspection of the landing gear system contributed to the failure, as the metal fatigue was not identified during routine checks.