History of Flight
On 11 May 2013, at 1300Z, a Beech 58 (registration ZS-KLL) departed from Wonderboom Airport (FAWB) for a local private flight with the pilot and three passengers. During the landing back at FAWB on Runway 06, the pilot felt the main undercarriage touch down, followed by the nose wheel. The pilot did not recall seeing the three green landing gear indicator lights. After shutting down the aircraft, inspection revealed that the main undercarriage had partially sunk into the runway and the nose undercarriage was not extended. The main landing gear was not fully extended.
Damage to Aircraft
The aircraft sustained damage to both propellers, the nose cone, and the landing gear. The propellers struck the ground, the nose wheel sunk into the surface before the aircraft came to a halt, and the main landing gear gradually collapsed under the weight of the aircraft. The left and right inboard main landing gear doors were severely chafed on their bottom edges due to being extended during landing. The nose landing gear doors were found closed and chafed on their face sides, not edges. The right-hand nose gear drag brace attachment bracket was chafed through approximately one-third of its thickness.
Findings
A walkaround inspection by an aircraft maintenance organization revealed that the nose wheel was not extended, both propellers were bent, and the nose cone was chafed at the base. The main landing gear extended only about one-quarter of the way and was not locked. Skid marks from the main landing gear tyres were present on the runway, but no nose tyre marks were observed. When the aircraft was lifted and the landing gear was manually extended using the emergency extension crank, the main gear extended fully, but the nose gear did not extend at all. To extend the nose gear, the doors had to be pried open with considerable effort; once open, the nose gear assembly dropped easily to the down position. The nose gear extension bellcrank on the landing gear actuator was found bent and cracked, and the aft nose gear extension rod was broken at the rod end. The chafing marks on the nose landing gear doors, drag brace, and attachment bracket aligned with the gear in the up position, indicating that the nose gear doors were closed during landing. The nose gear is held up only by tension on the retract mechanism, with no physical uplock hooks. With the aft retract rod broken, the nose gear should have extended but not locked by gravity, suggesting the nose gear doors jammed and prevented extension. The main gear was partially extended during landing; had it been fully extended or retracted, different damage patterns would have occurred. The chafing marks on the tyre sidewalls and skid marks indicate the main landing gear collapsed gradually as airspeed and lift decreased.
Probable Cause
Landing gear failure