What happened
On 21 April 2021, a BRM Land Africa (Citius) microlight, registration EI-FBY, was conducting a local VFR flight departing from Ballyheelan Airfield, Co. Cavan. At the start of the flight, the pilot estimated wind speeds at approximately 25 mph. During the flight, the pilot encountered severe thermal activity, and by the time the aircraft returned to the airfield for landing, wind speeds had increased to estimated gusts of 35 mph.
While performing the approach to Runway 17 using stage 2 flaps, the pilot reduced engine power as part of the standard landing procedure. As the aircraft was roughly four feet above the ground, it suddenly experienced a sudden loss of lift, causing the aircraft to sink and stall. This resulted in a hard landing on the runway, causing substantial damage to the aircraft's undercarriage and fuselage skin.
The investigation
The AAIU investigation examined the aircraft's condition and the environmental factors present at the time of the accident. The investigation found that the left undercarriage leg had been distorted and rotated upward, which caused the crossbeam to bend and crack, and led to buckling of the fuselage skin. The windscreen was also found to be cracked.
The investigation also reviewed the pilot's credentials and the meteorological conditions. The pilot held a valid National Private Pilot Licence and a valid medical certificate. Meteorological data from Met Éireann confirmed that the area was experiencing an easterly airflow with significant thermal activity, which is a known factor in creating localized wind disturbances.
Findings
- The primary cause of the hard landing was a probable windshear encounter at a low altitude above the runway.
- The presence of undulating terrain, hedgerows, and trees to the east of the approach path, combined with strong winds, created conditions highly conducive to low-level wind shear.
- Due to its low mass and low operating speeds, the BRM Land Africa (Citius) is particularly susceptible to the effects of turbulence, crosswinds, and terrain-induced wind shear.
- The aircraft's undercarriage sustained significant structural damage due to the impact of the hard landing.