What happened
On September 20, 2024, a Cessna 172S, registration LN-KAB, was performing a private flight from Gol Airport Klanten (ENKL) in Norway. During the takeoff roll on the paved portion of runway 29, the pilot experienced poor acceleration and increasing vibrations. As the aircraft approached the end of the asphalt, the pilot decided to abort the takeoff by reducing power.
At approximately the same moment the decision to abort was made, the aircraft became airborne. The vibrations ceased once the wheels left the ground. The aircraft landed on the grass approximately 170 meters past the paved surface. While attempting to brake, the aircraft traveled past the end of the runway and entered a wooded, marshy area. The aircraft struck a small spruce tree, causing the right landing gear to fail and the aircraft to nose over, eventually coming to rest upside down. The passenger sustained minor injuries, while the pilot was uninjured.
The investigation
The Norwegian Safety Investigation Authority (NSIA) examined the aircraft, the engine, and the landing gear. Technical inspections of the Lycoming IO-306-L2A engine, including borescope inspections and valve checks, revealed no mechanical failures or evidence of sticking valves. While a slight compression leak was noted in cylinder number three, it was not considered a primary cause of the event.
Investigators focused on the cause of the vibrations and the loss of acceleration. Examination of the right landing gear showed that the wheel axle and attachment bolt had suffered overload failures. Metallurgical analysis confirmed these were not fatigue breaks but were caused by the impact with a small spruce tree found at the scene. The investigation also noted that the aircraft's Garmin G1000 system was not utilizing an SD card to log engine parameters, which would have provided critical data for analyzing engine performance during the takeoff.
Findings
- The pilot's decision to abort the takeoff occurred too late, nearly coinciding with the aircraft becoming airborne, which left insufficient runway for a safe stop.
- The pilot likely experienced a lack of capacity to reassess the situation due to the high workload and the sudden onset of vibrations.
- The aircraft's speed and the braking effectiveness on the grass were insufficient to prevent the overrun.
- The destruction of the landing gear was caused by the impact with a small tree located just beyond the runway end.
- The lack of recorded engine data prevented a definitive analysis of whether the engine was underperforming.
Safety action
- The NSIA recommends that aircraft owners using Garmin G1000 or similar EFIS systems utilize SD cards to record flight and engine data to assist in future safety investigations.
- It is recommended that flight clubs and private pilots establish and practice fixed decision points during takeoff to ensure that an abort decision can be made early enough to maintain safe margins.