What happened
On December 23, 2002, a Robin DR 400-120, registration F-BVMF, was engaged in a navigation training flight. The pilot departed from Amboise airfield with the intention of either performing a circuit or landing at Châteauroux Villers. After approximately thirty minutes of flight, the pilot landed on unpaved runway 22 at Châteauroux Villers and taxied to the parking area.
During the subsequent departure from Châteauroux Villers, the pilot utilized the unpaved runway to align with the threshold of runway 22. The pilot noted that the takeoff roll distance felt significantly longer than usual, which was attributed to the muddy condition of the surface. As the aircraft reached rotation speed, the main landing gear wheels were abruptly braked by a waterlogged section of the runway. This caused the nose wheel to make firm contact with the ground. Surprised by the sudden deceleration, the pilot hesitated before applying the brakes. The aircraft subsequently slid along the muddy surface and exited the runway, coming to a stop approximately ten meters beyond the runway end. The aircraft sustained slight damage.
The investigation
Investigators examined the aircraft and the runway conditions following the excursion. During the recovery of the aircraft several days later, technicians removed the wheel fairings to clear accumulated mud. Upon inspection, it was discovered that the tire pressures were significantly lower than the manufacturer's recommendations. The pressures were measured at 0.5 bar for the nose tire and 0.8 bar for the main tire, whereas the manufacturer specifies 1.6 bar and 1.8 bar, respectively.
Findings
- The primary cause of the runway excursion was the delayed decision to abort the takeoff following the sudden loss of momentum.
- The muddy and waterlogged state of the unpaved runway contributed to an increased takeoff roll and unexpected braking of the main gear.
- Underinflated tires, which were significantly below the manufacturer's recommended pressures, likely contributed to the aircraft's handling and performance during the takeoff roll.