Event Description
On 7 June 2007 at 16:27 local time, a Mudry CAP 10B aircraft, registration I-IZAJ, experienced a nose-down pitch event during taxi at Viterbo Airport (LIRV). The aircraft had landed on runway 22R and was decelerating. As the crew prepared to reverse direction, the nose dropped until the propeller spinner and the lower fuselage contacted the runway surface. The aircraft came to rest in that nose-down attitude, with damage to the propeller tips, spinner, and wheel fairings. Both occupants, an instructor and a student pilot, were uninjured.
Aircraft Information
The Mudry CAP 10B is a two-seat, single-engine, low-wing monoplane with a wooden structure, designed for initial aerobatic training. It has a fixed tailwheel landing gear. The aircraft (serial number 251, built 1990) was equipped with an Avro Lycoming AEIO-360-B2F engine (134 kW) and a fixed-pitch two-blade propeller. Its maximum takeoff mass is 830 kg (780 kg in aerobatic category).
Personnel Information
The instructor, a 39-year-old male, held a valid CPL(A) with ratings for single-engine and multi-engine piston land aircraft, instrument, flight instructor, instrument instructor, aerobatic flight, and aerobatic flight instructor. He had approximately 2,900 total flight hours, including 500 hours on type. The student pilot, a 29-year-old female, held a CPL(A) obtained in November 2002, with single-engine and multi-engine piston land and instrument ratings. She had about 1,114 total flight hours, with 2 hours on type.
Meteorological and Aerodrome Information
At the time of the event, visibility was greater than 10 km, wind from 240° at 12 knots. Viterbo Airport (elevation 302 m) is a military airfield open to the local Aero Club. The runway in use, 04L/22R, is asphalt, 1,005 m long and 25 m wide, and was dry.
Analysis
The aircraft had departed at 16:07 local time for a VFR training flight aimed at obtaining an instructor rating. After the training area activity, the crew returned to Viterbo. The student pilot was at the controls. The approach, touchdown, and deceleration roll were normal. Near the end of the roll, the crew requested and received permission to reverse direction and back-taxi. Shortly after beginning the maneuver, the instructor told the student to stop. Perceiving a delay in execution, the instructor applied the brakes at the same moment the student also began braking. This simultaneous action resulted in abrupt brake application, causing the tail to lift and the propeller to strike the runway. The low speed prevented a full nose-over, and the aircraft stopped in a nose-down attitude, supported by the spinner and lower nose.
The CAP 10B's tailwheel configuration places the center of gravity behind the main wheels when on the ground. During braking, the resultant forces can cause a rotation about the main wheel axle, lifting the tail. Both pilots were aware of this characteristic. The event underscores the importance of clear communication in the cockpit, especially during low-workload phases like taxi. Any change of control should be preceded by a standardized verbal exchange to avoid simultaneous inputs.