What happened
On 17 October 2020, a DHC-1 Chipmunk 22, registration G-BCKN, was performing circuit training at Blackpool Airport. After an initial departure from Runway 28, air traffic control directed the pilot to use Runway 10 due to light and variable wind conditions.
The pilot performed a straight three-point touchdown at 50 kt. However, immediately following the touchdown, the aircraft unexpectedly swung to the left. Despite the pilot applying full right rudder, the aircraft departed the paved surface and moved onto the grass. During this excursion, the aircraft struck a Precision Approach Path Indicator (PAPI) light. The incident resulted in no injuries to the pilot or the passenger, though the aircraft sustained minor damage to the right wing surface and flap.
The investigation
The investigation examined the aircraft' and the pilot's actions during the landing roll. The pilot noted that he had opted not to use differential braking during the landing because he believed the wind conditions were calm or very light. He also stated that he had considered performing a go-around but decided to continue the landing roll to prevent a propeller strike on the soft ground.
An engineering inspection of G-BCKN found the tail wheel and the main wheel braking system to be in good working order, with all perishable components in good condition. The investigation also reviewed the mechanics of the Chipmunk's unique hand-operated wheel brake system, which allows for differential braking through a combination of a cockpit lever and rudder pedal input.
Findings
- The aircraft veered left during the landing roll despite full right rudder application.
- The pilot did not utilize differential braking to assist with directional control, as the wind was perceived to be minimal.
- The pilot could not account for the sudden loss of directional control during the touchdown phase.