AAIB investigation to Grob G109A, G-CINK
Aircraft tipped forward on landing, Deenethorpe Airfield, Northamptonshire, 19 October 2018.
Summary:
The Grob G109A is a tailwheel motor glider with dual-function airbrake levers which, when pulled, deploy the airbrakes and, when pulled further, apply the mainwheel brakes. The aircraft has a ‘car-type’ ratchet parking brake. After landing, pilots hold the control column fully back, to keep the tail from lifting, and pull the airbrake lever firmly aft to actuate the wheelbrakes. On this occasion the student pilot did not deflect the airbrake lever sufficiently to generate effective wheel-braking. The instructor called “more brake” three times to prompt him to apply greater force to the lever. The student mis-interpreted these calls and applied the parking brake instead, which resulted in “hard, uncontrolled braking”. Despite rapid intervention by the instructor, the aircraft tipped forward damaging the nose cowling and propeller.
The instructor had considered taking control of the braking sooner but had not wanted to dent the student’s confidence after a good landing. He never envisaged that the student would apply the parking brake. The instructor reflected that, in future, he would be more explicit in his use of terminology. Later models of the G109 have been redesigned with toe-brakes instead of the G109A’s lever-controlled system.
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