4th of March 2020, Blog #589
With a crew of two (Instructor and student) a Diamond DA 42 NG Twin Star was being operated as a training flight on this day in aviation history.
The aircraft shortly after coming to a stop (Source; AAIB © Unknown) After an uneventful take off from Stapleford Aerodrome, Essex (England) the aircraft entered the circuit of the aerodrome to perform circuit training, flying several touch-and-go approaches. As the aircraft was configured for the first touch-and-go on Runway 21L, the weather was calm with light East-South-Easterly winds. Runway 21L is a 1077-meter-long, 46-meter-wide Asphalt/Grass runway. The first 600 meters of the runway is asphalt, the remainder being grass. The declared Takeoff Run Available (TORA), Takeoff Distance Available (TODA) and Landing Distance Available (LDA) are 1,100 m, 1,150 m and 900 m respectively. The elevation is 115 ft at the Runway 21L threshold and 185 ft at the 03R threshold, giving a +1.98% upslope on Runway 21L.
Stapleford Aerodrome, Essex, England (Source; DuckDuckGo Annotation; V2Aviation.org)
As the aircraft touched down, with the student as pilot flying, for the first touch and go, the aircraft ballooned slightly. The instructor took control of the aircraft and decided to stabilise the aircraft on the runway before initiating a go-around. After stabilising the aircraft and having assessed whether the remaining runway length was sufficient, he applied full power and retracted the flaps. While initiating rotation the aircraft passed the point where the runway changed from asphalt to grass. This caused a deceleration of the aircraft preventing lift-off, after the initial deceleration the airspeed remained constant. The instructor kept the engines at full power to continue takeoff on the grass section of the runway as enough runway length still remained for a successful take-off. However, as the aircraft did not accelerate. he closed the throttles and applied light braking to stop the aircraft, As the aircraft decelerated the nosewheel sank into the soft grass surface, ripping it from the aircraft. The aircraft's nose settled in the grass and both propellors struck the ground, stopping the aircraft after a short distance, close to the end of the runway. The instructor and student pilot were not injured and evacuated the aircraft after completing the shutdown checks.
The aircraft in its final position, note the fractured nosewheel (Source; AAIB © Unknown) The Air Accidents Investigation Branch (AAIB) was alerted and an investigation was launched based on the accident report submitted by the pilot. In his report the pilot stated;
"Excessive rainfall throughout winter and particularly in the days immediately prior to the incident had led to soft ground conditions. Additionally, the absence of a headwind component and the high aircraft weight due to it being fully fuelled, both served to increase the required landing distance and takeoff run."
Furthermore, he stated that the student's most recent experience had been on tailwheel aerobatic aircraft. The instructor considered that during the flare and hold-off, the student had reverted to a technique more appropriate to the type they had most recently flown. This caused the aircraft to balloon on landing and as a result, increased the takeoff run required for the touch-and-go. The AAIB investigation into the accident concluded that;
"While performing a touch-and-go the aircraft ballooned on landing, increasing the landing distance required and causing the instructor to take control. During the ensuing takeoff roll, the aircraft travelled past the point where the runway surface changed from asphalt to grass. The soft ground conditions on the grass surface prevented the aircraft from accelerating sufficiently to achieve takeoff speed. As the aircraft was being brought to a stop the nosewheel detached."
The AAIB report on the accident (the source for this blog) can be accessed by clicking on the .pdf file below: