Jabiru UL veers off runway during practice takeoff at Kingsmuir Airfield

Casualties unknown • Kingsmuir Airfield, Fife, GB

A Jabiru UL aircraft veered off the grass runway and struck an earth bank during an intended accelerate-stop maneuver, resulting in significant structural damage but no injuries.

What happened

On 23 July 2010, a Jabiru UL, registration G-OMHP, was involved in an accident at Kingsmuir Airfield in Fife during a private flight. The pilot had prepared the aircraft for a scheduled inspection by a Light Aircraft Association (LAA) inspector. Following the rigging of the aircraft and a routine engine power check, the pilot intended to perform a practice takeoff, specifically an accelerate-stop maneuver, with a passenger on board.

During the ground roll on the grass runway, the aircraft reached a speed of approximately 50 kt when it began to drift toward the right. In an attempt to correct the deviation, the pilot reduced engine power and applied the brakes. This action caused the aircraft to run onto rough ground on the right side of the runway. The aircraft subsequently spun, causing the left wing to strike an earth bank and a fence. During the excursion, the nose landing gear collapsed, leading to the propeller contacting the ground and causing damage to the fuselage, left wing, nose leg, and propeller.

The investigation

Investigators examined the aircraft and the circumstances surrounding the flight. The aircraft had been stored in a trailer since late May 2010. An examination of the nose landing gear leg and the steering rod revealed that failures in the components were consistent with being subjected to overload during the accident, rather than being the cause of the initial excursion.

Additionally, the investigation noted that the right-hand flap was found in a fully deployed position. A safety pin, which normally secures the flap to its operating linkage, was missing. While it could not be definitively proven that the absence of this pin caused the directional instability, the investigation noted that the pilot had selected zero flap, and the loss of the pin could have allowed the flap to stream in the airflow.

Findings

  • The aircraft veered right at approximately 50 kt during a power application and subsequent braking maneuver.
  • The application of brakes during the deviation exacerbated the loss of control.
  • The nose landing gear collapsed due to overload forces during the excursion.
  • There was no evidence of mechanical issues with the braking system, such as disc roughness or dragging.
  • A safety pin intended to secure the right-hand flap was absent, though it was not determined if this was a primary factor in the loss of directional control.

Probable cause

The aircraft veered off the runway during an intended accelerate-stop maneuver, an event exacerbated by the pilot's application of brakes after the aircraft had already begun to drift, leading to a collision with an earth bank and subsequent structural failure of the nose gear.

Frequently asked questions

What happened in the 2010-07-23 Jabiru UL accident near Kingsmuir Airfield, Fife, GB?

A Jabiru UL aircraft veered off the grass runway and struck an earth bank during an intended accelerate-stop maneuver, resulting in significant structural damage but no injuries.

What aircraft was involved and where did it happen?

The accident on 2010-07-23 involved a Jabiru UL, registration G-OMHP, at Kingsmuir Airfield, Fife, GB.

What was the probable cause of the accident?

The aircraft veered off the runway during an intended accelerate-stop maneuver, an event exacerbated by the pilot's application of brakes after the aircraft had already begun to drift, leading to a collision with an earth bank and subsequent structural failure of the nose gear.

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