History of Flight
On 30 August 2000, a Jabiru UL aircraft, registration G-MGCA, was on a private flight. After an uneventful flight, the pilot made an approach to runway 08L at Redhill Aerodrome, Surrey. Realizing he would land too far along the runway, the pilot initiated a go-around by applying full power. After a few seconds, a sudden severe vibration and loss of thrust occurred. The pilot made a MAYDAY call and carried out a forced landing in an unprepared area of long grass beyond the runway but within the airfield boundary. The pilot was uninjured, and damage was limited to the propeller blades. The pilot and the chief flying instructor stated that the aircraft had not touched down during its approach and go-around. Air traffic control observed the go-around near the runway 26R identifying numbers, and debris was seen falling from the aircraft.
Propeller Examination
The two-bladed wooden propeller, sheathed in glassfibre and with polyurethane leading-edge inserts, was examined. Debris found adjacent to the runway consisted of the top skin from one blade (Blade 1); the bottom skin from this blade was missing. Blade 2 had lost top skin, wood core, and polyurethane insert to a distance of 11 cm from the tip. The detached piece showed no indication of ground impact while rotating; its leading edge was crushed with impacted vegetation, consistent with ground impact during the forced landing. Blade 1 had lost more tip material with jagged fractures along the grain and embedded vegetation, suggesting a lower fracture rate during the forced landing when the propeller had low rotational speed.
Further examination of wood and fibreglass surfaces on Blade 2 assessed the failure sequence. The lost lower skin was likely the first to fail. Good bonding (overload failure of resin) was observed near the root and leading edge. Towards the tip and trailing edge, the resin surface was featureless, making it impossible to determine if this resulted from poor bonding or fretting after bond separation. The detached top skin showed good bonding inboard but fretting near the tip, indicating some operation following disbonding. The tip also had abrasion damage on its outer surface, indicative of running damage. The anti-erosion strip was torn spanwise along the leading edge; near the tip, two small areas of dark brown material (likely insect debris) were embedded, but these were not involved in the initiation of skin delamination.
Conclusion
The investigation concluded that the material involved in the initiation of the propeller failure was not recovered. Although bonding quality could not be assessed in some areas, the evidence indicated that separation of both fibreglass skins on one blade started from the tip, where pre-existing running damage was present. The cause of that running damage could not be identified.