What happened
On 28 May 2002, a Sukhoi SU-26M2, registration RA44531, was conducting a private aerobatic practice flight over Knatts Valley, Kemsing, Kent. The weather conditions were favorable, with good visibility and light westerly winds. While cruising at 2,400 feet, the pilot transitioned from the main fuel tank to the M2 tank. Shortly after this selection, the engine experienced a significant loss of power following a drop in fuel pressure.
In an attempt to maintain engine power, the pilot used the fuel primer, but the power loss necessitated an immediate forced landing. The pilot identified a suitable field and performed a landing into the wind. While the approach was successful, the aircraft's wheels struck ruts in the field left by an agricultural vehicle. This impact caused the landing gear to collapse, resulting in damage to the propeller, oil cooler, and fuel tank. The pilot escaped the aircraft without injury.
The investigation
Investigators examined the aircraft and the fuel system to determine why the engine lost power following the tank change. During the inspection of the ruptured M2 tank, a 1.5-inch diameter rubber disc was discovered inside the tank. This piece of rubber appeared to be the center portion of a homemade gasket that had been cut out to create an aperture. It is believed that this debris fell into the tank and subsequently blocked the fuel tank outlet, preventing the necessary flow of fuel to the engine.
Findings
- The engine power loss was caused by the interruption of fuel flow following the switch to the M2 tank.
- A piece of rubber debris, likely from a poorly installed homemade gasket, obstructed the outlet of the M2 tank.
- The collapse of the landing gear was caused by the aircraft encountering deep ruts in the landing field.
- The pilot remained uninjured due to the structural integrity of the airframe and the effective use of the aerobatic harness.