What happened
On August 7, 2013, a Rotax 912 powered motor glider, registration VT-GJH, was conducting a test flight at the Deoghar uncontrolled airstrip. Shortly after departing from runway 09, the crew noticed a drop in engine RPM and power at approximately 25 feet of altitude. By the time the aircraft reached 50 feet, the propeller had ceased rotating entirely.
Following the engine failure, the instructor took control of the aircraft and attempted a 180-degree right turn to return to the airstrip. Due to the low altitude and lack of power, the glider lost altitude rapidly. During the maneuver, the right wing struck the airfield boundary wall, causing the aircraft to crash land short of the runway end. The impact caused the engine to dislodge from its mounts, rupturing fuel and oil lines and triggering a localized fire. While the pilot in command escaped without injury, the instructor sustained serious injuries.
The investigation
AAIB India examined the wreckage and the engine components, specifically focusing on the engine's cooling system. The investigation revealed that a punctured pipe in the coolant return line had caused the system to run dry. This led to severe overheating, which subsequently caused the piston rings in cylinders 2 and 4 to seize.
Investigators also scrutinized maintenance records and discovered significant irregularities. It was established that a required 25-hour/one-month maintenance inspection had not actually been performed, despite false entries being made in the airframe and engine logbooks. Furthermore, the investigation found that the instructor had recorded inaccurate flight details in the journey logbook regarding trips to Ranchi for maintenance.
Findings
- The engine failure was caused by piston seizure resulting from overheating due to a loss of coolant.
- The aircraft's right wing struck the boundary wall because the instructor attempted a 180-degree turn at a low altitude without sufficient power.
- Maintenance oversight was a critical factor, as the maintenance agency performed perfunctory inspections and falsified logbook entries to indicate completed inspections.
- The engine's cooling system failed due to a leak in the suspension tank to radiator pipe.