Incident Overview
On 20 October 2013, at 11:42 UTC, a Diamond DA-40 aircraft (registration TF-KFD) experienced a loss of engine power while cruising at 3,000 to 3,500 feet above mean sea level near Gullfoss and Geysir in southern Iceland. The pilot, accompanied by one passenger, had departed from Keflavik Airport (BIKF) at 10:36 UTC on a private cross-country flight intended to build flight hours toward a commercial pilot license. The aircraft was powered by a single TAE 125-02-99 diesel engine.
The pilot reported that the engine began running roughly for approximately five seconds. During this time, an oil pressure warning light and audio warning activated. The engine instrument display indicated a drop in oil pressure and a rapid decrease in engine load from 70% to 0%, accompanied by a red X over the engine load and RPM indications, confirming a complete loss of engine power.
Emergency Landing
The pilot attempted corrective actions, including moving the throttle to idle and back to full power and switching the Engine Control Unit (ECU) between channels A and B, but observed no change. The emergency checklist for low oil pressure was consulted and completed. The pilot configured the aircraft for best glide speed (68 knots) and began searching for a suitable landing site.
At the time of the power loss, the aircraft was flying southwest along Road 35, which connects Gullfoss and Geysir. The pilot decided to execute a 180-degree turn and land on the road toward the northeast. Factors influencing this decision included the absence of traffic, the road's upward slope to the northeast, a northeast wind, and the sun position. A nearby grass field was considered but deemed a secondary option due to uneven terrain.
During the descent, the pilot declared an emergency on frequency 121.5 MHz. Initial transmissions received no reply, but a subsequent call was answered by the crew of an international commercial flight, who relayed the emergency to Reykjavik Control.
Shortly before touchdown, the pilot fully extended the flaps, causing the airspeed to drop below 60 knots. The pilot pitched the nose down to regain speed, resulting in a loss of altitude greater than anticipated. The pilot pulled back on the elevator control just before landing, causing the aircraft to bounce once before making a firm landing on the road. Neither occupant was injured, and the aircraft sustained minor damage. After landing, the pilot and passenger moved the aircraft to clear one lane of the road. Engine oil was observed on the nose landing gear strut and the road surface.
Engine Examination
The Icelandic Transportation Safety Board (ITSB) was notified and dispatched an investigator. Removal of the engine cowlings revealed oil on the lower cowling and a V-ribbed belt drive out of position. The crankshaft pulley was found skewed. The engine and ECU were sent to Technify Motors in Germany for detailed analysis under ITSB and BFU supervision.
Disassembly of the engine, which had accumulated over 1,244 flight hours since installation, revealed extensive damage. A fastener (part number 05-7223-K000501) that attaches the crankshaft pulley to the crankshaft was missing and never found. The loss of this fastener allowed the pulley to shift, causing abnormal loading on the crankshaft. The pulley incorporates a torsional damper designed to dampen vibrations; without a secure connection, the damping effect was lost, leading to increased crankshaft bending and higher loads on the bearings.
This mechanical failure resulted in significant wear of the bearing halves, and debris blocked lubrication bores, causing overheating and oil starvation. The oil supply hole in the upper half of the crankshaft bearing closest to the pulley was completely closed by wear damage, preventing oil circulation from the oil pump to the crankshaft. The crankshaft subsequently fractured, with crack initiation at scratched areas, followed by fatigue growth and finally a forced fracture. Secondary damage included fractures of the engine bed plate, crankcase housing, and oil pump.
Investigation Findings
The ITSB investigated whether the missing fastener had been properly torqued during engine assembly. The manufacturer specified a torque of 200 Nm plus 90 degrees, with a final torque between 210 Nm and 395 Nm. Assembly task cards from the engine's manufacture indicated a correct torque procedure, with a recorded final torque of 350.10 Nm. No evidence of fastener failure, such as a broken head or damaged threads, was found; the fastener hole threads showed no indication of failure.