History of the Flight
On 15 July 2001 at 13:10 hours, a Jodel D 140E, registration F-PLJP, departed from Itxassou Airfield in the French Basque Country. After entering Spanish airspace, the aircraft overflew San Sebastián. The pilot noticed the engine was not operating properly and reported the issue to the control tower of the Airport of San Sebastián, indicating his intention to continue to Bilbao Airport. Near Deba, the propeller became dislodged, forcing the pilot to make an emergency landing. The aircraft landed on a slightly uphill grass-covered field. No injuries were sustained by the pilot and two passengers. The aircraft suffered no damage except for the loss of the propeller. The pilot contacted San Sebastián Airport control personnel via mobile phone, and Regional Police located the occupants about 20 minutes later.
Aircraft and Propeller Information
The aircraft was a Jodel D 140E, serial number 452, registered as an amateur-built aircraft on 21 December 2000, with an airworthiness certificate valid until 6 December 2003. It was powered by a Textron Lycoming O-360-A3A engine producing 134 kW (179 HP). The propeller was an EVRA model 94 79 26 C, serial number 42 ST, made of wood with plastic skin. It was assembled on 15 November 2000 and had accumulated 56:48 hours since new. The last inspection was performed on 14 May 2001, 19:55 flight hours before the incident.
Maintenance and Inspection
The propeller assembly and maintenance manual specifies tightening torque depending on screw type, with torque checks after the first hour of flight and mandatory checks between the 10th and 30th hours, then at least every 50 hours or 6 months. Lockwire of stainless steel is specified. The pilot, who held a private pilot license, performed the last propeller inspection himself. According to information from the airfield where the aircraft was based, the maintenance center that conducted the previous inspection advised the pilot to check the torque after 25 flight hours, but did not inspect the aircraft again.
After the incident, the propeller and two fastening screws were found near the landing site, along with the disk that fastens the assembly system to the rotating axis. The other four screws were not located. Visual inspection of the six holes on the propeller showed uniform wear, more marked on two holes. A full inspection of the aircraft systems revealed no other malfunctions.
Probable Cause
The investigation concluded that the probable cause of the in-flight propeller detachment was the incorrect fitting and locking of the propeller fastening screws, which was not detected during the maintenance tasks performed after the last recorded inspection.