What happened
On 25 June 2006, a Reims Cessna FR172K, registration G-PJTM, was performing a private flight from Haverfordwest to Filton. While on final approach to Runway 09, approximately 3.8 nm from the threshold and at an altitude of 1,300 ft, the pilot experienced a very loud and forceful thud at the front of the aircraft. Although the engine continued to operate normally, the pilot, concerned about potential damage to the nosewheel, declared a PAN and shut down the engine prior to touchdown. The landing was completed without further incident, and the aircraft was attended by airfield operations staff.
The investigation
Investigators examined the aircraft and found damage to the propeller and engine cowling. Specifically, both propeller blades had sustained heavy impacts on their rear faces, with one blade exhibiting a bulge and another showing material loss on the leading edge. The engine cowling also showed signs of impact where the paint had flaked off. Additionally, mechanical damage was noted on the cooling fins of the two front right cylinders.
While there was no direct evidence of an airborne object strike, a witness noted a mark on a propeller blade that resembled a tool. The investigation also noted that the aircraft had undergone a 50-hour maintenance check only four hours before the flight.
Findings
- The damage to the propeller blades appeared to be the result of a direct impact from behind rather than a glancing blow.
- The investigation considered the possibility that a loose tool or article left in the engine compartment during recent maintenance migrated forward through the cooling air intake, ricocheting between the propeller and the engine/cowling before falling away.