What happened
On August 11, 2012, a Cessna 177RG, registration D-EEDM, performed an emergency landing at Almeria Airport, Spain. The aircraft, operated privately, was on a flight from Italy that included stops in Sardinia and Murcia.
Upon approaching runway 25 at Almeria, the pilot attempted to extend the landing gear but received no indication that the main gear had locked. After a low-speed fly-fly-by to allow tower personnel to visually inspect the gear, the tower confirmed the gear was down but could not verify it was locked. The pilot attempted the manufacturer's emergency manual extension procedure using a hand pump, but the cockpit indication remained unchanged.
To mitigate risk, the pilot decided to land at the lowest possible speed. During the landing roll, the main landing gear legs, which were not secured, collapsed under the aircraft's weight. The aircraft struck the runway with its lower aft fuselage and horizontal stabilizer, eventually veering off the runway onto the dirt and gravel strip. All four occupants (the pilot and three passengers) were uninjured.
The investigation
The investigation focused on why the landing gear failed to lock despite the use of emergency procedures. While the hydraulic system and pump were found to be functioning correctly, inspectors discovered that the actuator rod end was broken. This breakage interrupted the mechanical continuity required to transmit force from the hydraulic piston to the gear mechanism.
Metallurgical analysis of the broken rod end revealed that the component had undergone significant plastic deformation before complete failure. The analysis also identified corrosion products on the fracture surfaces. The investigation confirmed that the aircraft's maintenance records were in order and that the flight was within all weight and balance limits.
Findings
- The primary cause of the incident was the instantaneous fracture of the main gear actuator rod end in flight, which rendered the extension and locking mechanism inoperative.
- A contributing factor was that the installed rod end was of the original design, which featured a greasing hole and an internal brass bearing. This specific design had been identified by the manufacturer, Cessna, in Service Information Letter SE71-37 as prone to failure.
- The manufacturer had recommended replacing this part with a stronger version without a greasing hole, but the replacement was not mandatory and had not been performed on this aircraft.
Safety action
- It is recommended that the FAA require the replacement of the original design rod end with the stronger version recommended in Cessna Service Information Letter SE79-37.