Incident Overview
On June 18, 2008, at 20:45 local time, a Cessna P210N, registration EC-KNF, was landing at Casarrubios del Monte aerodrome in Toledo, Spain. The aircraft, operated privately, was on a business flight from Sabadell Airport. The pilot, a 27-year-old commercial pilot with 900 total flight hours and 3 hours on type, was accompanied by one passenger. Both occupants were uninjured, and the aircraft sustained minor damage.
Pilot Actions
After entering the aerodrome traffic pattern, the pilot selected the landing gear lever down. He heard the electric motor operate and then stop, but the green down-and-locked indicator did not illuminate. Visual inspection confirmed the main gear legs were extended, but the nose gear was not visible. The pilot cycled the gear up and down again, still without a down-lock indication. He then attempted emergency extension, also unsuccessful, and replaced the indicator bulb to rule out bulb failure. After a low pass over the runway, ground personnel confirmed the nose gear appeared down. The pilot proceeded to land on runway 26, holding the nose wheel off as long as possible. After touchdown, when the pilot applied brakes, the nose gear collapsed, causing the nose to contact the runway. The aircraft slid to a stop on the main gear and nose, and the pilot and passenger exited safely.
Inspection Findings
Post-accident examination of the landing gear system revealed that the two downlock bolts on the nose gear actuator were broken at their circumferential grooves. The broken bolts had shifted, interfering with the actuator's extension rod and preventing the actuator from reaching its full travel. This interference physically blocked the downlock hooks from engaging the bolts, leaving the nose gear unlocked. Disassembly of the actuator confirmed the bolts had failed.
Maintenance History
In December 1995, the aircraft manufacturer issued Service Bulletin SEB95-20, addressing failures of the original downlock bolts. The bulletin recommended inspection and, if found satisfactory, repetitive inspections every 200 flight hours, or replacement with redesigned bolts that eliminated the inspection requirement. The maintenance records for EC-KNF did not contain evidence that this service bulletin had been implemented.
Analysis
The nose gear collapse occurred because the two downlock bolts failed. This failure allowed the bolts to move out of position and contact the actuator rod, preventing the actuator from fully retracting and the nose gear from locking. A similar issue had occurred a few days earlier during a landing at Córdoba Airport, where the nose gear locked only when the wheel touched the ground, likely due to the same bolt problem. At that time, the landing gear was inspected but no anomaly was found, indicating the bolt failure may have already been present.