Summary
On April 25, 2018, a Piper PA-28R-201T, registration LV-MDO, operated by a private owner, departed from Aeródromo Matanza (La Matanza, Buenos Aires) at 18:17 UTC for a navigation flight to La Plata and then Lobos. During the approach to La Plata, approximately 23 minutes into the flight, the pilot extended the landing gear but the nose landing gear did not lock in the down position (green light off). The pilot decided to return to the departure aerodrome.
Sequence of Events
During the return flight, the pilot performed the emergency procedures from the aircraft manual without success. After arriving in the vicinity of Aeródromo Matanza, the pilot manually extended the landing gear and conducted a low pass over the runway so that ground personnel could visually inspect the nose gear position. The nose gear appeared to be down, but it could not be confirmed whether it was locked. The pilot then planned and executed an emergency landing on runway 17.
The aircraft touched down normally. However, when the nose gear contacted the runway, it retracted. The aircraft continued its landing roll with the nose gear retracted, causing the propeller and forward section to strike the ground. The aircraft came to a stop approximately 300 meters from the runway 17 threshold, to the left of the runway centerline, after traveling about 230 meters from the touchdown point.
Investigation
Investigators interviewed the pilot, who reported that when extending the landing gear, both main gears indicated down and locked, while the nose gear indicator showed unlocked. The hydraulic pump operated continuously throughout. The pilot attempted two gear cycles with no change in indication, then manually extended the gear using the manual extension procedure.
At the accident site, investigators lifted the aircraft's nose and attempted to extend the nose gear. They found that the nose gear was obstructed by a duct connecting the lower cowl air intake to the exhaust collector, which provides cabin heat. The duct was contacting the right steering roller, preventing full extension. The engine cowling had to be removed to free the duct and extend the gear.
The aircraft was moved to a hangar for further testing. During retraction and extension tests, it was observed that the hook that secures the nose gear in the down position did not complete its travel because the retraction arm was deformed, moving the hook away from the lock roller. The assembly was disassembled to check the condition of bushings and holes; the actuating arm moved freely. No other malfunctions related to the event were found in the landing gear system.
Examination revealed that the position of the duct connecting the air intake to the exhaust collector obstructed the extension and retraction of the nose landing gear. The duct showed wear from rubbing against the right steering roller.