What happened
On the night of August 25, 2016, a Cessna 340, registration N340LT, was conducting a night instrument flight from La Rochelle to Toussus-le-Noble. While intercepting the ILS approach for runway 25R at approximately 3,000 feet, the pilot attempted to extend the landing gear but found it remained retracted. After checking the landing gear motor circuit breaker and attempting to re-engage the command without success, the pilot transitioned to a holding pattern near Toussus-le-Noble to attempt the emergency manual extension procedure.
Despite several attempts using the manual hand crank, the pilot could not confirm the gear had deployed, as the gear position indicator failed to show movement. Following advice from approach control, the pilot diverted to Paris-Orly to utilize available emergency services. The aircraft subsequently landed on runway 20 with the landing gear retracted, resulting in heavy damage to the airframe.
The investigation
The investigation focused on the mechanical failure of the retractable tricycle landing gear system, which is operated by an electric motor via a clutch. Investigators examined the aircraft's configuration and found the gear selector was in the neutral position and the manual extension crank was deployed. The landing gear motor circuit breaker was found in the closed position.
Technical analysis of the landing gear mechanism revealed that while the electric motor was fully functional, the clutch was positioned in a way that prevented the gear mechanism from being driven by either the electric motor or the manual hand crank. Once the clutch was returned to its nominal position, subsequent tests confirmed that both the electric and manual extension systems were functional.