Incident Sequence
On approach to land, the pilot moved the landing gear selector handle to the down position. The landing gear did not extend. The flight departed the airport traffic area while the pilot attempted to lower the gear using the emergency extension procedures, but was unable to do so.
The pilot then performed a low approach past the tower for confirmation of the gear position. Tower personnel advised that the gear appeared to be down. The flight returned for landing. After touchdown, the landing gear collapsed.
Post-Incident Examination
After the incident, while the aircraft was being raised from the runway, the pilot was asked to lower the gear via the emergency method. The pilot was unable to complete the extension because he released the clutch while cranking the gear down. The correct procedure required holding the clutch in during cranking.
An examination of the aircraft revealed a failure of the dynamic brake relay. The purpose of this relay was to prevent coasting of the gear motor and gears by momentarily reversing the motor when the up limit was reached. The failure prevented the relay from performing this function. The failed component was replaced, after which the landing gear operated normally.
Findings
The source did not provide an explicit probable cause statement. The dynamic brake relay failure was identified and the component replaced, restoring normal gear operation.