Date: 201308
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: Duchess 76
Operator: FBO
Operating under: Part 91
Flight plan: VFR
Mission: Training
Flight phase: Landing
Airspace: Class D ZZZ
ATC / advisory: Tower ZZZ
Aircraft component: Gear Lever/Selector
Component problem: Design; Improperly Operated
Reporter organization: Personal
Reporter function: Instructor
Reporter qualification: Flight Crew Flight Instructor; Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Commercial
Human factors: Training / Qualification; Workload
Anomaly: Aircraft Equipment Problem Critical; Ground Event / Encounter Ground Strike - Aircraft
Detector: Person Flight Crew
When detected: Taxi
Result: Aircraft Aircraft Damaged; General Maintenance Action
Contributing factors: Aircraft; Human Factors
Primary problem: Aircraft

Narrative: My student and I were executing a full stop landing. Prior to landing; we completed the Descent and Approach Checklist which included confirming that the gear lever was in the down position. All three gear position lights were illuminated green and the in-transit light was also confirmed off. As we approached the threshold; the student started to correct for crosswind. We touched down smoothly on [runway] with the main gear touching down first. After touchdown; we initiated deceleration and all wheels were on the ground. As we were slowing down; the student made corrective action with the rudder pedals in order to maintain the runway centerline as we were heading to exit [the runway.] At approximately 40 KTS IAS; the student's knee touched the gear handle while he was operating the rudder pedals. The gear handle switched into the up position and then the nose gear retracted instantaneously; while the main gear remained in its extended position. The nose then touched the runway and both propellers struck the ground. The airplane came to a full stop approximately 6 FT from the runway centerline. While securing the airplane; we noticed that the gear handle was in the up position and would not lock in the safety detent position. The student and I then finished securing the airplane and disembarked safely without any injuries. The gear lever in the BE-76 is located on the pilot's side - right above where the pilot's right knee would be when the pilot is using the rudder pedals. If the pilot is tall enough; the right knee could easily touch the gear handle from below. There is a feature in the gear lever that when functioning properly prevents inadvertent retraction or extension; it requires that the pilot pulls the lever out of the safety detent position before the handle can be shifted up or down. The safety detent position assembly is designed to not allow retraction or extension of the gear unless the pilot first pulls the handle out towards him/her.The BE76 also has a 'safety retraction switch' built into the gear system; this component deactivates the gear pump below a speed of approximately 59 to 63 KTS IAS to prevent inadvertent retraction of the gear on the ground. It is suspected that the gear lever safety detent was worn out and the safety retraction switch was defective; causing a failure in the safety feature of the gear lever; which made it possible for the student to accidentally deflect the lever in the up position with his knee. To prevent a recurrence of this incident in the future; the safety detent feature of the gear lever and the safety retraction switch should be stress tested regularly.




Synopsis: After landing a BE76 student pilot's right knee apparently moved the gear handle up and because of a failed 59-63 knot gear safety interlock; the nose gear retracted with the handle movement damaging both propellers and nose.