Landing gear retracted during landing rollout. Landing gear switch was reported as up by pilot.

Attributes
ACN	1320161
Time
Date	201512
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Small Aircraft Low Wing 2 Eng Retractable Gear
Operating Under FAR Part	Part 91
Flight Phase	Landing
Route In Use	Visual Approach
Flight Plan	None
Component
Aircraft Component	Landing Gear
Person 1
Function	Pilot Flying Single Pilot
Qualification	Flight Crew Multiengine Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument
Experience	Flight Crew Last 90 Days 17 Flight Crew Total 7397 Flight Crew Type 3123
Events
Anomaly	Ground Event / Encounter Ground Strike - Aircraft

Narrative:

Flight was under VFR conditions in accordance with far part 91. There was one passenger on the plane who was also a pilot.we landed with gear extended and three green lights. The passenger/pilot can attest to this. So can the tower operator who said during my report that 'we saw you lower the landing gear on down wind'. The approach; landing; and touchdown were uneventful. As we were rolling down the runway the nose dropped and shortly thereafter the main landing gear collapsed. Somehow; the landing gear switch ended up in the retract position.we were clearly rolling down the runway with weight on all three gears. The squat switch should have prevented retraction. There are two squat switches either one of which should have prevented retraction. But the shop manual only calls for the adjustment of one. If that switch failed; the other may not have been adjusted and would do no good.

Original NASA ASRS Text

Title: Landing gear retracted during landing rollout. Landing gear switch was reported as up by pilot.

Narrative: Flight was under VFR conditions in accordance with FAR Part 91. There was one passenger on the Plane who was also a Pilot.We landed with gear extended and three green lights. The Passenger/Pilot can attest to this. So can the Tower operator who said during my report that 'we saw you lower the landing Gear on Down Wind'. The Approach; Landing; and Touchdown were uneventful. As we were rolling down the runway the nose dropped and shortly thereafter the main landing gear collapsed. Somehow; the Landing Gear Switch ended up in the Retract Position.We were clearly rolling down the runway with weight on all three gears. The Squat switch should have prevented retraction. There are two squat switches either one of which should have prevented retraction. But the Shop Manual only calls for the adjustment of one. If that switch failed; the other may not have been adjusted and would do no good.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.